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230 lines
6.3 KiB
C
230 lines
6.3 KiB
C
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//
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// Book: OpenGL(R) ES 2.0 Programming Guide
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// Authors: Aaftab Munshi, Dan Ginsburg, Dave Shreiner
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// ISBN-10: 0321502795
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// ISBN-13: 9780321502797
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// Publisher: Addison-Wesley Professional
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// URLs: http://safari.informit.com/9780321563835
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// http://www.opengles-book.com
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//
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// Simple_TextureCubemap.c
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//
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// This is a simple example that draws a sphere with a cubemap image applied.
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//
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#include <stdlib.h>
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#include "esUtil.h"
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typedef struct
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{
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// Handle to a program object
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GLuint programObject;
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// Attribute locations
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GLint positionLoc;
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GLint normalLoc;
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// Sampler location
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GLint samplerLoc;
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// Texture handle
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GLuint textureId;
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// Vertex data
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int numIndices;
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GLfloat *vertices;
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GLfloat *normals;
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GLushort *indices;
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} UserData;
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///
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// Create a simple cubemap with a 1x1 face with a different
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// color for each face
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GLuint CreateSimpleTextureCubemap( )
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{
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GLuint textureId;
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// Six 1x1 RGB faces
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GLubyte cubePixels[6][3] =
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{
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// Face 0 - Red
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255, 0, 0,
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// Face 1 - Green,
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0, 255, 0,
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// Face 3 - Blue
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0, 0, 255,
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// Face 4 - Yellow
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255, 255, 0,
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// Face 5 - Purple
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255, 0, 255,
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// Face 6 - White
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255, 255, 255
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};
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// Generate a texture object
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glGenTextures ( 1, &textureId );
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// Bind the texture object
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glBindTexture ( GL_TEXTURE_CUBE_MAP, textureId );
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// Load the cube face - Positive X
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glTexImage2D ( GL_TEXTURE_CUBE_MAP_POSITIVE_X, 0, GL_RGB, 1, 1, 0,
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GL_RGB, GL_UNSIGNED_BYTE, &cubePixels[0] );
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// Load the cube face - Negative X
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glTexImage2D ( GL_TEXTURE_CUBE_MAP_NEGATIVE_X, 0, GL_RGB, 1, 1, 0,
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GL_RGB, GL_UNSIGNED_BYTE, &cubePixels[1] );
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// Load the cube face - Positive Y
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glTexImage2D ( GL_TEXTURE_CUBE_MAP_POSITIVE_Y, 0, GL_RGB, 1, 1, 0,
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GL_RGB, GL_UNSIGNED_BYTE, &cubePixels[2] );
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// Load the cube face - Negative Y
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glTexImage2D ( GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, 0, GL_RGB, 1, 1, 0,
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GL_RGB, GL_UNSIGNED_BYTE, &cubePixels[3] );
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// Load the cube face - Positive Z
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glTexImage2D ( GL_TEXTURE_CUBE_MAP_POSITIVE_Z, 0, GL_RGB, 1, 1, 0,
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GL_RGB, GL_UNSIGNED_BYTE, &cubePixels[4] );
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// Load the cube face - Negative Z
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glTexImage2D ( GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, 0, GL_RGB, 1, 1, 0,
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GL_RGB, GL_UNSIGNED_BYTE, &cubePixels[5] );
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// Set the filtering mode
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glTexParameteri ( GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_NEAREST );
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glTexParameteri ( GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_NEAREST );
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return textureId;
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}
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///
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// Initialize the shader and program object
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//
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int Init ( ESContext *esContext )
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{
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UserData *userData = esContext->userData;
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GLbyte vShaderStr[] =
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"attribute vec4 a_position; \n"
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"attribute vec3 a_normal; \n"
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"varying vec3 v_normal; \n"
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"void main() \n"
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"{ \n"
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" gl_Position = a_position; \n"
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" v_normal = a_normal; \n"
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"} \n";
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GLbyte fShaderStr[] =
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"precision mediump float; \n"
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"varying vec3 v_normal; \n"
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"uniform samplerCube s_texture; \n"
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"void main() \n"
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"{ \n"
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" gl_FragColor = textureCube( s_texture, v_normal );\n"
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"} \n";
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// Load the shaders and get a linked program object
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userData->programObject = esLoadProgram ( vShaderStr, fShaderStr );
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// Get the attribute locations
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userData->positionLoc = glGetAttribLocation ( userData->programObject, "a_position" );
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userData->normalLoc = glGetAttribLocation ( userData->programObject, "a_normal" );
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// Get the sampler locations
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userData->samplerLoc = glGetUniformLocation ( userData->programObject, "s_texture" );
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// Load the texture
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userData->textureId = CreateSimpleTextureCubemap ();
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// Generate the vertex data
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userData->numIndices = esGenSphere ( 20, 0.75f, &userData->vertices, &userData->normals,
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NULL, &userData->indices );
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glClearColor ( 0.0f, 0.0f, 0.0f, 0.0f );
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return TRUE;
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}
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///
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// Draw a triangle using the shader pair created in Init()
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//
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void Draw ( ESContext *esContext )
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{
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UserData *userData = esContext->userData;
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// Set the viewport
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glViewport ( 0, 0, esContext->width, esContext->height );
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// Clear the color buffer
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glClear ( GL_COLOR_BUFFER_BIT );
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glCullFace ( GL_BACK );
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glEnable ( GL_CULL_FACE );
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// Use the program object
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glUseProgram ( userData->programObject );
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// Load the vertex position
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glVertexAttribPointer ( userData->positionLoc, 3, GL_FLOAT,
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GL_FALSE, 0, userData->vertices );
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// Load the normal
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glVertexAttribPointer ( userData->normalLoc, 3, GL_FLOAT,
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GL_FALSE, 0, userData->normals );
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glEnableVertexAttribArray ( userData->positionLoc );
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glEnableVertexAttribArray ( userData->normalLoc );
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// Bind the texture
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glActiveTexture ( GL_TEXTURE0 );
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glBindTexture ( GL_TEXTURE_CUBE_MAP, userData->textureId );
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// Set the sampler texture unit to 0
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glUniform1i ( userData->samplerLoc, 0 );
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glDrawElements ( GL_TRIANGLES, userData->numIndices,
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GL_UNSIGNED_SHORT, userData->indices );
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eglSwapBuffers ( esContext->eglDisplay, esContext->eglSurface );
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}
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///
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// Cleanup
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//
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void ShutDown ( ESContext *esContext )
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{
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UserData *userData = esContext->userData;
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// Delete texture object
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glDeleteTextures ( 1, &userData->textureId );
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// Delete program object
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glDeleteProgram ( userData->programObject );
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free ( userData->vertices );
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free ( userData->normals );
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}
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int main ( int argc, char *argv[] )
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{
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ESContext esContext;
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UserData userData;
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esInitContext ( &esContext );
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esContext.userData = &userData;
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esCreateWindow ( &esContext, TEXT("Simple Texture Cubemap"), 320, 240, ES_WINDOW_RGB );
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if ( !Init ( &esContext ) )
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return 0;
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esRegisterDrawFunc ( &esContext, Draw );
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esMainLoop ( &esContext );
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ShutDown ( &esContext );
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}
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