Make GrConvexPolyEffect support inverse fills and non-AA rects

src/gpu/effects/GrConvexPolyEffect.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrConvexPolyEffect.h"
 
 #include "gl/GrGLEffect.h"
 #include "gl/GrGLSL.h"
 #include "GrTBackendEffectFactory.h"
 
 #include "SkPath.h"
 
 //////////////////////////////////////////////////////////////////////////////
 class GLAARectEffect;
 
 class AARectEffect : public GrEffect {
 public:
     typedef GLAARectEffect GLEffect;
+    typedef GrConvexPolyEffect::EdgeType EdgeType;
 
     const SkRect& getRect() const { return fRect; }
 
     static const char* Name() { return "AARect"; }
 
-    static GrEffectRef* Create(const SkRect& rect) {
-        return CreateEffectRef(AutoEffectUnref(SkNEW_ARGS(AARectEffect, (rect))));
+    static GrEffectRef* Create(EdgeType edgeType, const SkRect& rect) {
+        return CreateEffectRef(AutoEffectUnref(SkNEW_ARGS(AARectEffect, (edgeType, rect))));
     }
 
     virtual void getConstantColorComponents(GrColor* color,
                                             uint32_t* validFlags) const SK_OVERRIDE {
         if (fRect.isEmpty()) {
             // An empty rect will have no coverage anywhere.
             *color = 0x00000000;
             *validFlags = kRGBA_GrColorComponentFlags;
         } else {
             *validFlags = 0;
         }
     }
 
+    GrConvexPolyEffect::EdgeType getEdgeType() const { return fEdgeType; }
+
     virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE;
 
 private:
-    AARectEffect(const SkRect& rect) : fRect(rect) {
+    AARectEffect(EdgeType edgeType, const SkRect& rect) : fRect(rect), fEdgeType(edgeType) {
         this->setWillReadFragmentPosition();
     }
 
     virtual bool onIsEqual(const GrEffect& other) const SK_OVERRIDE {
         const AARectEffect& aare = CastEffect<AARectEffect>(other);
         return fRect == aare.fRect;
     }
 
     SkRect fRect;
+    EdgeType fEdgeType;
+
     typedef GrEffect INHERITED;
 
     GR_DECLARE_EFFECT_TEST;
 
 };
 
 GR_DEFINE_EFFECT_TEST(AARectEffect);
 
 GrEffectRef* AARectEffect::TestCreate(SkRandom* random,
                                       GrContext*,
                                       const GrDrawTargetCaps& caps,
                                       GrTexture*[]) {
+    EdgeType edgeType = static_cast<EdgeType>(
+                                    random->nextULessThan(GrConvexPolyEffect::kEdgeTypeCnt));
+
     SkRect rect = SkRect::MakeLTRB(random->nextSScalar1(),
                                    random->nextSScalar1(),
                                    random->nextSScalar1(),
                                    random->nextSScalar1());
-    return AARectEffect::Create(rect);
+    return AARectEffect::Create(edgeType, rect);
 }
 
 //////////////////////////////////////////////////////////////////////////////
 
 class GLAARectEffect : public GrGLEffect {
 public:
     GLAARectEffect(const GrBackendEffectFactory&, const GrDrawEffect&);
 
     virtual void emitCode(GrGLShaderBuilder* builder,
                           const GrDrawEffect& drawEffect,
                           EffectKey key,
                           const char* outputColor,
                           const char* inputColor,
                           const TransformedCoordsArray&,
                           const TextureSamplerArray&) SK_OVERRIDE;
 
-    static inline EffectKey GenKey(const GrDrawEffect&, const GrGLCaps&) { return 0; }
+    static inline EffectKey GenKey(const GrDrawEffect&, const GrGLCaps&);
 
     virtual void setData(const GrGLUniformManager&, const GrDrawEffect&) SK_OVERRIDE;
 
 private:
     GrGLUniformManager::UniformHandle   fRectUniform;
     SkRect                              fPrevRect;
     typedef GrGLEffect INHERITED;
 };
 
 GLAARectEffect::GLAARectEffect(const GrBackendEffectFactory& factory,
                                const GrDrawEffect& drawEffect)
     : INHERITED (factory) {
     fPrevRect.fLeft = SK_ScalarNaN;
 }
 
