diff --git a/app/android.go b/app/android.go
index 76a69c1..9e18c1a 100644
--- a/app/android.go
+++ b/app/android.go
@@ -268,6 +268,10 @@ func main(f func(App)) {
 var mainUserFn func(App)
 
 func mainUI(vm, jniEnv, ctx uintptr) error {
+	var worker gl.Worker
+	glctx, worker = gl.NewContext()
+	workAvailable := worker.WorkAvailable()
+
 	donec := make(chan struct{})
 	go func() {
 		mainUserFn(theApp)
@@ -326,8 +330,8 @@ func mainUI(vm, jniEnv, ctx uintptr) error {
 			}
 			C.surface = nil
 			theApp.sendLifecycle(lifecycle.StageAlive)
-		case <-gl.WorkAvailable:
-			gl.DoWork()
+		case <-workAvailable:
+			worker.DoWork()
 		case <-theApp.publish:
 			// TODO: compare a generation number to redrawGen for stale paints?
 			if C.surface != nil {
diff --git a/app/app.go b/app/app.go
index 38c6d99..44cca84 100644
--- a/app/app.go
+++ b/app/app.go
@@ -67,6 +67,8 @@ var theApp = &app{
 	publishResult:  make(chan PublishResult),
 }
 
+var glctx gl.Context // TODO: move into theApp
+
 func init() {
 	theApp.eventsIn = pump(theApp.eventsOut)
 }
@@ -76,8 +78,9 @@ func (a *app) sendLifecycle(to lifecycle.Stage) {
 		return
 	}
 	a.eventsIn <- lifecycle.Event{
-		From: a.lifecycleStage,
-		To:   to,
+		From:        a.lifecycleStage,
+		To:          to,
+		DrawContext: glctx,
 	}
 	a.lifecycleStage = to
 }
@@ -108,7 +111,7 @@ func (a *app) Publish() PublishResult {
 	//
 	// This enforces that the final receive (for this paint cycle) on
 	// gl.WorkAvailable happens before the send on endPaint.
-	gl.Flush()
+	glctx.Flush()
 	a.publish <- struct{}{}
 	return <-a.publishResult
 }
@@ -196,7 +199,7 @@ func pump(dst chan interface{}) (src chan interface{}) {
 func (a *app) registerGLViewportFilter() {
 	a.RegisterFilter(func(e interface{}) interface{} {
 		if e, ok := e.(size.Event); ok {
-			gl.Viewport(0, 0, e.WidthPx, e.HeightPx)
+			glctx.Viewport(0, 0, e.WidthPx, e.HeightPx)
 		}
 		return e
 	})
diff --git a/app/darwin_amd64.go b/app/darwin_amd64.go
index 77a3527..9351c82 100644
--- a/app/darwin_amd64.go
+++ b/app/darwin_amd64.go
@@ -78,17 +78,20 @@ func main(f func(App)) {
 func loop(ctx C.GLintptr) {
 	runtime.LockOSThread()
 	C.makeCurrentContext(ctx)
+	var worker gl.Worker
+	glctx, worker = gl.NewContext()
 
+	workAvailable := worker.WorkAvailable()
 	for {
 		select {
-		case <-gl.WorkAvailable:
-			gl.DoWork()
+		case <-workAvailable:
+			worker.DoWork()
 		case <-draw:
 		loop1:
 			for {
 				select {
-				case <-gl.WorkAvailable:
-					gl.DoWork()
+				case <-workAvailable:
+					worker.DoWork()
 				case <-theApp.publish:
 					C.CGLFlushDrawable(C.CGLGetCurrentContext())
 					theApp.publishResult <- PublishResult{}
diff --git a/app/darwin_armx.go b/app/darwin_armx.go
index 2d34771..01f43ee 100644
--- a/app/darwin_armx.go
+++ b/app/darwin_armx.go
@@ -119,8 +119,6 @@ func updateConfig(width, height, orientation int32) {
 	}
 }
 
-var startedgl = false
-
 // touchIDs is the current active touches. The position in the array
 // is the ID, the value is the UITouch* pointer value.
 //
@@ -168,11 +166,19 @@ func sendTouch(cTouch, cTouchType uintptr, x, y float32) {
 	}
 }
 
+var (
+	worker        gl.Worker
+	workAvailable <-chan struct{}
+)
+
 //export drawgl
 func drawgl(ctx uintptr) {
-	if !startedgl {
-		startedgl = true
+	if glctx == nil {
 		C.setContext(unsafe.Pointer(ctx))
+
+		glctx, worker = gl.NewContext()
+		workAvailable = worker.WorkAvailable()
+
 		// TODO(crawshaw): not just on process start.
 		theApp.sendLifecycle(lifecycle.StageFocused)
 	}
@@ -183,8 +189,8 @@ func drawgl(ctx uintptr) {
 
 	for {
 		select {
-		case <-gl.WorkAvailable:
-			gl.DoWork()
+		case <-workAvailable:
+			worker.DoWork()
 		case <-theApp.publish:
 			theApp.publishResult <- PublishResult{}
 			return
diff --git a/app/x11.go b/app/x11.go
index e366c58..841c743 100644
--- a/app/x11.go
+++ b/app/x11.go
@@ -41,6 +41,11 @@ func init() {
 
 func main(f func(App)) {
 	runtime.LockOSThread()
+
+	var worker gl.Worker
+	glctx, worker = gl.NewContext()
+	workAvailable := worker.WorkAvailable()
+
 	C.createWindow()
 
 	// TODO: send lifecycle events when e.g. the X11 window is iconified or moved off-screen.
@@ -65,8 +70,8 @@ func main(f func(App)) {
 		select {
 		case <-donec:
 			return
-		case <-gl.WorkAvailable:
-			gl.DoWork()
+		case <-workAvailable:
+			worker.DoWork()
 		case <-theApp.publish:
 			C.swapBuffers()
 			tc = ticker.C
diff --git a/event/lifecycle/lifecycle.go b/event/lifecycle/lifecycle.go
index 9376fe5..b25ca68 100644
--- a/event/lifecycle/lifecycle.go
+++ b/event/lifecycle/lifecycle.go
@@ -45,6 +45,13 @@ const (
 // Event is a lifecycle change from an old stage to a new stage.
 type Event struct {
 	From, To Stage
+
+	// DrawContext is the state used for painting, if any is valid.
+	//
+	// For OpenGL apps, a non-nil DrawContext is a gl.Context.
+	//
+	// TODO: make this an App method if we move away from an event channel?
+	DrawContext interface{}
 }
 
 // Crosses returns whether the transition from From to To crosses the stage s:
diff --git a/example/audio/main.go b/example/audio/main.go
index ba75ff6..e632bcb 100644
--- a/example/audio/main.go
+++ b/example/audio/main.go
@@ -72,6 +72,7 @@ var (
 
 func main() {
 	app.Main(func(a app.App) {
+		var glctx gl.Context
 		visible := false
 		for e := range a.Events() {
 			switch e := a.Filter(e).(type) {
@@ -79,7 +80,8 @@ func main() {
 				switch e.Crosses(lifecycle.StageVisible) {
 				case lifecycle.CrossOn:
 					visible = true
-					onStart()
+					glctx, _ = e.DrawContext.(gl.Context)
+					onStart(glctx)
 				case lifecycle.CrossOff:
 					visible = false
 					onStop()
@@ -87,7 +89,7 @@ func main() {
 			case size.Event:
 				sz = e
 			case paint.Event:
-				onPaint()
+				onPaint(glctx)
 				a.Publish()
 				if visible {
 					// Keep animating.
@@ -98,8 +100,8 @@ func main() {
 	})
 }
 
-func onStart() {
-	images = glutil.NewImages()
+func onStart(glctx gl.Context) {
+	images = glutil.NewImages(glctx)
 	eng = glsprite.Engine(images)
 	loadScene()
 
@@ -119,9 +121,9 @@ func onStop() {
 	player.Close()
 }
 
-func onPaint() {
-	gl.ClearColor(1, 1, 1, 1)
-	gl.Clear(gl.COLOR_BUFFER_BIT)
+func onPaint(glctx gl.Context) {
+	glctx.ClearColor(1, 1, 1, 1)
+	glctx.Clear(gl.COLOR_BUFFER_BIT)
 	now := clock.Time(time.Since(startTime) * 60 / time.Second)
 	eng.Render(scene, now, sz)
 }
diff --git a/example/basic/main.go b/example/basic/main.go
index 9756b89..bcd90e1 100644
--- a/example/basic/main.go
+++ b/example/basic/main.go
@@ -59,6 +59,7 @@ var (
 
 func main() {
 	app.Main(func(a app.App) {
+		var glctx gl.Context
 		visible, sz := false, size.Event{}
 		for e := range a.Events() {
 			switch e := a.Filter(e).(type) {
@@ -66,17 +67,18 @@ func main() {
 				switch e.Crosses(lifecycle.StageVisible) {
 				case lifecycle.CrossOn:
 					visible = true
-					onStart()
+					glctx, _ = e.DrawContext.(gl.Context)
+					onStart(glctx)
 				case lifecycle.CrossOff:
 					visible = false
-					onStop()
+					onStart(glctx)
 				}
 			case size.Event:
 				sz = e
 				touchX = float32(sz.WidthPx / 2)
 				touchY = float32(sz.HeightPx / 2)
 			case paint.Event:
-				onPaint(sz)
+				onPaint(glctx, sz)
 				a.Publish()
 				if visible {
 					// Drive the animation by preparing to paint the next frame
@@ -95,52 +97,52 @@ func main() {
 	})
 }
 
-func onStart() {
+func onStart(glctx gl.Context) {
 	var err error
-	program, err = glutil.CreateProgram(vertexShader, fragmentShader)
+	program, err = glutil.CreateProgram(glctx, vertexShader, fragmentShader)
 	if err != nil {
 		log.Printf("error creating GL program: %v", err)
 		return
 	}
 
-	buf = gl.CreateBuffer()
-	gl.BindBuffer(gl.ARRAY_BUFFER, buf)
-	gl.BufferData(gl.ARRAY_BUFFER, triangleData, gl.STATIC_DRAW)
+	buf = glctx.CreateBuffer()
+	glctx.BindBuffer(gl.ARRAY_BUFFER, buf)
+	glctx.BufferData(gl.ARRAY_BUFFER, triangleData, gl.STATIC_DRAW)
 
-	position = gl.GetAttribLocation(program, "position")
-	color = gl.GetUniformLocation(program, "color")
-	offset = gl.GetUniformLocation(program, "offset")
+	position = glctx.GetAttribLocation(program, "position")
+	color = glctx.GetUniformLocation(program, "color")
+	offset = glctx.GetUniformLocation(program, "offset")
 
-	images = glutil.NewImages()
+	images = glutil.NewImages(glctx)
 	fps = debug.NewFPS(images)
 }
 
-func onStop() {
-	gl.DeleteProgram(program)
-	gl.DeleteBuffer(buf)
+func onStop(glctx gl.Context) {
+	glctx.DeleteProgram(program)
+	glctx.DeleteBuffer(buf)
 	fps.Release()
 	images.Release()
 }
 
-func onPaint(sz size.Event) {
-	gl.ClearColor(1, 0, 0, 1)
-	gl.Clear(gl.COLOR_BUFFER_BIT)
+func onPaint(glctx gl.Context, sz size.Event) {
+	glctx.ClearColor(1, 0, 0, 1)
+	glctx.Clear(gl.COLOR_BUFFER_BIT)
 
-	gl.UseProgram(program)
+	glctx.UseProgram(program)
 
 	green += 0.01
 	if green > 1 {
 		green = 0
 	}
-	gl.Uniform4f(color, 0, green, 0, 1)
+	glctx.Uniform4f(color, 0, green, 0, 1)
 
-	gl.Uniform2f(offset, touchX/float32(sz.WidthPx), touchY/float32(sz.HeightPx))
+	glctx.Uniform2f(offset, touchX/float32(sz.WidthPx), touchY/float32(sz.HeightPx))
 
-	gl.BindBuffer(gl.ARRAY_BUFFER, buf)
-	gl.EnableVertexAttribArray(position)
-	gl.VertexAttribPointer(position, coordsPerVertex, gl.FLOAT, false, 0, 0)
-	gl.DrawArrays(gl.TRIANGLES, 0, vertexCount)
-	gl.DisableVertexAttribArray(position)
+	glctx.BindBuffer(gl.ARRAY_BUFFER, buf)
+	glctx.EnableVertexAttribArray(position)
+	glctx.VertexAttribPointer(position, coordsPerVertex, gl.FLOAT, false, 0, 0)
+	glctx.DrawArrays(gl.TRIANGLES, 0, vertexCount)
+	glctx.DisableVertexAttribArray(position)
 
 	fps.Draw(sz)
 }
diff --git a/example/network/main.go b/example/network/main.go
index aee316c..6e29a2d 100644
--- a/example/network/main.go
+++ b/example/network/main.go
@@ -43,9 +43,11 @@ import (
 	"net/http"
 
 	"golang.org/x/mobile/app"
+	"golang.org/x/mobile/event/lifecycle"
 	"golang.org/x/mobile/event/paint"
 	"golang.org/x/mobile/event/size"
 	"golang.org/x/mobile/exp/app/debug"
+	"golang.org/x/mobile/exp/gl/glutil"
 	"golang.org/x/mobile/gl"
 )
 
@@ -54,6 +56,7 @@ func main() {
 	go checkNetwork()
 
 	app.Main(func(a app.App) {
+		var glctx gl.Context
 		det, sz := determined, size.Event{}
 		for {
 			select {
@@ -63,10 +66,17 @@ func main() {
 
 			case e := <-a.Events():
 				switch e := a.Filter(e).(type) {
+				case lifecycle.Event:
+					glctx, _ = e.DrawContext.(gl.Context)
+					if glctx != nil {
+						glctx = e.DrawContext.(gl.Context)
+						images = glutil.NewImages(glctx)
+						fps = debug.NewFPS(images)
+					}
 				case size.Event:
 					sz = e
 				case paint.Event:
-					onDraw(sz)
+					onDraw(glctx, sz)
 					a.Publish()
 				}
 			}
@@ -75,6 +85,8 @@ func main() {
 }
 
 var (
+	images     *glutil.Images
+	fps        *debug.FPS
 	determined = make(chan struct{})
 	ok         = false
 )
@@ -89,18 +101,18 @@ func checkNetwork() {
 	ok = true
 }
 
-func onDraw(sz size.Event) {
+func onDraw(glctx gl.Context, sz size.Event) {
 	select {
 	case <-determined:
 		if ok {
-			gl.ClearColor(0, 1, 0, 1)
+			glctx.ClearColor(0, 1, 0, 1)
 		} else {
-			gl.ClearColor(1, 0, 0, 1)
+			glctx.ClearColor(1, 0, 0, 1)
 		}
 	default:
-		gl.ClearColor(0, 0, 0, 1)
+		glctx.ClearColor(0, 0, 0, 1)
 	}
-	gl.Clear(gl.COLOR_BUFFER_BIT)
+	glctx.Clear(gl.COLOR_BUFFER_BIT)
 
-	debug.DrawFPS(sz)
+	fps.Draw(sz)
 }
diff --git a/exp/gl/glutil/glimage.go b/exp/gl/glutil/glimage.go
index 0405adc..497fd89 100644
--- a/exp/gl/glutil/glimage.go
+++ b/exp/gl/glutil/glimage.go
@@ -20,6 +20,7 @@ import (
 
 // Images maintains the shared state used by a set of *Image objects.
 type Images struct {
+	glctx         gl.Context
 	quadXY        gl.Buffer
 	quadUV        gl.Buffer
 	program       gl.Program
@@ -29,35 +30,33 @@ type Images struct {
 	inUV          gl.Attrib
 	textureSample gl.Uniform
 
-	// TODO(crawshaw): store *gl.Context
-
 	mu           sync.Mutex
 	activeImages int
 }
 
 // NewImages creates an *Images.
-// TODO(crawshaw): take *gl.Context parameter
-func NewImages() *Images {
-	program, err := CreateProgram(vertexShader, fragmentShader)
+func NewImages(glctx gl.Context) *Images {
+	program, err := CreateProgram(glctx, vertexShader, fragmentShader)
 	if err != nil {
 		panic(err)
 	}
 
 	p := &Images{
-		quadXY:        gl.CreateBuffer(),
-		quadUV:        gl.CreateBuffer(),
+		glctx:         glctx,
+		quadXY:        glctx.CreateBuffer(),
+		quadUV:        glctx.CreateBuffer(),
 		program:       program,
-		pos:           gl.GetAttribLocation(program, "pos"),
-		mvp:           gl.GetUniformLocation(program, "mvp"),
-		uvp:           gl.GetUniformLocation(program, "uvp"),
-		inUV:          gl.GetAttribLocation(program, "inUV"),
-		textureSample: gl.GetUniformLocation(program, "textureSample"),
+		pos:           glctx.GetAttribLocation(program, "pos"),
+		mvp:           glctx.GetUniformLocation(program, "mvp"),
+		uvp:           glctx.GetUniformLocation(program, "uvp"),
+		inUV:          glctx.GetAttribLocation(program, "inUV"),
+		textureSample: glctx.GetUniformLocation(program, "textureSample"),
 	}
 
-	gl.BindBuffer(gl.ARRAY_BUFFER, p.quadXY)
-	gl.BufferData(gl.ARRAY_BUFFER, quadXYCoords, gl.STATIC_DRAW)
-	gl.BindBuffer(gl.ARRAY_BUFFER, p.quadUV)
-	gl.BufferData(gl.ARRAY_BUFFER, quadUVCoords, gl.STATIC_DRAW)
+	glctx.BindBuffer(gl.ARRAY_BUFFER, p.quadXY)
+	glctx.BufferData(gl.ARRAY_BUFFER, quadXYCoords, gl.STATIC_DRAW)
+	glctx.BindBuffer(gl.ARRAY_BUFFER, p.quadUV)
+	glctx.BufferData(gl.ARRAY_BUFFER, quadUVCoords, gl.STATIC_DRAW)
 
 	return p
 }
@@ -76,9 +75,9 @@ func (p *Images) Release() {
 		panic("glutil.Images.Release called, but active *Image objects remain")
 	}
 
-	gl.DeleteProgram(p.program)
-	gl.DeleteBuffer(p.quadXY)
-	gl.DeleteBuffer(p.quadUV)
+	p.glctx.DeleteProgram(p.program)
+	p.glctx.DeleteBuffer(p.quadXY)
+	p.glctx.DeleteBuffer(p.quadUV)
 
 	p.program = gl.Program{}
 }
@@ -122,14 +121,14 @@ func (p *Images) NewImage(w, h int) *Image {
 	p.activeImages++
 	p.mu.Unlock()
 
-	img.gltex = gl.CreateTexture()
+	img.gltex = p.glctx.CreateTexture()
 
-	gl.BindTexture(gl.TEXTURE_2D, img.gltex)
-	gl.TexImage2D(gl.TEXTURE_2D, 0, img.width, img.height, gl.RGBA, gl.UNSIGNED_BYTE, nil)
-	gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
-	gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR)
-	gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE)
-	gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE)
+	p.glctx.BindTexture(gl.TEXTURE_2D, img.gltex)
+	p.glctx.TexImage2D(gl.TEXTURE_2D, 0, img.width, img.height, gl.RGBA, gl.UNSIGNED_BYTE, nil)
+	p.glctx.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
+	p.glctx.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR)
+	p.glctx.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE)
+	p.glctx.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE)
 
 	runtime.SetFinalizer(img, (*Image).Release)
 	return img
@@ -145,8 +144,8 @@ func roundToPower2(x int) int {
 
 // Upload copies the host image data to the GL device.
 func (img *Image) Upload() {
-	gl.BindTexture(gl.TEXTURE_2D, img.gltex)
-	gl.TexSubImage2D(gl.TEXTURE_2D, 0, 0, 0, img.width, img.height, gl.RGBA, gl.UNSIGNED_BYTE, img.RGBA.Pix)
+	img.images.glctx.BindTexture(gl.TEXTURE_2D, img.gltex)
+	img.images.glctx.TexSubImage2D(gl.TEXTURE_2D, 0, 0, 0, img.width, img.height, gl.RGBA, gl.UNSIGNED_BYTE, img.RGBA.Pix)
 }
 
 // Release invalidates the Image and removes any underlying data structures.
@@ -156,7 +155,7 @@ func (img *Image) Release() {
 		return
 	}
 
-	gl.DeleteTexture(img.gltex)
+	img.images.glctx.DeleteTexture(img.gltex)
 	img.gltex = gl.Texture{}
 
 	img.images.mu.Lock()
@@ -168,9 +167,10 @@ func (img *Image) Release() {
 // three of its corners, in the current GL framebuffer.
 func (img *Image) Draw(sz size.Event, topLeft, topRight, bottomLeft geom.Point, srcBounds image.Rectangle) {
 	glimage := img.images
+	glctx := img.images.glctx
 
 	// TODO(crawshaw): Adjust viewport for the top bar on android?
-	gl.UseProgram(glimage.program)
+	glctx.UseProgram(glimage.program)
 	{
 		// We are drawing a parallelogram PQRS, defined by three of its
 		// corners, onto the entire GL framebuffer ABCD. The two quads may
@@ -226,7 +226,7 @@ func (img *Image) Draw(sz size.Event, topLeft, topRight, bottomLeft geom.Point,
 		// which gives:
 		//	a00 = (2*qx2 - 2*px2) / 2 = qx2 - px2
 		// and similarly for the other elements of a.
-		writeAffine(glimage.mvp, &f32.Affine{{
+		writeAffine(glctx, glimage.mvp, &f32.Affine{{
 			qx2 - px2,
 			px2 - sx2,
 			qx2 + sx2,
@@ -261,7 +261,7 @@ func (img *Image) Draw(sz size.Event, topLeft, topRight, bottomLeft geom.Point,
 		//	a10 +   0 + a12 = qy = py
 		//	  0 + a01 + a02 = sx = px
 		//	  0 + a11 + a12 = sy
-		writeAffine(glimage.uvp, &f32.Affine{{
+		writeAffine(glctx, glimage.uvp, &f32.Affine{{
 			qx - px,
 			0,
 			px,
@@ -272,22 +272,22 @@ func (img *Image) Draw(sz size.Event, topLeft, topRight, bottomLeft geom.Point,
 		}})
 	}
 
-	gl.ActiveTexture(gl.TEXTURE0)
-	gl.BindTexture(gl.TEXTURE_2D, img.gltex)
-	gl.Uniform1i(glimage.textureSample, 0)
+	glctx.ActiveTexture(gl.TEXTURE0)
+	glctx.BindTexture(gl.TEXTURE_2D, img.gltex)
+	glctx.Uniform1i(glimage.textureSample, 0)
 
-	gl.BindBuffer(gl.ARRAY_BUFFER, glimage.quadXY)
-	gl.EnableVertexAttribArray(glimage.pos)
-	gl.VertexAttribPointer(glimage.pos, 2, gl.FLOAT, false, 0, 0)
+	glctx.BindBuffer(gl.ARRAY_BUFFER, glimage.quadXY)
+	glctx.EnableVertexAttribArray(glimage.pos)
+	glctx.VertexAttribPointer(glimage.pos, 2, gl.FLOAT, false, 0, 0)
 
-	gl.BindBuffer(gl.ARRAY_BUFFER, glimage.quadUV)
-	gl.EnableVertexAttribArray(glimage.inUV)
-	gl.VertexAttribPointer(glimage.inUV, 2, gl.FLOAT, false, 0, 0)
+	glctx.BindBuffer(gl.ARRAY_BUFFER, glimage.quadUV)
+	glctx.EnableVertexAttribArray(glimage.inUV)
+	glctx.VertexAttribPointer(glimage.inUV, 2, gl.FLOAT, false, 0, 0)
 
