Bug 771406 - Add emulation for GLSL faceForward() to ANGLE - r=bjacob

gfx/angle/src/compiler/BuiltInFunctionEmulator.cpp

@@ -31,6 +31,12 @@ const char* kFunctionEmulationVertexSource[] = {
     "#error no emulation for dot(vec3, vec3)",
     "#error no emulation for dot(vec4, vec4)",
 
+    // |faceforward(N, I, Nref)| is |dot(NRef, I) < 0 ? N : -N|
+    "#define webgl_faceforward_emu(N, I, Nref) (((Nref) * (I) < 0.0) ? (N) : -(N))",
+    "#error no emulation for faceforward(vec2, vec2, vec2)",
+    "#error no emulation for faceforward(vec3, vec3, vec3)",
+    "#error no emulation for faceforward(vec4, vec4, vec4)",
+
     "#define webgl_length_emu(x) ((x) >= 0.0 ? (x) : -(x))",
     "#error no emulation for length(vec2)",
     "#error no emulation for length(vec3)",
@@ -63,6 +69,12 @@ const char* kFunctionEmulationFragmentSource[] = {
     "#error no emulation for dot(vec3, vec3)",
     "#error no emulation for dot(vec4, vec4)",
 
+    // |faceforward(N, I, Nref)| is |dot(NRef, I) < 0 ? N : -N|
+    "#define webgl_faceforward_emu(N, I, Nref) (((Nref) * (I) < 0.0) ? (N) : -(N))",
+    "#error no emulation for faceforward(vec2, vec2, vec2)",
+    "#error no emulation for faceforward(vec3, vec3, vec3)",
+    "#error no emulation for faceforward(vec4, vec4, vec4)",
+
     "#define webgl_length_emu(x) ((x) >= 0.0 ? (x) : -(x))",
     "#error no emulation for length(vec2)",
     "#error no emulation for length(vec3)",
@@ -94,6 +106,10 @@ const bool kFunctionEmulationVertexMask[] = {
     false, // TFunctionDot2_2
     false, // TFunctionDot3_3
     false, // TFunctionDot4_4
+    true,  // TFunctionFaceForward1_1_1
+    false, // TFunctionFaceForward2_2_2
+    false, // TFunctionFaceForward3_3_3
+    false, // TFunctionFaceForward4_4_4
     true,  // TFunctionLength1
     false, // TFunctionLength2
     false, // TFunctionLength3
@@ -120,6 +136,10 @@ const bool kFunctionEmulationVertexMask[] = {
     false, // TFunctionDot2_2
     false, // TFunctionDot3_3
     false, // TFunctionDot4_4
+    false, // TFunctionFaceForward1_1_1
+    false, // TFunctionFaceForward2_2_2
+    false, // TFunctionFaceForward3_3_3
+    false, // TFunctionFaceForward4_4_4
     false, // TFunctionLength1
     false, // TFunctionLength2
     false, // TFunctionLength3
@@ -151,6 +171,10 @@ const bool kFunctionEmulationFragmentMask[] = {
     false, // TFunctionDot2_2
     false, // TFunctionDot3_3
     false, // TFunctionDot4_4
+    true,  // TFunctionFaceForward1_1_1
+    false, // TFunctionFaceForward2_2_2
+    false, // TFunctionFaceForward3_3_3
+    false, // TFunctionFaceForward4_4_4
     true,  // TFunctionLength1
     false, // TFunctionLength2
     false, // TFunctionLength3
@@ -177,6 +201,10 @@ const bool kFunctionEmulationFragmentMask[] = {
     false, // TFunctionDot2_2
     false, // TFunctionDot3_3
     false, // TFunctionDot4_4
+    false, // TFunctionFaceForward1_1_1
+    false, // TFunctionFaceForward2_2_2
+    false, // TFunctionFaceForward3_3_3
+    false, // TFunctionFaceForward4_4_4
     false, // TFunctionLength1
     false, // TFunctionLength2
     false, // TFunctionLength3
@@ -244,15 +272,27 @@ public:
                     return true;
             };
             const TIntermSequence& sequence = node->getSequence();
-            // Right now we only handle built-in functions with two parameters.
-            if (sequence.size() != 2)
+            bool needToEmulate = false;
+
+            if (sequence.size() == 2) {
+                TIntermTyped* param1 = sequence[0]->getAsTyped();
+                TIntermTyped* param2 = sequence[1]->getAsTyped();
+                if (!param1 || !param2)
+                    return true;
+                needToEmulate = mEmulator.SetFunctionCalled(
+                    node->getOp(), param1->getType(), param2->getType());
+            } else if (sequence.size() == 3) {
+                TIntermTyped* param1 = sequence[0]->getAsTyped();
+                TIntermTyped* param2 = sequence[1]->getAsTyped();
+                TIntermTyped* param3 = sequence[2]->getAsTyped();
+                if (!param1 || !param2 || !param3)
+                    return true;
+                needToEmulate = mEmulator.SetFunctionCalled(
+                    node->getOp(), param1->getType(), param2->getType(), param3->getType());
+            } else {
                 return true;
-            TIntermTyped* param1 = sequence[0]->getAsTyped();
-            TIntermTyped* param2 = sequence[1]->getAsTyped();
-            if (!param1 || !param2)
-                return true;
-            bool needToEmulate = mEmulator.SetFunctionCalled(
-                node->getOp(), param1->getType(), param2->getType());
+            }
+
             if (needToEmulate)
                 node->setUseEmulatedFunction();
         }
@@ -290,6 +330,13 @@ bool BuiltInFunctionEmulator::SetFunctionCalled(
     return SetFunctionCalled(function);
 }
 
