Make the GPU dashing effect MSAA-friendly.

src/gpu/effects/GrDashingEffect.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 "GrDashingEffect.h"
 
 #include "GrBatch.h"
@@ skipping 13 matching lines @@
 #include "gl/GrGLProcessor.h"
 #include "gl/GrGLSL.h"
 #include "gl/builders/GrGLProgramBuilder.h"
 
 ///////////////////////////////////////////////////////////////////////////////
 
 // Returns whether or not the gpu can fast path the dash line effect.
 static bool can_fast_path_dash(const SkPoint pts[2], const GrStrokeInfo& strokeInfo,
                                const GrDrawTarget& target, const GrPipelineBuilder& pipelineBuilder,
                                const SkMatrix& viewMatrix) {
-    if (pipelineBuilder.getRenderTarget()->isMultisampled()) {
-        return false;
-    }
-
     // Pts must be either horizontal or vertical in src space
     if (pts[0].fX != pts[1].fX && pts[0].fY != pts[1].fY) {
         return false;
     }
 
     // May be able to relax this to include skew. As of now cannot do perspective
     // because of the non uniform scaling of bloating a rect
     if (!viewMatrix.preservesRightAngles()) {
         return false;
     }
@@ skipping 23 matching lines @@
     SkScalar fIntervalLength;
     SkRect fRect;
 };
 struct DashCircleVertex {
     SkPoint fPos;
     SkPoint fDashPos;
     SkScalar fIntervalLength;
     SkScalar fRadius;
     SkScalar fCenterX;
 };
+
+enum DashAAMode {
+    kBW_DashAAMode,
+    kEdgeAA_DashAAMode,
+    kMSAA_DashAAMode,
+
+    kDashAAModeCnt = 3,
+};
 };
 
 static void calc_dash_scaling(SkScalar* parallelScale, SkScalar* perpScale,
                             const SkMatrix& viewMatrix, const SkPoint pts[2]) {
     SkVector vecSrc = pts[1] - pts[0];
     SkScalar magSrc = vecSrc.length();
     SkScalar invSrc = magSrc ? SkScalarInvert(magSrc) : 0;
     vecSrc.scale(invSrc);
 
     SkVector vecSrcPerp;
@@ skipping 136 matching lines @@
 }
 
 
 /**
  * An GrGeometryProcessor that renders a dashed line.
  * This GrGeometryProcessor is meant for dashed lines that only have a single on/off interval pair.
  * Bounding geometry is rendered and the effect computes coverage based on the fragment's
  * position relative to the dashed line.
  */
 static GrGeometryProcessor* create_dash_gp(GrColor,
-                                           GrPrimitiveEdgeType edgeType,
+                                           DashAAMode aaMode,
                                            DashCap cap,
                                            const SkMatrix& localMatrix);
 
 class DashBatch : public GrBatch {
 public:
     struct Geometry {
         GrColor fColor;
         SkMatrix fViewMatrix;
         SkMatrix fSrcRotInv;
         SkPoint fPtsRot[2];
         SkScalar fSrcStrokeWidth;
         SkScalar fPhase;
         SkScalar fIntervals[2];
         SkScalar fParallelScale;
         SkScalar fPerpendicularScale;
         SkDEBUGCODE(SkRect fDevBounds;)
     };
 
-    static GrBatch* Create(const Geometry& geometry, SkPaint::Cap cap, bool useAA, bool fullDash) {
-        return SkNEW_ARGS(DashBatch, (geometry, cap, useAA, fullDash));
+    static GrBatch* Create(const Geometry& geometry, SkPaint::Cap cap, DashAAMode aaMode, bool fullDash) {
+        return SkNEW_ARGS(DashBatch, (geometry, cap, aaMode, fullDash));
     }
 
     const char* name() const override { return "DashBatch"; }
 
     void getInvariantOutputColor(GrInitInvariantOutput* out) const override {
         // When this is called on a batch, there is only one geometry bundle
         out->setKnownFourComponents(fGeoData[0].fColor);
     }
     void getInvariantOutputCoverage(GrInitInvariantOutput* out) const override {
         out->setUnknownSingleComponent();
@@ skipping 34 matching lines @@
             return;
         }
 