-	gl.DrawArrays(gl.TRIANGLE_STRIP, 0, 4)
+	glctx.DrawArrays(gl.TRIANGLE_STRIP, 0, 4)
 
-	gl.DisableVertexAttribArray(glimage.pos)
-	gl.DisableVertexAttribArray(glimage.inUV)
+	glctx.DisableVertexAttribArray(glimage.pos)
+	glctx.DisableVertexAttribArray(glimage.inUV)
 }
 
 var quadXYCoords = f32.Bytes(binary.LittleEndian,
diff --git a/exp/gl/glutil/glutil.go b/exp/gl/glutil/glutil.go
index 2ac6c87..d742913 100644
--- a/exp/gl/glutil/glutil.go
+++ b/exp/gl/glutil/glutil.go
@@ -14,53 +14,53 @@ import (
 )
 
 // CreateProgram creates, compiles, and links a gl.Program.
-func CreateProgram(vertexSrc, fragmentSrc string) (gl.Program, error) {
-	program := gl.CreateProgram()
+func CreateProgram(glctx gl.Context, vertexSrc, fragmentSrc string) (gl.Program, error) {
+	program := glctx.CreateProgram()
 	if program.Value == 0 {
 		return gl.Program{}, fmt.Errorf("glutil: no programs available")
 	}
 
-	vertexShader, err := loadShader(gl.VERTEX_SHADER, vertexSrc)
+	vertexShader, err := loadShader(glctx, gl.VERTEX_SHADER, vertexSrc)
 	if err != nil {
 		return gl.Program{}, err
 	}
-	fragmentShader, err := loadShader(gl.FRAGMENT_SHADER, fragmentSrc)
+	fragmentShader, err := loadShader(glctx, gl.FRAGMENT_SHADER, fragmentSrc)
 	if err != nil {
-		gl.DeleteShader(vertexShader)
+		glctx.DeleteShader(vertexShader)
 		return gl.Program{}, err
 	}
 
-	gl.AttachShader(program, vertexShader)
-	gl.AttachShader(program, fragmentShader)
-	gl.LinkProgram(program)
+	glctx.AttachShader(program, vertexShader)
+	glctx.AttachShader(program, fragmentShader)
+	glctx.LinkProgram(program)
 
 	// Flag shaders for deletion when program is unlinked.
-	gl.DeleteShader(vertexShader)
-	gl.DeleteShader(fragmentShader)
+	glctx.DeleteShader(vertexShader)
+	glctx.DeleteShader(fragmentShader)
 
-	if gl.GetProgrami(program, gl.LINK_STATUS) == 0 {
-		defer gl.DeleteProgram(program)
-		return gl.Program{}, fmt.Errorf("glutil: %s", gl.GetProgramInfoLog(program))
+	if glctx.GetProgrami(program, gl.LINK_STATUS) == 0 {
+		defer glctx.DeleteProgram(program)
+		return gl.Program{}, fmt.Errorf("glutil: %s", glctx.GetProgramInfoLog(program))
 	}
 	return program, nil
 }
 
-func loadShader(shaderType gl.Enum, src string) (gl.Shader, error) {
-	shader := gl.CreateShader(shaderType)
+func loadShader(glctx gl.Context, shaderType gl.Enum, src string) (gl.Shader, error) {
+	shader := glctx.CreateShader(shaderType)
 	if shader.Value == 0 {
 		return gl.Shader{}, fmt.Errorf("glutil: could not create shader (type %v)", shaderType)
 	}
-	gl.ShaderSource(shader, src)
-	gl.CompileShader(shader)
-	if gl.GetShaderi(shader, gl.COMPILE_STATUS) == 0 {
-		defer gl.DeleteShader(shader)
-		return gl.Shader{}, fmt.Errorf("shader compile: %s", gl.GetShaderInfoLog(shader))
+	glctx.ShaderSource(shader, src)
+	glctx.CompileShader(shader)
+	if glctx.GetShaderi(shader, gl.COMPILE_STATUS) == 0 {
+		defer glctx.DeleteShader(shader)
+		return gl.Shader{}, fmt.Errorf("shader compile: %s", glctx.GetShaderInfoLog(shader))
 	}
 	return shader, nil
 }
 
 // writeAffine writes the contents of an Affine to a 3x3 matrix GL uniform.
-func writeAffine(u gl.Uniform, a *f32.Affine) {
+func writeAffine(glctx gl.Context, u gl.Uniform, a *f32.Affine) {
 	var m [9]float32
 	m[0*3+0] = a[0][0]
 	m[0*3+1] = a[1][0]
@@ -71,5 +71,5 @@ func writeAffine(u gl.Uniform, a *f32.Affine) {
 	m[2*3+0] = a[0][2]
 	m[2*3+1] = a[1][2]
 	m[2*3+2] = 1
-	gl.UniformMatrix3fv(u, m[:])
+	glctx.UniformMatrix3fv(u, m[:])
 }
diff --git a/gl/doc.go b/gl/doc.go
index 1309f43..1ea6efb 100644
--- a/gl/doc.go
+++ b/gl/doc.go
@@ -14,9 +14,7 @@ https://www.khronos.org/opengles/sdk/docs/man/
 One notable departure from the C API is the introduction of types
 to represent common uses of GLint: Texture, Surface, Buffer, etc.
 
-Calls are not safe for concurrent use. However calls can be made from
-any goroutine, the gl package removes the notion of thread-local
-context.
+Debug Logging
 
 A tracing version of the OpenGL bindings is behind the `gldebug` build
 tag. It acts as a simplified version of apitrace. Build your Go binary
diff --git a/gl/gendebug.go b/gl/gendebug.go
index 67fa42d..9dc7c5c 100644
--- a/gl/gendebug.go
+++ b/gl/gendebug.go
@@ -84,14 +84,14 @@ func main() {
 
 	for _, d := range f.Decls {
 		// Before:
-		// func StencilMask(mask uint32) {
+		// func (ctx *context) StencilMask(mask uint32) {
 		//	C.glStencilMask(C.GLuint(mask))
 		// }
 		//
 		// After:
-		// func StencilMask(mask uint32) {
+		// func (ctx *context) StencilMask(mask uint32) {
 		// 	defer func() {
-		// 		errstr := errDrain()
+		// 		errstr := ctx.errDrain()
 		// 		log.Printf("gl.StencilMask(%v) %v", mask, errstr)
 		//	}()
 		//	C.glStencilMask(C.GLuint(mask))
@@ -100,7 +100,7 @@ func main() {
 		if !ok {
 			continue
 		}
-		if fn.Recv != nil {
+		if fn.Recv == nil || fn.Recv.List[0].Names[0].Name != "ctx" {
 			continue
 		}
 
@@ -112,7 +112,7 @@ func main() {
 		)
 
 		// Print function signature.
-		fmt.Fprintf(buf, "func %s(", fn.Name.Name)
+		fmt.Fprintf(buf, "func (ctx *context) %s(", fn.Name.Name)
 		for i, p := range fn.Type.Params.List {
 			if i > 0 {
 				fmt.Fprint(buf, ", ")
@@ -162,7 +162,7 @@ func main() {
 		if !skip {
 			// Insert a defer block for tracing.
 			fmt.Fprintf(buf, "defer func() {\n")
-			fmt.Fprintf(buf, "\terrstr := errDrain()\n")
+			fmt.Fprintf(buf, "\terrstr := ctx.errDrain()\n")
 			switch fn.Name.Name {
 			case "GetUniformLocation", "GetAttribLocation":
 				fmt.Fprintf(buf, "\tr0.name = name\n")
@@ -243,10 +243,10 @@ import (
 	"unsafe"
 )
 
-func errDrain() string {
+func (ctx *context) errDrain() string {
 	var errs []Enum
 	for {
-		e := GetError()
+		e := ctx.GetError()
 		if e == 0 {
 			break
 		}
diff --git a/gl/gl.go b/gl/gl.go
index e10c1ae..45f0103 100644
--- a/gl/gl.go
+++ b/gl/gl.go
@@ -10,7 +10,7 @@ package gl
 // TODO(crawshaw): build on more host platforms (makes it easier to gobind).
 // TODO(crawshaw): expand to cover OpenGL ES 3.
 // TODO(crawshaw): should functions on specific types become methods? E.g.
-//                 	func (t Texture) Bind(target Enum)
+//                 func (t Texture) Bind(target Enum)
 //                 this seems natural in Go, but moves us slightly
 //                 further away from the underlying OpenGL spec.
 
@@ -22,11 +22,8 @@ import (
 	"unsafe"
 )
 
-// ActiveTexture sets the active texture unit.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glActiveTexture.xhtml
-func ActiveTexture(texture Enum) {
-	enqueue(call{
+func (ctx *context) ActiveTexture(texture Enum) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnActiveTexture,
 			a0: texture.c(),
@@ -34,11 +31,8 @@ func ActiveTexture(texture Enum) {
 	})
 }
 
-// AttachShader attaches a shader to a program.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glAttachShader.xhtml
-func AttachShader(p Program, s Shader) {
-	enqueue(call{
+func (ctx *context) AttachShader(p Program, s Shader) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnAttachShader,
 			a0: p.c(),
@@ -47,12 +41,8 @@ func AttachShader(p Program, s Shader) {
 	})
 }
 
-// BindAttribLocation binds a vertex attribute index with a named
-// variable.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glBindAttribLocation.xhtml
-func BindAttribLocation(p Program, a Attrib, name string) {
-	enqueue(call{
+func (ctx *context) BindAttribLocation(p Program, a Attrib, name string) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBindAttribLocation,
 			a0: p.c(),
@@ -62,11 +52,8 @@ func BindAttribLocation(p Program, a Attrib, name string) {
 	})
 }
 
-// BindBuffer binds a buffer.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glBindBuffer.xhtml
-func BindBuffer(target Enum, b Buffer) {
-	enqueue(call{
+func (ctx *context) BindBuffer(target Enum, b Buffer) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBindBuffer,
 			a0: target.c(),
@@ -75,11 +62,8 @@ func BindBuffer(target Enum, b Buffer) {
 	})
 }
 
-// BindFramebuffer binds a framebuffer.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glBindFramebuffer.xhtml
-func BindFramebuffer(target Enum, fb Framebuffer) {
-	enqueue(call{
+func (ctx *context) BindFramebuffer(target Enum, fb Framebuffer) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBindFramebuffer,
 			a0: target.c(),
@@ -88,11 +72,8 @@ func BindFramebuffer(target Enum, fb Framebuffer) {
 	})
 }
 
-// BindRenderbuffer binds a render buffer.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glBindRenderbuffer.xhtml
-func BindRenderbuffer(target Enum, rb Renderbuffer) {
-	enqueue(call{
+func (ctx *context) BindRenderbuffer(target Enum, rb Renderbuffer) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBindRenderbuffer,
 			a0: target.c(),
@@ -101,11 +82,8 @@ func BindRenderbuffer(target Enum, rb Renderbuffer) {
 	})
 }
 
-// BindTexture binds a texture.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glBindTexture.xhtml
-func BindTexture(target Enum, t Texture) {
-	enqueue(call{
+func (ctx *context) BindTexture(target Enum, t Texture) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBindTexture,
 			a0: target.c(),
@@ -114,11 +92,8 @@ func BindTexture(target Enum, t Texture) {
 	})
 }
 
-// BlendColor sets the blend color.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glBlendColor.xhtml
-func BlendColor(red, green, blue, alpha float32) {
-	enqueue(call{
+func (ctx *context) BlendColor(red, green, blue, alpha float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBlendColor,
 			a0: C.uintptr_t(math.Float32bits(red)),
@@ -129,11 +104,8 @@ func BlendColor(red, green, blue, alpha float32) {
 	})
 }
 
-// BlendEquation sets both RGB and alpha blend equations.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glBlendEquation.xhtml
-func BlendEquation(mode Enum) {
-	enqueue(call{
+func (ctx *context) BlendEquation(mode Enum) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBlendEquation,
 			a0: mode.c(),
@@ -141,11 +113,8 @@ func BlendEquation(mode Enum) {
 	})
 }
 
-// BlendEquationSeparate sets RGB and alpha blend equations separately.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glBlendEquationSeparate.xhtml
-func BlendEquationSeparate(modeRGB, modeAlpha Enum) {
-	enqueue(call{
+func (ctx *context) BlendEquationSeparate(modeRGB, modeAlpha Enum) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBlendEquationSeparate,
 			a0: modeRGB.c(),
@@ -154,11 +123,8 @@ func BlendEquationSeparate(modeRGB, modeAlpha Enum) {
 	})
 }
 
-// BlendFunc sets the pixel blending factors.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glBlendFunc.xhtml
-func BlendFunc(sfactor, dfactor Enum) {
-	enqueue(call{
+func (ctx *context) BlendFunc(sfactor, dfactor Enum) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBlendFunc,
 			a0: sfactor.c(),
@@ -167,11 +133,8 @@ func BlendFunc(sfactor, dfactor Enum) {
 	})
 }
 
-// BlendFunc sets the pixel RGB and alpha blending factors separately.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glBlendFuncSeparate.xhtml
-func BlendFuncSeparate(sfactorRGB, dfactorRGB, sfactorAlpha, dfactorAlpha Enum) {
-	enqueue(call{
+func (ctx *context) BlendFuncSeparate(sfactorRGB, dfactorRGB, sfactorAlpha, dfactorAlpha Enum) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBlendFuncSeparate,
 			a0: sfactorRGB.c(),
@@ -182,11 +145,8 @@ func BlendFuncSeparate(sfactorRGB, dfactorRGB, sfactorAlpha, dfactorAlpha Enum)
 	})
 }
 
-// BufferData creates a new data store for the bound buffer object.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glBufferData.xhtml
-func BufferData(target Enum, src []byte, usage Enum) {
-	enqueue(call{
+func (ctx *context) BufferData(target Enum, src []byte, usage Enum) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBufferData,
 			a0: target.c(),
@@ -198,11 +158,8 @@ func BufferData(target Enum, src []byte, usage Enum) {
 	})
 }
 
-// BufferInit creates a new uninitialized data store for the bound buffer object.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glBufferData.xhtml
-func BufferInit(target Enum, size int, usage Enum) {
-	enqueue(call{
+func (ctx *context) BufferInit(target Enum, size int, usage Enum) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBufferData,
 			a0: target.c(),
@@ -213,11 +170,8 @@ func BufferInit(target Enum, size int, usage Enum) {
 	})
 }
 
-// BufferSubData sets some of data in the bound buffer object.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glBufferSubData.xhtml
-func BufferSubData(target Enum, offset int, data []byte) {
-	enqueue(call{
+func (ctx *context) BufferSubData(target Enum, offset int, data []byte) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBufferSubData,
 			a0: target.c(),
@@ -229,12 +183,8 @@ func BufferSubData(target Enum, offset int, data []byte) {
 	})
 }
 
-// CheckFramebufferStatus reports the completeness status of the
-// active framebuffer.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glCheckFramebufferStatus.xhtml
-func CheckFramebufferStatus(target Enum) Enum {
-	return Enum(enqueue(call{
+func (ctx *context) CheckFramebufferStatus(target Enum) Enum {
+	return Enum(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnCheckFramebufferStatus,
 			a0: target.c(),
@@ -243,14 +193,8 @@ func CheckFramebufferStatus(target Enum) Enum {
 	}))
 }
 
-// Clear clears the window.
-//
-// The behavior of Clear is influenced by the pixel ownership test,
-// the scissor test, dithering, and the buffer writemasks.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glClear.xhtml
-func Clear(mask Enum) {
-	enqueue(call{
+func (ctx *context) Clear(mask Enum) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnClear,
 			a0: C.uintptr_t(mask),
@@ -258,11 +202,8 @@ func Clear(mask Enum) {
 	})
 }
 
-// ClearColor specifies the RGBA values used to clear color buffers.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glClearColor.xhtml
-func ClearColor(red, green, blue, alpha float32) {
-	enqueue(call{
+func (ctx *context) ClearColor(red, green, blue, alpha float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnClearColor,
 			a0: C.uintptr_t(math.Float32bits(red)),
@@ -273,11 +214,8 @@ func ClearColor(red, green, blue, alpha float32) {
 	})
 }
 
-// ClearDepthf sets the depth value used to clear the depth buffer.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glClearDepthf.xhtml
-func ClearDepthf(d float32) {
-	enqueue(call{
+func (ctx *context) ClearDepthf(d float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnClearDepthf,
 			a0: C.uintptr_t(math.Float32bits(d)),
@@ -285,11 +223,8 @@ func ClearDepthf(d float32) {
 	})
 }
 
-// ClearStencil sets the index used to clear the stencil buffer.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glClearStencil.xhtml
-func ClearStencil(s int) {
-	enqueue(call{
+func (ctx *context) ClearStencil(s int) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnClearStencil,
 			a0: C.uintptr_t(s),
@@ -297,12 +232,8 @@ func ClearStencil(s int) {
 	})
 }
 
-// ColorMask specifies whether color components in the framebuffer
-// can be written.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glColorMask.xhtml
-func ColorMask(red, green, blue, alpha bool) {
-	enqueue(call{
+func (ctx *context) ColorMask(red, green, blue, alpha bool) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnColorMask,
 			a0: glBoolean(red),
@@ -313,11 +244,8 @@ func ColorMask(red, green, blue, alpha bool) {
 	})
 }
 
-// CompileShader compiles the source code of s.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glCompileShader.xhtml
-func CompileShader(s Shader) {
-	enqueue(call{
+func (ctx *context) CompileShader(s Shader) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnCompileShader,
 			a0: s.c(),
@@ -325,11 +253,8 @@ func CompileShader(s Shader) {
 	})
 }
 
-// CompressedTexImage2D writes a compressed 2D texture.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glCompressedTexImage2D.xhtml
-func CompressedTexImage2D(target Enum, level int, internalformat Enum, width, height, border int, data []byte) {
-	enqueue(call{
+func (ctx *context) CompressedTexImage2D(target Enum, level int, internalformat Enum, width, height, border int, data []byte) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnCompressedTexImage2D,
 			a0: target.c(),
@@ -345,11 +270,8 @@ func CompressedTexImage2D(target Enum, level int, internalformat Enum, width, he
 	})
 }
 
-// CompressedTexSubImage2D writes a subregion of a compressed 2D texture.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glCompressedTexSubImage2D.xhtml
-func CompressedTexSubImage2D(target Enum, level, xoffset, yoffset, width, height int, format Enum, data []byte) {
-	enqueue(call{
+func (ctx *context) CompressedTexSubImage2D(target Enum, level, xoffset, yoffset, width, height int, format Enum, data []byte) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnCompressedTexSubImage2D,
 			a0: target.c(),
@@ -366,11 +288,8 @@ func CompressedTexSubImage2D(target Enum, level, xoffset, yoffset, width, height
 	})
 }
 
-// CopyTexImage2D writes a 2D texture from the current framebuffer.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glCopyTexImage2D.xhtml
-func CopyTexImage2D(target Enum, level int, internalformat Enum, x, y, width, height, border int) {
-	enqueue(call{
+func (ctx *context) CopyTexImage2D(target Enum, level int, internalformat Enum, x, y, width, height, border int) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnCopyTexImage2D,
 			a0: target.c(),
@@ -385,12 +304,8 @@ func CopyTexImage2D(target Enum, level int, internalformat Enum, x, y, width, he
 	})
 }
 
-// CopyTexSubImage2D writes a 2D texture subregion from the
-// current framebuffer.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glCopyTexSubImage2D.xhtml
-func CopyTexSubImage2D(target Enum, level, xoffset, yoffset, x, y, width, height int) {
-	enqueue(call{
+func (ctx *context) CopyTexSubImage2D(target Enum, level, xoffset, yoffset, x, y, width, height int) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnCopyTexSubImage2D,
 			a0: target.c(),
@@ -405,11 +320,8 @@ func CopyTexSubImage2D(target Enum, level, xoffset, yoffset, x, y, width, height
 	})
 }
 
-// CreateBuffer creates a buffer object.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGenBuffers.xhtml
-func CreateBuffer() Buffer {
-	return Buffer{Value: uint32(enqueue(call{
+func (ctx *context) CreateBuffer() Buffer {
+	return Buffer{Value: uint32(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGenBuffer,
 		},
@@ -417,11 +329,8 @@ func CreateBuffer() Buffer {
 	}))}
 }
 
-// CreateFramebuffer creates a framebuffer object.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGenFramebuffers.xhtml
-func CreateFramebuffer() Framebuffer {
-	return Framebuffer{Value: uint32(enqueue(call{
+func (ctx *context) CreateFramebuffer() Framebuffer {
+	return Framebuffer{Value: uint32(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGenFramebuffer,
 		},
@@ -429,11 +338,8 @@ func CreateFramebuffer() Framebuffer {
 	}))}
 }
 
-// CreateProgram creates a new empty program object.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glCreateProgram.xhtml
-func CreateProgram() Program {
-	return Program{Value: uint32(enqueue(call{
+func (ctx *context) CreateProgram() Program {
+	return Program{Value: uint32(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnCreateProgram,
 		},
@@ -441,11 +347,8 @@ func CreateProgram() Program {
 	}))}
 }
 
-// CreateRenderbuffer create a renderbuffer object.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGenRenderbuffers.xhtml
-func CreateRenderbuffer() Renderbuffer {
-	return Renderbuffer{Value: uint32(enqueue(call{
+func (ctx *context) CreateRenderbuffer() Renderbuffer {
+	return Renderbuffer{Value: uint32(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGenRenderbuffer,
 		},
@@ -453,11 +356,8 @@ func CreateRenderbuffer() Renderbuffer {
 	}))}
 }
 
-// CreateShader creates a new empty shader object.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glCreateShader.xhtml
-func CreateShader(ty Enum) Shader {
-	return Shader{Value: uint32(enqueue(call{
+func (ctx *context) CreateShader(ty Enum) Shader {
+	return Shader{Value: uint32(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnCreateShader,
 			a0: C.uintptr_t(ty),
@@ -466,11 +366,8 @@ func CreateShader(ty Enum) Shader {
 	}))}
 }
 
-// CreateTexture creates a texture object.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGenTextures.xhtml
-func CreateTexture() Texture {
-	return Texture{Value: uint32(enqueue(call{
+func (ctx *context) CreateTexture() Texture {
+	return Texture{Value: uint32(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGenTexture,
 		},
@@ -478,13 +375,8 @@ func CreateTexture() Texture {
 	}))}
 }
 
-// CullFace specifies which polygons are candidates for culling.
-//
-// Valid modes: FRONT, BACK, FRONT_AND_BACK.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glCullFace.xhtml
-func CullFace(mode Enum) {
-	enqueue(call{
+func (ctx *context) CullFace(mode Enum) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnCullFace,
 			a0: mode.c(),
@@ -492,11 +384,8 @@ func CullFace(mode Enum) {
 	})
 }
 
-// DeleteBuffer deletes the given buffer object.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glDeleteBuffers.xhtml
-func DeleteBuffer(v Buffer) {
-	enqueue(call{
+func (ctx *context) DeleteBuffer(v Buffer) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDeleteBuffer,
 			a0: C.uintptr_t(v.Value),
@@ -504,11 +393,8 @@ func DeleteBuffer(v Buffer) {
 	})
 }
 
-// DeleteFramebuffer deletes the given framebuffer object.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glDeleteFramebuffers.xhtml
-func DeleteFramebuffer(v Framebuffer) {
-	enqueue(call{
+func (ctx *context) DeleteFramebuffer(v Framebuffer) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDeleteFramebuffer,
 			a0: C.uintptr_t(v.Value),
@@ -516,11 +402,8 @@ func DeleteFramebuffer(v Framebuffer) {
 	})
 }
 
