uniquely name FS functions, add lighting effects to unit test

Review URL: http://codereview.appspot.com/6458080/


git-svn-id: http://skia.googlecode.com/svn/trunk@4992 2bbb7eff-a529-9590-31e7-b0007b416f81

6 files changed, 249 insertions, 64 deletions

diff --git a/src/effects/SkLightingImageFilter.cpp b/src/effects/SkLightingImageFilter.cpp
index c590c262e8..9700249347 100644
--- a/src/effects/SkLightingImageFilter.cpp
+++ b/src/effects/SkLightingImageFilter.cpp
@@ -338,6 +338,7 @@ public:
     virtual bool isEqual(const GrCustomStage&) const SK_OVERRIDE;
     SkScalar kd() const { return fKD; }
 private:
+    GR_DECLARE_CUSTOM_STAGE_TEST;
     typedef GrLightingEffect INHERITED;
     SkScalar fKD;
 };
@@ -360,6 +361,7 @@ public:
     SkScalar shininess() const { return fShininess; }
 
 private:
+    GR_DECLARE_CUSTOM_STAGE_TEST;
     typedef GrLightingEffect INHERITED;
     SkScalar fKS;
     SkScalar fShininess;
@@ -372,12 +374,11 @@ public:
     virtual ~GrGLLight() {}
     virtual void setupVariables(GrGLShaderBuilder* builder);
     virtual void emitVS(SkString* out) const {}
-    virtual void emitFuncs(const GrGLShaderBuilder* builder, SkString* out) const {}
+    virtual void emitFuncs(GrGLShaderBuilder* builder) {}
     virtual void emitSurfaceToLight(const GrGLShaderBuilder*,
                                     SkString* out,
                                     const char* z) const = 0;
-    virtual void emitLightColor(const GrGLShaderBuilder*,
-                                SkString* out,
+    virtual void emitLightColor(GrGLShaderBuilder*,
                                 const char *surfaceToLight) const;
     virtual void setData(const GrGLUniformManager&, const GrRenderTarget* rt, const SkLight* light) const;
 
@@ -428,17 +429,17 @@ public:
     virtual void setupVariables(GrGLShaderBuilder* builder) SK_OVERRIDE;
     virtual void setData(const GrGLUniformManager&, const GrRenderTarget* rt, const SkLight* light) const SK_OVERRIDE;
     virtual void emitVS(SkString* out) const SK_OVERRIDE;
-    virtual void emitFuncs(const GrGLShaderBuilder* builder, SkString* out) const;
+    virtual void emitFuncs(GrGLShaderBuilder* builder);
     virtual void emitSurfaceToLight(const GrGLShaderBuilder* builder,
                                     SkString* out,
                                     const char* z) const SK_OVERRIDE;
-    virtual void emitLightColor(const GrGLShaderBuilder*,
-                                SkString* out,
+    virtual void emitLightColor(GrGLShaderBuilder*,
                                 const char *surfaceToLight) const SK_OVERRIDE;
 
 private:
     typedef GrGLLight INHERITED;
 
+    SkString        fLightColorFunc;
     UniformHandle   fLocationUni;
     UniformHandle   fExponentUni;
     UniformHandle   fCosOuterConeAngleUni;
@@ -905,6 +906,38 @@ bool SkSpecularLightingImageFilter::asNewCustomStage(GrCustomStage** stage,
 ///////////////////////////////////////////////////////////////////////////////
 
