Revert of removing equality / compute invariant loops from GrGeometryProcessors

src/gpu/GrGeometryProcessor.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGeometryProcessor_DEFINED
 #define GrGeometryProcessor_DEFINED
 
 #include "GrPrimitiveProcessor.h"
 
 /**
  * A GrGeometryProcessor is a flexible method for rendering a primitive.  The GrGeometryProcessor
  * has complete control over vertex attributes and uniforms(aside from the render target) but it
  * must obey the same contract as any GrPrimitiveProcessor, specifically it must emit a color and
  * coverage into the fragment shader.  Where this color and coverage come from is completely the
  * responsibility of the GrGeometryProcessor.
  */
 class GrGeometryProcessor : public GrPrimitiveProcessor {
 public:
     // TODO the Hint can be handled in a much more clean way when we have deferred geometry or
     // atleast bundles
     GrGeometryProcessor(GrColor color,
                         const SkMatrix& viewMatrix = SkMatrix::I(),
-                        const SkMatrix& localMatrix = SkMatrix::I())
+                        const SkMatrix& localMatrix = SkMatrix::I(),
+                        bool opaqueVertexColors = false)
         : INHERITED(viewMatrix, localMatrix, false)
         , fColor(color)
+        , fOpaqueVertexColors(opaqueVertexColors)
         , fWillUseGeoShader(false)
+        , fHasVertexColor(false)
         , fHasLocalCoords(false) {}
 
     bool willUseGeoShader() const { return fWillUseGeoShader; }
 
-    // TODO delete this when paths are in batch
+    /*
+     * In an ideal world, two GrGeometryProcessors with the same class id and texture accesses
+     * would ALWAYS be able to batch together.  If two GrGeometryProcesosrs are the same then we
+     * will only keep one of them.  The remaining GrGeometryProcessor then updates its
+     * GrBatchTracker to incorporate the draw information from the GrGeometryProcessor we discard.
+     * Any bundles associated with the discarded GrGeometryProcessor will be attached to the
+     * remaining GrGeometryProcessor.
+     */
     bool canMakeEqual(const GrBatchTracker& mine,
                       const GrPrimitiveProcessor& that,
                       const GrBatchTracker& theirs) const override {
-        SkFAIL("Unsupported\n");
-        return false;
+        if (this->classID() != that.classID() || !this->hasSameTextureAccesses(that)) {
+            return false;
+        }
+
+        // TODO let the GPs decide this
+        if (!this->viewMatrix().cheapEqualTo(that.viewMatrix())) {
+            return false;
+        }
+
+        // TODO remove the hint
+        const GrGeometryProcessor& other = that.cast<GrGeometryProcessor>();
+        if (fHasVertexColor && fOpaqueVertexColors != other.fOpaqueVertexColors) {
+            return false;
+        }
+
+        // TODO this equality test should really be broken up, some of this can live on the batch
+        // tracker test and some of this should be in bundles
+        if (!this->onIsEqual(other)) {
+            return false;
+        }
+
+        return this->onCanMakeEqual(mine, other, theirs);
     }
     
     // TODO we can remove color from the GrGeometryProcessor base class once we have bundles of
     // primitive data
     GrColor color() const { return fColor; }
 
-    // TODO Delete when paths are in batch
-    void getInvariantOutputColor(GrInitInvariantOutput* out) const override {
-        SkFAIL("Unsupported\n");
-    }
-    void getInvariantOutputCoverage(GrInitInvariantOutput* out) const override {
-        SkFAIL("Unsupported\n");
-    }
+    // TODO this is a total hack until the gp can do deferred geometry
+    bool hasVertexColor() const { return fHasVertexColor; }
+
+    void getInvariantOutputColor(GrInitInvariantOutput* out) const override;
+    void getInvariantOutputCoverage(GrInitInvariantOutput* out) const override;
 
 protected:
     /*
      * An optional simple helper function to determine by what means the GrGeometryProcessor should
      * use to provide color.  If we are given an override color(ie the given overridecolor is NOT
      * GrColor_ILLEGAL) then we must always emit that color(currently overrides are only supported
      * via uniform, but with deferred Geometry we could use attributes).  Otherwise, if our color is
      * ignored then we should not emit a color.  Lastly, if we don't have vertex colors then we must
      * emit a color via uniform
      * TODO this function changes quite a bit with deferred geometry.  There the GrGeometryProcessor
@@ skipping 30 matching lines @@
     const Attribute& addVertexAttrib(const Attribute& attribute) {
         SkASSERT(fNumAttribs < kMaxVertexAttribs);
         fVertexStride += attribute.fOffset;
         fAttribs[fNumAttribs] = attribute;
         return fAttribs[fNumAttribs++];
     }
 
     void setWillUseGeoShader() { fWillUseGeoShader = true; }
 
     // TODO hack see above
+    void setHasVertexColor() { fHasVertexColor = true; }
     void setHasLocalCoords() { fHasLocalCoords = true; }
 
+    virtual void onGetInvariantOutputColor(GrInitInvariantOutput*) const {}
+    virtual void onGetInvariantOutputCoverage(GrInitInvariantOutput*) const = 0;
+
 private:
+    virtual bool onCanMakeEqual(const GrBatchTracker& mine,
+                                const GrGeometryProcessor& that,
+                                const GrBatchTracker& theirs) const = 0;
+
+    // TODO delete this when we have more advanced equality testing via bundles and the BT
+    virtual bool onIsEqual(const GrGeometryProcessor&) const = 0;
+
     bool hasExplicitLocalCoords() const override { return fHasLocalCoords; }
 
     GrColor fColor;
+    bool fOpaqueVertexColors;
     bool fWillUseGeoShader;
+    bool fHasVertexColor;
     bool fHasLocalCoords;
 
     typedef GrPrimitiveProcessor INHERITED;
 };
 
 #endif