         SkPaint::Cap cap = this->cap();
 
         SkAutoTUnref<const GrGeometryProcessor> gp;
 
         bool isRoundCap = SkPaint::kRound_Cap == cap;
         DashCap capType = isRoundCap ? kRound_DashCap : kNonRound_DashCap;
         if (this->fullDash()) {
-            GrPrimitiveEdgeType edgeType = this->useAA() ? kFillAA_GrProcessorEdgeType :
-                                                           kFillBW_GrProcessorEdgeType;
-            gp.reset(create_dash_gp(this->color(), edgeType, capType, invert));
+            gp.reset(create_dash_gp(this->color(), this->aaMode(), capType, invert));
         } else {
             // Set up the vertex data for the line and start/end dashes
             gp.reset(GrDefaultGeoProcFactory::Create(GrDefaultGeoProcFactory::kPosition_GPType,
                                                      this->color(),
                                                      SkMatrix::I(),
                                                      invert));
         }
 
         batchTarget->initDraw(gp, pipeline);
 
         // TODO remove this when batch is everywhere
         GrPipelineInfo init;
         init.fColorIgnored = fBatch.fColorIgnored;
         init.fOverrideColor = GrColor_ILLEGAL;
         init.fCoverageIgnored = fBatch.fCoverageIgnored;
         init.fUsesLocalCoords = this->usesLocalCoords();
         gp->initBatchTracker(batchTarget->currentBatchTracker(), init);
 
-        bool useAA = this->useAA();
+        // useAA here means Edge AA or MSAA
+        bool useAA = this->aaMode() != kBW_DashAAMode;
         bool fullDash = this->fullDash();
 
         // We do two passes over all of the dashes.  First we setup the start, end, and bounds,
         // rectangles.  We preserve all of this work in the rects / draws arrays below.  Then we
         // iterate again over these decomposed dashes to generate vertices
         SkSTArray<128, SkRect, true> rects;
         SkSTArray<128, DashDraw, true> draws;
 
         int totalRectCount = 0;
         int rectOffset = 0;
@@ skipping 93 matching lines @@
                 args.fPhase = 0;
             }
 
             // Change the dashing info from src space into device space
             SkScalar* devIntervals = args.fIntervals;
             devIntervals[0] = args.fIntervals[0] * args.fParallelScale;
             devIntervals[1] = args.fIntervals[1] * args.fParallelScale;
             SkScalar devPhase = args.fPhase * args.fParallelScale;
             SkScalar strokeWidth = args.fSrcStrokeWidth * args.fPerpendicularScale;
 
-            if ((strokeWidth < 1.f && !useAA) || 0.f == strokeWidth) {
+            if ((strokeWidth < 1.f && useAA) || 0.f == strokeWidth) {
                 strokeWidth = 1.f;
             }
 
             SkScalar halfDevStroke = strokeWidth * 0.5f;
 
             if (SkPaint::kSquare_Cap == cap && 0 != args.fSrcStrokeWidth) {
                 // add cap to on interval and remove from off interval
                 devIntervals[0] += strokeWidth;
                 devIntervals[1] -= strokeWidth;
             }
             SkScalar startOffset = devIntervals[1] * 0.5f + devPhase;
 
-            SkScalar bloatX = useAA ? 0.5f / args.fParallelScale : 0.f;
-            SkScalar bloatY = useAA ? 0.5f / args.fPerpendicularScale : 0.f;
+            SkScalar devBloat = this->aaMode() == kEdgeAA_DashAAMode ? 0.5f : 0.0f;
 
-            SkScalar devBloat = useAA ? 0.5f : 0.f;
+            SkScalar bloatX = devBloat / args.fParallelScale;
+            SkScalar bloatY = devBloat / args.fPerpendicularScale;
 
             if (devIntervals[1] <= 0.f && useAA) {
                 // Case when we end up drawing a solid AA rect
                 // Reset the start rect to draw this single solid rect
                 // but it requires to upload a new intervals uniform so we can mimic
                 // one giant dash
                 args.fPtsRot[0].fX -= hasStartRect ? startAdj : 0;
                 args.fPtsRot[1].fX += hasEndRect ? endAdj : 0;
                 startRect.set(args.fPtsRot, 2);
                 startRect.outset(strokeAdj, halfSrcStroke);
@@ skipping 143 matching lines @@
             batchTarget->draw(drawInfo);
 
             drawInfo.setStartVertex(drawInfo.startVertex() + drawInfo.vertexCount());
             totalRectCount -= drawInfo.instanceCount();
        }
     }
 