 #if SK_SUPPORT_GPU
+
+namespace {
+SkPoint3 random_point3(SkRandom* random) {
+    return SkPoint3(SkScalarToFloat(random->nextSScalar1()),
+                    SkScalarToFloat(random->nextSScalar1()),
+                    SkScalarToFloat(random->nextSScalar1()));
+}
+
+SkLight* create_random_light(SkRandom* random) {
+    int type = random->nextULessThan(3);
+    switch (type) {
+        case 0: {
+            return SkNEW_ARGS(SkDistantLight, (random_point3(random), random->nextU()));
+        }
+        case 1: {
+            return SkNEW_ARGS(SkPointLight, (random_point3(random), random->nextU()));
+        }
+        case 2: {
+            return SkNEW_ARGS(SkSpotLight, (random_point3(random),
+                                            random_point3(random),
+                                            random->nextUScalar1(),
+                                            random->nextUScalar1(), 
+                                            random->nextU()));
+        }
+        default:
+            GrCrash();
+            return NULL;
+    }
+}
+
+}
+
 class GrGLLightingEffect  : public GrGLProgramStage {
 public:
     GrGLLightingEffect(const GrProgramStageFactory& factory,
@@ -919,7 +952,7 @@ public:
                         const char* inputColor,
                         const char* samplerName) SK_OVERRIDE;
 
-    virtual void emitLightFunc(const GrGLShaderBuilder*, SkString* funcs) = 0;
+    virtual void emitLightFunc(GrGLShaderBuilder*, SkString* funcName) = 0;
 
     static inline StageKey GenKey(const GrCustomStage& s, const GrGLCaps& caps);
 
@@ -943,7 +976,7 @@ public:
     GrGLDiffuseLightingEffect(const GrProgramStageFactory& factory,
                               const GrCustomStage& stage);
     virtual void setupVariables(GrGLShaderBuilder* builder) SK_OVERRIDE;
-    virtual void emitLightFunc(const GrGLShaderBuilder*, SkString* funcs) SK_OVERRIDE;
+    virtual void emitLightFunc(GrGLShaderBuilder*, SkString* funcName) SK_OVERRIDE;
     virtual void setData(const GrGLUniformManager&,
                          const GrCustomStage&,
                          const GrRenderTarget*,
@@ -962,7 +995,7 @@ public:
     GrGLSpecularLightingEffect(const GrProgramStageFactory& factory,
                                const GrCustomStage& stage);
     virtual void setupVariables(GrGLShaderBuilder* builder) SK_OVERRIDE;
-    virtual void emitLightFunc(const GrGLShaderBuilder*, SkString* funcs) SK_OVERRIDE;
+    virtual void emitLightFunc(GrGLShaderBuilder*, SkString* funcName) SK_OVERRIDE;
     virtual void setData(const GrGLUniformManager&,
                          const GrCustomStage&,
                          const GrRenderTarget*,
@@ -1013,6 +1046,19 @@ bool GrDiffuseLightingEffect::isEqual(const GrCustomStage& sBase) const {
             this->kd() == s.kd();
 }
 
+GR_DEFINE_CUSTOM_STAGE_TEST(GrDiffuseLightingEffect);
+
+GrCustomStage* GrDiffuseLightingEffect::TestCreate(SkRandom* random,
+                                                   GrContext* context,
+                                                   GrTexture* textures[]) {
+    SkScalar surfaceScale = random->nextSScalar1();
+    SkScalar kd = random->nextUScalar1();
+    SkAutoTUnref<SkLight> light(create_random_light(random));
+    return SkNEW_ARGS(GrDiffuseLightingEffect, (textures[GrCustomStageUnitTest::kAlphaTextureIdx],
+                                                light, surfaceScale, kd));
+}
+
+
 ///////////////////////////////////////////////////////////////////////////////
 
