GrFP can express distance vector field req., program builder declares variable for it

This update allows fragment processors to require a field of vectors to the nearest edge. This requirement propagates:

- from child FPs to their parent
- from parent FPs to the GrPaint
- from GrPaint through the PipelineBuilder into GrPipeline
- acessed from GrPipeline by GrGLSLProgramBuilder

GrGLSL generates a variable for the distance vector and passes it down to the GeometryProcessor->emitCode() method.

This CL's base is the CL for adding the BevelNormalSource API: https://codereview.chromium.org/2080993002

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2114993002

Committed: https://skia.googlesource.com/skia/+/4ef6dfa7089c092c67b0d5ec34e89c1e319af196
Review-Url: https://codereview.chromium.org/2114993002

18 files changed, 137 insertions, 21 deletions

diff --git a/src/core/SkNormalBevelSource.cpp b/src/core/SkNormalBevelSource.cpp
index feccb0cce8..a63e434c3f 100644
--- a/src/core/SkNormalBevelSource.cpp
+++ b/src/core/SkNormalBevelSource.cpp
@@ -8,6 +8,7 @@
 #include "SkNormalBevelSource.h"
 
 #include "SkNormalSource.h"
+#include "SkNormalSourcePriv.h"
 #include "SkPoint3.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
@@ -25,17 +26,19 @@ public:
         , fWidth(width)
         , fHeight(height) {
         this->initClassID<NormalBevelFP>();
+
+        fUsesDistanceVectorField = true;
     }
 
-    class GLSLNormalBevelFP : public GrGLSLFragmentProcessor {
+    class GLSLNormalBevelFP : public GLSLNormalFP {
     public:
         GLSLNormalBevelFP() {
             fPrevWidth = SkFloatToScalar(0.0f);
             fPrevHeight = SkFloatToScalar(0.0f);
         }
 
-        void emitCode(EmitArgs& args) override {
-            GrGLSLFragmentBuilder* fragBuilder = args.fFragBuilder;
+        void onEmitCode(EmitArgs& args) override {
+            GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
             GrGLSLUniformHandler* uniformHandler = args.fUniformHandler;
 
             const char* widthUniName = nullptr;
@@ -46,7 +49,7 @@ public:
             fHeightUni = uniformHandler->addUniform(kFragment_GrShaderFlag, kFloat_GrSLType,
                     kDefault_GrSLPrecision, "Height", &heightUniName);
 
-            fragBuilder->codeAppendf("%s = vec4(0, 0, 1, 0);", args.fOutputColor);
+            fragBuilder->codeAppendf("%s = vec4(0.0, 0.0, 1.0, 0.0);", args.fOutputColor);
         }
 
         static void GenKey(const GrProcessor& proc, const GrGLSLCaps&,
@@ -56,7 +59,8 @@ public:
         }
 
     protected:
-        void onSetData(const GrGLSLProgramDataManager& pdman, const GrProcessor& proc) override {
+        void setNormalData(const GrGLSLProgramDataManager& pdman,
+                           const GrProcessor& proc) override {
             const NormalBevelFP& normalBevelFP = proc.cast<NormalBevelFP>();
 
             if (fPrevWidth  != normalBevelFP.fWidth) {
diff --git a/src/core/SkNormalFlatSource.cpp b/src/core/SkNormalFlatSource.cpp
index fcb1a4f3ad..bdd65b03e9 100644
--- a/src/core/SkNormalFlatSource.cpp
+++ b/src/core/SkNormalFlatSource.cpp
@@ -8,6 +8,7 @@
 #include "SkNormalFlatSource.h"
 
 #include "SkNormalSource.h"
+#include "SkNormalSourcePriv.h"
 #include "SkPoint3.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
@@ -23,12 +24,12 @@ public:
         this->initClassID<NormalFlatFP>();
     }
 
-    class GLSLNormalFlatFP : public GrGLSLFragmentProcessor {
+    class GLSLNormalFlatFP : public GLSLNormalFP {
     public:
         GLSLNormalFlatFP() {}
 