     SkSTArray<1, Geometry, true>* geoData() { return &fGeoData; }
 
 private:
-    DashBatch(const Geometry& geometry, SkPaint::Cap cap, bool useAA, bool fullDash) {
+    DashBatch(const Geometry& geometry, SkPaint::Cap cap, DashAAMode aaMode, bool fullDash) {
         this->initClassID<DashBatch>();
         fGeoData.push_back(geometry);
 
-        fBatch.fUseAA = useAA;
+        fBatch.fAAMode = aaMode;
         fBatch.fCap = cap;
         fBatch.fFullDash = fullDash;
     }
 
     bool onCombineIfPossible(GrBatch* t) override {
         DashBatch* that = t->cast<DashBatch>();
 
-        if (this->useAA() != that->useAA()) {
+        if (this->aaMode() != that->aaMode()) {
             return false;
         }
 
         if (this->fullDash() != that->fullDash()) {
             return false;
         }
 
         if (this->cap() != that->cap()) {
             return false;
         }
 
         // TODO vertex color
         if (this->color() != that->color()) {
             return false;
         }
 
         SkASSERT(this->usesLocalCoords() == that->usesLocalCoords());
         if (this->usesLocalCoords() && !this->viewMatrix().cheapEqualTo(that->viewMatrix())) {
             return false;
         }
 
         fGeoData.push_back_n(that->geoData()->count(), that->geoData()->begin());
         return true;
     }
 
     GrColor color() const { return fBatch.fColor; }
     bool usesLocalCoords() const { return fBatch.fUsesLocalCoords; }
     const SkMatrix& viewMatrix() const { return fGeoData[0].fViewMatrix; }
-    bool useAA() const { return fBatch.fUseAA; }
+    DashAAMode aaMode() const { return fBatch.fAAMode; }
     bool fullDash() const { return fBatch.fFullDash; }
     SkPaint::Cap cap() const { return fBatch.fCap; }
 
     struct BatchTracker {
         GrColor fColor;
         bool fUsesLocalCoords;
         bool fColorIgnored;
         bool fCoverageIgnored;
         SkPaint::Cap fCap;
-        bool fUseAA;
+        DashAAMode fAAMode;
         bool fFullDash;
     };
 
     static const int kVertsPerDash = 4;
     static const int kIndicesPerDash = 6;
 
     BatchTracker fBatch;
     SkSTArray<1, Geometry, true> fGeoData;
 };
 
@@ skipping 34 matching lines @@
                       geometry.fPtsRot);
 
     SkScalar offInterval = info.fIntervals[1] * geometry.fParallelScale;
     SkScalar strokeWidth = geometry.fSrcStrokeWidth * geometry.fPerpendicularScale;
 
     if (SkPaint::kSquare_Cap == cap && 0 != geometry.fSrcStrokeWidth) {
         // add cap to on interveal and remove from off interval
         offInterval -= strokeWidth;
     }
 
-    bool useAA = paint.isAntiAlias();
+    DashAAMode aaMode = pipelineBuilder->getRenderTarget()->isMultisampled() ? kMSAA_DashAAMode :
+                        paint.isAntiAlias() ? kEdgeAA_DashAAMode :
+                                              kBW_DashAAMode;
+
     // TODO we can do a real rect call if not using fulldash(ie no off interval, not using AA)
-    bool fullDash = offInterval > 0.f || useAA;
+    bool fullDash = offInterval > 0.f || aaMode != kBW_DashAAMode;
 
     geometry.fColor = color;
     geometry.fViewMatrix = viewMatrix;
     geometry.fPhase = info.fPhase;
     geometry.fIntervals[0] = info.fIntervals[0];
     geometry.fIntervals[1] = info.fIntervals[1];
 