+bool BuiltInFunctionEmulator::SetFunctionCalled(
+    TOperator op, const TType& param1, const TType& param2, const TType& param3)
+{
+    TBuiltInFunction function = IdentifyFunction(op, param1, param2, param3);
+    return SetFunctionCalled(function);
+}
+
 bool BuiltInFunctionEmulator::SetFunctionCalled(
     BuiltInFunctionEmulator::TBuiltInFunction function) {
     if (function == TFunctionUnknown || mFunctionMask[function] == false)
@@ -382,6 +429,34 @@ BuiltInFunctionEmulator::IdentifyFunction(
     return static_cast<TBuiltInFunction>(function);
 }
 
+BuiltInFunctionEmulator::TBuiltInFunction
+BuiltInFunctionEmulator::IdentifyFunction(
+    TOperator op, const TType& param1, const TType& param2, const TType& param3)
+{
+    // Check that all params have the same type, length,
+    // and that they're not too large.
+    if (param1.isVector() != param2.isVector() ||
+        param2.isVector() != param3.isVector() ||
+        param1.getNominalSize() != param2.getNominalSize() ||
+        param2.getNominalSize() != param3.getNominalSize() ||
+        param1.getNominalSize() > 4)
+        return TFunctionUnknown;
+
+    unsigned int function = TFunctionUnknown;
+    switch (op) {
+        case EOpFaceForward:
+            function = TFunctionFaceForward1_1_1;
+            break;
+        default:
+            break;
+    }
+    if (function == TFunctionUnknown)
+        return TFunctionUnknown;
+    if (param1.isVector())
+        function += param1.getNominalSize() - 1;
+    return static_cast<TBuiltInFunction>(function);
+}
+
 void BuiltInFunctionEmulator::MarkBuiltInFunctionsForEmulation(
     TIntermNode* root)
 {

gfx/angle/src/compiler/BuiltInFunctionEmulator.h

@@ -28,6 +28,8 @@ public:
     bool SetFunctionCalled(TOperator op, const TType& param);
     bool SetFunctionCalled(
         TOperator op, const TType& param1, const TType& param2);
+    bool SetFunctionCalled(
+        TOperator op, const TType& param1, const TType& param2, const TType& param3);
 
     // Output function emulation definition.  This should be before any other
     // shader source.
@@ -60,6 +62,11 @@ private:
         TFunctionDot3_3,  // vec3 dot(vec3, vec3);
         TFunctionDot4_4,  // vec4 dot(vec4, vec4);
 
+        TFunctionFaceForward1_1_1,  // float faceforward(float, float, float);
+        TFunctionFaceForward2_2_2,  // vec2 faceforward(vec2, vec2, vec2);
+        TFunctionFaceForward3_3_3,  // vec3 faceforward(vec3, vec3, vec3);
+        TFunctionFaceForward4_4_4,  // vec4 faceforward(vec4, vec4, vec4);
+
         TFunctionLength1,  // float length(float);
         TFunctionLength2,  // float length(vec2);
         TFunctionLength3,  // float length(vec3);
@@ -81,6 +88,8 @@ private:
     TBuiltInFunction IdentifyFunction(TOperator op, const TType& param);
     TBuiltInFunction IdentifyFunction(
         TOperator op, const TType& param1, const TType& param2);
+    TBuiltInFunction IdentifyFunction(
+        TOperator op, const TType& param1, const TType& param2, const TType& param3);
 
     bool SetFunctionCalled(TBuiltInFunction function);