-// DeleteProgram deletes the given program object.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glDeleteProgram.xhtml
-func DeleteProgram(p Program) {
-	enqueue(call{
+func (ctx *context) DeleteProgram(p Program) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDeleteProgram,
 			a0: p.c(),
@@ -528,11 +411,8 @@ func DeleteProgram(p Program) {
 	})
 }
 
-// DeleteRenderbuffer deletes the given render buffer object.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glDeleteRenderbuffers.xhtml
-func DeleteRenderbuffer(v Renderbuffer) {
-	enqueue(call{
+func (ctx *context) DeleteRenderbuffer(v Renderbuffer) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDeleteRenderbuffer,
 			a0: v.c(),
@@ -540,11 +420,8 @@ func DeleteRenderbuffer(v Renderbuffer) {
 	})
 }
 
-// DeleteShader deletes shader s.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glDeleteShader.xhtml
-func DeleteShader(s Shader) {
-	enqueue(call{
+func (ctx *context) DeleteShader(s Shader) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDeleteShader,
 			a0: s.c(),
@@ -552,11 +429,8 @@ func DeleteShader(s Shader) {
 	})
 }
 
-// DeleteTexture deletes the given texture object.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glDeleteTextures.xhtml
-func DeleteTexture(v Texture) {
-	enqueue(call{
+func (ctx *context) DeleteTexture(v Texture) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDeleteTexture,
 			a0: v.c(),
@@ -564,21 +438,8 @@ func DeleteTexture(v Texture) {
 	})
 }
 
-// DepthFunc sets the function used for depth buffer comparisons.
-//
-// Valid fn values:
-//	NEVER
-//	LESS
-//	EQUAL
-//	LEQUAL
-//	GREATER
-//	NOTEQUAL
-//	GEQUAL
-//	ALWAYS
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glDepthFunc.xhtml
-func DepthFunc(fn Enum) {
-	enqueue(call{
+func (ctx *context) DepthFunc(fn Enum) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDepthFunc,
 			a0: fn.c(),
@@ -586,11 +447,8 @@ func DepthFunc(fn Enum) {
 	})
 }
 
-// DepthMask sets the depth buffer enabled for writing.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glDepthMask.xhtml
-func DepthMask(flag bool) {
-	enqueue(call{
+func (ctx *context) DepthMask(flag bool) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDepthMask,
 			a0: glBoolean(flag),
@@ -598,12 +456,8 @@ func DepthMask(flag bool) {
 	})
 }
 
-// DepthRangef sets the mapping from normalized device coordinates to
-// window coordinates.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glDepthRangef.xhtml
-func DepthRangef(n, f float32) {
-	enqueue(call{
+func (ctx *context) DepthRangef(n, f float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDepthRangef,
 			a0: C.uintptr_t(math.Float32bits(n)),
@@ -612,11 +466,8 @@ func DepthRangef(n, f float32) {
 	})
 }
 
-// DetachShader detaches the shader s from the program p.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glDetachShader.xhtml
-func DetachShader(p Program, s Shader) {
-	enqueue(call{
+func (ctx *context) DetachShader(p Program, s Shader) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDetachShader,
 			a0: p.c(),
@@ -625,11 +476,8 @@ func DetachShader(p Program, s Shader) {
 	})
 }
 
-// Disable disables various GL capabilities.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glDisable.xhtml
-func Disable(cap Enum) {
-	enqueue(call{
+func (ctx *context) Disable(cap Enum) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDisable,
 			a0: cap.c(),
@@ -637,11 +485,8 @@ func Disable(cap Enum) {
 	})
 }
 
-// DisableVertexAttribArray disables a vertex attribute array.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glDisableVertexAttribArray.xhtml
-func DisableVertexAttribArray(a Attrib) {
-	enqueue(call{
+func (ctx *context) DisableVertexAttribArray(a Attrib) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDisableVertexAttribArray,
 			a0: a.c(),
@@ -649,11 +494,8 @@ func DisableVertexAttribArray(a Attrib) {
 	})
 }
 
-// DrawArrays renders geometric primitives from the bound data.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glDrawArrays.xhtml
-func DrawArrays(mode Enum, first, count int) {
-	enqueue(call{
+func (ctx *context) DrawArrays(mode Enum, first, count int) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDrawArrays,
 			a0: mode.c(),
@@ -663,11 +505,8 @@ func DrawArrays(mode Enum, first, count int) {
 	})
 }
 
-// DrawElements renders primitives from a bound buffer.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glDrawElements.xhtml
-func DrawElements(mode Enum, count int, ty Enum, offset int) {
-	enqueue(call{
+func (ctx *context) DrawElements(mode Enum, count int, ty Enum, offset int) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDrawElements,
 			a0: mode.c(),
@@ -678,13 +517,8 @@ func DrawElements(mode Enum, count int, ty Enum, offset int) {
 	})
 }
 
-// TODO(crawshaw): consider DrawElements8 / DrawElements16 / DrawElements32
-
-// Enable enables various GL capabilities.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glEnable.xhtml
-func Enable(cap Enum) {
-	enqueue(call{
+func (ctx *context) Enable(cap Enum) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnEnable,
 			a0: cap.c(),
@@ -692,11 +526,8 @@ func Enable(cap Enum) {
 	})
 }
 
-// EnableVertexAttribArray enables a vertex attribute array.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glEnableVertexAttribArray.xhtml
-func EnableVertexAttribArray(a Attrib) {
-	enqueue(call{
+func (ctx *context) EnableVertexAttribArray(a Attrib) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnEnableVertexAttribArray,
 			a0: a.c(),
@@ -704,12 +535,8 @@ func EnableVertexAttribArray(a Attrib) {
 	})
 }
 
-// Finish blocks until the effects of all previously called GL
-// commands are complete.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glFinish.xhtml
-func Finish() {
-	enqueue(call{
+func (ctx *context) Finish() {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnFinish,
 		},
@@ -717,14 +544,8 @@ func Finish() {
 	})
 }
 
-// Flush empties all buffers. It does not block.
-//
-// An OpenGL implementation may buffer network communication,
-// the command stream, or data inside the graphics accelerator.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glFlush.xhtml
-func Flush() {
-	enqueue(call{
+func (ctx *context) Flush() {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnFlush,
 		},
@@ -732,11 +553,8 @@ func Flush() {
 	})
 }
 
-// FramebufferRenderbuffer attaches rb to the current frame buffer.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glFramebufferRenderbuffer.xhtml
-func FramebufferRenderbuffer(target, attachment, rbTarget Enum, rb Renderbuffer) {
-	enqueue(call{
+func (ctx *context) FramebufferRenderbuffer(target, attachment, rbTarget Enum, rb Renderbuffer) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnFramebufferRenderbuffer,
 			a0: target.c(),
@@ -747,11 +565,8 @@ func FramebufferRenderbuffer(target, attachment, rbTarget Enum, rb Renderbuffer)
 	})
 }
 
-// FramebufferTexture2D attaches the t to the current frame buffer.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glFramebufferTexture2D.xhtml
-func FramebufferTexture2D(target, attachment, texTarget Enum, t Texture, level int) {
-	enqueue(call{
+func (ctx *context) FramebufferTexture2D(target, attachment, texTarget Enum, t Texture, level int) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnFramebufferTexture2D,
 			a0: target.c(),
@@ -763,13 +578,8 @@ func FramebufferTexture2D(target, attachment, texTarget Enum, t Texture, level i
 	})
 }
 
-// FrontFace defines which polygons are front-facing.
-//
-// Valid modes: CW, CCW.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glFrontFace.xhtml
-func FrontFace(mode Enum) {
-	enqueue(call{
+func (ctx *context) FrontFace(mode Enum) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnFrontFace,
 			a0: mode.c(),
@@ -777,11 +587,8 @@ func FrontFace(mode Enum) {
 	})
 }
 
-// GenerateMipmap generates mipmaps for the current texture.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGenerateMipmap.xhtml
-func GenerateMipmap(target Enum) {
-	enqueue(call{
+func (ctx *context) GenerateMipmap(target Enum) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGenerateMipmap,
 			a0: target.c(),
@@ -789,20 +596,14 @@ func GenerateMipmap(target Enum) {
 	})
 }
 
-// GetActiveAttrib returns details about an active attribute variable.
-// A value of 0 for index selects the first active attribute variable.
-// Permissible values for index range from 0 to the number of active
-// attribute variables minus 1.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetActiveAttrib.xhtml
-func GetActiveAttrib(p Program, index uint32) (name string, size int, ty Enum) {
-	bufSize := GetProgrami(p, ACTIVE_ATTRIBUTE_MAX_LENGTH)
+func (ctx *context) GetActiveAttrib(p Program, index uint32) (name string, size int, ty Enum) {
+	bufSize := ctx.GetProgrami(p, ACTIVE_ATTRIBUTE_MAX_LENGTH)
 	buf := C.malloc(C.size_t(bufSize))
 	defer C.free(buf)
 	var cSize C.GLint
 	var cType C.GLenum
 
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetActiveAttrib,
 			a0: p.c(),
@@ -819,20 +620,14 @@ func GetActiveAttrib(p Program, index uint32) (name string, size int, ty Enum) {
 	return C.GoString((*C.char)(buf)), int(cSize), Enum(cType)
 }
 
-// GetActiveUniform returns details about an active uniform variable.
-// A value of 0 for index selects the first active uniform variable.
-// Permissible values for index range from 0 to the number of active
-// uniform variables minus 1.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetActiveUniform.xhtml
-func GetActiveUniform(p Program, index uint32) (name string, size int, ty Enum) {
-	bufSize := GetProgrami(p, ACTIVE_UNIFORM_MAX_LENGTH)
+func (ctx *context) GetActiveUniform(p Program, index uint32) (name string, size int, ty Enum) {
+	bufSize := ctx.GetProgrami(p, ACTIVE_UNIFORM_MAX_LENGTH)
 	buf := C.malloc(C.size_t(bufSize))
 	defer C.free(buf)
 	var cSize C.GLint
 	var cType C.GLenum
 
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetActiveUniform,
 			a0: p.c(),
@@ -849,18 +644,15 @@ func GetActiveUniform(p Program, index uint32) (name string, size int, ty Enum)
 	return C.GoString((*C.char)(buf)), int(cSize), Enum(cType)
 }
 
-// GetAttachedShaders returns the shader objects attached to program p.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetAttachedShaders.xhtml
-func GetAttachedShaders(p Program) []Shader {
-	shadersLen := GetProgrami(p, ATTACHED_SHADERS)
+func (ctx *context) GetAttachedShaders(p Program) []Shader {
+	shadersLen := ctx.GetProgrami(p, ATTACHED_SHADERS)
 	if shadersLen == 0 {
 		return nil
 	}
 	var n C.GLsizei
 	buf := make([]C.GLuint, shadersLen)
 
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetAttachedShaders,
 			a0: p.c(),
@@ -879,11 +671,8 @@ func GetAttachedShaders(p Program) []Shader {
 	return shaders
 }
 
-// GetAttribLocation returns the location of an attribute variable.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetAttribLocation.xhtml
-func GetAttribLocation(p Program, name string) Attrib {
-	return Attrib{Value: uint(enqueue(call{
+func (ctx *context) GetAttribLocation(p Program, name string) Attrib {
+	return Attrib{Value: uint(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetAttribLocation,
 			a0: p.c(),
@@ -893,15 +682,10 @@ func GetAttribLocation(p Program, name string) Attrib {
 	}))}
 }
 
-// GetBooleanv returns the boolean values of parameter pname.
-//
-// Many boolean parameters can be queried more easily using IsEnabled.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGet.xhtml
-func GetBooleanv(dst []bool, pname Enum) {
+func (ctx *context) GetBooleanv(dst []bool, pname Enum) {
 	buf := make([]C.GLboolean, len(dst))
 
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetBooleanv,
 			a0: pname.c(),
@@ -915,11 +699,8 @@ func GetBooleanv(dst []bool, pname Enum) {
 	}
 }
 
-// GetFloatv returns the float values of parameter pname.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGet.xhtml
-func GetFloatv(dst []float32, pname Enum) {
-	enqueue(call{
+func (ctx *context) GetFloatv(dst []float32, pname Enum) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetFloatv,
 			a0: pname.c(),
@@ -929,15 +710,10 @@ func GetFloatv(dst []float32, pname Enum) {
 	})
 }
 
-// GetIntegerv returns the int values of parameter pname.
-//
-// Single values may be queried more easily using GetInteger.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGet.xhtml
-func GetIntegerv(dst []int32, pname Enum) {
+func (ctx *context) GetIntegerv(dst []int32, pname Enum) {
 	buf := make([]C.GLint, len(dst))
 
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetIntegerv,
 			a0: pname.c(),
@@ -951,20 +727,14 @@ func GetIntegerv(dst []int32, pname Enum) {
 	}
 }
 
-// GetInteger returns the int value of parameter pname.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGet.xhtml
-func GetInteger(pname Enum) int {
+func (ctx *context) GetInteger(pname Enum) int {
 	var v [1]int32
-	GetIntegerv(v[:], pname)
+	ctx.GetIntegerv(v[:], pname)
 	return int(v[0])
 }
 
-// GetBufferParameteri returns a parameter for the active buffer.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetBufferParameter.xhtml
-func GetBufferParameteri(target, value Enum) int {
-	return int(enqueue(call{
+func (ctx *context) GetBufferParameteri(target, value Enum) int {
+	return int(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetBufferParameteri,
 			a0: target.c(),
@@ -974,11 +744,8 @@ func GetBufferParameteri(target, value Enum) int {
 	}))
 }
 
-// GetError returns the next error.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetError.xhtml
-func GetError() Enum {
-	return Enum(enqueue(call{
+func (ctx *context) GetError() Enum {
+	return Enum(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetError,
 		},
@@ -986,12 +753,8 @@ func GetError() Enum {
 	}))
 }
 
-// GetFramebufferAttachmentParameteri returns attachment parameters
-// for the active framebuffer object.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetFramebufferAttachmentParameteriv.xhtml
-func GetFramebufferAttachmentParameteri(target, attachment, pname Enum) int {
-	return int(enqueue(call{
+func (ctx *context) GetFramebufferAttachmentParameteri(target, attachment, pname Enum) int {
+	return int(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetFramebufferAttachmentParameteriv,
 			a0: target.c(),
@@ -1002,11 +765,8 @@ func GetFramebufferAttachmentParameteri(target, attachment, pname Enum) int {
 	}))
 }
 
-// GetProgrami returns a parameter value for a program.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetProgramiv.xhtml
-func GetProgrami(p Program, pname Enum) int {
-	return int(enqueue(call{
+func (ctx *context) GetProgrami(p Program, pname Enum) int {
+	return int(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetProgramiv,
 			a0: p.c(),
@@ -1016,15 +776,12 @@ func GetProgrami(p Program, pname Enum) int {
 	}))
 }
 
-// GetProgramInfoLog returns the information log for a program.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetProgramInfoLog.xhtml
-func GetProgramInfoLog(p Program) string {
-	infoLen := GetProgrami(p, INFO_LOG_LENGTH)
+func (ctx *context) GetProgramInfoLog(p Program) string {
+	infoLen := ctx.GetProgrami(p, INFO_LOG_LENGTH)
 	buf := C.malloc(C.size_t(infoLen))
 	defer C.free(buf)
 
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetProgramInfoLog,
 			a0: p.c(),
@@ -1038,11 +795,8 @@ func GetProgramInfoLog(p Program) string {
 	return C.GoString((*C.char)(buf))
 }
 
-// GetRenderbufferParameteri returns a parameter value for a render buffer.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetRenderbufferParameteriv.xhtml
-func GetRenderbufferParameteri(target, pname Enum) int {
-	return int(enqueue(call{
+func (ctx *context) GetRenderbufferParameteri(target, pname Enum) int {
+	return int(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetRenderbufferParameteriv,
 			a0: target.c(),
@@ -1052,11 +806,8 @@ func GetRenderbufferParameteri(target, pname Enum) int {
 	}))
 }
 
-// GetShaderi returns a parameter value for a shader.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetShaderiv.xhtml
-func GetShaderi(s Shader, pname Enum) int {
-	return int(enqueue(call{
+func (ctx *context) GetShaderi(s Shader, pname Enum) int {
+	return int(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetShaderiv,
 			a0: s.c(),
@@ -1066,15 +817,12 @@ func GetShaderi(s Shader, pname Enum) int {
 	}))
 }
 
-// GetShaderInfoLog returns the information log for a shader.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetShaderInfoLog.xhtml
-func GetShaderInfoLog(s Shader) string {
-	infoLen := GetShaderi(s, INFO_LOG_LENGTH)
+func (ctx *context) GetShaderInfoLog(s Shader) string {
+	infoLen := ctx.GetShaderi(s, INFO_LOG_LENGTH)
 	buf := C.malloc(C.size_t(infoLen))
 	defer C.free(buf)
 
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetShaderInfoLog,
 			a0: s.c(),
@@ -1088,15 +836,11 @@ func GetShaderInfoLog(s Shader) string {
 	return C.GoString((*C.char)(buf))
 }
 
-// GetShaderPrecisionFormat returns range and precision limits for
-// shader types.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetShaderPrecisionFormat.xhtml
-func GetShaderPrecisionFormat(shadertype, precisiontype Enum) (rangeLow, rangeHigh, precision int) {
+func (ctx *context) GetShaderPrecisionFormat(shadertype, precisiontype Enum) (rangeLow, rangeHigh, precision int) {
 	var cRange [2]C.GLint
 	var cPrecision C.GLint
 
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetShaderPrecisionFormat,
 			a0: shadertype.c(),
@@ -1110,18 +854,15 @@ func GetShaderPrecisionFormat(shadertype, precisiontype Enum) (rangeLow, rangeHi
 	return int(cRange[0]), int(cRange[1]), int(cPrecision)
 }
 
-// GetShaderSource returns source code of shader s.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetShaderSource.xhtml
-func GetShaderSource(s Shader) string {
-	sourceLen := GetShaderi(s, SHADER_SOURCE_LENGTH)
+func (ctx *context) GetShaderSource(s Shader) string {
+	sourceLen := ctx.GetShaderi(s, SHADER_SOURCE_LENGTH)
 	if sourceLen == 0 {
 		return ""
 	}
 	buf := C.malloc(C.size_t(sourceLen))
 	defer C.free(buf)
 
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetShaderSource,
 			a0: s.c(),
@@ -1135,18 +876,8 @@ func GetShaderSource(s Shader) string {
 	return C.GoString((*C.char)(buf))
 }
 
-// GetString reports current GL state.
-//
-// Valid name values:
-//	EXTENSIONS
-//	RENDERER
-//	SHADING_LANGUAGE_VERSION
-//	VENDOR
-//	VERSION
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetString.xhtml
-func GetString(pname Enum) string {
-	ret := enqueue(call{
+func (ctx *context) GetString(pname Enum) string {
+	ret := ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetString,
 			a0: pname.c(),
@@ -1156,11 +887,8 @@ func GetString(pname Enum) string {
 	return C.GoString((*C.char)((unsafe.Pointer(uintptr(ret)))))
 }
 
-// GetTexParameterfv returns the float values of a texture parameter.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetTexParameter.xhtml
-func GetTexParameterfv(dst []float32, target, pname Enum) {
-	enqueue(call{
+func (ctx *context) GetTexParameterfv(dst []float32, target, pname Enum) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetTexParameterfv,
 			a0: target.c(),
@@ -1171,11 +899,8 @@ func GetTexParameterfv(dst []float32, target, pname Enum) {
 	})
 }
 
-// GetTexParameteriv returns the int values of a texture parameter.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetTexParameter.xhtml
-func GetTexParameteriv(dst []int32, target, pname Enum) {
-	enqueue(call{
+func (ctx *context) GetTexParameteriv(dst []int32, target, pname Enum) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetTexParameteriv,
 			a0: target.c(),
@@ -1186,11 +911,8 @@ func GetTexParameteriv(dst []int32, target, pname Enum) {
 	})
 }
 
-// GetUniformfv returns the float values of a uniform variable.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetUniform.xhtml
-func GetUniformfv(dst []float32, src Uniform, p Program) {
-	enqueue(call{
+func (ctx *context) GetUniformfv(dst []float32, src Uniform, p Program) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetUniformfv,
 			a0: p.c(),
@@ -1201,11 +923,8 @@ func GetUniformfv(dst []float32, src Uniform, p Program) {
 	})
 }
 
-// GetUniformiv returns the float values of a uniform variable.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetUniform.xhtml
-func GetUniformiv(dst []int32, src Uniform, p Program) {
-	enqueue(call{
+func (ctx *context) GetUniformiv(dst []int32, src Uniform, p Program) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetUniformiv,
 			a0: p.c(),
@@ -1216,11 +935,8 @@ func GetUniformiv(dst []int32, src Uniform, p Program) {
 	})
 }
 
-// GetUniformLocation returns the location of a uniform variable.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetUniformLocation.xhtml
-func GetUniformLocation(p Program, name string) Uniform {
-	return Uniform{Value: int32(enqueue(call{
+func (ctx *context) GetUniformLocation(p Program, name string) Uniform {
+	return Uniform{Value: int32(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetUniformLocation,
 			a0: p.c(),
@@ -1230,20 +946,14 @@ func GetUniformLocation(p Program, name string) Uniform {
 	}))}
 }
 
-// GetVertexAttribf reads the float value of a vertex attribute.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetVertexAttrib.xhtml
-func GetVertexAttribf(src Attrib, pname Enum) float32 {
+func (ctx *context) GetVertexAttribf(src Attrib, pname Enum) float32 {
 	var params [1]float32
-	GetVertexAttribfv(params[:], src, pname)
+	ctx.GetVertexAttribfv(params[:], src, pname)
 	return params[0]
 }
 
-// GetVertexAttribfv reads float values of a vertex attribute.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetVertexAttrib.xhtml
-func GetVertexAttribfv(dst []float32, src Attrib, pname Enum) {
-	enqueue(call{
+func (ctx *context) GetVertexAttribfv(dst []float32, src Attrib, pname Enum) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetVertexAttribfv,
 			a0: src.c(),
@@ -1254,20 +964,14 @@ func GetVertexAttribfv(dst []float32, src Attrib, pname Enum) {
 	})
 }
 
-// GetVertexAttribi reads the int value of a vertex attribute.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetVertexAttrib.xhtml
-func GetVertexAttribi(src Attrib, pname Enum) int32 {
+func (ctx *context) GetVertexAttribi(src Attrib, pname Enum) int32 {
 	var params [1]int32
-	GetVertexAttribiv(params[:], src, pname)
+	ctx.GetVertexAttribiv(params[:], src, pname)
 	return params[0]
 }
 
-// GetVertexAttribiv reads int values of a vertex attribute.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetVertexAttrib.xhtml
-func GetVertexAttribiv(dst []int32, src Attrib, pname Enum) {
-	enqueue(call{
+func (ctx *context) GetVertexAttribiv(dst []int32, src Attrib, pname Enum) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetVertexAttribiv,
 			a0: src.c(),
@@ -1278,13 +982,8 @@ func GetVertexAttribiv(dst []int32, src Attrib, pname Enum) {
 	})
 }
 
-// TODO(crawshaw): glGetVertexAttribPointerv
-
-// Hint sets implementation-specific modes.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glHint.xhtml
-func Hint(target, mode Enum) {
-	enqueue(call{
+func (ctx *context) Hint(target, mode Enum) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnHint,
 			a0: target.c(),
@@ -1293,11 +992,8 @@ func Hint(target, mode Enum) {
 	})
 }
 
-// IsBuffer reports if b is a valid buffer.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glIsBuffer.xhtml
-func IsBuffer(b Buffer) bool {
-	return 0 != enqueue(call{
+func (ctx *context) IsBuffer(b Buffer) bool {
+	return 0 != ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnIsBuffer,
 			a0: b.c(),
@@ -1306,11 +1002,8 @@ func IsBuffer(b Buffer) bool {
 	})
 }
 