 void GLAARectEffect::emitCode(GrGLShaderBuilder* builder,
                               const GrDrawEffect& drawEffect,
                               EffectKey key,
                               const char* outputColor,
                               const char* inputColor,
                               const TransformedCoordsArray&,
                               const TextureSamplerArray& samplers) {
+    const AARectEffect& aare = drawEffect.castEffect<AARectEffect>();
     const char *rectName;
+    // The rect uniform's xyzw refer to (left + 0.5, top + 0.5, right - 0.5, bottom - 0.5),
+    // respectively.
     fRectUniform = builder->addUniform(GrGLShaderBuilder::kFragment_Visibility,
                                        kVec4f_GrSLType,
                                        "rect",
                                        &rectName);
     const char* fragmentPos = builder->fragmentPosition();
-    // The rect uniform's xyzw refer to (left + 0.5, top + 0.5, right - 0.5, bottom - 0.5),
-    // respectively. The amount of coverage removed in x and y by the edges is computed as a pair of
-    // negative numbers, xSub and ySub.
-    builder->fsCodeAppend("\t\tfloat xSub, ySub;\n");
-    builder->fsCodeAppendf("\t\txSub = min(%s.x - %s.x, 0.0);\n", fragmentPos, rectName);
-    builder->fsCodeAppendf("\t\txSub += min(%s.z - %s.x, 0.0);\n", rectName, fragmentPos);
-    builder->fsCodeAppendf("\t\tySub = min(%s.y - %s.y, 0.0);\n", fragmentPos, rectName);
-    builder->fsCodeAppendf("\t\tySub += min(%s.w - %s.y, 0.0);\n", rectName, fragmentPos);
-    // Now compute coverage in x and y and multiply them to get the fraction of the pixel covered.
-    builder->fsCodeAppendf("\t\tfloat alpha = (1.0 + max(xSub, -1.0)) * (1.0 + max(ySub, -1.0));\n");
+    if (GrConvexPolyEffect::kFillAA_EdgeType == aare.getEdgeType() ||
+        GrConvexPolyEffect::kInverseFillAA_EdgeType == aare.getEdgeType()) {
+        // The amount of coverage removed in x and y by the edges is computed as a pair of negative
+        // numbers, xSub and ySub.
+        builder->fsCodeAppend("\t\tfloat xSub, ySub;\n");
+        builder->fsCodeAppendf("\t\txSub = min(%s.x - %s.x, 0.0);\n", fragmentPos, rectName);
+        builder->fsCodeAppendf("\t\txSub += min(%s.z - %s.x, 0.0);\n", rectName, fragmentPos);
+        builder->fsCodeAppendf("\t\tySub = min(%s.y - %s.y, 0.0);\n", fragmentPos, rectName);
+        builder->fsCodeAppendf("\t\tySub += min(%s.w - %s.y, 0.0);\n", rectName, fragmentPos);
+        // Now compute coverage in x and y and multiply them to get the fraction of the pixel
+        // covered.
+        builder->fsCodeAppendf("\t\tfloat alpha = (1.0 + max(xSub, -1.0)) * (1.0 + max(ySub, -1.0));\n");
+    } else {
+        builder->fsCodeAppendf("\t\tfloat alpha = 1.0;\n");
+        builder->fsCodeAppendf("\t\talpha *= (%s.x - %s.x) > -0.5 ? 1.0 : 0.0;\n", fragmentPos, rectName);
+        builder->fsCodeAppendf("\t\talpha *= (%s.z - %s.x) > -0.5 ? 1.0 : 0.0;\n", rectName, fragmentPos);
+        builder->fsCodeAppendf("\t\talpha *= (%s.y - %s.y) > 0.5 ? 1.0 : 0.0;\n", fragmentPos, rectName);
+        builder->fsCodeAppendf("\t\talpha *= (%s.w - %s.y) > 0.5 ? 1.0 : 0.0;\n", rectName, fragmentPos);
+    }
 
+    if (GrConvexPolyEffect::kInverseFillAA_EdgeType == aare.getEdgeType() ||
+        GrConvexPolyEffect::kInverseFillNoAA_EdgeType == aare.getEdgeType()) {
+        builder->fsCodeAppend("\t\talpha = 1.0 - alpha;\n");
+    }
     builder->fsCodeAppendf("\t\t%s = %s;\n", outputColor,
                            (GrGLSLExpr4(inputColor) * GrGLSLExpr1("alpha")).c_str());
 }
 
 void GLAARectEffect::setData(const GrGLUniformManager& uman, const GrDrawEffect& drawEffect) {
     const AARectEffect& aare = drawEffect.castEffect<AARectEffect>();
     const SkRect& rect = aare.getRect();
     if (rect != fPrevRect) {
         uman.set4f(fRectUniform, rect.fLeft + 0.5f, rect.fTop + 0.5f,
                    rect.fRight - 0.5f, rect.fBottom - 0.5f);
         fPrevRect = rect;
     }
 }
 
+GrGLEffect::EffectKey GLAARectEffect::GenKey(const GrDrawEffect& drawEffect, const GrGLCaps&) {
+    const AARectEffect& aare = drawEffect.castEffect<AARectEffect>();
+    return aare.getEdgeType();
+}
+
 const GrBackendEffectFactory& AARectEffect::getFactory() const {
     return GrTBackendEffectFactory<AARectEffect>::getInstance();
 }
 