-    SkAutoTUnref<GrBatch> batch(DashBatch::Create(geometry, cap, useAA, fullDash));
+    SkAutoTUnref<GrBatch> batch(DashBatch::Create(geometry, cap, aaMode, fullDash));
     target->drawBatch(pipelineBuilder, batch);
 
     return true;
 }
 
 //////////////////////////////////////////////////////////////////////////////
 
 class GLDashingCircleEffect;
 
 struct DashingCircleBatchTracker {
     GrGPInput fInputColorType;
     GrColor fColor;
     bool fUsesLocalCoords;
 };
 
 /*
  * This effect will draw a dotted line (defined as a dashed lined with round caps and no on
  * interval). The radius of the dots is given by the strokeWidth and the spacing by the DashInfo.
  * Both of the previous two parameters are in device space. This effect also requires the setting of
  * a vec2 vertex attribute for the the four corners of the bounding rect. This attribute is the
  * "dash position" of each vertex. In other words it is the vertex coords (in device space) if we
  * transform the line to be horizontal, with the start of line at the origin then shifted to the
  * right by half the off interval. The line then goes in the positive x direction.
  */
 class DashingCircleEffect : public GrGeometryProcessor {
 public:
     typedef SkPathEffect::DashInfo DashInfo;
 
     static GrGeometryProcessor* Create(GrColor,
-                                       GrPrimitiveEdgeType edgeType,
+                                       DashAAMode aaMode,
                                        const SkMatrix& localMatrix);
 
     virtual ~DashingCircleEffect();
 
     const char* name() const override { return "DashingCircleEffect"; }
 
     const Attribute* inPosition() const { return fInPosition; }
 
     const Attribute* inDashParams() const { return fInDashParams; }
 
     const Attribute* inCircleParams() const { return fInCircleParams; }
 
-    GrPrimitiveEdgeType getEdgeType() const { return fEdgeType; }
+    DashAAMode aaMode() const { return fAAMode; }
 
     virtual void getGLProcessorKey(const GrBatchTracker&,
                                    const GrGLCaps&,
                                    GrProcessorKeyBuilder* b) const override;
 
     virtual GrGLPrimitiveProcessor* createGLInstance(const GrBatchTracker&,
                                                      const GrGLCaps&) const override;
 
     void initBatchTracker(GrBatchTracker* bt, const GrPipelineInfo& init) const override;
 
     bool onCanMakeEqual(const GrBatchTracker&,
                         const GrGeometryProcessor&,
                         const GrBatchTracker&) const override;
 
 private:
-    DashingCircleEffect(GrColor, GrPrimitiveEdgeType edgeType, const SkMatrix& localMatrix);
+    DashingCircleEffect(GrColor, DashAAMode aaMode, const SkMatrix& localMatrix);
 
     bool onIsEqual(const GrGeometryProcessor& other) const override;
 
     void onGetInvariantOutputCoverage(GrInitInvariantOutput*) const override;
 
-    GrPrimitiveEdgeType fEdgeType;
+    DashAAMode          fAAMode;
     const Attribute*    fInPosition;
     const Attribute*    fInDashParams;
     const Attribute*    fInCircleParams;
 
     GR_DECLARE_GEOMETRY_PROCESSOR_TEST;
 
     typedef GrGeometryProcessor INHERITED;
 };
 
 //////////////////////////////////////////////////////////////////////////////
@@ skipping 38 matching lines @@
     GrGLVertexBuilder* vsBuilder = args.fPB->getVertexShaderBuilder();
 
     // emit attributes
     vsBuilder->emitAttributes(dce);
 
     // XY are dashPos, Z is dashInterval
     GrGLVertToFrag dashParams(kVec3f_GrSLType);
     args.fPB->addVarying("DashParam", &dashParams);
     vsBuilder->codeAppendf("%s = %s;", dashParams.vsOut(), dce.inDashParams()->fName);
 
     // xy, refer to circle radius - 0.5, z refers to cicles center x coord

[egdaniel, 2015/04/20 19:55:13]

silly nit not from you, but do you mind changing this comment to be x refers to
radius - 0.5, y refers to circle's center. There is no z component

[Stephen White, 2015/04/20 20:20:32]

Done.