 GrGLLightingEffect::GrGLLightingEffect(const GrProgramStageFactory& factory,
@@ -1048,20 +1094,59 @@ void GrGLLightingEffect::emitFS(GrGLShaderBuilder* builder,
                                 const char* inputColor,
                                 const char* samplerName) {
     SkString* code = &builder->fFSCode;
-    SkString* funcs = &builder->fFSFunctions;
-    fLight->emitFuncs(builder, funcs);
-    this->emitLightFunc(builder, funcs);
-    funcs->appendf("float sobel(float a, float b, float c, float d, float e, float f, float scale) {\n");
-    funcs->appendf("\treturn (-a + b - 2.0 * c + 2.0 * d -e + f) * scale;\n");
-    funcs->appendf("}\n");
-    funcs->appendf("vec3 pointToNormal(float x, float y, float scale) {\n");
-    funcs->appendf("\treturn normalize(vec3(-x * scale, -y * scale, 1));\n");
-    funcs->appendf("}\n");
-    funcs->append("\n\
-vec3 interiorNormal(float m[9], float surfaceScale) {\n\
-    return pointToNormal(sobel(m[0], m[2], m[3], m[5], m[6], m[8], 0.25),\n\
-                         sobel(m[0], m[6], m[1], m[7], m[2], m[8], 0.25),\n\
-                         surfaceScale);\n}\n");
+    fLight->emitFuncs(builder);
+    SkString lightFunc;
+    this->emitLightFunc(builder, &lightFunc);
+    static const GrGLShaderVar gSobelArgs[] =  {
+        GrGLShaderVar("a", kFloat_GrSLType),
+        GrGLShaderVar("b", kFloat_GrSLType),
+        GrGLShaderVar("c", kFloat_GrSLType),
+        GrGLShaderVar("d", kFloat_GrSLType),
+        GrGLShaderVar("e", kFloat_GrSLType),
+        GrGLShaderVar("f", kFloat_GrSLType),
+        GrGLShaderVar("scale", kFloat_GrSLType),
+    };
+    SkString sobelFuncName;
+    builder->emitFunction(GrGLShaderBuilder::kFragment_ShaderType,
+                          kFloat_GrSLType,
+                          "sobel",
+                          SK_ARRAY_COUNT(gSobelArgs),
+                          gSobelArgs,
+                          "\treturn (-a + b - 2.0 * c + 2.0 * d -e + f) * scale;\n",
+                          &sobelFuncName);
+    static const GrGLShaderVar gPointToNormalArgs[] =  {
+        GrGLShaderVar("x", kFloat_GrSLType),
+        GrGLShaderVar("y", kFloat_GrSLType),
+        GrGLShaderVar("scale", kFloat_GrSLType),
+    };
+    SkString pointToNormalName;
+    builder->emitFunction(GrGLShaderBuilder::kFragment_ShaderType,
+                          kVec3f_GrSLType,
+                          "pointToNormal",
+                          SK_ARRAY_COUNT(gPointToNormalArgs),
+                          gPointToNormalArgs,
+                          "\treturn normalize(vec3(-x * scale, -y * scale, 1));\n",
+                          &pointToNormalName);
+
+    static const GrGLShaderVar gInteriorNormalArgs[] =  {
+        GrGLShaderVar("m", kFloat_GrSLType, 9),
+        GrGLShaderVar("surfaceScale", kFloat_GrSLType),
+    };
+    SkString interiorNormalBody;
+    interiorNormalBody.appendf("\treturn %s(%s(m[0], m[2], m[3], m[5], m[6], m[8], 0.25),\n"
+                               "\t       %s(m[0], m[6], m[1], m[7], m[2], m[8], 0.25),\n"
+                               "\t       surfaceScale);\n",
+                                pointToNormalName.c_str(),
+                                sobelFuncName.c_str(),
+                                sobelFuncName.c_str());
+    SkString interiorNormalName;
+    builder->emitFunction(GrGLShaderBuilder::kFragment_ShaderType,
+                          kVec3f_GrSLType,
+                          "interiorNormal",
+                          SK_ARRAY_COUNT(gInteriorNormalArgs),
+                          gInteriorNormalArgs,
+                          interiorNormalBody.c_str(),
+                          &interiorNormalName);
 