-        void emitCode(EmitArgs& args) override {
-            GrGLSLFragmentBuilder* fragBuilder = args.fFragBuilder;
+        void onEmitCode(EmitArgs& args) override {
+            GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
 
             fragBuilder->codeAppendf("%s = vec4(0, 0, 1, 0);", args.fOutputColor);
         }
@@ -39,7 +40,8 @@ public:
         }
 
     protected:
-        void onSetData(const GrGLSLProgramDataManager& pdman, const GrProcessor& proc) override {}
+        void setNormalData(const GrGLSLProgramDataManager& pdman,
+                           const GrProcessor& proc) override {}
     };
 
     void onGetGLSLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const override {
diff --git a/src/core/SkNormalMapSource.cpp b/src/core/SkNormalMapSource.cpp
index 2ecf1d310d..c2cda099ab 100644
--- a/src/core/SkNormalMapSource.cpp
+++ b/src/core/SkNormalMapSource.cpp
@@ -10,6 +10,7 @@
 #include "SkLightingShader.h"
 #include "SkMatrix.h"
 #include "SkNormalSource.h"
+#include "SkNormalSourcePriv.h"
 #include "SkPM4f.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
@@ -31,13 +32,13 @@ public:
         this->initClassID<NormalMapFP>();
     }
 
-    class GLSLNormalMapFP : public GrGLSLFragmentProcessor {
+    class GLSLNormalMapFP : public GLSLNormalFP {
     public:
         GLSLNormalMapFP()
             : fColumnMajorInvCTM22{0.0f} {}
 
-        void emitCode(EmitArgs& args) override {
-            GrGLSLFragmentBuilder* fragBuilder = args.fFragBuilder;
+        void onEmitCode(EmitArgs& args) override {
+            GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
             GrGLSLUniformHandler* uniformHandler = args.fUniformHandler;
 
             // add uniform
@@ -78,7 +79,8 @@ public:
         }
 
     protected:
-        void onSetData(const GrGLSLProgramDataManager& pdman, const GrProcessor& proc) override {
+        void setNormalData(const GrGLSLProgramDataManager& pdman,
+                           const GrProcessor& proc) override {
             const NormalMapFP& normalMapFP = proc.cast<NormalMapFP>();
 
             const SkMatrix& invCTM = normalMapFP.invCTM();
diff --git a/src/core/SkNormalSource.h b/src/core/SkNormalSource.h
index 8cbb3e4fae..4b09d0b411 100644
--- a/src/core/SkNormalSource.h
+++ b/src/core/SkNormalSource.h
@@ -111,7 +111,7 @@ public:
     /** Returns a normal source that generates a bevel for the given shape. UNIMPLEMENTED: Will
         return straight-up normals only.
 