     GrGLVertToFrag circleParams(kVec2f_GrSLType);
     args.fPB->addVarying("CircleParams", &circleParams);
     vsBuilder->codeAppendf("%s = %s;", circleParams.vsOut(), dce.inCircleParams()->fName);
 
     // Setup pass through color
     this->setupColorPassThrough(pb, local.fInputColorType, args.fOutputColor, NULL, &fColorUniform);
 
     // Setup position
     this->setupPosition(pb, gpArgs, dce.inPosition()->fName, dce.viewMatrix());
 
     // emit transforms
     this->emitTransforms(args.fPB, gpArgs->fPositionVar, dce.inPosition()->fName, dce.localMatrix(),
                          args.fTransformsIn, args.fTransformsOut);
 
     // transforms all points so that we can compare them to our test circle
     GrGLGPFragmentBuilder* fsBuilder = args.fPB->getFragmentShaderBuilder();
     fsBuilder->codeAppendf("float xShifted = %s.x - floor(%s.x / %s.z) * %s.z;",
                            dashParams.fsIn(), dashParams.fsIn(), dashParams.fsIn(),
                            dashParams.fsIn());
     fsBuilder->codeAppendf("vec2 fragPosShifted = vec2(xShifted, %s.y);", dashParams.fsIn());
     fsBuilder->codeAppendf("vec2 center = vec2(%s.y, 0.0);", circleParams.fsIn());
     fsBuilder->codeAppend("float dist = length(center - fragPosShifted);");
-    if (GrProcessorEdgeTypeIsAA(dce.getEdgeType())) {
+    if (dce.aaMode() == kEdgeAA_DashAAMode) {
         fsBuilder->codeAppendf("float diff = dist - %s.x;", circleParams.fsIn());
         fsBuilder->codeAppend("diff = 1.0 - diff;");
         fsBuilder->codeAppend("float alpha = clamp(diff, 0.0, 1.0);");
     } else {
         fsBuilder->codeAppendf("float alpha = 1.0;");

[egdaniel, 2015/04/20 19:55:13]

since we fall into the else here for both msaa and bw, can we end up in a case
with msaa where the top/bottom points of the circles have some coverage but the
sides do not?

[Stephen White, 2015/04/20 20:20:32]

Yeah, I wasn't sure about this. Since we're not bloating the edges anymore for
MSAA, I don't *think* it will introduce artifacts, but I'll definitely keep an
eye on the bot results and circle back to this if need be.

         fsBuilder->codeAppendf("alpha *=  dist < %s.x + 0.5 ? 1.0 : 0.0;", circleParams.fsIn());
     }
     fsBuilder->codeAppendf("%s = vec4(alpha);", args.fOutputCoverage);
 }
 
 void GLDashingCircleEffect::setData(const GrGLProgramDataManager& pdman,
                                     const GrPrimitiveProcessor& processor,
                                     const GrBatchTracker& bt) {
     this->setUniformViewMatrix(pdman, processor.viewMatrix());
 
     const DashingCircleBatchTracker& local = bt.cast<DashingCircleBatchTracker>();
     if (kUniform_GrGPInput == local.fInputColorType && local.fColor != fColor) {
         GrGLfloat c[4];
         GrColorToRGBAFloat(local.fColor, c);
         pdman.set4fv(fColorUniform, 1, c);
         fColor = local.fColor;
     }
 }
 
 void GLDashingCircleEffect::GenKey(const GrGeometryProcessor& gp,
                                    const GrBatchTracker& bt,
                                    const GrGLCaps&,
                                    GrProcessorKeyBuilder* b) {
     const DashingCircleBatchTracker& local = bt.cast<DashingCircleBatchTracker>();
     const DashingCircleEffect& dce = gp.cast<DashingCircleEffect>();
     uint32_t key = 0;
     key |= local.fUsesLocalCoords && gp.localMatrix().hasPerspective() ? 0x1 : 0x0;
     key |= ComputePosKey(gp.viewMatrix()) << 1;
-    key |= dce.getEdgeType() << 8;
+    key |= dce.aaMode() << 8;
     b->add32(key << 16 | local.fInputColorType);
 }
 