     code->appendf("\t\tvec2 coord = %s;\n", builder->fSampleCoords.c_str());
     code->appendf("\t\tfloat m[9];\n");
@@ -1084,8 +1169,9 @@ vec3 interiorNormal(float m[9], float surfaceScale) {\n\
     arg.appendf("%s * m[4]", surfScale);
     fLight->emitSurfaceToLight(builder, code, arg.c_str());
     code->appendf(";\n");
-    code->appendf("\t\t%s = light(interiorNormal(m, %s), surfaceToLight, ", outputColor, surfScale);
-    fLight->emitLightColor(builder, code, "surfaceToLight");
+    code->appendf("\t\t%s = %s(%s(m, %s), surfaceToLight, ",
+                  outputColor, lightFunc.c_str(), interiorNormalName.c_str(), surfScale);
+    fLight->emitLightColor(builder, "surfaceToLight");
     code->appendf(")%s;\n", builder->fModulate.c_str());
 }
 
@@ -1122,12 +1208,23 @@ void GrGLDiffuseLightingEffect::setupVariables(GrGLShaderBuilder* builder) {
     fKDUni = builder->addUniform(GrGLShaderBuilder::kFragment_ShaderType, kFloat_GrSLType, "KD");
 }
 
-void GrGLDiffuseLightingEffect::emitLightFunc(const GrGLShaderBuilder* builder, SkString* funcs) {
+void GrGLDiffuseLightingEffect::emitLightFunc(GrGLShaderBuilder* builder, SkString* funcName) {
     const char* kd = builder->getUniformCStr(fKDUni);
-    funcs->appendf("vec4 light(vec3 normal, vec3 surfaceToLight, vec3 lightColor) {\n");
-    funcs->appendf("\tfloat colorScale = %s * dot(normal, surfaceToLight);\n", kd);
-    funcs->appendf("\treturn vec4(lightColor * clamp(colorScale, 0.0, 1.0), 1.0);\n");
-    funcs->appendf("}\n");
+    static const GrGLShaderVar gLightArgs[] = {
+        GrGLShaderVar("normal", kVec3f_GrSLType),
+        GrGLShaderVar("surfaceToLight", kVec3f_GrSLType),
+        GrGLShaderVar("lightColor", kVec3f_GrSLType)
+    };
+    SkString lightBody;
+    lightBody.appendf("\tfloat colorScale = %s * dot(normal, surfaceToLight);\n", kd);
+    lightBody.appendf("\treturn vec4(lightColor * clamp(colorScale, 0.0, 1.0), 1.0);\n");
+    builder->emitFunction(GrGLShaderBuilder::kFragment_ShaderType,
+                          kVec4f_GrSLType,
+                          "light",
+                          SK_ARRAY_COUNT(gLightArgs),
+                          gLightArgs,
+                          lightBody.c_str(),
+                          funcName);
 }
 
 void GrGLDiffuseLightingEffect::setData(const GrGLUniformManager& uman,
@@ -1160,6 +1257,19 @@ bool GrSpecularLightingEffect::isEqual(const GrCustomStage& sBase) const {
            this->shininess() == s.shininess();
 }
 
+GR_DEFINE_CUSTOM_STAGE_TEST(GrSpecularLightingEffect);
+
+GrCustomStage* GrSpecularLightingEffect::TestCreate(SkRandom* random,
+                                                    GrContext* context,
+                                                    GrTexture* textures[]) {
+    SkScalar surfaceScale = random->nextSScalar1();
+    SkScalar ks = random->nextUScalar1();
+    SkScalar shininess = random->nextUScalar1();
+    SkAutoTUnref<SkLight> light(create_random_light(random));
+    return SkNEW_ARGS(GrSpecularLightingEffect, (textures[GrCustomStageUnitTest::kAlphaTextureIdx],
+                                                 light, surfaceScale, ks, shininess));
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 GrGLSpecularLightingEffect::GrGLSpecularLightingEffect(const GrProgramStageFactory& factory,
@@ -1177,15 +1287,26 @@ void GrGLSpecularLightingEffect::setupVariables(GrGLShaderBuilder* builder) {
                                         kFloat_GrSLType, "Shininess");
 }
 