-// IsEnabled reports if cap is an enabled capability.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glIsEnabled.xhtml
-func IsEnabled(cap Enum) bool {
-	return 0 != enqueue(call{
+func (ctx *context) IsEnabled(cap Enum) bool {
+	return 0 != ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnIsEnabled,
 			a0: cap.c(),
@@ -1319,11 +1012,8 @@ func IsEnabled(cap Enum) bool {
 	})
 }
 
-// IsFramebuffer reports if fb is a valid frame buffer.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glIsFramebuffer.xhtml
-func IsFramebuffer(fb Framebuffer) bool {
-	return 0 != enqueue(call{
+func (ctx *context) IsFramebuffer(fb Framebuffer) bool {
+	return 0 != ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnIsFramebuffer,
 			a0: fb.c(),
@@ -1332,11 +1022,8 @@ func IsFramebuffer(fb Framebuffer) bool {
 	})
 }
 
-// IsProgram reports if p is a valid program object.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glIsProgram.xhtml
-func IsProgram(p Program) bool {
-	return 0 != enqueue(call{
+func (ctx *context) IsProgram(p Program) bool {
+	return 0 != ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnIsProgram,
 			a0: p.c(),
@@ -1345,11 +1032,8 @@ func IsProgram(p Program) bool {
 	})
 }
 
-// IsRenderbuffer reports if rb is a valid render buffer.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glIsRenderbuffer.xhtml
-func IsRenderbuffer(rb Renderbuffer) bool {
-	return 0 != enqueue(call{
+func (ctx *context) IsRenderbuffer(rb Renderbuffer) bool {
+	return 0 != ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnIsRenderbuffer,
 			a0: rb.c(),
@@ -1358,11 +1042,8 @@ func IsRenderbuffer(rb Renderbuffer) bool {
 	})
 }
 
-// IsShader reports if s is valid shader.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glIsShader.xhtml
-func IsShader(s Shader) bool {
-	return 0 != enqueue(call{
+func (ctx *context) IsShader(s Shader) bool {
+	return 0 != ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnIsShader,
 			a0: s.c(),
@@ -1371,11 +1052,8 @@ func IsShader(s Shader) bool {
 	})
 }
 
-// IsTexture reports if t is a valid texture.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glIsTexture.xhtml
-func IsTexture(t Texture) bool {
-	return 0 != enqueue(call{
+func (ctx *context) IsTexture(t Texture) bool {
+	return 0 != ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnIsTexture,
 			a0: t.c(),
@@ -1384,11 +1062,8 @@ func IsTexture(t Texture) bool {
 	})
 }
 
-// LineWidth specifies the width of lines.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glLineWidth.xhtml
-func LineWidth(width float32) {
-	enqueue(call{
+func (ctx *context) LineWidth(width float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnLineWidth,
 			a0: C.uintptr_t(math.Float32bits(width)),
@@ -1396,11 +1071,8 @@ func LineWidth(width float32) {
 	})
 }
 
-// LinkProgram links the specified program.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glLinkProgram.xhtml
-func LinkProgram(p Program) {
-	enqueue(call{
+func (ctx *context) LinkProgram(p Program) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnLinkProgram,
 			a0: p.c(),
@@ -1408,11 +1080,8 @@ func LinkProgram(p Program) {
 	})
 }
 
-// PixelStorei sets pixel storage parameters.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glPixelStorei.xhtml
-func PixelStorei(pname Enum, param int32) {
-	enqueue(call{
+func (ctx *context) PixelStorei(pname Enum, param int32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnPixelStorei,
 			a0: pname.c(),
@@ -1421,11 +1090,8 @@ func PixelStorei(pname Enum, param int32) {
 	})
 }
 
-// PolygonOffset sets the scaling factors for depth offsets.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glPolygonOffset.xhtml
-func PolygonOffset(factor, units float32) {
-	enqueue(call{
+func (ctx *context) PolygonOffset(factor, units float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnPolygonOffset,
 			a0: C.uintptr_t(math.Float32bits(factor)),
@@ -1434,13 +1100,8 @@ func PolygonOffset(factor, units float32) {
 	})
 }
 
-// ReadPixels returns pixel data from a buffer.
-//
-// In GLES 3, the source buffer is controlled with ReadBuffer.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glReadPixels.xhtml
-func ReadPixels(dst []byte, x, y, width, height int, format, ty Enum) {
-	enqueue(call{
+func (ctx *context) ReadPixels(dst []byte, x, y, width, height int, format, ty Enum) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnReadPixels,
 			// TODO(crawshaw): support PIXEL_PACK_BUFFER in GLES3, uses offset.
@@ -1456,23 +1117,16 @@ func ReadPixels(dst []byte, x, y, width, height int, format, ty Enum) {
 	})
 }
 
-// ReleaseShaderCompiler frees resources allocated by the shader compiler.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glReleaseShaderCompiler.xhtml
-func ReleaseShaderCompiler() {
-	enqueue(call{
+func (ctx *context) ReleaseShaderCompiler() {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnReleaseShaderCompiler,
 		},
 	})
 }
 
-// RenderbufferStorage establishes the data storage, format, and
-// dimensions of a renderbuffer object's image.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glRenderbufferStorage.xhtml
-func RenderbufferStorage(target, internalFormat Enum, width, height int) {
-	enqueue(call{
+func (ctx *context) RenderbufferStorage(target, internalFormat Enum, width, height int) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnRenderbufferStorage,
 			a0: target.c(),
@@ -1483,11 +1137,8 @@ func RenderbufferStorage(target, internalFormat Enum, width, height int) {
 	})
 }
 
-// SampleCoverage sets multisample coverage parameters.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glSampleCoverage.xhtml
-func SampleCoverage(value float32, invert bool) {
-	enqueue(call{
+func (ctx *context) SampleCoverage(value float32, invert bool) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnSampleCoverage,
 			a0: C.uintptr_t(math.Float32bits(value)),
@@ -1496,11 +1147,8 @@ func SampleCoverage(value float32, invert bool) {
 	})
 }
 
-// Scissor defines the scissor box rectangle, in window coordinates.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glScissor.xhtml
-func Scissor(x, y, width, height int32) {
-	enqueue(call{
+func (ctx *context) Scissor(x, y, width, height int32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnScissor,
 			a0: C.uintptr_t(x),
@@ -1511,12 +1159,7 @@ func Scissor(x, y, width, height int32) {
 	})
 }
 
-// TODO(crawshaw): ShaderBinary
-
-// ShaderSource sets the source code of s to the given source code.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glShaderSource.xhtml
-func ShaderSource(s Shader, src string) {
+func (ctx *context) ShaderSource(s Shader, src string) {
 	// We are passing a char**. Make sure both the string and its
 	// containing 1-element array are off the stack. Both are freed
 	// in work.c.
@@ -1524,7 +1167,7 @@ func ShaderSource(s Shader, src string) {
 	cstrp := (**C.char)(C.malloc(C.size_t(unsafe.Sizeof(cstr))))
 	*cstrp = cstr
 
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnShaderSource,
 			a0: s.c(),
@@ -1534,11 +1177,8 @@ func ShaderSource(s Shader, src string) {
 	})
 }
 
-// StencilFunc sets the front and back stencil test reference value.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glStencilFunc.xhtml
-func StencilFunc(fn Enum, ref int, mask uint32) {
-	enqueue(call{
+func (ctx *context) StencilFunc(fn Enum, ref int, mask uint32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnStencilFunc,
 			a0: fn.c(),
@@ -1548,11 +1188,8 @@ func StencilFunc(fn Enum, ref int, mask uint32) {
 	})
 }
 
-// StencilFunc sets the front or back stencil test reference value.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glStencilFuncSeparate.xhtml
-func StencilFuncSeparate(face, fn Enum, ref int, mask uint32) {
-	enqueue(call{
+func (ctx *context) StencilFuncSeparate(face, fn Enum, ref int, mask uint32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnStencilFuncSeparate,
 			a0: face.c(),
@@ -1563,11 +1200,8 @@ func StencilFuncSeparate(face, fn Enum, ref int, mask uint32) {
 	})
 }
 
-// StencilMask controls the writing of bits in the stencil planes.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glStencilMask.xhtml
-func StencilMask(mask uint32) {
-	enqueue(call{
+func (ctx *context) StencilMask(mask uint32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnStencilMask,
 			a0: C.uintptr_t(mask),
@@ -1575,11 +1209,8 @@ func StencilMask(mask uint32) {
 	})
 }
 
-// StencilMaskSeparate controls the writing of bits in the stencil planes.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glStencilMaskSeparate.xhtml
-func StencilMaskSeparate(face Enum, mask uint32) {
-	enqueue(call{
+func (ctx *context) StencilMaskSeparate(face Enum, mask uint32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnStencilMaskSeparate,
 			a0: face.c(),
@@ -1588,11 +1219,8 @@ func StencilMaskSeparate(face Enum, mask uint32) {
 	})
 }
 
-// StencilOp sets front and back stencil test actions.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glStencilOp.xhtml
-func StencilOp(fail, zfail, zpass Enum) {
-	enqueue(call{
+func (ctx *context) StencilOp(fail, zfail, zpass Enum) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnStencilOp,
 			a0: fail.c(),
@@ -1602,11 +1230,8 @@ func StencilOp(fail, zfail, zpass Enum) {
 	})
 }
 
-// StencilOpSeparate sets front or back stencil tests.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glStencilOpSeparate.xhtml
-func StencilOpSeparate(face, sfail, dpfail, dppass Enum) {
-	enqueue(call{
+func (ctx *context) StencilOpSeparate(face, sfail, dpfail, dppass Enum) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnStencilOpSeparate,
 			a0: face.c(),
@@ -1617,10 +1242,7 @@ func StencilOpSeparate(face, sfail, dpfail, dppass Enum) {
 	})
 }
 
-// TexImage2D writes a 2D texture image.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glTexImage2D.xhtml
-func TexImage2D(target Enum, level int, width, height int, format Enum, ty Enum, data []byte) {
+func (ctx *context) TexImage2D(target Enum, level int, width, height int, format Enum, ty Enum, data []byte) {
 	// It is common to pass TexImage2D a nil data, indicating that a
 	// bound GL buffer is being used as the source. In that case, it
 	// is not necessary to block.
@@ -1629,7 +1251,7 @@ func TexImage2D(target Enum, level int, width, height int, format Enum, ty Enum,
 		blocking, a7 = true, C.uintptr_t(uintptr(unsafe.Pointer(&data[0])))
 	}
 
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnTexImage2D,
 			// TODO(crawshaw): GLES3 offset for PIXEL_UNPACK_BUFFER and PIXEL_PACK_BUFFER.
@@ -1646,11 +1268,8 @@ func TexImage2D(target Enum, level int, width, height int, format Enum, ty Enum,
 	})
 }
 
-// TexSubImage2D writes a subregion of a 2D texture image.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glTexSubImage2D.xhtml
-func TexSubImage2D(target Enum, level int, x, y, width, height int, format, ty Enum, data []byte) {
-	enqueue(call{
+func (ctx *context) TexSubImage2D(target Enum, level int, x, y, width, height int, format, ty Enum, data []byte) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnTexSubImage2D,
 			// TODO(crawshaw): GLES3 offset for PIXEL_UNPACK_BUFFER and PIXEL_PACK_BUFFER.
@@ -1668,11 +1287,8 @@ func TexSubImage2D(target Enum, level int, x, y, width, height int, format, ty E
 	})
 }
 
-// TexParameterf sets a float texture parameter.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glTexParameter.xhtml
-func TexParameterf(target, pname Enum, param float32) {
-	enqueue(call{
+func (ctx *context) TexParameterf(target, pname Enum, param float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnTexParameterf,
 			a0: target.c(),
@@ -1682,11 +1298,8 @@ func TexParameterf(target, pname Enum, param float32) {
 	})
 }
 
-// TexParameterfv sets a float texture parameter array.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glTexParameter.xhtml
-func TexParameterfv(target, pname Enum, params []float32) {
-	enqueue(call{
+func (ctx *context) TexParameterfv(target, pname Enum, params []float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnTexParameterfv,
 			a0: target.c(),
@@ -1697,11 +1310,8 @@ func TexParameterfv(target, pname Enum, params []float32) {
 	})
 }
 
-// TexParameteri sets an integer texture parameter.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glTexParameter.xhtml
-func TexParameteri(target, pname Enum, param int) {
-	enqueue(call{
+func (ctx *context) TexParameteri(target, pname Enum, param int) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnTexParameteri,
 			a0: target.c(),
@@ -1711,11 +1321,8 @@ func TexParameteri(target, pname Enum, param int) {
 	})
 }
 
-// TexParameteriv sets an integer texture parameter array.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glTexParameter.xhtml
-func TexParameteriv(target, pname Enum, params []int32) {
-	enqueue(call{
+func (ctx *context) TexParameteriv(target, pname Enum, params []int32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnTexParameteriv,
 			a0: target.c(),
@@ -1726,11 +1333,8 @@ func TexParameteriv(target, pname Enum, params []int32) {
 	})
 }
 
-// Uniform1f writes a float uniform variable.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
-func Uniform1f(dst Uniform, v float32) {
-	enqueue(call{
+func (ctx *context) Uniform1f(dst Uniform, v float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform1f,
 			a0: dst.c(),
@@ -1739,11 +1343,8 @@ func Uniform1f(dst Uniform, v float32) {
 	})
 }
 
-// Uniform1fv writes a [len(src)]float uniform array.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
-func Uniform1fv(dst Uniform, src []float32) {
-	enqueue(call{
+func (ctx *context) Uniform1fv(dst Uniform, src []float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform1fv,
 			a0: dst.c(),
@@ -1754,15 +1355,8 @@ func Uniform1fv(dst Uniform, src []float32) {
 	})
 }
 
-// Uniform1i writes an int uniform variable.
-//
-// Uniform1i and Uniform1iv are the only two functions that may be used
-// to load uniform variables defined as sampler types. Loading samplers
-// with any other function will result in a INVALID_OPERATION error.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
-func Uniform1i(dst Uniform, v int) {
-	enqueue(call{
+func (ctx *context) Uniform1i(dst Uniform, v int) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform1i,
 			a0: dst.c(),
@@ -1771,15 +1365,8 @@ func Uniform1i(dst Uniform, v int) {
 	})
 }
 
-// Uniform1iv writes a int uniform array of len(src) elements.
-//
-// Uniform1i and Uniform1iv are the only two functions that may be used
-// to load uniform variables defined as sampler types. Loading samplers
-// with any other function will result in a INVALID_OPERATION error.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
-func Uniform1iv(dst Uniform, src []int32) {
-	enqueue(call{
+func (ctx *context) Uniform1iv(dst Uniform, src []int32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform1iv,
 			a0: dst.c(),
@@ -1790,11 +1377,8 @@ func Uniform1iv(dst Uniform, src []int32) {
 	})
 }
 
-// Uniform2f writes a vec2 uniform variable.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
-func Uniform2f(dst Uniform, v0, v1 float32) {
-	enqueue(call{
+func (ctx *context) Uniform2f(dst Uniform, v0, v1 float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform2f,
 			a0: dst.c(),
@@ -1804,11 +1388,8 @@ func Uniform2f(dst Uniform, v0, v1 float32) {
 	})
 }
 
-// Uniform2fv writes a vec2 uniform array of len(src)/2 elements.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
-func Uniform2fv(dst Uniform, src []float32) {
-	enqueue(call{
+func (ctx *context) Uniform2fv(dst Uniform, src []float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform2fv,
 			a0: dst.c(),
@@ -1819,11 +1400,8 @@ func Uniform2fv(dst Uniform, src []float32) {
 	})
 }
 
-// Uniform2i writes an ivec2 uniform variable.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
-func Uniform2i(dst Uniform, v0, v1 int) {
-	enqueue(call{
+func (ctx *context) Uniform2i(dst Uniform, v0, v1 int) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform2i,
 			a0: dst.c(),
@@ -1833,11 +1411,8 @@ func Uniform2i(dst Uniform, v0, v1 int) {
 	})
 }
 
-// Uniform2iv writes an ivec2 uniform array of len(src)/2 elements.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
-func Uniform2iv(dst Uniform, src []int32) {
-	enqueue(call{
+func (ctx *context) Uniform2iv(dst Uniform, src []int32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform2iv,
 			a0: dst.c(),
@@ -1848,11 +1423,8 @@ func Uniform2iv(dst Uniform, src []int32) {
 	})
 }
 
-// Uniform3f writes a vec3 uniform variable.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
-func Uniform3f(dst Uniform, v0, v1, v2 float32) {
-	enqueue(call{
+func (ctx *context) Uniform3f(dst Uniform, v0, v1, v2 float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform3f,
 			a0: dst.c(),
@@ -1863,11 +1435,8 @@ func Uniform3f(dst Uniform, v0, v1, v2 float32) {
 	})
 }
 
-// Uniform3fv writes a vec3 uniform array of len(src)/3 elements.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
-func Uniform3fv(dst Uniform, src []float32) {
-	enqueue(call{
+func (ctx *context) Uniform3fv(dst Uniform, src []float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform3fv,
 			a0: dst.c(),
@@ -1878,11 +1447,8 @@ func Uniform3fv(dst Uniform, src []float32) {
 	})
 }
 
-// Uniform3i writes an ivec3 uniform variable.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
-func Uniform3i(dst Uniform, v0, v1, v2 int32) {
-	enqueue(call{
+func (ctx *context) Uniform3i(dst Uniform, v0, v1, v2 int32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform3i,
 			a0: dst.c(),
@@ -1893,11 +1459,8 @@ func Uniform3i(dst Uniform, v0, v1, v2 int32) {
 	})
 }
 
-// Uniform3iv writes an ivec3 uniform array of len(src)/3 elements.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
-func Uniform3iv(dst Uniform, src []int32) {
-	enqueue(call{
+func (ctx *context) Uniform3iv(dst Uniform, src []int32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform3iv,
 			a0: dst.c(),
@@ -1908,11 +1471,8 @@ func Uniform3iv(dst Uniform, src []int32) {
 	})
 }
 
-// Uniform4f writes a vec4 uniform variable.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
-func Uniform4f(dst Uniform, v0, v1, v2, v3 float32) {
-	enqueue(call{
+func (ctx *context) Uniform4f(dst Uniform, v0, v1, v2, v3 float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform4f,
 			a0: dst.c(),
@@ -1924,11 +1484,8 @@ func Uniform4f(dst Uniform, v0, v1, v2, v3 float32) {
 	})
 }
 
-// Uniform4fv writes a vec4 uniform array of len(src)/4 elements.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
-func Uniform4fv(dst Uniform, src []float32) {
-	enqueue(call{
+func (ctx *context) Uniform4fv(dst Uniform, src []float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform4fv,
 			a0: dst.c(),
@@ -1939,11 +1496,8 @@ func Uniform4fv(dst Uniform, src []float32) {
 	})
 }
 
-// Uniform4i writes an ivec4 uniform variable.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
-func Uniform4i(dst Uniform, v0, v1, v2, v3 int32) {
-	enqueue(call{
+func (ctx *context) Uniform4i(dst Uniform, v0, v1, v2, v3 int32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform4i,
 			a0: dst.c(),
@@ -1955,11 +1509,8 @@ func Uniform4i(dst Uniform, v0, v1, v2, v3 int32) {
 	})
 }
 
-// Uniform4i writes an ivec4 uniform array of len(src)/4 elements.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
-func Uniform4iv(dst Uniform, src []int32) {
-	enqueue(call{
+func (ctx *context) Uniform4iv(dst Uniform, src []int32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform4iv,
 			a0: dst.c(),
@@ -1970,14 +1521,8 @@ func Uniform4iv(dst Uniform, src []int32) {
 	})
 }
 
-// UniformMatrix2fv writes 2x2 matrices. Each matrix uses four
-// float32 values, so the number of matrices written is len(src)/4.
-//
-// Each matrix must be supplied in column major order.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
-func UniformMatrix2fv(dst Uniform, src []float32) {
-	enqueue(call{
+func (ctx *context) UniformMatrix2fv(dst Uniform, src []float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniformMatrix2fv,
 			// OpenGL ES 2 does not support transpose.
@@ -1989,14 +1534,8 @@ func UniformMatrix2fv(dst Uniform, src []float32) {
 	})
 }
 
-// UniformMatrix3fv writes 3x3 matrices. Each matrix uses nine
-// float32 values, so the number of matrices written is len(src)/9.
-//
-// Each matrix must be supplied in column major order.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
-func UniformMatrix3fv(dst Uniform, src []float32) {
-	enqueue(call{
+func (ctx *context) UniformMatrix3fv(dst Uniform, src []float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniformMatrix3fv,
 			a0: dst.c(),
@@ -2007,14 +1546,8 @@ func UniformMatrix3fv(dst Uniform, src []float32) {
 	})
 }
 
-// UniformMatrix4fv writes 4x4 matrices. Each matrix uses 16
-// float32 values, so the number of matrices written is len(src)/16.
-//
-// Each matrix must be supplied in column major order.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
-func UniformMatrix4fv(dst Uniform, src []float32) {
-	enqueue(call{
+func (ctx *context) UniformMatrix4fv(dst Uniform, src []float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniformMatrix4fv,
 			a0: dst.c(),
@@ -2025,11 +1558,8 @@ func UniformMatrix4fv(dst Uniform, src []float32) {
 	})
 }
 
-// UseProgram sets the active program.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glUseProgram.xhtml
-func UseProgram(p Program) {
-	enqueue(call{
+func (ctx *context) UseProgram(p Program) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUseProgram,
 			a0: p.c(),
@@ -2037,14 +1567,8 @@ func UseProgram(p Program) {
 	})
 }
 
-// ValidateProgram checks to see whether the executables contained in
-// program can execute given the current OpenGL state.
-//
-// Typically only used for debugging.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glValidateProgram.xhtml
-func ValidateProgram(p Program) {
-	enqueue(call{
+func (ctx *context) ValidateProgram(p Program) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnValidateProgram,
 			a0: p.c(),
@@ -2052,11 +1576,8 @@ func ValidateProgram(p Program) {
 	})
 }
 
-// VertexAttrib1f writes a float vertex attribute.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttrib.xhtml
-func VertexAttrib1f(dst Attrib, x float32) {
-	enqueue(call{
+func (ctx *context) VertexAttrib1f(dst Attrib, x float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnVertexAttrib1f,
 			a0: dst.c(),
@@ -2065,11 +1586,8 @@ func VertexAttrib1f(dst Attrib, x float32) {
 	})
 }
 
-// VertexAttrib1fv writes a float vertex attribute.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttrib.xhtml
-func VertexAttrib1fv(dst Attrib, src []float32) {
-	enqueue(call{
+func (ctx *context) VertexAttrib1fv(dst Attrib, src []float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnVertexAttrib1fv,
 			a0: dst.c(),
@@ -2079,11 +1597,8 @@ func VertexAttrib1fv(dst Attrib, src []float32) {
 	})
 }
 
-// VertexAttrib2f writes a vec2 vertex attribute.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttrib.xhtml
-func VertexAttrib2f(dst Attrib, x, y float32) {
-	enqueue(call{
+func (ctx *context) VertexAttrib2f(dst Attrib, x, y float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnVertexAttrib2f,
 			a0: dst.c(),
@@ -2093,11 +1608,8 @@ func VertexAttrib2f(dst Attrib, x, y float32) {
 	})
 }
 
-// VertexAttrib2fv writes a vec2 vertex attribute.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttrib.xhtml
-func VertexAttrib2fv(dst Attrib, src []float32) {
-	enqueue(call{
+func (ctx *context) VertexAttrib2fv(dst Attrib, src []float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnVertexAttrib2fv,
 			a0: dst.c(),
@@ -2107,11 +1619,8 @@ func VertexAttrib2fv(dst Attrib, src []float32) {
 	})
 }
 