-        @param  type   the type of bevel to add
+        @param  type   the type of bevel to add.
         @param  width  the width of the bevel, in source space. Must be positive.
         @param  height the height of the plateau, in source space. Can be positive, negative,
                        or zero. A negative height means the simulated bevels slope downwards.
diff --git a/src/core/SkNormalSourcePriv.h b/src/core/SkNormalSourcePriv.h
new file mode 100644
index 0000000000..ce8baf61e4
--- /dev/null
+++ b/src/core/SkNormalSourcePriv.h
@@ -0,0 +1,57 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkNormalSourcePriv_DEFINED
+#define SkNormalSourcePriv_DEFINED
+
+#if SK_SUPPORT_GPU
+#include "glsl/GrGLSLFragmentProcessor.h"
+#include "glsl/GrGLSLFragmentShaderBuilder.h"
+
+/* GLSLFragmentProcessors for NormalSourceImpls must sub-class this class and override onEmitCode,
+ * and setNormalData calls, as well as all other calls FPs normally override, except for the 2
+ * defined in this superclass.
+ * This class exists to intercept emitCode calls and emit <0, 0, 1> if the FP requires a distance
+ * vector but the GP doesn't provide it. onSetData calls need to be intercepted too because
+ * uniform handlers will be invalid in subclasses where onEmitCode isn't called.
+ * We don't need to adjust the key here since the use of a given GP (through its class ID already in
+ * the key), will determine what code gets emitted here.
+ */
+class GLSLNormalFP : public GrGLSLFragmentProcessor {
+public:
+    GLSLNormalFP()
+        : fDidIntercept(false) {}
+
+    void emitCode(EmitArgs& args) final override {
+        if (args.fFp.usesDistanceVectorField() && !args.fGpImplementsDistanceVector) {
+            GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
+            fragBuilder->codeAppendf("// GLSLNormalFP intercepted emitCode call, GP does not "
+                                             "implement required distance vector feature\n");
+            fragBuilder->codeAppendf("%s = vec4(0, 0, 1, 0);", args.fOutputColor);
+
+            fDidIntercept = true;
+        } else {
+            this->onEmitCode(args);
+        }
+    }
+
+    void onSetData(const GrGLSLProgramDataManager& pdman, const GrProcessor& proc) final override {
+        if (!fDidIntercept) {
+            this->setNormalData(pdman, proc);
+        }
+    }
+
+protected:
+    virtual void onEmitCode(EmitArgs& args) = 0;
+    virtual void setNormalData(const GrGLSLProgramDataManager& pdman, const GrProcessor& proc) = 0;
+
+private:
+    bool fDidIntercept;
+};
+#endif
+
+#endif
diff --git a/src/gpu/GrFragmentProcessor.cpp b/src/gpu/GrFragmentProcessor.cpp
index fdba610356..a8a4898e78 100644
--- a/src/gpu/GrFragmentProcessor.cpp
+++ b/src/gpu/GrFragmentProcessor.cpp
@@ -106,6 +106,9 @@ int GrFragmentProcessor::registerChildProcessor(sk_sp<GrFragmentProcessor> child
     if (child->usesLocalCoords()) {
         fUsesLocalCoords = true;
     }
+    if (child->usesDistanceVectorField()) {
+        fUsesDistanceVectorField = true;
+    }
 
     int index = fChildProcessors.count();
     fChildProcessors.push_back(child.release());
diff --git a/src/gpu/GrPaint.cpp b/src/gpu/GrPaint.cpp
index dda687e7c1..7bf9b6d568 100644
--- a/src/gpu/GrPaint.cpp
+++ b/src/gpu/GrPaint.cpp
@@ -16,6 +16,7 @@ GrPaint::GrPaint()
     : fAntiAlias(false)
     , fDisableOutputConversionToSRGB(false)
     , fAllowSRGBInputs(false)
+    , fUsesDistanceVectorField(false)
     , fColor(GrColor4f::FromGrColor(GrColor_WHITE)) {}
 
 void GrPaint::setCoverageSetOpXPFactory(SkRegion::Op regionOp, bool invertCoverage) {
diff --git a/src/gpu/GrPipeline.cpp b/src/gpu/GrPipeline.cpp
index 7767bf220d..c60a94be7e 100644
--- a/src/gpu/GrPipeline.cpp
+++ b/src/gpu/GrPipeline.cpp
@@ -48,6 +48,9 @@ GrPipeline* GrPipeline::CreateAt(void* memory, const CreateArgs& args,
     if (builder.getAllowSRGBInputs()) {
         pipeline->fFlags |= kAllowSRGBInputs_Flag;
     }
+    if (builder.getUsesDistanceVectorField()) {
+        pipeline->fFlags |= kUsesDistanceVectorField_Flag;
+    }
     if (args.fHasStencilClip) {
         pipeline->fFlags |= kHasStencilClip_Flag;
     }
diff --git a/src/gpu/GrPipeline.h b/src/gpu/GrPipeline.h
index 5ec572d0ae..1457dbc3f5 100644
--- a/src/gpu/GrPipeline.h
+++ b/src/gpu/GrPipeline.h
@@ -160,6 +160,9 @@ public:
     bool getAllowSRGBInputs() const {
         return SkToBool(fFlags & kAllowSRGBInputs_Flag);
     }
+    bool usesDistanceVectorField() const {
+        return SkToBool(fFlags & kUsesDistanceVectorField_Flag);
+    }
     bool hasStencilClip() const {
         return SkToBool(fFlags & kHasStencilClip_Flag);
     }
@@ -206,7 +209,8 @@ private:
         kSnapVertices_Flag                  = 0x2,
         kDisableOutputConversionToSRGB_Flag = 0x4,
         kAllowSRGBInputs_Flag               = 0x8,
-        kHasStencilClip_Flag                = 0x10
+        kUsesDistanceVectorField_Flag       = 0x10,
+        kHasStencilClip_Flag                = 0x20,
     };
 