 //////////////////////////////////////////////////////////////////////////////
 
 class GrGLConvexPolyEffect : public GrGLEffect {
 public:
     GrGLConvexPolyEffect(const GrBackendEffectFactory&, const GrDrawEffect&);
 
@@ skipping 37 matching lines @@
                                             cpe.getEdgeCount(),
                                             &edgeArrayName);
     builder->fsCodeAppend("\t\tfloat alpha = 1.0;\n");
     builder->fsCodeAppend("\t\tfloat edge;\n");
     const char* fragmentPos = builder->fragmentPosition();
     for (int i = 0; i < cpe.getEdgeCount(); ++i) {
         builder->fsCodeAppendf("\t\tedge = dot(%s[%d], vec3(%s.x, %s.y, 1));\n",
                                edgeArrayName, i, fragmentPos, fragmentPos);
         switch (cpe.getEdgeType()) {
             case GrConvexPolyEffect::kFillAA_EdgeType:
+            case GrConvexPolyEffect::kInverseFillAA_EdgeType: // inverse handled at the end
                 builder->fsCodeAppend("\t\tedge = clamp(edge, 0.0, 1.0);\n");
-                builder->fsCodeAppend("\t\talpha *= edge;\n");
                 break;
             case GrConvexPolyEffect::kFillNoAA_EdgeType:
+            case GrConvexPolyEffect::kInverseFillNoAA_EdgeType: // inverse handled at the end
                 builder->fsCodeAppend("\t\tedge = edge >= 0.5 ? 1.0 : 0.0;\n");
-                builder->fsCodeAppend("\t\talpha *= edge;\n");
                 break;
         }
+        builder->fsCodeAppend("\t\talpha *= edge;\n");
     }
 
     // Woe is me. See skbug.com/2149.
     if (kTegra2_GrGLRenderer == builder->ctxInfo().renderer()) {
         builder->fsCodeAppend("\t\tif (-1.0 == alpha) {\n\t\t\tdiscard;\n\t\t}\n");
     }
+
+    if (GrConvexPolyEffect::kInverseFillAA_EdgeType == cpe.getEdgeType() ||
+        GrConvexPolyEffect::kInverseFillNoAA_EdgeType == cpe.getEdgeType() ) {
+        builder->fsCodeAppend("\talpha = 1.0 - alpha;\n");
+    }
     builder->fsCodeAppendf("\t%s = %s;\n", outputColor,
                            (GrGLSLExpr4(inputColor) * GrGLSLExpr1("alpha")).c_str());
 }
 
 void GrGLConvexPolyEffect::setData(const GrGLUniformManager& uman, const GrDrawEffect& drawEffect) {
     const GrConvexPolyEffect& cpe = drawEffect.castEffect<GrConvexPolyEffect>();
     size_t byteSize = 3 * cpe.getEdgeCount() * sizeof(SkScalar);
     if (0 != memcmp(fPrevEdges, cpe.getEdges(), byteSize)) {
         uman.set3fv(fEdgeUniform, cpe.getEdgeCount(), cpe.getEdges());
         memcpy(fPrevEdges, cpe.getEdges(), byteSize);
@@ skipping 47 matching lines @@
                 edges[3 * n + 1] = v.fX;
             }
             SkPoint p = pts[i] + t;
             edges[3 * n + 2] = -(edges[3 * n] * p.fX + edges[3 * n + 1] * p.fY);
             ++n;
         }
     }
     return Create(type, n, edges);
 }
 
-GrEffectRef* GrConvexPolyEffect::CreateForAAFillRect(const SkRect& rect) {
-    return AARectEffect::Create(rect);
+GrEffectRef* GrConvexPolyEffect::Create(EdgeType edgeType, const SkRect& rect) {
+    return AARectEffect::Create(edgeType, rect);
 }
 
 GrConvexPolyEffect::~GrConvexPolyEffect() {}
 
 void GrConvexPolyEffect::getConstantColorComponents(GrColor* color, uint32_t* validFlags) const {
     *validFlags = 0;
 }
 
 const GrBackendEffectFactory& GrConvexPolyEffect::getFactory() const {
     return GrTBackendEffectFactory<GrConvexPolyEffect>::getInstance();
@@ skipping 30 matching lines @@
                                             GrTexture*[]) {
     EdgeType edgeType = static_cast<EdgeType>(random->nextULessThan(kEdgeTypeCnt));
     int count = random->nextULessThan(kMaxEdges) + 1;
     SkScalar edges[kMaxEdges * 3];
     for (int i = 0; i < 3 * count; ++i) {
         edges[i] = random->nextSScalar1();
     }
 
     return GrConvexPolyEffect::Create(edgeType, count, edges);
 }