-void GrGLSpecularLightingEffect::emitLightFunc(const GrGLShaderBuilder* builder, SkString* funcs) {
-    funcs->appendf("vec4 light(vec3 normal, vec3 surfaceToLight, vec3 lightColor) {\n");
-    funcs->appendf("\tvec3 halfDir = vec3(normalize(surfaceToLight + vec3(0, 0, 1)));\n");
-
+void GrGLSpecularLightingEffect::emitLightFunc(GrGLShaderBuilder* builder, SkString* funcName) {
     const char* ks = builder->getUniformCStr(fKSUni);
     const char* shininess = builder->getUniformCStr(fShininessUni);
-    funcs->appendf("\tfloat colorScale = %s * pow(dot(normal, halfDir), %s);\n", ks, shininess);
-    funcs->appendf("\treturn vec4(lightColor * clamp(colorScale, 0.0, 1.0), 1.0);\n");
-    funcs->appendf("}\n");
+
+    static const GrGLShaderVar gLightArgs[] = {
+        GrGLShaderVar("normal", kVec3f_GrSLType),
+        GrGLShaderVar("surfaceToLight", kVec3f_GrSLType),
+        GrGLShaderVar("lightColor", kVec3f_GrSLType)
+    };
+    SkString lightBody;
+    lightBody.appendf("\tvec3 halfDir = vec3(normalize(surfaceToLight + vec3(0, 0, 1)));\n");
+    lightBody.appendf("\tfloat colorScale = %s * pow(dot(normal, halfDir), %s);\n", ks, shininess);
+    lightBody.appendf("\treturn vec4(lightColor * clamp(colorScale, 0.0, 1.0), 1.0);\n");
+    builder->emitFunction(GrGLShaderBuilder::kFragment_ShaderType,
+                          kVec4f_GrSLType,
+                          "light",
+                          SK_ARRAY_COUNT(gLightArgs),
+                          gLightArgs,
+                          lightBody.c_str(),
+                          funcName);
 }
 
 void GrGLSpecularLightingEffect::setData(const GrGLUniformManager& uman,
@@ -1200,11 +1321,10 @@ void GrGLSpecularLightingEffect::setData(const GrGLUniformManager& uman,
 
 ///////////////////////////////////////////////////////////////////////////////
 
-void GrGLLight::emitLightColor(const GrGLShaderBuilder* builder,
-                               SkString* out,
+void GrGLLight::emitLightColor(GrGLShaderBuilder* builder,
                                const char *surfaceToLight) const {
     const char* color = builder->getUniformCStr(fColorUni);
-    out->append(color);
+    builder->fFSCode.append(color);
 }
 
 void GrGLLight::setupVariables(GrGLShaderBuilder* builder) {
@@ -1304,25 +1424,34 @@ void GrGLSpotLight::setData(const GrGLUniformManager& uman,
 void GrGLSpotLight::emitVS(SkString* out) const {
 }
 