-// VertexAttrib3f writes a vec3 vertex attribute.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttrib.xhtml
-func VertexAttrib3f(dst Attrib, x, y, z float32) {
-	enqueue(call{
+func (ctx *context) VertexAttrib3f(dst Attrib, x, y, z float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnVertexAttrib3f,
 			a0: dst.c(),
@@ -2122,11 +1631,8 @@ func VertexAttrib3f(dst Attrib, x, y, z float32) {
 	})
 }
 
-// VertexAttrib3fv writes a vec3 vertex attribute.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttrib.xhtml
-func VertexAttrib3fv(dst Attrib, src []float32) {
-	enqueue(call{
+func (ctx *context) VertexAttrib3fv(dst Attrib, src []float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnVertexAttrib3fv,
 			a0: dst.c(),
@@ -2136,11 +1642,8 @@ func VertexAttrib3fv(dst Attrib, src []float32) {
 	})
 }
 
-// VertexAttrib4f writes a vec4 vertex attribute.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttrib.xhtml
-func VertexAttrib4f(dst Attrib, x, y, z, w float32) {
-	enqueue(call{
+func (ctx *context) VertexAttrib4f(dst Attrib, x, y, z, w float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnVertexAttrib4f,
 			a0: dst.c(),
@@ -2152,11 +1655,8 @@ func VertexAttrib4f(dst Attrib, x, y, z, w float32) {
 	})
 }
 
-// VertexAttrib4fv writes a vec4 vertex attribute.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttrib.xhtml
-func VertexAttrib4fv(dst Attrib, src []float32) {
-	enqueue(call{
+func (ctx *context) VertexAttrib4fv(dst Attrib, src []float32) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnVertexAttrib4fv,
 			a0: dst.c(),
@@ -2166,19 +1666,8 @@ func VertexAttrib4fv(dst Attrib, src []float32) {
 	})
 }
 
-// VertexAttribPointer uses a bound buffer to define vertex attribute data.
-//
-// Direct use of VertexAttribPointer to load data into OpenGL is not
-// supported via the Go bindings. Instead, use BindBuffer with an
-// ARRAY_BUFFER and then fill it using BufferData.
-//
-// The size argument specifies the number of components per attribute,
-// between 1-4. The stride argument specifies the byte offset between
-// consecutive vertex attributes.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttribPointer.xhtml
-func VertexAttribPointer(dst Attrib, size int, ty Enum, normalized bool, stride, offset int) {
-	enqueue(call{
+func (ctx *context) VertexAttribPointer(dst Attrib, size int, ty Enum, normalized bool, stride, offset int) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnVertexAttribPointer,
 			a0: dst.c(),
@@ -2191,12 +1680,8 @@ func VertexAttribPointer(dst Attrib, size int, ty Enum, normalized bool, stride,
 	})
 }
 
-// Viewport sets the viewport, an affine transformation that
-// normalizes device coordinates to window coordinates.
-//
-// http://www.khronos.org/opengles/sdk/docs/man3/html/glViewport.xhtml
-func Viewport(x, y, width, height int) {
-	enqueue(call{
+func (ctx *context) Viewport(x, y, width, height int) {
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnViewport,
 			a0: C.uintptr_t(x),
diff --git a/gl/gldebug.go b/gl/gldebug.go
index 552c6ab..a0d152e 100644
--- a/gl/gldebug.go
+++ b/gl/gldebug.go
@@ -20,10 +20,10 @@ import (
 	"unsafe"
 )
 
-func errDrain() string {
+func (ctx *context) errDrain() string {
 	var errs []Enum
 	for {
-		e := GetError()
+		e := ctx.GetError()
 		if e == 0 {
 			break
 		}
@@ -630,12 +630,12 @@ func (v Enum) String() string {
 	}
 }
 
-func ActiveTexture(texture Enum) {
+func (ctx *context) ActiveTexture(texture Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.ActiveTexture(%v) %v", texture, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnActiveTexture,
 			a0: texture.c(),
@@ -643,12 +643,12 @@ func ActiveTexture(texture Enum) {
 	})
 }
 
-func AttachShader(p Program, s Shader) {
+func (ctx *context) AttachShader(p Program, s Shader) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.AttachShader(%v, %v) %v", p, s, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnAttachShader,
 			a0: p.c(),
@@ -657,12 +657,12 @@ func AttachShader(p Program, s Shader) {
 	})
 }
 
-func BindAttribLocation(p Program, a Attrib, name string) {
+func (ctx *context) BindAttribLocation(p Program, a Attrib, name string) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.BindAttribLocation(%v, %v, %v) %v", p, a, name, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBindAttribLocation,
 			a0: p.c(),
@@ -672,12 +672,12 @@ func BindAttribLocation(p Program, a Attrib, name string) {
 	})
 }
 
-func BindBuffer(target Enum, b Buffer) {
+func (ctx *context) BindBuffer(target Enum, b Buffer) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.BindBuffer(%v, %v) %v", target, b, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBindBuffer,
 			a0: target.c(),
@@ -686,12 +686,12 @@ func BindBuffer(target Enum, b Buffer) {
 	})
 }
 
-func BindFramebuffer(target Enum, fb Framebuffer) {
+func (ctx *context) BindFramebuffer(target Enum, fb Framebuffer) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.BindFramebuffer(%v, %v) %v", target, fb, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBindFramebuffer,
 			a0: target.c(),
@@ -700,12 +700,12 @@ func BindFramebuffer(target Enum, fb Framebuffer) {
 	})
 }
 
-func BindRenderbuffer(target Enum, rb Renderbuffer) {
+func (ctx *context) BindRenderbuffer(target Enum, rb Renderbuffer) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.BindRenderbuffer(%v, %v) %v", target, rb, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBindRenderbuffer,
 			a0: target.c(),
@@ -714,12 +714,12 @@ func BindRenderbuffer(target Enum, rb Renderbuffer) {
 	})
 }
 
-func BindTexture(target Enum, t Texture) {
+func (ctx *context) BindTexture(target Enum, t Texture) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.BindTexture(%v, %v) %v", target, t, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBindTexture,
 			a0: target.c(),
@@ -728,12 +728,12 @@ func BindTexture(target Enum, t Texture) {
 	})
 }
 
-func BlendColor(red, green, blue, alpha float32) {
+func (ctx *context) BlendColor(red, green, blue, alpha float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.BlendColor(%v, %v, %v, %v) %v", red, green, blue, alpha, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBlendColor,
 			a0: C.uintptr_t(math.Float32bits(red)),
@@ -744,12 +744,12 @@ func BlendColor(red, green, blue, alpha float32) {
 	})
 }
 
-func BlendEquation(mode Enum) {
+func (ctx *context) BlendEquation(mode Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.BlendEquation(%v) %v", mode, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBlendEquation,
 			a0: mode.c(),
@@ -757,12 +757,12 @@ func BlendEquation(mode Enum) {
 	})
 }
 
-func BlendEquationSeparate(modeRGB, modeAlpha Enum) {
+func (ctx *context) BlendEquationSeparate(modeRGB, modeAlpha Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.BlendEquationSeparate(%v, %v) %v", modeRGB, modeAlpha, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBlendEquationSeparate,
 			a0: modeRGB.c(),
@@ -771,12 +771,12 @@ func BlendEquationSeparate(modeRGB, modeAlpha Enum) {
 	})
 }
 
-func BlendFunc(sfactor, dfactor Enum) {
+func (ctx *context) BlendFunc(sfactor, dfactor Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.BlendFunc(%v, %v) %v", sfactor, dfactor, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBlendFunc,
 			a0: sfactor.c(),
@@ -785,12 +785,12 @@ func BlendFunc(sfactor, dfactor Enum) {
 	})
 }
 
-func BlendFuncSeparate(sfactorRGB, dfactorRGB, sfactorAlpha, dfactorAlpha Enum) {
+func (ctx *context) BlendFuncSeparate(sfactorRGB, dfactorRGB, sfactorAlpha, dfactorAlpha Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.BlendFuncSeparate(%v, %v, %v, %v) %v", sfactorRGB, dfactorRGB, sfactorAlpha, dfactorAlpha, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBlendFuncSeparate,
 			a0: sfactorRGB.c(),
@@ -801,12 +801,12 @@ func BlendFuncSeparate(sfactorRGB, dfactorRGB, sfactorAlpha, dfactorAlpha Enum)
 	})
 }
 
-func BufferData(target Enum, src []byte, usage Enum) {
+func (ctx *context) BufferData(target Enum, src []byte, usage Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.BufferData(%v, len(%d), %v) %v", target, len(src), usage, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBufferData,
 			a0: target.c(),
@@ -818,12 +818,12 @@ func BufferData(target Enum, src []byte, usage Enum) {
 	})
 }
 
-func BufferInit(target Enum, size int, usage Enum) {
+func (ctx *context) BufferInit(target Enum, size int, usage Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.BufferInit(%v, %v, %v) %v", target, size, usage, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBufferData,
 			a0: target.c(),
@@ -834,12 +834,12 @@ func BufferInit(target Enum, size int, usage Enum) {
 	})
 }
 
-func BufferSubData(target Enum, offset int, data []byte) {
+func (ctx *context) BufferSubData(target Enum, offset int, data []byte) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.BufferSubData(%v, %v, len(%d)) %v", target, offset, len(data), errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnBufferSubData,
 			a0: target.c(),
@@ -851,12 +851,12 @@ func BufferSubData(target Enum, offset int, data []byte) {
 	})
 }
 
-func CheckFramebufferStatus(target Enum) (r0 Enum) {
+func (ctx *context) CheckFramebufferStatus(target Enum) (r0 Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.CheckFramebufferStatus(%v) %v%v", target, r0, errstr)
 	}()
-	return Enum(enqueue(call{
+	return Enum(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnCheckFramebufferStatus,
 			a0: target.c(),
@@ -865,12 +865,12 @@ func CheckFramebufferStatus(target Enum) (r0 Enum) {
 	}))
 }
 
-func Clear(mask Enum) {
+func (ctx *context) Clear(mask Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.Clear(%v) %v", mask, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnClear,
 			a0: C.uintptr_t(mask),
@@ -878,12 +878,12 @@ func Clear(mask Enum) {
 	})
 }
 
-func ClearColor(red, green, blue, alpha float32) {
+func (ctx *context) ClearColor(red, green, blue, alpha float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.ClearColor(%v, %v, %v, %v) %v", red, green, blue, alpha, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnClearColor,
 			a0: C.uintptr_t(math.Float32bits(red)),
@@ -894,12 +894,12 @@ func ClearColor(red, green, blue, alpha float32) {
 	})
 }
 
-func ClearDepthf(d float32) {
+func (ctx *context) ClearDepthf(d float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.ClearDepthf(%v) %v", d, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnClearDepthf,
 			a0: C.uintptr_t(math.Float32bits(d)),
@@ -907,12 +907,12 @@ func ClearDepthf(d float32) {
 	})
 }
 
-func ClearStencil(s int) {
+func (ctx *context) ClearStencil(s int) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.ClearStencil(%v) %v", s, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnClearStencil,
 			a0: C.uintptr_t(s),
@@ -920,12 +920,12 @@ func ClearStencil(s int) {
 	})
 }
 
-func ColorMask(red, green, blue, alpha bool) {
+func (ctx *context) ColorMask(red, green, blue, alpha bool) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.ColorMask(%v, %v, %v, %v) %v", red, green, blue, alpha, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnColorMask,
 			a0: glBoolean(red),
@@ -936,12 +936,12 @@ func ColorMask(red, green, blue, alpha bool) {
 	})
 }
 
-func CompileShader(s Shader) {
+func (ctx *context) CompileShader(s Shader) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.CompileShader(%v) %v", s, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnCompileShader,
 			a0: s.c(),
@@ -949,12 +949,12 @@ func CompileShader(s Shader) {
 	})
 }
 
-func CompressedTexImage2D(target Enum, level int, internalformat Enum, width, height, border int, data []byte) {
+func (ctx *context) CompressedTexImage2D(target Enum, level int, internalformat Enum, width, height, border int, data []byte) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.CompressedTexImage2D(%v, %v, %v, %v, %v, %v, len(%d)) %v", target, level, internalformat, width, height, border, len(data), errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnCompressedTexImage2D,
 			a0: target.c(),
@@ -970,12 +970,12 @@ func CompressedTexImage2D(target Enum, level int, internalformat Enum, width, he
 	})
 }
 
-func CompressedTexSubImage2D(target Enum, level, xoffset, yoffset, width, height int, format Enum, data []byte) {
+func (ctx *context) CompressedTexSubImage2D(target Enum, level, xoffset, yoffset, width, height int, format Enum, data []byte) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.CompressedTexSubImage2D(%v, %v, %v, %v, %v, %v, %v, len(%d)) %v", target, level, xoffset, yoffset, width, height, format, len(data), errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnCompressedTexSubImage2D,
 			a0: target.c(),
@@ -992,12 +992,12 @@ func CompressedTexSubImage2D(target Enum, level, xoffset, yoffset, width, height
 	})
 }
 
-func CopyTexImage2D(target Enum, level int, internalformat Enum, x, y, width, height, border int) {
+func (ctx *context) CopyTexImage2D(target Enum, level int, internalformat Enum, x, y, width, height, border int) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.CopyTexImage2D(%v, %v, %v, %v, %v, %v, %v, %v) %v", target, level, internalformat, x, y, width, height, border, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnCopyTexImage2D,
 			a0: target.c(),
@@ -1012,12 +1012,12 @@ func CopyTexImage2D(target Enum, level int, internalformat Enum, x, y, width, he
 	})
 }
 
-func CopyTexSubImage2D(target Enum, level, xoffset, yoffset, x, y, width, height int) {
+func (ctx *context) CopyTexSubImage2D(target Enum, level, xoffset, yoffset, x, y, width, height int) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.CopyTexSubImage2D(%v, %v, %v, %v, %v, %v, %v, %v) %v", target, level, xoffset, yoffset, x, y, width, height, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnCopyTexSubImage2D,
 			a0: target.c(),
@@ -1032,12 +1032,12 @@ func CopyTexSubImage2D(target Enum, level, xoffset, yoffset, x, y, width, height
 	})
 }
 
-func CreateBuffer() (r0 Buffer) {
+func (ctx *context) CreateBuffer() (r0 Buffer) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.CreateBuffer() %v%v", r0, errstr)
 	}()
-	return Buffer{Value: uint32(enqueue(call{
+	return Buffer{Value: uint32(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGenBuffer,
 		},
@@ -1045,12 +1045,12 @@ func CreateBuffer() (r0 Buffer) {
 	}))}
 }
 
-func CreateFramebuffer() (r0 Framebuffer) {
+func (ctx *context) CreateFramebuffer() (r0 Framebuffer) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.CreateFramebuffer() %v%v", r0, errstr)
 	}()
-	return Framebuffer{Value: uint32(enqueue(call{
+	return Framebuffer{Value: uint32(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGenFramebuffer,
 		},
@@ -1058,12 +1058,12 @@ func CreateFramebuffer() (r0 Framebuffer) {
 	}))}
 }
 
-func CreateProgram() (r0 Program) {
+func (ctx *context) CreateProgram() (r0 Program) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.CreateProgram() %v%v", r0, errstr)
 	}()
-	return Program{Value: uint32(enqueue(call{
+	return Program{Value: uint32(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnCreateProgram,
 		},
@@ -1071,12 +1071,12 @@ func CreateProgram() (r0 Program) {
 	}))}
 }
 
-func CreateRenderbuffer() (r0 Renderbuffer) {
+func (ctx *context) CreateRenderbuffer() (r0 Renderbuffer) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.CreateRenderbuffer() %v%v", r0, errstr)
 	}()
-	return Renderbuffer{Value: uint32(enqueue(call{
+	return Renderbuffer{Value: uint32(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGenRenderbuffer,
 		},
@@ -1084,12 +1084,12 @@ func CreateRenderbuffer() (r0 Renderbuffer) {
 	}))}
 }
 
-func CreateShader(ty Enum) (r0 Shader) {
+func (ctx *context) CreateShader(ty Enum) (r0 Shader) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.CreateShader(%v) %v%v", ty, r0, errstr)
 	}()
-	return Shader{Value: uint32(enqueue(call{
+	return Shader{Value: uint32(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnCreateShader,
 			a0: C.uintptr_t(ty),
@@ -1098,12 +1098,12 @@ func CreateShader(ty Enum) (r0 Shader) {
 	}))}
 }
 
-func CreateTexture() (r0 Texture) {
+func (ctx *context) CreateTexture() (r0 Texture) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.CreateTexture() %v%v", r0, errstr)
 	}()
-	return Texture{Value: uint32(enqueue(call{
+	return Texture{Value: uint32(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGenTexture,
 		},
@@ -1111,12 +1111,12 @@ func CreateTexture() (r0 Texture) {
 	}))}
 }
 
-func CullFace(mode Enum) {
+func (ctx *context) CullFace(mode Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.CullFace(%v) %v", mode, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnCullFace,
 			a0: mode.c(),
@@ -1124,12 +1124,12 @@ func CullFace(mode Enum) {
 	})
 }
 
-func DeleteBuffer(v Buffer) {
+func (ctx *context) DeleteBuffer(v Buffer) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.DeleteBuffer(%v) %v", v, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDeleteBuffer,
 			a0: C.uintptr_t(v.Value),
@@ -1137,12 +1137,12 @@ func DeleteBuffer(v Buffer) {
 	})
 }
 
-func DeleteFramebuffer(v Framebuffer) {
+func (ctx *context) DeleteFramebuffer(v Framebuffer) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.DeleteFramebuffer(%v) %v", v, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDeleteFramebuffer,
 			a0: C.uintptr_t(v.Value),
@@ -1150,12 +1150,12 @@ func DeleteFramebuffer(v Framebuffer) {
 	})
 }
 
-func DeleteProgram(p Program) {
+func (ctx *context) DeleteProgram(p Program) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.DeleteProgram(%v) %v", p, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDeleteProgram,
 			a0: p.c(),
@@ -1163,12 +1163,12 @@ func DeleteProgram(p Program) {
 	})
 }
 
-func DeleteRenderbuffer(v Renderbuffer) {
+func (ctx *context) DeleteRenderbuffer(v Renderbuffer) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.DeleteRenderbuffer(%v) %v", v, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDeleteRenderbuffer,
 			a0: v.c(),
@@ -1176,12 +1176,12 @@ func DeleteRenderbuffer(v Renderbuffer) {
 	})
 }
 
-func DeleteShader(s Shader) {
+func (ctx *context) DeleteShader(s Shader) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.DeleteShader(%v) %v", s, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDeleteShader,
 			a0: s.c(),
@@ -1189,12 +1189,12 @@ func DeleteShader(s Shader) {
 	})
 }
 
-func DeleteTexture(v Texture) {
+func (ctx *context) DeleteTexture(v Texture) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.DeleteTexture(%v) %v", v, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDeleteTexture,
 			a0: v.c(),
@@ -1202,12 +1202,12 @@ func DeleteTexture(v Texture) {
 	})
 }
 
-func DepthFunc(fn Enum) {
+func (ctx *context) DepthFunc(fn Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.DepthFunc(%v) %v", fn, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDepthFunc,
 			a0: fn.c(),
@@ -1215,12 +1215,12 @@ func DepthFunc(fn Enum) {
 	})
 }
 
-func DepthMask(flag bool) {
+func (ctx *context) DepthMask(flag bool) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.DepthMask(%v) %v", flag, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDepthMask,
 			a0: glBoolean(flag),
@@ -1228,12 +1228,12 @@ func DepthMask(flag bool) {
 	})
 }
 
-func DepthRangef(n, f float32) {
+func (ctx *context) DepthRangef(n, f float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.DepthRangef(%v, %v) %v", n, f, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDepthRangef,
 			a0: C.uintptr_t(math.Float32bits(n)),
@@ -1242,12 +1242,12 @@ func DepthRangef(n, f float32) {
 	})
 }
 
-func DetachShader(p Program, s Shader) {
+func (ctx *context) DetachShader(p Program, s Shader) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.DetachShader(%v, %v) %v", p, s, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDetachShader,
 			a0: p.c(),
@@ -1256,12 +1256,12 @@ func DetachShader(p Program, s Shader) {
 	})
 }
 
-func Disable(cap Enum) {
+func (ctx *context) Disable(cap Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.Disable(%v) %v", cap, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDisable,
 			a0: cap.c(),
@@ -1269,12 +1269,12 @@ func Disable(cap Enum) {
 	})
 }
 
-func DisableVertexAttribArray(a Attrib) {
+func (ctx *context) DisableVertexAttribArray(a Attrib) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.DisableVertexAttribArray(%v) %v", a, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDisableVertexAttribArray,
 			a0: a.c(),
@@ -1282,12 +1282,12 @@ func DisableVertexAttribArray(a Attrib) {
 	})
 }
 
-func DrawArrays(mode Enum, first, count int) {
+func (ctx *context) DrawArrays(mode Enum, first, count int) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.DrawArrays(%v, %v, %v) %v", mode, first, count, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDrawArrays,
 			a0: mode.c(),
@@ -1297,12 +1297,12 @@ func DrawArrays(mode Enum, first, count int) {
 	})
 }
 
-func DrawElements(mode Enum, count int, ty Enum, offset int) {
+func (ctx *context) DrawElements(mode Enum, count int, ty Enum, offset int) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.DrawElements(%v, %v, %v, %v) %v", mode, count, ty, offset, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnDrawElements,
 			a0: mode.c(),
@@ -1313,12 +1313,12 @@ func DrawElements(mode Enum, count int, ty Enum, offset int) {
 	})
 }
 
-func Enable(cap Enum) {
+func (ctx *context) Enable(cap Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.Enable(%v) %v", cap, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnEnable,
 			a0: cap.c(),
@@ -1326,12 +1326,12 @@ func Enable(cap Enum) {
 	})
 }
 
-func EnableVertexAttribArray(a Attrib) {
+func (ctx *context) EnableVertexAttribArray(a Attrib) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.EnableVertexAttribArray(%v) %v", a, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnEnableVertexAttribArray,
 			a0: a.c(),
@@ -1339,12 +1339,12 @@ func EnableVertexAttribArray(a Attrib) {
 	})
 }
 
-func Finish() {
+func (ctx *context) Finish() {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.Finish() %v", errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnFinish,
 		},
@@ -1352,12 +1352,12 @@ func Finish() {
 	})
 }
 
-func Flush() {
+func (ctx *context) Flush() {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.Flush() %v", errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnFlush,
 		},
@@ -1365,12 +1365,12 @@ func Flush() {
 	})
 }
 
-func FramebufferRenderbuffer(target, attachment, rbTarget Enum, rb Renderbuffer) {
+func (ctx *context) FramebufferRenderbuffer(target, attachment, rbTarget Enum, rb Renderbuffer) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.FramebufferRenderbuffer(%v, %v, %v, %v) %v", target, attachment, rbTarget, rb, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnFramebufferRenderbuffer,
 			a0: target.c(),
@@ -1381,12 +1381,12 @@ func FramebufferRenderbuffer(target, attachment, rbTarget Enum, rb Renderbuffer)
 	})
 }
 
-func FramebufferTexture2D(target, attachment, texTarget Enum, t Texture, level int) {
+func (ctx *context) FramebufferTexture2D(target, attachment, texTarget Enum, t Texture, level int) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.FramebufferTexture2D(%v, %v, %v, %v, %v) %v", target, attachment, texTarget, t, level, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnFramebufferTexture2D,
 			a0: target.c(),
@@ -1398,12 +1398,12 @@ func FramebufferTexture2D(target, attachment, texTarget Enum, t Texture, level i
 	})
 }
 
-func FrontFace(mode Enum) {
+func (ctx *context) FrontFace(mode Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.FrontFace(%v) %v", mode, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnFrontFace,
 			a0: mode.c(),
@@ -1411,12 +1411,12 @@ func FrontFace(mode Enum) {
 	})
 }
 