     typedef GrPendingIOResource<GrRenderTarget, kWrite_GrIOType> RenderTarget;
diff --git a/src/gpu/GrPipelineBuilder.cpp b/src/gpu/GrPipelineBuilder.cpp
index 60cbc62cf2..864d6f1bc6 100644
--- a/src/gpu/GrPipelineBuilder.cpp
+++ b/src/gpu/GrPipelineBuilder.cpp
@@ -41,6 +41,8 @@ GrPipelineBuilder::GrPipelineBuilder(const GrPaint& paint, bool useHWAA)
                    paint.getDisableOutputConversionToSRGB());
     this->setState(GrPipelineBuilder::kAllowSRGBInputs_Flag,
                    paint.getAllowSRGBInputs());
+    this->setState(GrPipelineBuilder::kUsesDistanceVectorField_Flag,
+                   paint.usesDistanceVectorField());
 }
 
 //////////////////////////////////////////////////////////////////////////////s
diff --git a/src/gpu/GrPipelineBuilder.h b/src/gpu/GrPipelineBuilder.h
index dca7f36034..0c33eb344f 100644
--- a/src/gpu/GrPipelineBuilder.h
+++ b/src/gpu/GrPipelineBuilder.h
@@ -221,7 +221,13 @@ public:
          */
         kAllowSRGBInputs_Flag = 0x08,
 
-        kLast_Flag = kAllowSRGBInputs_Flag,
+        /**
+         * Signals that one or more FPs need access to the distance vector field to the nearest
+         * edge
+         */
+        kUsesDistanceVectorField_Flag = 0x10,
+
+        kLast_Flag = kUsesDistanceVectorField_Flag,
     };
 
     bool isHWAntialias() const { return SkToBool(fFlags & kHWAntialias_Flag); }
@@ -231,6 +237,8 @@ public:
         return SkToBool(fFlags & kDisableOutputConversionToSRGB_Flag); }
     bool getAllowSRGBInputs() const {
         return SkToBool(fFlags & kAllowSRGBInputs_Flag); }
+    bool getUsesDistanceVectorField() const {
+        return SkToBool(fFlags & kUsesDistanceVectorField_Flag); }
 
     /**
      * Enable render state settings.
diff --git a/src/gpu/GrPrimitiveProcessor.h b/src/gpu/GrPrimitiveProcessor.h
index 0d5280fbd3..d27a6f31c7 100644
--- a/src/gpu/GrPrimitiveProcessor.h
+++ b/src/gpu/GrPrimitiveProcessor.h
@@ -221,6 +221,10 @@ public:
         return 0.0;
     }
 
+    /* Sub-class should override and return true if this primitive processor implements the distance
+     * vector field, a field of vectors to the nearest point in the edge of the shape.  */
+    virtual bool implementsDistanceVector() const { return false; }
+
 protected:
     GrPrimitiveProcessor() : fVertexStride(0) {}
 
diff --git a/src/gpu/glsl/GrGLSLFragmentProcessor.cpp b/src/gpu/glsl/GrGLSLFragmentProcessor.cpp
index 9533d5a8cb..46945bdc6b 100644
--- a/src/gpu/glsl/GrGLSLFragmentProcessor.cpp
+++ b/src/gpu/glsl/GrGLSLFragmentProcessor.cpp
@@ -107,7 +107,8 @@ void GrGLSLFragmentProcessor::internalEmitChild(int childIndex, const char* inpu
                        inputColor,
                        childCoords,
                        childTexSamplers,
-                       childBufferSamplers);
+                       childBufferSamplers,
+                       args.fGpImplementsDistanceVector);
     this->childProcessor(childIndex)->emitCode(childArgs);
     fragBuilder->codeAppend("}\n");
 