-void GrGLSpotLight::emitFuncs(const GrGLShaderBuilder* builder, SkString* out) const {
+void GrGLSpotLight::emitFuncs(GrGLShaderBuilder* builder) {
     const char* exponent = builder->getUniformCStr(fExponentUni);
     const char* cosInner = builder->getUniformCStr(fCosInnerConeAngleUni);
     const char* cosOuter = builder->getUniformCStr(fCosOuterConeAngleUni);
     const char* coneScale = builder->getUniformCStr(fConeScaleUni);
     const char* s = builder->getUniformCStr(fSUni);
     const char* color = builder->getUniformCStr(fColorUni);
-
-    out->appendf("vec3 lightColor(vec3 surfaceToLight) {\n");
-    out->appendf("\tfloat cosAngle = -dot(surfaceToLight, %s);\n", s);
-    out->appendf("\tif (cosAngle < %s) {\n", cosOuter);
-    out->appendf("\t\treturn vec3(0);\n");
-    out->appendf("\t}\n");
-    out->appendf("\tfloat scale = pow(cosAngle, %s);\n", exponent);
-    out->appendf("\tif (cosAngle < %s) {\n", cosInner);
-    out->appendf("\t\treturn %s * scale * (cosAngle - %s) * %s;\n", color, cosOuter, coneScale);
-    out->appendf("\t}\n");
-    out->appendf("\treturn %s;\n", color);
-    out->appendf("}\n");
+    static const GrGLShaderVar gLightColorArgs[] = {
+        GrGLShaderVar("surfaceToLight", kVec3f_GrSLType)
+    };
+    SkString lightColorBody;
+    lightColorBody.appendf("\tfloat cosAngle = -dot(surfaceToLight, %s);\n", s);
+    lightColorBody.appendf("\tif (cosAngle < %s) {\n", cosOuter);
+    lightColorBody.appendf("\t\treturn vec3(0);\n");
+    lightColorBody.appendf("\t}\n");
+    lightColorBody.appendf("\tfloat scale = pow(cosAngle, %s);\n", exponent);
+    lightColorBody.appendf("\tif (cosAngle < %s) {\n", cosInner);
+    lightColorBody.appendf("\t\treturn %s * scale * (cosAngle - %s) * %s;\n",
+                           color, cosOuter, coneScale);
+    lightColorBody.appendf("\t}\n");
+    lightColorBody.appendf("\treturn %s;\n", color);
+    builder->emitFunction(GrGLShaderBuilder::kFragment_ShaderType,
+                          kVec3f_GrSLType,
+                          "lightColor",
+                          SK_ARRAY_COUNT(gLightColorArgs),
+                          gLightColorArgs,
+                          lightColorBody.c_str(),
+                          &fLightColorFunc);
 }
 
 void GrGLSpotLight::emitSurfaceToLight(const GrGLShaderBuilder* builder,
@@ -1332,9 +1461,9 @@ void GrGLSpotLight::emitSurfaceToLight(const GrGLShaderBuilder* builder,
     out->appendf("normalize(%s - vec3(gl_FragCoord.xy, %s))", location, z);
 }
 
-void GrGLSpotLight::emitLightColor(const GrGLShaderBuilder* builder,
-                                   SkString* out, const char *surfaceToLight) const {
-    out->appendf("lightColor(%s)", surfaceToLight);
+void GrGLSpotLight::emitLightColor(GrGLShaderBuilder* builder,
+                                   const char *surfaceToLight) const {
+    builder->fFSCode.appendf("%s(%s)", fLightColorFunc.c_str(), surfaceToLight);
 }
 
 #endif
diff --git a/src/gpu/gl/GrGLSL.cpp b/src/gpu/gl/GrGLSL.cpp
index 759a17c39a..ff4d498eaf 100644
--- a/src/gpu/gl/GrGLSL.cpp
+++ b/src/gpu/gl/GrGLSL.cpp
@@ -66,12 +66,12 @@ bool GrGLSLSetupFSColorOuput(GrGLSLGeneration gen,
 }
 
 GrSLType GrSLFloatVectorType (int count) {
-    GR_STATIC_ASSERT(kFloat_GrSLType == 0);
-    GR_STATIC_ASSERT(kVec2f_GrSLType == 1);
-    GR_STATIC_ASSERT(kVec3f_GrSLType == 2);
-    GR_STATIC_ASSERT(kVec4f_GrSLType == 3);
+    GR_STATIC_ASSERT(kFloat_GrSLType == 1);
+    GR_STATIC_ASSERT(kVec2f_GrSLType == 2);
+    GR_STATIC_ASSERT(kVec3f_GrSLType == 3);
+    GR_STATIC_ASSERT(kVec4f_GrSLType == 4);
     GrAssert(count > 0 && count <= 4);
-    return (GrSLType)(count - 1);
+    return (GrSLType)(count);
 }
 