-func GenerateMipmap(target Enum) {
+func (ctx *context) GenerateMipmap(target Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GenerateMipmap(%v) %v", target, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGenerateMipmap,
 			a0: target.c(),
@@ -1424,17 +1424,17 @@ func GenerateMipmap(target Enum) {
 	})
 }
 
-func GetActiveAttrib(p Program, index uint32) (name string, size int, ty Enum) {
+func (ctx *context) GetActiveAttrib(p Program, index uint32) (name string, size int, ty Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetActiveAttrib(%v, %v) (%v, %v, %v) %v", p, index, name, size, ty, errstr)
 	}()
-	bufSize := GetProgrami(p, ACTIVE_ATTRIBUTE_MAX_LENGTH)
+	bufSize := ctx.GetProgrami(p, ACTIVE_ATTRIBUTE_MAX_LENGTH)
 	buf := C.malloc(C.size_t(bufSize))
 	defer C.free(buf)
 	var cSize C.GLint
 	var cType C.GLenum
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetActiveAttrib,
 			a0: p.c(),
@@ -1450,17 +1450,17 @@ func GetActiveAttrib(p Program, index uint32) (name string, size int, ty Enum) {
 	return C.GoString((*C.char)(buf)), int(cSize), Enum(cType)
 }
 
-func GetActiveUniform(p Program, index uint32) (name string, size int, ty Enum) {
+func (ctx *context) GetActiveUniform(p Program, index uint32) (name string, size int, ty Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetActiveUniform(%v, %v) (%v, %v, %v) %v", p, index, name, size, ty, errstr)
 	}()
-	bufSize := GetProgrami(p, ACTIVE_UNIFORM_MAX_LENGTH)
+	bufSize := ctx.GetProgrami(p, ACTIVE_UNIFORM_MAX_LENGTH)
 	buf := C.malloc(C.size_t(bufSize))
 	defer C.free(buf)
 	var cSize C.GLint
 	var cType C.GLenum
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetActiveUniform,
 			a0: p.c(),
@@ -1476,18 +1476,18 @@ func GetActiveUniform(p Program, index uint32) (name string, size int, ty Enum)
 	return C.GoString((*C.char)(buf)), int(cSize), Enum(cType)
 }
 
-func GetAttachedShaders(p Program) (r0 []Shader) {
+func (ctx *context) GetAttachedShaders(p Program) (r0 []Shader) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetAttachedShaders(%v) %v%v", p, r0, errstr)
 	}()
-	shadersLen := GetProgrami(p, ATTACHED_SHADERS)
+	shadersLen := ctx.GetProgrami(p, ATTACHED_SHADERS)
 	if shadersLen == 0 {
 		return nil
 	}
 	var n C.GLsizei
 	buf := make([]C.GLuint, shadersLen)
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetAttachedShaders,
 			a0: p.c(),
@@ -1505,13 +1505,13 @@ func GetAttachedShaders(p Program) (r0 []Shader) {
 	return shaders
 }
 
-func GetAttribLocation(p Program, name string) (r0 Attrib) {
+func (ctx *context) GetAttribLocation(p Program, name string) (r0 Attrib) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		r0.name = name
 		log.Printf("gl.GetAttribLocation(%v, %v) %v%v", p, name, r0, errstr)
 	}()
-	return Attrib{Value: uint(enqueue(call{
+	return Attrib{Value: uint(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetAttribLocation,
 			a0: p.c(),
@@ -1521,13 +1521,13 @@ func GetAttribLocation(p Program, name string) (r0 Attrib) {
 	}))}
 }
 
-func GetBooleanv(dst []bool, pname Enum) {
+func (ctx *context) GetBooleanv(dst []bool, pname Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetBooleanv(%v, %v) %v", dst, pname, errstr)
 	}()
 	buf := make([]C.GLboolean, len(dst))
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetBooleanv,
 			a0: pname.c(),
@@ -1540,12 +1540,12 @@ func GetBooleanv(dst []bool, pname Enum) {
 	}
 }
 
-func GetFloatv(dst []float32, pname Enum) {
+func (ctx *context) GetFloatv(dst []float32, pname Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetFloatv(len(%d), %v) %v", len(dst), pname, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetFloatv,
 			a0: pname.c(),
@@ -1555,13 +1555,13 @@ func GetFloatv(dst []float32, pname Enum) {
 	})
 }
 
-func GetIntegerv(dst []int32, pname Enum) {
+func (ctx *context) GetIntegerv(dst []int32, pname Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetIntegerv(%v, %v) %v", dst, pname, errstr)
 	}()
 	buf := make([]C.GLint, len(dst))
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetIntegerv,
 			a0: pname.c(),
@@ -1574,22 +1574,22 @@ func GetIntegerv(dst []int32, pname Enum) {
 	}
 }
 
-func GetInteger(pname Enum) (r0 int) {
+func (ctx *context) GetInteger(pname Enum) (r0 int) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetInteger(%v) %v%v", pname, r0, errstr)
 	}()
 	var v [1]int32
-	GetIntegerv(v[:], pname)
+	ctx.GetIntegerv(v[:], pname)
 	return int(v[0])
 }
 
-func GetBufferParameteri(target, value Enum) (r0 int) {
+func (ctx *context) GetBufferParameteri(target, value Enum) (r0 int) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetBufferParameteri(%v, %v) %v%v", target, value, r0, errstr)
 	}()
-	return int(enqueue(call{
+	return int(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetBufferParameteri,
 			a0: target.c(),
@@ -1599,8 +1599,8 @@ func GetBufferParameteri(target, value Enum) (r0 int) {
 	}))
 }
 
-func GetError() (r0 Enum) {
-	return Enum(enqueue(call{
+func (ctx *context) GetError() (r0 Enum) {
+	return Enum(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetError,
 		},
@@ -1608,12 +1608,12 @@ func GetError() (r0 Enum) {
 	}))
 }
 
-func GetFramebufferAttachmentParameteri(target, attachment, pname Enum) (r0 int) {
+func (ctx *context) GetFramebufferAttachmentParameteri(target, attachment, pname Enum) (r0 int) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetFramebufferAttachmentParameteri(%v, %v, %v) %v%v", target, attachment, pname, r0, errstr)
 	}()
-	return int(enqueue(call{
+	return int(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetFramebufferAttachmentParameteriv,
 			a0: target.c(),
@@ -1624,12 +1624,12 @@ func GetFramebufferAttachmentParameteri(target, attachment, pname Enum) (r0 int)
 	}))
 }
 
-func GetProgrami(p Program, pname Enum) (r0 int) {
+func (ctx *context) GetProgrami(p Program, pname Enum) (r0 int) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetProgrami(%v, %v) %v%v", p, pname, r0, errstr)
 	}()
-	return int(enqueue(call{
+	return int(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetProgramiv,
 			a0: p.c(),
@@ -1639,15 +1639,15 @@ func GetProgrami(p Program, pname Enum) (r0 int) {
 	}))
 }
 
-func GetProgramInfoLog(p Program) (r0 string) {
+func (ctx *context) GetProgramInfoLog(p Program) (r0 string) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetProgramInfoLog(%v) %v%v", p, r0, errstr)
 	}()
-	infoLen := GetProgrami(p, INFO_LOG_LENGTH)
+	infoLen := ctx.GetProgrami(p, INFO_LOG_LENGTH)
 	buf := C.malloc(C.size_t(infoLen))
 	defer C.free(buf)
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetProgramInfoLog,
 			a0: p.c(),
@@ -1660,12 +1660,12 @@ func GetProgramInfoLog(p Program) (r0 string) {
 	return C.GoString((*C.char)(buf))
 }
 
-func GetRenderbufferParameteri(target, pname Enum) (r0 int) {
+func (ctx *context) GetRenderbufferParameteri(target, pname Enum) (r0 int) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetRenderbufferParameteri(%v, %v) %v%v", target, pname, r0, errstr)
 	}()
-	return int(enqueue(call{
+	return int(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetRenderbufferParameteriv,
 			a0: target.c(),
@@ -1675,12 +1675,12 @@ func GetRenderbufferParameteri(target, pname Enum) (r0 int) {
 	}))
 }
 
-func GetShaderi(s Shader, pname Enum) (r0 int) {
+func (ctx *context) GetShaderi(s Shader, pname Enum) (r0 int) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetShaderi(%v, %v) %v%v", s, pname, r0, errstr)
 	}()
-	return int(enqueue(call{
+	return int(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetShaderiv,
 			a0: s.c(),
@@ -1690,15 +1690,15 @@ func GetShaderi(s Shader, pname Enum) (r0 int) {
 	}))
 }
 
-func GetShaderInfoLog(s Shader) (r0 string) {
+func (ctx *context) GetShaderInfoLog(s Shader) (r0 string) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetShaderInfoLog(%v) %v%v", s, r0, errstr)
 	}()
-	infoLen := GetShaderi(s, INFO_LOG_LENGTH)
+	infoLen := ctx.GetShaderi(s, INFO_LOG_LENGTH)
 	buf := C.malloc(C.size_t(infoLen))
 	defer C.free(buf)
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetShaderInfoLog,
 			a0: s.c(),
@@ -1711,14 +1711,14 @@ func GetShaderInfoLog(s Shader) (r0 string) {
 	return C.GoString((*C.char)(buf))
 }
 
-func GetShaderPrecisionFormat(shadertype, precisiontype Enum) (rangeLow, rangeHigh, precision int) {
+func (ctx *context) GetShaderPrecisionFormat(shadertype, precisiontype Enum) (rangeLow, rangeHigh, precision int) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetShaderPrecisionFormat(%v, %v) (%v, %v, %v) %v", shadertype, precisiontype, rangeLow, rangeHigh, precision, errstr)
 	}()
 	var cRange [2]C.GLint
 	var cPrecision C.GLint
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetShaderPrecisionFormat,
 			a0: shadertype.c(),
@@ -1731,18 +1731,18 @@ func GetShaderPrecisionFormat(shadertype, precisiontype Enum) (rangeLow, rangeHi
 	return int(cRange[0]), int(cRange[1]), int(cPrecision)
 }
 
-func GetShaderSource(s Shader) (r0 string) {
+func (ctx *context) GetShaderSource(s Shader) (r0 string) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetShaderSource(%v) %v%v", s, r0, errstr)
 	}()
-	sourceLen := GetShaderi(s, SHADER_SOURCE_LENGTH)
+	sourceLen := ctx.GetShaderi(s, SHADER_SOURCE_LENGTH)
 	if sourceLen == 0 {
 		return ""
 	}
 	buf := C.malloc(C.size_t(sourceLen))
 	defer C.free(buf)
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetShaderSource,
 			a0: s.c(),
@@ -1755,12 +1755,12 @@ func GetShaderSource(s Shader) (r0 string) {
 	return C.GoString((*C.char)(buf))
 }
 
-func GetString(pname Enum) (r0 string) {
+func (ctx *context) GetString(pname Enum) (r0 string) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetString(%v) %v%v", pname, r0, errstr)
 	}()
-	ret := enqueue(call{
+	ret := ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetString,
 			a0: pname.c(),
@@ -1770,12 +1770,12 @@ func GetString(pname Enum) (r0 string) {
 	return C.GoString((*C.char)((unsafe.Pointer(uintptr(ret)))))
 }
 
-func GetTexParameterfv(dst []float32, target, pname Enum) {
+func (ctx *context) GetTexParameterfv(dst []float32, target, pname Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetTexParameterfv(len(%d), %v, %v) %v", len(dst), target, pname, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetTexParameterfv,
 			a0: target.c(),
@@ -1786,12 +1786,12 @@ func GetTexParameterfv(dst []float32, target, pname Enum) {
 	})
 }
 
-func GetTexParameteriv(dst []int32, target, pname Enum) {
+func (ctx *context) GetTexParameteriv(dst []int32, target, pname Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetTexParameteriv(%v, %v, %v) %v", dst, target, pname, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetTexParameteriv,
 			a0: target.c(),
@@ -1802,12 +1802,12 @@ func GetTexParameteriv(dst []int32, target, pname Enum) {
 	})
 }
 
-func GetUniformfv(dst []float32, src Uniform, p Program) {
+func (ctx *context) GetUniformfv(dst []float32, src Uniform, p Program) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetUniformfv(len(%d), %v, %v) %v", len(dst), src, p, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetUniformfv,
 			a0: p.c(),
@@ -1818,12 +1818,12 @@ func GetUniformfv(dst []float32, src Uniform, p Program) {
 	})
 }
 
-func GetUniformiv(dst []int32, src Uniform, p Program) {
+func (ctx *context) GetUniformiv(dst []int32, src Uniform, p Program) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetUniformiv(%v, %v, %v) %v", dst, src, p, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetUniformiv,
 			a0: p.c(),
@@ -1834,13 +1834,13 @@ func GetUniformiv(dst []int32, src Uniform, p Program) {
 	})
 }
 
-func GetUniformLocation(p Program, name string) (r0 Uniform) {
+func (ctx *context) GetUniformLocation(p Program, name string) (r0 Uniform) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		r0.name = name
 		log.Printf("gl.GetUniformLocation(%v, %v) %v%v", p, name, r0, errstr)
 	}()
-	return Uniform{Value: int32(enqueue(call{
+	return Uniform{Value: int32(ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetUniformLocation,
 			a0: p.c(),
@@ -1850,22 +1850,22 @@ func GetUniformLocation(p Program, name string) (r0 Uniform) {
 	}))}
 }
 
-func GetVertexAttribf(src Attrib, pname Enum) (r0 float32) {
+func (ctx *context) GetVertexAttribf(src Attrib, pname Enum) (r0 float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetVertexAttribf(%v, %v) %v%v", src, pname, r0, errstr)
 	}()
 	var params [1]float32
-	GetVertexAttribfv(params[:], src, pname)
+	ctx.GetVertexAttribfv(params[:], src, pname)
 	return params[0]
 }
 
-func GetVertexAttribfv(dst []float32, src Attrib, pname Enum) {
+func (ctx *context) GetVertexAttribfv(dst []float32, src Attrib, pname Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetVertexAttribfv(len(%d), %v, %v) %v", len(dst), src, pname, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetVertexAttribfv,
 			a0: src.c(),
@@ -1876,22 +1876,22 @@ func GetVertexAttribfv(dst []float32, src Attrib, pname Enum) {
 	})
 }
 
-func GetVertexAttribi(src Attrib, pname Enum) (r0 int32) {
+func (ctx *context) GetVertexAttribi(src Attrib, pname Enum) (r0 int32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetVertexAttribi(%v, %v) %v%v", src, pname, r0, errstr)
 	}()
 	var params [1]int32
-	GetVertexAttribiv(params[:], src, pname)
+	ctx.GetVertexAttribiv(params[:], src, pname)
 	return params[0]
 }
 
-func GetVertexAttribiv(dst []int32, src Attrib, pname Enum) {
+func (ctx *context) GetVertexAttribiv(dst []int32, src Attrib, pname Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.GetVertexAttribiv(%v, %v, %v) %v", dst, src, pname, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnGetVertexAttribiv,
 			a0: src.c(),
@@ -1902,12 +1902,12 @@ func GetVertexAttribiv(dst []int32, src Attrib, pname Enum) {
 	})
 }
 
-func Hint(target, mode Enum) {
+func (ctx *context) Hint(target, mode Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.Hint(%v, %v) %v", target, mode, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnHint,
 			a0: target.c(),
@@ -1916,12 +1916,12 @@ func Hint(target, mode Enum) {
 	})
 }
 
-func IsBuffer(b Buffer) (r0 bool) {
+func (ctx *context) IsBuffer(b Buffer) (r0 bool) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.IsBuffer(%v) %v%v", b, r0, errstr)
 	}()
-	return 0 != enqueue(call{
+	return 0 != ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnIsBuffer,
 			a0: b.c(),
@@ -1930,12 +1930,12 @@ func IsBuffer(b Buffer) (r0 bool) {
 	})
 }
 
-func IsEnabled(cap Enum) (r0 bool) {
+func (ctx *context) IsEnabled(cap Enum) (r0 bool) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.IsEnabled(%v) %v%v", cap, r0, errstr)
 	}()
-	return 0 != enqueue(call{
+	return 0 != ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnIsEnabled,
 			a0: cap.c(),
@@ -1944,12 +1944,12 @@ func IsEnabled(cap Enum) (r0 bool) {
 	})
 }
 
-func IsFramebuffer(fb Framebuffer) (r0 bool) {
+func (ctx *context) IsFramebuffer(fb Framebuffer) (r0 bool) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.IsFramebuffer(%v) %v%v", fb, r0, errstr)
 	}()
-	return 0 != enqueue(call{
+	return 0 != ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnIsFramebuffer,
 			a0: fb.c(),
@@ -1958,12 +1958,12 @@ func IsFramebuffer(fb Framebuffer) (r0 bool) {
 	})
 }
 
-func IsProgram(p Program) (r0 bool) {
+func (ctx *context) IsProgram(p Program) (r0 bool) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.IsProgram(%v) %v%v", p, r0, errstr)
 	}()
-	return 0 != enqueue(call{
+	return 0 != ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnIsProgram,
 			a0: p.c(),
@@ -1972,12 +1972,12 @@ func IsProgram(p Program) (r0 bool) {
 	})
 }
 
-func IsRenderbuffer(rb Renderbuffer) (r0 bool) {
+func (ctx *context) IsRenderbuffer(rb Renderbuffer) (r0 bool) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.IsRenderbuffer(%v) %v%v", rb, r0, errstr)
 	}()
-	return 0 != enqueue(call{
+	return 0 != ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnIsRenderbuffer,
 			a0: rb.c(),
@@ -1986,12 +1986,12 @@ func IsRenderbuffer(rb Renderbuffer) (r0 bool) {
 	})
 }
 
-func IsShader(s Shader) (r0 bool) {
+func (ctx *context) IsShader(s Shader) (r0 bool) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.IsShader(%v) %v%v", s, r0, errstr)
 	}()
-	return 0 != enqueue(call{
+	return 0 != ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnIsShader,
 			a0: s.c(),
@@ -2000,12 +2000,12 @@ func IsShader(s Shader) (r0 bool) {
 	})
 }
 
-func IsTexture(t Texture) (r0 bool) {
+func (ctx *context) IsTexture(t Texture) (r0 bool) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.IsTexture(%v) %v%v", t, r0, errstr)
 	}()
-	return 0 != enqueue(call{
+	return 0 != ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnIsTexture,
 			a0: t.c(),
@@ -2014,12 +2014,12 @@ func IsTexture(t Texture) (r0 bool) {
 	})
 }
 
-func LineWidth(width float32) {
+func (ctx *context) LineWidth(width float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.LineWidth(%v) %v", width, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnLineWidth,
 			a0: C.uintptr_t(math.Float32bits(width)),
@@ -2027,12 +2027,12 @@ func LineWidth(width float32) {
 	})
 }
 
-func LinkProgram(p Program) {
+func (ctx *context) LinkProgram(p Program) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.LinkProgram(%v) %v", p, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnLinkProgram,
 			a0: p.c(),
@@ -2040,12 +2040,12 @@ func LinkProgram(p Program) {
 	})
 }
 
-func PixelStorei(pname Enum, param int32) {
+func (ctx *context) PixelStorei(pname Enum, param int32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.PixelStorei(%v, %v) %v", pname, param, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnPixelStorei,
 			a0: pname.c(),
@@ -2054,12 +2054,12 @@ func PixelStorei(pname Enum, param int32) {
 	})
 }
 
-func PolygonOffset(factor, units float32) {
+func (ctx *context) PolygonOffset(factor, units float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.PolygonOffset(%v, %v) %v", factor, units, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnPolygonOffset,
 			a0: C.uintptr_t(math.Float32bits(factor)),
@@ -2068,12 +2068,12 @@ func PolygonOffset(factor, units float32) {
 	})
 }
 
-func ReadPixels(dst []byte, x, y, width, height int, format, ty Enum) {
+func (ctx *context) ReadPixels(dst []byte, x, y, width, height int, format, ty Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.ReadPixels(len(%d), %v, %v, %v, %v, %v, %v) %v", len(dst), x, y, width, height, format, ty, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnReadPixels,
 
@@ -2089,24 +2089,24 @@ func ReadPixels(dst []byte, x, y, width, height int, format, ty Enum) {
 	})
 }
 
-func ReleaseShaderCompiler() {
+func (ctx *context) ReleaseShaderCompiler() {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.ReleaseShaderCompiler() %v", errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnReleaseShaderCompiler,
 		},
 	})
 }
 
-func RenderbufferStorage(target, internalFormat Enum, width, height int) {
+func (ctx *context) RenderbufferStorage(target, internalFormat Enum, width, height int) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.RenderbufferStorage(%v, %v, %v, %v) %v", target, internalFormat, width, height, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnRenderbufferStorage,
 			a0: target.c(),
@@ -2117,12 +2117,12 @@ func RenderbufferStorage(target, internalFormat Enum, width, height int) {
 	})
 }
 
-func SampleCoverage(value float32, invert bool) {
+func (ctx *context) SampleCoverage(value float32, invert bool) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.SampleCoverage(%v, %v) %v", value, invert, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnSampleCoverage,
 			a0: C.uintptr_t(math.Float32bits(value)),
@@ -2131,12 +2131,12 @@ func SampleCoverage(value float32, invert bool) {
 	})
 }
 
-func Scissor(x, y, width, height int32) {
+func (ctx *context) Scissor(x, y, width, height int32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.Scissor(%v, %v, %v, %v) %v", x, y, width, height, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnScissor,
 			a0: C.uintptr_t(x),
@@ -2147,15 +2147,15 @@ func Scissor(x, y, width, height int32) {
 	})
 }
 
-func ShaderSource(s Shader, src string) {
+func (ctx *context) ShaderSource(s Shader, src string) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.ShaderSource(%v, %v) %v", s, src, errstr)
 	}()
 	cstr := C.CString(src)
 	cstrp := (**C.char)(C.malloc(C.size_t(unsafe.Sizeof(cstr))))
 	*cstrp = cstr
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnShaderSource,
 			a0: s.c(),
@@ -2165,12 +2165,12 @@ func ShaderSource(s Shader, src string) {
 	})
 }
 
-func StencilFunc(fn Enum, ref int, mask uint32) {
+func (ctx *context) StencilFunc(fn Enum, ref int, mask uint32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.StencilFunc(%v, %v, %v) %v", fn, ref, mask, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnStencilFunc,
 			a0: fn.c(),
@@ -2180,12 +2180,12 @@ func StencilFunc(fn Enum, ref int, mask uint32) {
 	})
 }
 
-func StencilFuncSeparate(face, fn Enum, ref int, mask uint32) {
+func (ctx *context) StencilFuncSeparate(face, fn Enum, ref int, mask uint32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.StencilFuncSeparate(%v, %v, %v, %v) %v", face, fn, ref, mask, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnStencilFuncSeparate,
 			a0: face.c(),
@@ -2196,12 +2196,12 @@ func StencilFuncSeparate(face, fn Enum, ref int, mask uint32) {
 	})
 }
 
-func StencilMask(mask uint32) {
+func (ctx *context) StencilMask(mask uint32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.StencilMask(%v) %v", mask, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnStencilMask,
 			a0: C.uintptr_t(mask),
@@ -2209,12 +2209,12 @@ func StencilMask(mask uint32) {
 	})
 }
 
-func StencilMaskSeparate(face Enum, mask uint32) {
+func (ctx *context) StencilMaskSeparate(face Enum, mask uint32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.StencilMaskSeparate(%v, %v) %v", face, mask, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnStencilMaskSeparate,
 			a0: face.c(),
@@ -2223,12 +2223,12 @@ func StencilMaskSeparate(face Enum, mask uint32) {
 	})
 }
 