diff --git a/src/gpu/glsl/GrGLSLFragmentProcessor.h b/src/gpu/glsl/GrGLSLFragmentProcessor.h
index 43614f2279..c6eb016a32 100644
--- a/src/gpu/glsl/GrGLSLFragmentProcessor.h
+++ b/src/gpu/glsl/GrGLSLFragmentProcessor.h
@@ -61,7 +61,8 @@ public:
                  const char* inputColor,
                  const GrGLSLTransformedCoordsArray& coords,
                  const SamplerHandle* texSamplers,
-                 const SamplerHandle* bufferSamplers)
+                 const SamplerHandle* bufferSamplers,
+                 bool gpImplementsDistanceVector)
             : fFragBuilder(fragBuilder)
             , fUniformHandler(uniformHandler)
             , fGLSLCaps(caps)
@@ -70,7 +71,8 @@ public:
             , fInputColor(inputColor)
             , fCoords(coords)
             , fTexSamplers(texSamplers)
-            , fBufferSamplers(bufferSamplers) {}
+            , fBufferSamplers(bufferSamplers)
+            , fGpImplementsDistanceVector(gpImplementsDistanceVector){}
         GrGLSLFPFragmentBuilder* fFragBuilder;
         GrGLSLUniformHandler* fUniformHandler;
         const GrGLSLCaps* fGLSLCaps;
@@ -80,6 +82,7 @@ public:
         const GrGLSLTransformedCoordsArray& fCoords;
         const SamplerHandle* fTexSamplers;
         const SamplerHandle* fBufferSamplers;
+        bool fGpImplementsDistanceVector;
     };
 
     virtual void emitCode(EmitArgs&) = 0;
diff --git a/src/gpu/glsl/GrGLSLFragmentShaderBuilder.cpp b/src/gpu/glsl/GrGLSLFragmentShaderBuilder.cpp
index 5d1ba511b7..e6ecf8c171 100644
--- a/src/gpu/glsl/GrGLSLFragmentShaderBuilder.cpp
+++ b/src/gpu/glsl/GrGLSLFragmentShaderBuilder.cpp
@@ -189,6 +189,10 @@ const char* GrGLSLFragmentShaderBuilder::fragmentPosition() {
     }
 }
 
+const char* GrGLSLFragmentShaderBuilder::distanceVectorName() const {
+    return "fsDistanceVector";
+}
+
 void GrGLSLFragmentShaderBuilder::appendOffsetToSample(const char* sampleIdx, Coordinates coords) {
     SkASSERT(fProgramBuilder->header().fSamplePatternKey);
     SkDEBUGCODE(fUsedProcessorFeatures |= GrProcessor::kSampleLocations_RequiredFeature);
diff --git a/src/gpu/glsl/GrGLSLFragmentShaderBuilder.h b/src/gpu/glsl/GrGLSLFragmentShaderBuilder.h
index 614b04f54b..6845376261 100644
--- a/src/gpu/glsl/GrGLSLFragmentShaderBuilder.h
+++ b/src/gpu/glsl/GrGLSLFragmentShaderBuilder.h
@@ -96,6 +96,10 @@ public:
      */
     virtual void maskSampleCoverage(const char* mask, bool invert = false) = 0;
 
+    /** Returns a variable name that represents a vector to the nearest edge of the shape, in source
+        space coordinates. */
+    virtual const char* distanceVectorName() const = 0;
+
     /**
      * Fragment procs with child procs should call these functions before/after calling emitCode
      * on a child proc.
@@ -166,6 +170,7 @@ public:
     virtual SkString ensureFSCoords2D(const GrGLSLTransformedCoordsArray& coords,
                                       int index) override;
     const char* fragmentPosition() override;
+    const char* distanceVectorName() const override;
 
     // GrGLSLFPFragmentBuilder interface.
     void appendOffsetToSample(const char* sampleIdx, Coordinates) override;
@@ -235,6 +240,7 @@ private:
     bool       fHasSecondaryOutput;
     uint8_t    fUsedSampleOffsetArrays;
     bool       fHasInitializedSampleMask;
+    SkString   fDistanceVectorOutput;
 