 const char* GrGLSLVectorHomogCoord(int count) {
diff --git a/src/gpu/gl/GrGLSL.h b/src/gpu/gl/GrGLSL.h
index 7b92c23434..a58f7e8e75 100644
--- a/src/gpu/gl/GrGLSL.h
+++ b/src/gpu/gl/GrGLSL.h
@@ -35,6 +35,7 @@ enum GrGLSLGeneration {
  * langauges.)
  */
 enum GrSLType {
+    kVoid_GrSLType,
     kFloat_GrSLType,
     kVec2f_GrSLType,
     kVec3f_GrSLType,
diff --git a/src/gpu/gl/GrGLShaderBuilder.cpp b/src/gpu/gl/GrGLShaderBuilder.cpp
index 3ca408618c..167eb78bcc 100644
--- a/src/gpu/gl/GrGLShaderBuilder.cpp
+++ b/src/gpu/gl/GrGLShaderBuilder.cpp
@@ -291,6 +291,32 @@ void GrGLShaderBuilder::addVarying(GrSLType type,
     }
 }
 
+void GrGLShaderBuilder::emitFunction(ShaderType shader,
+                                     GrSLType returnType,
+                                     const char* name,
+                                     int argCnt,
+                                     const GrGLShaderVar* args,
+                                     const char* body,
+                                     SkString* outName) {
+    GrAssert(kFragment_ShaderType == shader);
+    fFSFunctions.append(GrGLShaderVar::TypeString(returnType));
+    if (kNonStageIdx != fCurrentStage) {
+        outName->printf(" %s_%d", name, fCurrentStage);
+    } else {
+        *outName = name;
+    }
+    fFSFunctions.append(*outName);
+    fFSFunctions.append("(");
+    for (int i = 0; i < argCnt; ++i) {
+        args[i].appendDecl(fContext, &fFSFunctions);
+        if (i < argCnt - 1) {
+            fFSFunctions.append(", ");
+        }
+    }
+    fFSFunctions.append(") {\n");
+    fFSFunctions.append(body);
+    fFSFunctions.append("}\n\n");
+}
 
 namespace {
 
@@ -321,6 +347,7 @@ inline void append_default_precision_qualifier(GrGLShaderVar::Precision p,
 void GrGLShaderBuilder::appendDecls(const VarArray& vars, SkString* out) const {
     for (int i = 0; i < vars.count(); ++i) {
         vars[i].appendDecl(fContext, out);
+        out->append(";\n");
     }
 }
 
@@ -328,6 +355,7 @@ void GrGLShaderBuilder::appendUniformDecls(ShaderType stype, SkString* out) cons
     for (int i = 0; i < fUniforms.count(); ++i) {
         if (fUniforms[i].fVisibility & stype) {
             fUniforms[i].fVariable.appendDecl(fContext, out);
+            out->append(";\n");
         }
     }
 }
diff --git a/src/gpu/gl/GrGLShaderBuilder.h b/src/gpu/gl/GrGLShaderBuilder.h
index ab0792b0cf..31d603a8d2 100644
--- a/src/gpu/gl/GrGLShaderBuilder.h
+++ b/src/gpu/gl/GrGLShaderBuilder.h
@@ -66,6 +66,16 @@ public:
                                  const char* samplerName,
                                  const char* coordName);
 