-func StencilOp(fail, zfail, zpass Enum) {
+func (ctx *context) StencilOp(fail, zfail, zpass Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.StencilOp(%v, %v, %v) %v", fail, zfail, zpass, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnStencilOp,
 			a0: fail.c(),
@@ -2238,12 +2238,12 @@ func StencilOp(fail, zfail, zpass Enum) {
 	})
 }
 
-func StencilOpSeparate(face, sfail, dpfail, dppass Enum) {
+func (ctx *context) StencilOpSeparate(face, sfail, dpfail, dppass Enum) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.StencilOpSeparate(%v, %v, %v, %v) %v", face, sfail, dpfail, dppass, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnStencilOpSeparate,
 			a0: face.c(),
@@ -2254,16 +2254,16 @@ func StencilOpSeparate(face, sfail, dpfail, dppass Enum) {
 	})
 }
 
-func TexImage2D(target Enum, level int, width, height int, format Enum, ty Enum, data []byte) {
+func (ctx *context) TexImage2D(target Enum, level int, width, height int, format Enum, ty Enum, data []byte) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.TexImage2D(%v, %v, %v, %v, %v, %v, len(%d)) %v", target, level, width, height, format, ty, len(data), errstr)
 	}()
 	blocking, a7 := false, C.uintptr_t(0)
 	if len(data) > 0 {
 		blocking, a7 = true, C.uintptr_t(uintptr(unsafe.Pointer(&data[0])))
 	}
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnTexImage2D,
 
@@ -2280,12 +2280,12 @@ func TexImage2D(target Enum, level int, width, height int, format Enum, ty Enum,
 	})
 }
 
-func TexSubImage2D(target Enum, level int, x, y, width, height int, format, ty Enum, data []byte) {
+func (ctx *context) TexSubImage2D(target Enum, level int, x, y, width, height int, format, ty Enum, data []byte) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.TexSubImage2D(%v, %v, %v, %v, %v, %v, %v, %v, len(%d)) %v", target, level, x, y, width, height, format, ty, len(data), errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnTexSubImage2D,
 
@@ -2303,12 +2303,12 @@ func TexSubImage2D(target Enum, level int, x, y, width, height int, format, ty E
 	})
 }
 
-func TexParameterf(target, pname Enum, param float32) {
+func (ctx *context) TexParameterf(target, pname Enum, param float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.TexParameterf(%v, %v, %v) %v", target, pname, param, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnTexParameterf,
 			a0: target.c(),
@@ -2318,12 +2318,12 @@ func TexParameterf(target, pname Enum, param float32) {
 	})
 }
 
-func TexParameterfv(target, pname Enum, params []float32) {
+func (ctx *context) TexParameterfv(target, pname Enum, params []float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.TexParameterfv(%v, %v, len(%d)) %v", target, pname, len(params), errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnTexParameterfv,
 			a0: target.c(),
@@ -2334,12 +2334,12 @@ func TexParameterfv(target, pname Enum, params []float32) {
 	})
 }
 
-func TexParameteri(target, pname Enum, param int) {
+func (ctx *context) TexParameteri(target, pname Enum, param int) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.TexParameteri(%v, %v, %v) %v", target, pname, param, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnTexParameteri,
 			a0: target.c(),
@@ -2349,12 +2349,12 @@ func TexParameteri(target, pname Enum, param int) {
 	})
 }
 
-func TexParameteriv(target, pname Enum, params []int32) {
+func (ctx *context) TexParameteriv(target, pname Enum, params []int32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.TexParameteriv(%v, %v, %v) %v", target, pname, params, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnTexParameteriv,
 			a0: target.c(),
@@ -2365,12 +2365,12 @@ func TexParameteriv(target, pname Enum, params []int32) {
 	})
 }
 
-func Uniform1f(dst Uniform, v float32) {
+func (ctx *context) Uniform1f(dst Uniform, v float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.Uniform1f(%v, %v) %v", dst, v, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform1f,
 			a0: dst.c(),
@@ -2379,12 +2379,12 @@ func Uniform1f(dst Uniform, v float32) {
 	})
 }
 
-func Uniform1fv(dst Uniform, src []float32) {
+func (ctx *context) Uniform1fv(dst Uniform, src []float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.Uniform1fv(%v, len(%d)) %v", dst, len(src), errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform1fv,
 			a0: dst.c(),
@@ -2395,12 +2395,12 @@ func Uniform1fv(dst Uniform, src []float32) {
 	})
 }
 
-func Uniform1i(dst Uniform, v int) {
+func (ctx *context) Uniform1i(dst Uniform, v int) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.Uniform1i(%v, %v) %v", dst, v, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform1i,
 			a0: dst.c(),
@@ -2409,12 +2409,12 @@ func Uniform1i(dst Uniform, v int) {
 	})
 }
 
-func Uniform1iv(dst Uniform, src []int32) {
+func (ctx *context) Uniform1iv(dst Uniform, src []int32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.Uniform1iv(%v, %v) %v", dst, src, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform1iv,
 			a0: dst.c(),
@@ -2425,12 +2425,12 @@ func Uniform1iv(dst Uniform, src []int32) {
 	})
 }
 
-func Uniform2f(dst Uniform, v0, v1 float32) {
+func (ctx *context) Uniform2f(dst Uniform, v0, v1 float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.Uniform2f(%v, %v, %v) %v", dst, v0, v1, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform2f,
 			a0: dst.c(),
@@ -2440,12 +2440,12 @@ func Uniform2f(dst Uniform, v0, v1 float32) {
 	})
 }
 
-func Uniform2fv(dst Uniform, src []float32) {
+func (ctx *context) Uniform2fv(dst Uniform, src []float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.Uniform2fv(%v, len(%d)) %v", dst, len(src), errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform2fv,
 			a0: dst.c(),
@@ -2456,12 +2456,12 @@ func Uniform2fv(dst Uniform, src []float32) {
 	})
 }
 
-func Uniform2i(dst Uniform, v0, v1 int) {
+func (ctx *context) Uniform2i(dst Uniform, v0, v1 int) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.Uniform2i(%v, %v, %v) %v", dst, v0, v1, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform2i,
 			a0: dst.c(),
@@ -2471,12 +2471,12 @@ func Uniform2i(dst Uniform, v0, v1 int) {
 	})
 }
 
-func Uniform2iv(dst Uniform, src []int32) {
+func (ctx *context) Uniform2iv(dst Uniform, src []int32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.Uniform2iv(%v, %v) %v", dst, src, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform2iv,
 			a0: dst.c(),
@@ -2487,12 +2487,12 @@ func Uniform2iv(dst Uniform, src []int32) {
 	})
 }
 
-func Uniform3f(dst Uniform, v0, v1, v2 float32) {
+func (ctx *context) Uniform3f(dst Uniform, v0, v1, v2 float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.Uniform3f(%v, %v, %v, %v) %v", dst, v0, v1, v2, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform3f,
 			a0: dst.c(),
@@ -2503,12 +2503,12 @@ func Uniform3f(dst Uniform, v0, v1, v2 float32) {
 	})
 }
 
-func Uniform3fv(dst Uniform, src []float32) {
+func (ctx *context) Uniform3fv(dst Uniform, src []float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.Uniform3fv(%v, len(%d)) %v", dst, len(src), errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform3fv,
 			a0: dst.c(),
@@ -2519,12 +2519,12 @@ func Uniform3fv(dst Uniform, src []float32) {
 	})
 }
 
-func Uniform3i(dst Uniform, v0, v1, v2 int32) {
+func (ctx *context) Uniform3i(dst Uniform, v0, v1, v2 int32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.Uniform3i(%v, %v, %v, %v) %v", dst, v0, v1, v2, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform3i,
 			a0: dst.c(),
@@ -2535,12 +2535,12 @@ func Uniform3i(dst Uniform, v0, v1, v2 int32) {
 	})
 }
 
-func Uniform3iv(dst Uniform, src []int32) {
+func (ctx *context) Uniform3iv(dst Uniform, src []int32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.Uniform3iv(%v, %v) %v", dst, src, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform3iv,
 			a0: dst.c(),
@@ -2551,12 +2551,12 @@ func Uniform3iv(dst Uniform, src []int32) {
 	})
 }
 
-func Uniform4f(dst Uniform, v0, v1, v2, v3 float32) {
+func (ctx *context) Uniform4f(dst Uniform, v0, v1, v2, v3 float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.Uniform4f(%v, %v, %v, %v, %v) %v", dst, v0, v1, v2, v3, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform4f,
 			a0: dst.c(),
@@ -2568,12 +2568,12 @@ func Uniform4f(dst Uniform, v0, v1, v2, v3 float32) {
 	})
 }
 
-func Uniform4fv(dst Uniform, src []float32) {
+func (ctx *context) Uniform4fv(dst Uniform, src []float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.Uniform4fv(%v, len(%d)) %v", dst, len(src), errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform4fv,
 			a0: dst.c(),
@@ -2584,12 +2584,12 @@ func Uniform4fv(dst Uniform, src []float32) {
 	})
 }
 
-func Uniform4i(dst Uniform, v0, v1, v2, v3 int32) {
+func (ctx *context) Uniform4i(dst Uniform, v0, v1, v2, v3 int32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.Uniform4i(%v, %v, %v, %v, %v) %v", dst, v0, v1, v2, v3, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform4i,
 			a0: dst.c(),
@@ -2601,12 +2601,12 @@ func Uniform4i(dst Uniform, v0, v1, v2, v3 int32) {
 	})
 }
 
-func Uniform4iv(dst Uniform, src []int32) {
+func (ctx *context) Uniform4iv(dst Uniform, src []int32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.Uniform4iv(%v, %v) %v", dst, src, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniform4iv,
 			a0: dst.c(),
@@ -2617,12 +2617,12 @@ func Uniform4iv(dst Uniform, src []int32) {
 	})
 }
 
-func UniformMatrix2fv(dst Uniform, src []float32) {
+func (ctx *context) UniformMatrix2fv(dst Uniform, src []float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.UniformMatrix2fv(%v, len(%d)) %v", dst, len(src), errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniformMatrix2fv,
 
@@ -2634,12 +2634,12 @@ func UniformMatrix2fv(dst Uniform, src []float32) {
 	})
 }
 
-func UniformMatrix3fv(dst Uniform, src []float32) {
+func (ctx *context) UniformMatrix3fv(dst Uniform, src []float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.UniformMatrix3fv(%v, len(%d)) %v", dst, len(src), errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniformMatrix3fv,
 			a0: dst.c(),
@@ -2650,12 +2650,12 @@ func UniformMatrix3fv(dst Uniform, src []float32) {
 	})
 }
 
-func UniformMatrix4fv(dst Uniform, src []float32) {
+func (ctx *context) UniformMatrix4fv(dst Uniform, src []float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.UniformMatrix4fv(%v, len(%d)) %v", dst, len(src), errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUniformMatrix4fv,
 			a0: dst.c(),
@@ -2666,12 +2666,12 @@ func UniformMatrix4fv(dst Uniform, src []float32) {
 	})
 }
 
-func UseProgram(p Program) {
+func (ctx *context) UseProgram(p Program) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.UseProgram(%v) %v", p, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnUseProgram,
 			a0: p.c(),
@@ -2679,12 +2679,12 @@ func UseProgram(p Program) {
 	})
 }
 
-func ValidateProgram(p Program) {
+func (ctx *context) ValidateProgram(p Program) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.ValidateProgram(%v) %v", p, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnValidateProgram,
 			a0: p.c(),
@@ -2692,12 +2692,12 @@ func ValidateProgram(p Program) {
 	})
 }
 
-func VertexAttrib1f(dst Attrib, x float32) {
+func (ctx *context) VertexAttrib1f(dst Attrib, x float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.VertexAttrib1f(%v, %v) %v", dst, x, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnVertexAttrib1f,
 			a0: dst.c(),
@@ -2706,12 +2706,12 @@ func VertexAttrib1f(dst Attrib, x float32) {
 	})
 }
 
-func VertexAttrib1fv(dst Attrib, src []float32) {
+func (ctx *context) VertexAttrib1fv(dst Attrib, src []float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.VertexAttrib1fv(%v, len(%d)) %v", dst, len(src), errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnVertexAttrib1fv,
 			a0: dst.c(),
@@ -2721,12 +2721,12 @@ func VertexAttrib1fv(dst Attrib, src []float32) {
 	})
 }
 
-func VertexAttrib2f(dst Attrib, x, y float32) {
+func (ctx *context) VertexAttrib2f(dst Attrib, x, y float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.VertexAttrib2f(%v, %v, %v) %v", dst, x, y, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnVertexAttrib2f,
 			a0: dst.c(),
@@ -2736,12 +2736,12 @@ func VertexAttrib2f(dst Attrib, x, y float32) {
 	})
 }
 
-func VertexAttrib2fv(dst Attrib, src []float32) {
+func (ctx *context) VertexAttrib2fv(dst Attrib, src []float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.VertexAttrib2fv(%v, len(%d)) %v", dst, len(src), errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnVertexAttrib2fv,
 			a0: dst.c(),
@@ -2751,12 +2751,12 @@ func VertexAttrib2fv(dst Attrib, src []float32) {
 	})
 }
 
-func VertexAttrib3f(dst Attrib, x, y, z float32) {
+func (ctx *context) VertexAttrib3f(dst Attrib, x, y, z float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.VertexAttrib3f(%v, %v, %v, %v) %v", dst, x, y, z, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnVertexAttrib3f,
 			a0: dst.c(),
@@ -2767,12 +2767,12 @@ func VertexAttrib3f(dst Attrib, x, y, z float32) {
 	})
 }
 
-func VertexAttrib3fv(dst Attrib, src []float32) {
+func (ctx *context) VertexAttrib3fv(dst Attrib, src []float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.VertexAttrib3fv(%v, len(%d)) %v", dst, len(src), errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnVertexAttrib3fv,
 			a0: dst.c(),
@@ -2782,12 +2782,12 @@ func VertexAttrib3fv(dst Attrib, src []float32) {
 	})
 }
 
-func VertexAttrib4f(dst Attrib, x, y, z, w float32) {
+func (ctx *context) VertexAttrib4f(dst Attrib, x, y, z, w float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.VertexAttrib4f(%v, %v, %v, %v, %v) %v", dst, x, y, z, w, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnVertexAttrib4f,
 			a0: dst.c(),
@@ -2799,12 +2799,12 @@ func VertexAttrib4f(dst Attrib, x, y, z, w float32) {
 	})
 }
 
-func VertexAttrib4fv(dst Attrib, src []float32) {
+func (ctx *context) VertexAttrib4fv(dst Attrib, src []float32) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.VertexAttrib4fv(%v, len(%d)) %v", dst, len(src), errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnVertexAttrib4fv,
 			a0: dst.c(),
@@ -2814,12 +2814,12 @@ func VertexAttrib4fv(dst Attrib, src []float32) {
 	})
 }
 
-func VertexAttribPointer(dst Attrib, size int, ty Enum, normalized bool, stride, offset int) {
+func (ctx *context) VertexAttribPointer(dst Attrib, size int, ty Enum, normalized bool, stride, offset int) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.VertexAttribPointer(%v, %v, %v, %v, %v, %v) %v", dst, size, ty, normalized, stride, offset, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnVertexAttribPointer,
 			a0: dst.c(),
@@ -2832,12 +2832,12 @@ func VertexAttribPointer(dst Attrib, size int, ty Enum, normalized bool, stride,
 	})
 }
 
-func Viewport(x, y, width, height int) {
+func (ctx *context) Viewport(x, y, width, height int) {
 	defer func() {
-		errstr := errDrain()
+		errstr := ctx.errDrain()
 		log.Printf("gl.Viewport(%v, %v, %v, %v) %v", x, y, width, height, errstr)
 	}()
-	enqueue(call{
+	ctx.enqueue(call{
 		args: C.struct_fnargs{
 			fn: C.glfnViewport,
 			a0: C.uintptr_t(x),
diff --git a/gl/interface.go b/gl/interface.go
new file mode 100644
index 0000000..4178a3a
--- /dev/null
+++ b/gl/interface.go
@@ -0,0 +1,856 @@
+// Copyright 2014 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gl
+
+// Context is an OpenGL context.
+//
+// Calls are not safe for concurrent use. However calls can be made from
+// any goroutine, the gl package removes the notion of thread-local
+// context.
+//
+// Contexts are independent. Two contexts can be used concurrently.
+type Context interface {
+	// ActiveTexture sets the active texture unit.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glActiveTexture.xhtml
+	ActiveTexture(texture Enum)
+
+	// AttachShader attaches a shader to a program.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glAttachShader.xhtml
+	AttachShader(p Program, s Shader)
+
+	// BindAttribLocation binds a vertex attribute index with a named
+	// variable.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glBindAttribLocation.xhtml
+	BindAttribLocation(p Program, a Attrib, name string)
+
+	// BindBuffer binds a buffer.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glBindBuffer.xhtml
+	BindBuffer(target Enum, b Buffer)
+
+	// BindFramebuffer binds a framebuffer.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glBindFramebuffer.xhtml
+	BindFramebuffer(target Enum, fb Framebuffer)
+
+	// BindRenderbuffer binds a render buffer.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glBindRenderbuffer.xhtml
+	BindRenderbuffer(target Enum, rb Renderbuffer)
+
+	// BindTexture binds a texture.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glBindTexture.xhtml
+	BindTexture(target Enum, t Texture)
+
+	// BlendColor sets the blend color.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glBlendColor.xhtml
+	BlendColor(red, green, blue, alpha float32)
+
+	// BlendEquation sets both RGB and alpha blend equations.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glBlendEquation.xhtml
+	BlendEquation(mode Enum)
+
+	// BlendEquationSeparate sets RGB and alpha blend equations separately.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glBlendEquationSeparate.xhtml
+	BlendEquationSeparate(modeRGB, modeAlpha Enum)
+
+	// BlendFunc sets the pixel blending factors.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glBlendFunc.xhtml
+	BlendFunc(sfactor, dfactor Enum)
+
+	// BlendFunc sets the pixel RGB and alpha blending factors separately.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glBlendFuncSeparate.xhtml
+	BlendFuncSeparate(sfactorRGB, dfactorRGB, sfactorAlpha, dfactorAlpha Enum)
+
+	// BufferData creates a new data store for the bound buffer object.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glBufferData.xhtml
+	BufferData(target Enum, src []byte, usage Enum)
+
+	// BufferInit creates a new uninitialized data store for the bound buffer object.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glBufferData.xhtml
+	BufferInit(target Enum, size int, usage Enum)
+
+	// BufferSubData sets some of data in the bound buffer object.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glBufferSubData.xhtml
+	BufferSubData(target Enum, offset int, data []byte)
+
+	// CheckFramebufferStatus reports the completeness status of the
+	// active framebuffer.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glCheckFramebufferStatus.xhtml
+	CheckFramebufferStatus(target Enum) Enum
+
+	// Clear clears the window.
+	//
+	// The behavior of Clear is influenced by the pixel ownership test,
+	// the scissor test, dithering, and the buffer writemasks.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glClear.xhtml
+	Clear(mask Enum)
+
+	// ClearColor specifies the RGBA values used to clear color buffers.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glClearColor.xhtml
+	ClearColor(red, green, blue, alpha float32)
+
+	// ClearDepthf sets the depth value used to clear the depth buffer.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glClearDepthf.xhtml
+	ClearDepthf(d float32)
+
+	// ClearStencil sets the index used to clear the stencil buffer.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glClearStencil.xhtml
+	ClearStencil(s int)
+
+	// ColorMask specifies whether color components in the framebuffer
+	// can be written.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glColorMask.xhtml
+	ColorMask(red, green, blue, alpha bool)
+
+	// CompileShader compiles the source code of s.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glCompileShader.xhtml
+	CompileShader(s Shader)
+
+	// CompressedTexImage2D writes a compressed 2D texture.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glCompressedTexImage2D.xhtml
+	CompressedTexImage2D(target Enum, level int, internalformat Enum, width, height, border int, data []byte)
+
+	// CompressedTexSubImage2D writes a subregion of a compressed 2D texture.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glCompressedTexSubImage2D.xhtml
+	CompressedTexSubImage2D(target Enum, level, xoffset, yoffset, width, height int, format Enum, data []byte)
+
+	// CopyTexImage2D writes a 2D texture from the current framebuffer.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glCopyTexImage2D.xhtml
+	CopyTexImage2D(target Enum, level int, internalformat Enum, x, y, width, height, border int)
+
+	// CopyTexSubImage2D writes a 2D texture subregion from the
+	// current framebuffer.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glCopyTexSubImage2D.xhtml
+	CopyTexSubImage2D(target Enum, level, xoffset, yoffset, x, y, width, height int)
+
+	// CreateBuffer creates a buffer object.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGenBuffers.xhtml
+	CreateBuffer() Buffer
+
+	// CreateFramebuffer creates a framebuffer object.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGenFramebuffers.xhtml
+	CreateFramebuffer() Framebuffer
+
+	// CreateProgram creates a new empty program object.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glCreateProgram.xhtml
+	CreateProgram() Program
+
+	// CreateRenderbuffer create a renderbuffer object.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGenRenderbuffers.xhtml
+	CreateRenderbuffer() Renderbuffer
+
+	// CreateShader creates a new empty shader object.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glCreateShader.xhtml
+	CreateShader(ty Enum) Shader
+
+	// CreateTexture creates a texture object.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGenTextures.xhtml
+	CreateTexture() Texture
+
+	// CullFace specifies which polygons are candidates for culling.
+	//
+	// Valid modes: FRONT, BACK, FRONT_AND_BACK.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glCullFace.xhtml
+	CullFace(mode Enum)
+
+	// DeleteBuffer deletes the given buffer object.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glDeleteBuffers.xhtml
+	DeleteBuffer(v Buffer)
+
+	// DeleteFramebuffer deletes the given framebuffer object.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glDeleteFramebuffers.xhtml
+	DeleteFramebuffer(v Framebuffer)
+
+	// DeleteProgram deletes the given program object.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glDeleteProgram.xhtml
+	DeleteProgram(p Program)
+
+	// DeleteRenderbuffer deletes the given render buffer object.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glDeleteRenderbuffers.xhtml
+	DeleteRenderbuffer(v Renderbuffer)
+
+	// DeleteShader deletes shader s.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glDeleteShader.xhtml
+	DeleteShader(s Shader)
+
+	// DeleteTexture deletes the given texture object.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glDeleteTextures.xhtml
+	DeleteTexture(v Texture)
+
+	// DepthFunc sets the function used for depth buffer comparisons.
+	//
+	// Valid fn values:
+	//	NEVER
+	//	LESS
+	//	EQUAL
+	//	LEQUAL
+	//	GREATER
+	//	NOTEQUAL
+	//	GEQUAL
+	//	ALWAYS
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glDepthFunc.xhtml
+	DepthFunc(fn Enum)
+
+	// DepthMask sets the depth buffer enabled for writing.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glDepthMask.xhtml
+	DepthMask(flag bool)
+
+	// DepthRangef sets the mapping from normalized device coordinates to
+	// window coordinates.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glDepthRangef.xhtml
+	DepthRangef(n, f float32)
+
+	// DetachShader detaches the shader s from the program p.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glDetachShader.xhtml
+	DetachShader(p Program, s Shader)
+
+	// Disable disables various GL capabilities.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glDisable.xhtml
+	Disable(cap Enum)
+
+	// DisableVertexAttribArray disables a vertex attribute array.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glDisableVertexAttribArray.xhtml
+	DisableVertexAttribArray(a Attrib)
+
+	// DrawArrays renders geometric primitives from the bound data.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glDrawArrays.xhtml
+	DrawArrays(mode Enum, first, count int)
+
+	// DrawElements renders primitives from a bound buffer.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glDrawElements.xhtml
+	DrawElements(mode Enum, count int, ty Enum, offset int)
+
+	// TODO(crawshaw): consider DrawElements8 / DrawElements16 / DrawElements32
+
+	// Enable enables various GL capabilities.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glEnable.xhtml
+	Enable(cap Enum)
+
+	// EnableVertexAttribArray enables a vertex attribute array.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glEnableVertexAttribArray.xhtml
+	EnableVertexAttribArray(a Attrib)
+
+	// Finish blocks until the effects of all previously called GL
+	// commands are complete.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glFinish.xhtml
+	Finish()
+
+	// Flush empties all buffers. It does not block.
+	//
+	// An OpenGL implementation may buffer network communication,
+	// the command stream, or data inside the graphics accelerator.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glFlush.xhtml
+	Flush()
+
+	// FramebufferRenderbuffer attaches rb to the current frame buffer.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glFramebufferRenderbuffer.xhtml
+	FramebufferRenderbuffer(target, attachment, rbTarget Enum, rb Renderbuffer)
+
+	// FramebufferTexture2D attaches the t to the current frame buffer.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glFramebufferTexture2D.xhtml
+	FramebufferTexture2D(target, attachment, texTarget Enum, t Texture, level int)
+
+	// FrontFace defines which polygons are front-facing.
+	//
+	// Valid modes: CW, CCW.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glFrontFace.xhtml
+	FrontFace(mode Enum)
+
+	// GenerateMipmap generates mipmaps for the current texture.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGenerateMipmap.xhtml
+	GenerateMipmap(target Enum)
+
+	// GetActiveAttrib returns details about an active attribute variable.
+	// A value of 0 for index selects the first active attribute variable.
+	// Permissible values for index range from 0 to the number of active
+	// attribute variables minus 1.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetActiveAttrib.xhtml
+	GetActiveAttrib(p Program, index uint32) (name string, size int, ty Enum)
+
+	// GetActiveUniform returns details about an active uniform variable.
+	// A value of 0 for index selects the first active uniform variable.
+	// Permissible values for index range from 0 to the number of active
+	// uniform variables minus 1.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetActiveUniform.xhtml
+	GetActiveUniform(p Program, index uint32) (name string, size int, ty Enum)
+
+	// GetAttachedShaders returns the shader objects attached to program p.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetAttachedShaders.xhtml
+	GetAttachedShaders(p Program) []Shader
+
+	// GetAttribLocation returns the location of an attribute variable.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetAttribLocation.xhtml
+	GetAttribLocation(p Program, name string) Attrib
+
+	// GetBooleanv returns the boolean values of parameter pname.
+	//
+	// Many boolean parameters can be queried more easily using IsEnabled.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGet.xhtml
+	GetBooleanv(dst []bool, pname Enum)
+
+	// GetFloatv returns the float values of parameter pname.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGet.xhtml
+	GetFloatv(dst []float32, pname Enum)
+
+	// GetIntegerv returns the int values of parameter pname.
+	//
+	// Single values may be queried more easily using GetInteger.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGet.xhtml
+	GetIntegerv(dst []int32, pname Enum)
+
+	// GetInteger returns the int value of parameter pname.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGet.xhtml
+	GetInteger(pname Enum) int
+
+	// GetBufferParameteri returns a parameter for the active buffer.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetBufferParameter.xhtml
+	GetBufferParameteri(target, value Enum) int
+
+	// GetError returns the next error.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetError.xhtml
+	GetError() Enum
+
+	// GetFramebufferAttachmentParameteri returns attachment parameters
+	// for the active framebuffer object.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetFramebufferAttachmentParameteriv.xhtml
+	GetFramebufferAttachmentParameteri(target, attachment, pname Enum) int
+
+	// GetProgrami returns a parameter value for a program.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetProgramiv.xhtml
+	GetProgrami(p Program, pname Enum) int
+
+	// GetProgramInfoLog returns the information log for a program.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetProgramInfoLog.xhtml
+	GetProgramInfoLog(p Program) string
+
+	// GetRenderbufferParameteri returns a parameter value for a render buffer.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetRenderbufferParameteriv.xhtml
+	GetRenderbufferParameteri(target, pname Enum) int
+
+	// GetShaderi returns a parameter value for a shader.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetShaderiv.xhtml
+	GetShaderi(s Shader, pname Enum) int
+
+	// GetShaderInfoLog returns the information log for a shader.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetShaderInfoLog.xhtml
+	GetShaderInfoLog(s Shader) string
+
+	// GetShaderPrecisionFormat returns range and precision limits for
+	// shader types.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetShaderPrecisionFormat.xhtml
+	GetShaderPrecisionFormat(shadertype, precisiontype Enum) (rangeLow, rangeHigh, precision int)
+
+	// GetShaderSource returns source code of shader s.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetShaderSource.xhtml
+	GetShaderSource(s Shader) string
+
+	// GetString reports current GL state.
+	//
+	// Valid name values:
+	//	EXTENSIONS
+	//	RENDERER
+	//	SHADING_LANGUAGE_VERSION
+	//	VENDOR
+	//	VERSION
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetString.xhtml
+	GetString(pname Enum) string
+
+	// GetTexParameterfv returns the float values of a texture parameter.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetTexParameter.xhtml
+	GetTexParameterfv(dst []float32, target, pname Enum)
+
+	// GetTexParameteriv returns the int values of a texture parameter.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetTexParameter.xhtml
+	GetTexParameteriv(dst []int32, target, pname Enum)
+
+	// GetUniformfv returns the float values of a uniform variable.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetUniform.xhtml
+	GetUniformfv(dst []float32, src Uniform, p Program)
+
+	// GetUniformiv returns the float values of a uniform variable.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetUniform.xhtml
+	GetUniformiv(dst []int32, src Uniform, p Program)
+
+	// GetUniformLocation returns the location of a uniform variable.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetUniformLocation.xhtml
+	GetUniformLocation(p Program, name string) Uniform
+
+	// GetVertexAttribf reads the float value of a vertex attribute.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetVertexAttrib.xhtml
+	GetVertexAttribf(src Attrib, pname Enum) float32
+
+	// GetVertexAttribfv reads float values of a vertex attribute.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetVertexAttrib.xhtml
+	GetVertexAttribfv(dst []float32, src Attrib, pname Enum)
+
+	// GetVertexAttribi reads the int value of a vertex attribute.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetVertexAttrib.xhtml
+	GetVertexAttribi(src Attrib, pname Enum) int32
+
+	// GetVertexAttribiv reads int values of a vertex attribute.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glGetVertexAttrib.xhtml
+	GetVertexAttribiv(dst []int32, src Attrib, pname Enum)
+
+	// TODO(crawshaw): glGetVertexAttribPointerv
+
+	// Hint sets implementation-specific modes.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glHint.xhtml
+	Hint(target, mode Enum)
+
+	// IsBuffer reports if b is a valid buffer.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glIsBuffer.xhtml
+	IsBuffer(b Buffer) bool
+
+	// IsEnabled reports if cap is an enabled capability.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glIsEnabled.xhtml
+	IsEnabled(cap Enum) bool
+
+	// IsFramebuffer reports if fb is a valid frame buffer.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glIsFramebuffer.xhtml
+	IsFramebuffer(fb Framebuffer) bool
+
+	// IsProgram reports if p is a valid program object.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glIsProgram.xhtml
+	IsProgram(p Program) bool
+
+	// IsRenderbuffer reports if rb is a valid render buffer.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glIsRenderbuffer.xhtml
+	IsRenderbuffer(rb Renderbuffer) bool
+
+	// IsShader reports if s is valid shader.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glIsShader.xhtml
+	IsShader(s Shader) bool
+
+	// IsTexture reports if t is a valid texture.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glIsTexture.xhtml
+	IsTexture(t Texture) bool
+
+	// LineWidth specifies the width of lines.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glLineWidth.xhtml
+	LineWidth(width float32)
+
+	// LinkProgram links the specified program.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glLinkProgram.xhtml
+	LinkProgram(p Program)
+
+	// PixelStorei sets pixel storage parameters.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glPixelStorei.xhtml
+	PixelStorei(pname Enum, param int32)
+
+	// PolygonOffset sets the scaling factors for depth offsets.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glPolygonOffset.xhtml
+	PolygonOffset(factor, units float32)
+
+	// ReadPixels returns pixel data from a buffer.
+	//
+	// In GLES 3, the source buffer is controlled with ReadBuffer.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glReadPixels.xhtml
+	ReadPixels(dst []byte, x, y, width, height int, format, ty Enum)
+
+	// ReleaseShaderCompiler frees resources allocated by the shader compiler.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glReleaseShaderCompiler.xhtml
+	ReleaseShaderCompiler()
+
+	// RenderbufferStorage establishes the data storage, format, and
+	// dimensions of a renderbuffer object's image.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glRenderbufferStorage.xhtml
+	RenderbufferStorage(target, internalFormat Enum, width, height int)
+
+	// SampleCoverage sets multisample coverage parameters.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glSampleCoverage.xhtml
+	SampleCoverage(value float32, invert bool)
+
+	// Scissor defines the scissor box rectangle, in window coordinates.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glScissor.xhtml
+	Scissor(x, y, width, height int32)
+
+	// TODO(crawshaw): ShaderBinary
+
+	// ShaderSource sets the source code of s to the given source code.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glShaderSource.xhtml
+	ShaderSource(s Shader, src string)
+
+	// StencilFunc sets the front and back stencil test reference value.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glStencilFunc.xhtml
+	StencilFunc(fn Enum, ref int, mask uint32)
+
+	// StencilFunc sets the front or back stencil test reference value.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glStencilFuncSeparate.xhtml
+	StencilFuncSeparate(face, fn Enum, ref int, mask uint32)
+
+	// StencilMask controls the writing of bits in the stencil planes.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glStencilMask.xhtml
+	StencilMask(mask uint32)
+
+	// StencilMaskSeparate controls the writing of bits in the stencil planes.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glStencilMaskSeparate.xhtml
+	StencilMaskSeparate(face Enum, mask uint32)
+
+	// StencilOp sets front and back stencil test actions.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glStencilOp.xhtml
+	StencilOp(fail, zfail, zpass Enum)
+
+	// StencilOpSeparate sets front or back stencil tests.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glStencilOpSeparate.xhtml
+	StencilOpSeparate(face, sfail, dpfail, dppass Enum)
+
+	// TexImage2D writes a 2D texture image.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glTexImage2D.xhtml
+	TexImage2D(target Enum, level int, width, height int, format Enum, ty Enum, data []byte)
+
+	// TexSubImage2D writes a subregion of a 2D texture image.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glTexSubImage2D.xhtml
+	TexSubImage2D(target Enum, level int, x, y, width, height int, format, ty Enum, data []byte)
+
+	// TexParameterf sets a float texture parameter.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glTexParameter.xhtml
+	TexParameterf(target, pname Enum, param float32)
+
+	// TexParameterfv sets a float texture parameter array.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glTexParameter.xhtml
+	TexParameterfv(target, pname Enum, params []float32)
+
+	// TexParameteri sets an integer texture parameter.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glTexParameter.xhtml
+	TexParameteri(target, pname Enum, param int)
+
+	// TexParameteriv sets an integer texture parameter array.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glTexParameter.xhtml
+	TexParameteriv(target, pname Enum, params []int32)
+
+	// Uniform1f writes a float uniform variable.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
+	Uniform1f(dst Uniform, v float32)
+
+	// Uniform1fv writes a [len(src)]float uniform array.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
+	Uniform1fv(dst Uniform, src []float32)
+
+	// Uniform1i writes an int uniform variable.
+	//
+	// Uniform1i and Uniform1iv are the only two functions that may be used
+	// to load uniform variables defined as sampler types. Loading samplers
+	// with any other function will result in a INVALID_OPERATION error.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
+	Uniform1i(dst Uniform, v int)
+
+	// Uniform1iv writes a int uniform array of len(src) elements.
+	//
+	// Uniform1i and Uniform1iv are the only two functions that may be used
+	// to load uniform variables defined as sampler types. Loading samplers
+	// with any other function will result in a INVALID_OPERATION error.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
+	Uniform1iv(dst Uniform, src []int32)
+
+	// Uniform2f writes a vec2 uniform variable.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
+	Uniform2f(dst Uniform, v0, v1 float32)
+
+	// Uniform2fv writes a vec2 uniform array of len(src)/2 elements.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
+	Uniform2fv(dst Uniform, src []float32)
+
+	// Uniform2i writes an ivec2 uniform variable.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
+	Uniform2i(dst Uniform, v0, v1 int)
+
+	// Uniform2iv writes an ivec2 uniform array of len(src)/2 elements.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
+	Uniform2iv(dst Uniform, src []int32)
+
+	// Uniform3f writes a vec3 uniform variable.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
+	Uniform3f(dst Uniform, v0, v1, v2 float32)
+
+	// Uniform3fv writes a vec3 uniform array of len(src)/3 elements.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
+	Uniform3fv(dst Uniform, src []float32)
+
+	// Uniform3i writes an ivec3 uniform variable.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
+	Uniform3i(dst Uniform, v0, v1, v2 int32)
+
+	// Uniform3iv writes an ivec3 uniform array of len(src)/3 elements.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
+	Uniform3iv(dst Uniform, src []int32)
+
+	// Uniform4f writes a vec4 uniform variable.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
+	Uniform4f(dst Uniform, v0, v1, v2, v3 float32)
+
+	// Uniform4fv writes a vec4 uniform array of len(src)/4 elements.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
+	Uniform4fv(dst Uniform, src []float32)
+
+	// Uniform4i writes an ivec4 uniform variable.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
+	Uniform4i(dst Uniform, v0, v1, v2, v3 int32)
+
+	// Uniform4i writes an ivec4 uniform array of len(src)/4 elements.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
+	Uniform4iv(dst Uniform, src []int32)
+
+	// UniformMatrix2fv writes 2x2 matrices. Each matrix uses four
+	// float32 values, so the number of matrices written is len(src)/4.
+	//
+	// Each matrix must be supplied in column major order.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
+	UniformMatrix2fv(dst Uniform, src []float32)
+
+	// UniformMatrix3fv writes 3x3 matrices. Each matrix uses nine
+	// float32 values, so the number of matrices written is len(src)/9.
+	//
+	// Each matrix must be supplied in column major order.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
+	UniformMatrix3fv(dst Uniform, src []float32)
+
+	// UniformMatrix4fv writes 4x4 matrices. Each matrix uses 16
+	// float32 values, so the number of matrices written is len(src)/16.
+	//
+	// Each matrix must be supplied in column major order.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glUniform.xhtml
+	UniformMatrix4fv(dst Uniform, src []float32)
+
+	// UseProgram sets the active program.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glUseProgram.xhtml
+	UseProgram(p Program)
+
+	// ValidateProgram checks to see whether the executables contained in
+	// program can execute given the current OpenGL state.
+	//
+	// Typically only used for debugging.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glValidateProgram.xhtml
+	ValidateProgram(p Program)
+
+	// VertexAttrib1f writes a float vertex attribute.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttrib.xhtml
+	VertexAttrib1f(dst Attrib, x float32)
+
+	// VertexAttrib1fv writes a float vertex attribute.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttrib.xhtml
+	VertexAttrib1fv(dst Attrib, src []float32)
+
+	// VertexAttrib2f writes a vec2 vertex attribute.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttrib.xhtml
+	VertexAttrib2f(dst Attrib, x, y float32)
+
+	// VertexAttrib2fv writes a vec2 vertex attribute.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttrib.xhtml
+	VertexAttrib2fv(dst Attrib, src []float32)
+
+	// VertexAttrib3f writes a vec3 vertex attribute.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttrib.xhtml
+	VertexAttrib3f(dst Attrib, x, y, z float32)
+
+	// VertexAttrib3fv writes a vec3 vertex attribute.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttrib.xhtml
+	VertexAttrib3fv(dst Attrib, src []float32)
+
+	// VertexAttrib4f writes a vec4 vertex attribute.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttrib.xhtml
+	VertexAttrib4f(dst Attrib, x, y, z, w float32)
+
+	// VertexAttrib4fv writes a vec4 vertex attribute.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttrib.xhtml
+	VertexAttrib4fv(dst Attrib, src []float32)
+
+	// VertexAttribPointer uses a bound buffer to define vertex attribute data.
+	//
+	// Direct use of VertexAttribPointer to load data into OpenGL is not
+	// supported via the Go bindings. Instead, use BindBuffer with an
+	// ARRAY_BUFFER and then fill it using BufferData.
+	//
+	// The size argument specifies the number of components per attribute,
+	// between 1-4. The stride argument specifies the byte offset between
+	// consecutive vertex attributes.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glVertexAttribPointer.xhtml
+	VertexAttribPointer(dst Attrib, size int, ty Enum, normalized bool, stride, offset int)
+
+	// Viewport sets the viewport, an affine transformation that
+	// normalizes device coordinates to window coordinates.
+	//
+	// http://www.khronos.org/opengles/sdk/docs/man3/html/glViewport.xhtml
+	Viewport(x, y, width, height int)
+}
+
+// Worker is used by display driver code to execute OpenGL calls.
+//
+// Typically display driver code creates a gl.Context for an application,
+// and along with it establishes a locked OS thread to execute the cgo
+// calls:
+//
+//	go func() {
+//		runtime.LockOSThread()
+//		// ... platform-specific cgo call to bind a C OpenGL context
+//		// into thread-local storage.
+//
+//		glctx, worker := gl.NewContext()
+//		workAvailable := glctx.WorkAvailable()
+//		go userAppCode(glctx)
+//		for {
+//			select {
+//			case <-workAvailable:
+//				glctx.DoWork()
+//			case <-drawEvent:
+//				// ... platform-specific cgo call to draw screen
+//			}
+//		}
+//	}()
+type Worker interface {
+	// WorkAvailable returns a channel that communicates when DoWork
+	// should be called.
+	//
+	// This is an internal implementation detail and should only be
+	// used by the package responsible for managing the screen (e.g.
+	// golang.org/x/mobile/app).
+	WorkAvailable() <-chan struct{}
+
+	// DoWork performs any pending OpenGL calls.
+	//
+	// This is an internal implementation detail and should only be used by the
+	// golang.org/x/mobile/app package.
+	DoWork()
+}
diff --git a/gl/work.c b/gl/work.c
index eb5802b..bcc1b4c 100644
--- a/gl/work.c
+++ b/gl/work.c
@@ -8,7 +8,8 @@
 #include "_cgo_export.h"
 #include "work.h"
 
-void processFn(struct fnargs* args) {
+uintptr_t processFn(struct fnargs* args) {
+	uintptr_t ret = 0;
 	switch (args->fn) {
 	case glfnUNDEFINED:
 		abort(); // bad glfn
@@ -475,4 +476,5 @@ void processFn(struct fnargs* args) {
 		glViewport((GLint)args->a0, (GLint)args->a1, (GLint)args->a2, (GLint)args->a3);
 		break;
 	}
+	return ret;
 }
diff --git a/gl/work.go b/gl/work.go
index 7df0492..3c4b34a 100644
--- a/gl/work.go
+++ b/gl/work.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin linux
+// +build darwin linux cgo
 
 package gl
 
@@ -20,71 +20,81 @@ package gl
 #include <stdint.h>
 #include "work.h"
 
-struct fnargs cargs[10];
-uintptr_t ret;
-
-void process(int count) {
+// TODO: return uintptr_t instead of taking ret.
+void process(struct fnargs* cargs, int count, uintptr_t* ret) {
 	int i;
 	for (i = 0; i < count; i++) {
-		processFn(&cargs[i]);
+		*ret = processFn(&cargs[i]);
 	}
 }
 */
 import "C"
 
-// work is a queue of calls to execute.
-var work = make(chan call, 10)
+const workbufLen = 10
 
-// retvalue is sent a return value when blocking calls complete.
-// It is safe to use a global unbuffered channel here as calls
-// cannot currently be made concurrently.
+type context struct {
+	cptr uintptr
+
+	workAvailable chan struct{}
+
+	// work is a queue of calls to execute.
+	work chan call
+
+	// retvalue is sent a return value when blocking calls complete.
+	// It is safe to use a global unbuffered channel here as calls
+	// cannot currently be made concurrently.
+	//
+	// TODO: the comment above about concurrent calls isn't actually true: package
+	// app calls package gl, but it has to do so in a separate goroutine, which
+	// means that its gl calls (which may be blocking) can race with other gl calls
+	// in the main program. We should make it safe to issue blocking gl calls
+	// concurrently, or get the gl calls out of package app, or both.
+	retvalue chan C.uintptr_t
+
+	cargs [workbufLen]C.struct_fnargs
+	ret   C.uintptr_t
+}
+
+func (ctx *context) WorkAvailable() <-chan struct{} { return ctx.workAvailable }
+
+// NewContext creates a cgo OpenGL context.
 //
-// TODO: the comment above about concurrent calls isn't actually true: package
-// app calls package gl, but it has to do so in a separate goroutine, which
-// means that its gl calls (which may be blocking) can race with other gl calls
-// in the main program. We should make it safe to issue blocking gl calls
-// concurrently, or get the gl calls out of package app, or both.
-var retvalue = make(chan C.uintptr_t)
+// See the Worker interface for more details on how it is used.
+func NewContext() (Context, Worker) {
+	glctx := &context{
+		workAvailable: make(chan struct{}, 1),
+		work:          make(chan call, workbufLen),
+		retvalue:      make(chan C.uintptr_t),
+	}
+	return glctx, glctx
+}
 
 type call struct {
 	args     C.struct_fnargs
 	blocking bool
 }
 
-func enqueue(c call) C.uintptr_t {
-	work <- c
+func (ctx *context) enqueue(c call) C.uintptr_t {
+	ctx.work <- c
 
 	select {
-	case workAvailable <- struct{}{}:
+	case ctx.workAvailable <- struct{}{}:
 	default:
 	}
 
 	if c.blocking {
-		return <-retvalue
+		return <-ctx.retvalue
 	}
 	return 0
 }
 
-var (
-	workAvailable = make(chan struct{}, 1)
-	// WorkAvailable communicates when DoWork should be called.
-	//
-	// This is an internal implementation detail and should only be used by the
-	// golang.org/x/mobile/app package.
-	WorkAvailable <-chan struct{} = workAvailable
-)
-
-// DoWork performs any pending OpenGL calls.
-//
-// This is an internal implementation detail and should only be used by the
-// golang.org/x/mobile/app package.
-func DoWork() {
-	queue := make([]call, 0, len(work))
+func (ctx *context) DoWork() {
+	queue := make([]call, 0, len(ctx.work))
 	for {
 		// Wait until at least one piece of work is ready.
 		// Accumulate work until a piece is marked as blocking.
 		select {
-		case w := <-work:
+		case w := <-ctx.work:
 			queue = append(queue, w)
 		default:
 			return
@@ -93,7 +103,7 @@ func DoWork() {
 	enqueue:
 		for len(queue) < cap(queue) && !blocking {
 			select {
-			case w := <-work:
+			case w := <-ctx.work:
 				queue = append(queue, w)
 				blocking = queue[len(queue)-1].blocking
 			default:
@@ -103,14 +113,14 @@ func DoWork() {
 
 		// Process the queued GL functions.
 		for i, q := range queue {
-			C.cargs[i] = q.args
+			ctx.cargs[i] = q.args
 		}
-		C.process(C.int(len(queue)))
+		C.process(&ctx.cargs[0], C.int(len(queue)), &ctx.ret)
 
 		// Cleanup and signal.
 		queue = queue[:0]
 		if blocking {
-			retvalue <- C.ret
+			ctx.retvalue <- ctx.ret
 		}
 	}
 }
diff --git a/gl/work.h b/gl/work.h
index dc7d0f0..bfd3a6e 100644
--- a/gl/work.h
+++ b/gl/work.h
@@ -176,4 +176,4 @@ struct fnargs {
 
 extern uintptr_t ret;
 
-extern void processFn(struct fnargs* args);
+extern uintptr_t processFn(struct fnargs* args);