 #ifdef SK_DEBUG
     // some state to verify shaders and effects are consistent, this is reset between effects by
diff --git a/src/gpu/glsl/GrGLSLPrimitiveProcessor.h b/src/gpu/glsl/GrGLSLPrimitiveProcessor.h
index d726027686..a94099656b 100644
--- a/src/gpu/glsl/GrGLSLPrimitiveProcessor.h
+++ b/src/gpu/glsl/GrGLSLPrimitiveProcessor.h
@@ -42,6 +42,7 @@ public:
                  const GrPrimitiveProcessor& gp,
                  const char* outputColor,
                  const char* outputCoverage,
+                 const char* distanceVectorName,
                  const SamplerHandle* texSamplers,
                  const SamplerHandle* bufferSamplers,
                  const TransformsIn& transformsIn,
@@ -54,6 +55,7 @@ public:
             , fGP(gp)
             , fOutputColor(outputColor)
             , fOutputCoverage(outputCoverage)
+            , fDistanceVectorName(distanceVectorName)
             , fTexSamplers(texSamplers)
             , fBufferSamplers(bufferSamplers)
             , fTransformsIn(transformsIn)
@@ -66,6 +68,7 @@ public:
         const GrPrimitiveProcessor& fGP;
         const char* fOutputColor;
         const char* fOutputCoverage;
+        const char* fDistanceVectorName;
         const SamplerHandle* fTexSamplers;
         const SamplerHandle* fBufferSamplers;
         const TransformsIn& fTransformsIn;
@@ -78,7 +81,6 @@ public:
      */
     virtual void emitCode(EmitArgs&) = 0;
 
-
     /** A GrGLSLPrimitiveProcessor instance can be reused with any GrGLSLPrimitiveProcessor that
         produces the same stage key; this function reads data from a GrGLSLPrimitiveProcessor and
         uploads any uniform variables required  by the shaders created in emitCode(). The
diff --git a/src/gpu/glsl/GrGLSLProgramBuilder.cpp b/src/gpu/glsl/GrGLSLProgramBuilder.cpp
index 64bc0640b9..1f28f19bb9 100644
--- a/src/gpu/glsl/GrGLSLProgramBuilder.cpp
+++ b/src/gpu/glsl/GrGLSLProgramBuilder.cpp
@@ -87,6 +87,13 @@ void GrGLSLProgramBuilder::emitAndInstallPrimProc(const GrPrimitiveProcessor& pr
     this->nameExpression(outputColor, "outputColor");
     this->nameExpression(outputCoverage, "outputCoverage");
 
+    const char* distanceVectorName = nullptr;
+    if (this->fPipeline.usesDistanceVectorField() && proc.implementsDistanceVector()) {
+        distanceVectorName = fFS.distanceVectorName();
+        fFS.codeAppend( "// Un-normalized vector to the closed geometric edge (in source space)\n");
+        fFS.codeAppendf("vec2 %s;", distanceVectorName);
+    }
+
     // Enclose custom code in a block to avoid namespace conflicts
     SkString openBrace;
     openBrace.printf("{ // Stage %d, %s\n", fStageIndex, proc.name());
@@ -108,6 +115,7 @@ void GrGLSLProgramBuilder::emitAndInstallPrimProc(const GrPrimitiveProcessor& pr
                                            proc,
                                            outputColor->c_str(),
                                            outputCoverage->c_str(),
+                                           distanceVectorName,
                                            texSamplers.begin(),
                                            bufferSamplers.begin(),
                                            fCoordTransforms,
@@ -161,7 +169,9 @@ void GrGLSLProgramBuilder::emitAndInstallFragProc(const GrFragmentProcessor& fp,
                                            input.isOnes() ? nullptr : input.c_str(),
                                            fOutCoords[index],
                                            texSamplers.begin(),
-                                           bufferSamplers.begin());
+                                           bufferSamplers.begin(),
+                                           this->primitiveProcessor().implementsDistanceVector());
+
     fragProc->emitCode(args);
 
     // We have to check that effects and the code they emit are consistent, ie if an effect