+    /** Emits a helper function outside of main(). Currently ShaderType must be
+        kFragment_ShaderType. */
+    void emitFunction(ShaderType shader,
+                      GrSLType returnType,
+                      const char* name,
+                      int argCnt,
+                      const GrGLShaderVar* args,
+                      const char* body,
+                      SkString* outName);
+
     /** Generates a StageKey for the shader code based on the texture access parameters and the
         capabilities of the GL context.  This is useful for keying the shader programs that may
         have multiple representations, based on the type/format of textures used. */
@@ -144,7 +154,6 @@ public:
     VarArray    fFSInputs;
     SkString    fGSHeader; // layout qualifiers specific to GS
     VarArray    fFSOutputs;
-    SkString    fFSFunctions;
     SkString    fVSCode;
     SkString    fGSCode;
     SkString    fFSCode;
@@ -176,6 +185,7 @@ private:
     const GrGLContextInfo&  fContext;
     GrGLUniformManager&     fUniformManager;
     int                     fCurrentStage;
+    SkString                fFSFunctions;
 };
 
 #endif
diff --git a/src/gpu/gl/GrGLShaderVar.h b/src/gpu/gl/GrGLShaderVar.h
index 0231d214d3..92d7ee07fd 100644
--- a/src/gpu/gl/GrGLShaderVar.h
+++ b/src/gpu/gl/GrGLShaderVar.h
@@ -55,13 +55,25 @@ public:
         fUseUniformFloatArrays = USE_UNIFORM_FLOAT_ARRAYS;
     }
 
+    GrGLShaderVar(const char* name, GrSLType type, int arrayCount = kNonArray) {
+        GrAssert(kVoid_GrSLType != type);
+        fType = type;
+        fTypeModifier = kNone_TypeModifier;
+        fCount = arrayCount;
+        fPrecision = kDefault_Precision;
+        fUseUniformFloatArrays = USE_UNIFORM_FLOAT_ARRAYS;
+        fName = name;
+    }
+
     GrGLShaderVar(const GrGLShaderVar& var)
         : fType(var.fType)
         , fTypeModifier(var.fTypeModifier)
         , fName(var.fName)
         , fCount(var.fCount)
         , fPrecision(var.fPrecision)
-        , fUseUniformFloatArrays(var.fUseUniformFloatArrays) {}
+        , fUseUniformFloatArrays(var.fUseUniformFloatArrays) {
+        GrAssert(kVoid_GrSLType != var.fType);
+    }
 
     /**
      * Values for array count that have special meaning. We allow 1-sized arrays.
@@ -79,6 +91,7 @@ public:
              const SkString& name,
              Precision precision = kDefault_Precision,
              bool useUniformFloatArrays = USE_UNIFORM_FLOAT_ARRAYS) {
+        GrAssert(kVoid_GrSLType != type);
         fType = type;
         fTypeModifier = typeModifier;
         fName = name;
@@ -95,6 +108,7 @@ public:
              const char* name,
              Precision precision = kDefault_Precision,
              bool useUniformFloatArrays = USE_UNIFORM_FLOAT_ARRAYS) {
+        GrAssert(kVoid_GrSLType != type);
         fType = type;
         fTypeModifier = typeModifier;
         fName = name;
@@ -112,6 +126,7 @@ public:
              int count,
              Precision precision = kDefault_Precision,
              bool useUniformFloatArrays = USE_UNIFORM_FLOAT_ARRAYS) {
+        GrAssert(kVoid_GrSLType != type);
         fType = type;
         fTypeModifier = typeModifier;
         fName = name;
@@ -129,6 +144,7 @@ public:
              int count,
              Precision precision = kDefault_Precision,
              bool useUniformFloatArrays = USE_UNIFORM_FLOAT_ARRAYS) {
+        GrAssert(kVoid_GrSLType != type);
         fType = type;
         fTypeModifier = typeModifier;
         fName = name;
@@ -232,11 +248,12 @@ public:
                          TypeString(effectiveType),
                          this->getName().c_str());
         }
-        out->append(";\n");
     }
 
     static const char* TypeString(GrSLType t) {
         switch (t) {
+            case kVoid_GrSLType:
+                return "void";
             case kFloat_GrSLType:
                 return "float";
             case kVec2f_GrSLType: