vkd3d-shader/hlsl: Implement the faceforward() intrinsic.

Approved-by: Elizabeth Figura (@zfigura)
Approved-by: Henri Verbeet (@hverbeet)
Merge-Request: https://gitlab.winehq.org/wine/vkd3d/-/merge_requests/929

Makefile.am

@@ -108,6 +108,7 @@ vkd3d_shader_tests = \
 	tests/hlsl/entry-point-semantics.shader_test \
 	tests/hlsl/exp.shader_test \
 	tests/hlsl/expr-indexing.shader_test \
+	tests/hlsl/faceforward.shader_test \
 	tests/hlsl/float-comparison.shader_test \
 	tests/hlsl/floor.shader_test \
 	tests/hlsl/fmod.shader_test \

libs/vkd3d-shader/hlsl.y

@@ -3614,6 +3614,34 @@ static bool intrinsic_exp2(struct hlsl_ctx *ctx,
     return !!add_unary_arithmetic_expr(ctx, params->instrs, HLSL_OP1_EXP2, arg, loc);
 }
 
+static bool intrinsic_faceforward(struct hlsl_ctx *ctx,
+        const struct parse_initializer *params, const struct vkd3d_shader_location *loc)
+{
+    struct hlsl_ir_function_decl *func;
+    struct hlsl_type *type;
+    char *body;
+
+    static const char template[] =
+            "%s faceforward(%s n, %s i, %s ng)\n"
+            "{\n"
+            "    return dot(i, ng) < 0 ? n : -n;\n"
+            "}\n";
+
+    if (!(type = elementwise_intrinsic_get_common_type(ctx, params, loc)))
+        return false;
+    type = hlsl_get_numeric_type(ctx, type->class, HLSL_TYPE_FLOAT, type->dimx, type->dimy);
+
+    if (!(body = hlsl_sprintf_alloc(ctx, template,
+            type->name, type->name, type->name, type->name)))
+        return false;
+    func = hlsl_compile_internal_function(ctx, "faceforward", body);
+    vkd3d_free(body);
+    if (!func)
+        return false;
+
+    return add_user_call(ctx, func, params, loc);
+}
+
 static bool intrinsic_floor(struct hlsl_ctx *ctx,
         const struct parse_initializer *params, const struct vkd3d_shader_location *loc)
 {
@@ -4687,6 +4715,7 @@ intrinsic_functions[] =
     {"dot",                                 2, true,  intrinsic_dot},
     {"exp",                                 1, true,  intrinsic_exp},
     {"exp2",                                1, true,  intrinsic_exp2},
+    {"faceforward",                         3, true,  intrinsic_faceforward},
     {"floor",                               1, true,  intrinsic_floor},
     {"fmod",                                2, true,  intrinsic_fmod},
     {"frac",                                1, true,  intrinsic_frac},

tests/hlsl/faceforward.shader_test

@@ -0,0 +1,52 @@
+[pixel shader]
+uniform float4 n;
+uniform float4 i;
+uniform float4 ng;
+
+float4 main() : sv_target
+{
+    return faceforward(n, i, ng);
+}
+
+[test]
+uniform 0 float4 10.0 20.0 30.0 40.0
+uniform 4 float4 1.0 0.0 0.0 0.0
+uniform 8 float4 1.0 0.2 0.0 0.0
+todo(glsl) draw quad
+probe (0, 0) rgba (-10.0, -20.0, -30.0, -40.0)
+
+uniform 0 float4 10.0 20.0 30.0 40.0
+uniform 4 float4 1.0 0.0 0.0 0.0
+uniform 8 float4 1.0 -0.2 0.0 0.0
+todo(glsl) draw quad
+probe (0, 0) rgba (-10.0, -20.0, -30.0, -40.0)
+
+uniform 0 float4 10.0 20.0 30.0 40.0
+uniform 4 float4 1.0 0.0 0.0 0.0
+uniform 8 float4 -1.0 0.0 0.0 0.0
+todo(glsl) draw quad
+probe (0, 0) rgba (10.0, 20.0, 30.0, 40.0)
+
+uniform 0 float4 10.0 20.0 30.0 40.0
+uniform 4 float4 0.0 -1.0 0.0 0.0
+uniform 8 float4 0.0 1.0 0.0 0.0
+todo(glsl) draw quad
+probe (0, 0) rgba (10.0, 20.0, 30.0, 40.0)
+
+uniform 0 float4 10.0 20.0 30.0 40.0
+uniform 4 float4 1.0 0.0 0.0 0.0
+uniform 8 float4 0.0 1.0 0.0 0.0
+todo(glsl) draw quad
+probe (0, 0) rgba (-10.0, -20.0, -30.0, -40.0)
+
+uniform 0 float4 10.0 20.0 30.0 40.0
+uniform 4 float4 0.0 0.0 0.0 0.0
+uniform 8 float4 0.0 1.0 0.0 0.0
+todo(glsl) draw quad
+probe (0, 0) rgba (-10.0, -20.0, -30.0, -40.0)
+
+uniform 0 float4 10.0 20.0 30.0 40.0
+uniform 4 float4 0.0 0.0 0.0 0.0
+uniform 8 float4 0.0 0.0 0.0 0.0
+todo(glsl) draw quad
+probe (0, 0) rgba (-10.0, -20.0, -30.0, -40.0)