 //////////////////////////////////////////////////////////////////////////////
 
 GrGeometryProcessor* DashingCircleEffect::Create(GrColor color,
-                                                 GrPrimitiveEdgeType edgeType,
+                                                 DashAAMode aaMode,
                                                  const SkMatrix& localMatrix) {
-    return SkNEW_ARGS(DashingCircleEffect, (color, edgeType, localMatrix));
+    return SkNEW_ARGS(DashingCircleEffect, (color, aaMode, localMatrix));
 }
 
 DashingCircleEffect::~DashingCircleEffect() {}
 
 void DashingCircleEffect::onGetInvariantOutputCoverage(GrInitInvariantOutput* out) const {
     out->setUnknownSingleComponent();
 }
 
 void DashingCircleEffect::getGLProcessorKey(const GrBatchTracker& bt,
                                             const GrGLCaps& caps,
                                             GrProcessorKeyBuilder* b) const {
     GLDashingCircleEffect::GenKey(*this, bt, caps, b);
 }
 
 GrGLPrimitiveProcessor* DashingCircleEffect::createGLInstance(const GrBatchTracker& bt,
                                                               const GrGLCaps&) const {
     return SkNEW_ARGS(GLDashingCircleEffect, (*this, bt));
 }
 
 DashingCircleEffect::DashingCircleEffect(GrColor color,
-                                         GrPrimitiveEdgeType edgeType,
+                                         DashAAMode aaMode,
                                          const SkMatrix& localMatrix)
-    : INHERITED(color, SkMatrix::I(), localMatrix), fEdgeType(edgeType) {
+    : INHERITED(color, SkMatrix::I(), localMatrix), fAAMode(aaMode) {
     this->initClassID<DashingCircleEffect>();
     fInPosition = &this->addVertexAttrib(Attribute("inPosition", kVec2f_GrVertexAttribType));
     fInDashParams = &this->addVertexAttrib(Attribute("inDashParams", kVec3f_GrVertexAttribType));
     fInCircleParams = &this->addVertexAttrib(Attribute("inCircleParams",
                                                        kVec2f_GrVertexAttribType));
 }
 
 bool DashingCircleEffect::onIsEqual(const GrGeometryProcessor& other) const {
     const DashingCircleEffect& dce = other.cast<DashingCircleEffect>();
-    return fEdgeType == dce.fEdgeType;
+    return fAAMode == dce.fAAMode;
 }
 
 void DashingCircleEffect::initBatchTracker(GrBatchTracker* bt, const GrPipelineInfo& init) const {
     DashingCircleBatchTracker* local = bt->cast<DashingCircleBatchTracker>();
     local->fInputColorType = GetColorInputType(&local->fColor, this->color(), init, false);
     local->fUsesLocalCoords = init.fUsesLocalCoords;
 }
 
 bool DashingCircleEffect::onCanMakeEqual(const GrBatchTracker& m,
                                          const GrGeometryProcessor& that,
                                          const GrBatchTracker& t) const {
     const DashingCircleBatchTracker& mine = m.cast<DashingCircleBatchTracker>();
     const DashingCircleBatchTracker& theirs = t.cast<DashingCircleBatchTracker>();
     return CanCombineLocalMatrices(*this, mine.fUsesLocalCoords,
                                    that, theirs.fUsesLocalCoords) &&
            CanCombineOutput(mine.fInputColorType, mine.fColor,
                             theirs.fInputColorType, theirs.fColor);
 }
 
 GR_DEFINE_GEOMETRY_PROCESSOR_TEST(DashingCircleEffect);
 
 GrGeometryProcessor* DashingCircleEffect::TestCreate(SkRandom* random,
                                                      GrContext*,
                                                      const GrDrawTargetCaps& caps,
                                                      GrTexture*[]) {
-    GrPrimitiveEdgeType edgeType = static_cast<GrPrimitiveEdgeType>(random->nextULessThan(
-            kGrProcessorEdgeTypeCnt));
+    DashAAMode aaMode = static_cast<DashAAMode>(random->nextULessThan(kDashAAModeCnt));
     return DashingCircleEffect::Create(GrRandomColor(random),
-                                       edgeType, GrProcessorUnitTest::TestMatrix(random));
+                                      aaMode, GrProcessorUnitTest::TestMatrix(random));
 }
 
 //////////////////////////////////////////////////////////////////////////////
 
 class GLDashingLineEffect;
 
 struct DashingLineBatchTracker {
     GrGPInput fInputColorType;
     GrColor  fColor;
     bool fUsesLocalCoords;
 };
 
 /*
  * This effect will draw a dashed line. The width of the dash is given by the strokeWidth and the
  * length and spacing by the DashInfo. Both of the previous two parameters are in device space.
  * This effect also requires the setting of a vec2 vertex attribute for the the four corners of the
  * bounding rect. This attribute is the "dash position" of each vertex. In other words it is the
  * vertex coords (in device space) if we transform the line to be horizontal, with the start of
  * line at the origin then shifted to the right by half the off interval. The line then goes in the
  * positive x direction.
  */
 class DashingLineEffect : public GrGeometryProcessor {
 public:
     typedef SkPathEffect::DashInfo DashInfo;
 
     static GrGeometryProcessor* Create(GrColor,
-                                       GrPrimitiveEdgeType edgeType,
+                                       DashAAMode aaMode,
                                        const SkMatrix& localMatrix);
 
     virtual ~DashingLineEffect();
 
     const char* name() const override { return "DashingEffect"; }
 
     const Attribute* inPosition() const { return fInPosition; }
 
     const Attribute* inDashParams() const { return fInDashParams; }
 
     const Attribute* inRectParams() const { return fInRectParams; }
 
-    GrPrimitiveEdgeType getEdgeType() const { return fEdgeType; }
+    DashAAMode aaMode() const { return fAAMode; }
 
     virtual void getGLProcessorKey(const GrBatchTracker& bt,
                                    const GrGLCaps& caps,
                                    GrProcessorKeyBuilder* b) const override;
 
     virtual GrGLPrimitiveProcessor* createGLInstance(const GrBatchTracker& bt,
                                                      const GrGLCaps&) const override;
 
     void initBatchTracker(GrBatchTracker* bt, const GrPipelineInfo& init) const override;
 
     bool onCanMakeEqual(const GrBatchTracker&,
                         const GrGeometryProcessor&,
                         const GrBatchTracker&) const override;
 
 private:
-    DashingLineEffect(GrColor, GrPrimitiveEdgeType edgeType, const SkMatrix& localMatrix);
+    DashingLineEffect(GrColor, DashAAMode aaMode, const SkMatrix& localMatrix);
 
     bool onIsEqual(const GrGeometryProcessor& other) const override;
 
     void onGetInvariantOutputCoverage(GrInitInvariantOutput*) const override;
 
-    GrPrimitiveEdgeType fEdgeType;
+    DashAAMode          fAAMode;
     const Attribute*    fInPosition;
     const Attribute*    fInDashParams;
     const Attribute*    fInRectParams;
 
     GR_DECLARE_GEOMETRY_PROCESSOR_TEST;
 
     typedef GrGeometryProcessor INHERITED;
 };
 
 //////////////////////////////////////////////////////////////////////////////
@@ skipping 54 matching lines @@
     // emit transforms
     this->emitTransforms(args.fPB, gpArgs->fPositionVar, de.inPosition()->fName, de.localMatrix(),
                          args.fTransformsIn, args.fTransformsOut);
 
     // transforms all points so that we can compare them to our test rect
     GrGLGPFragmentBuilder* fsBuilder = args.fPB->getFragmentShaderBuilder();
     fsBuilder->codeAppendf("float xShifted = %s.x - floor(%s.x / %s.z) * %s.z;",
                            inDashParams.fsIn(), inDashParams.fsIn(), inDashParams.fsIn(),
                            inDashParams.fsIn());
     fsBuilder->codeAppendf("vec2 fragPosShifted = vec2(xShifted, %s.y);", inDashParams.fsIn());
-    if (GrProcessorEdgeTypeIsAA(de.getEdgeType())) {
+    if (de.aaMode() == kEdgeAA_DashAAMode) {
         // The amount of coverage removed in x and y by the edges is computed as a pair of negative
         // numbers, xSub and ySub.
         fsBuilder->codeAppend("float xSub, ySub;");
         fsBuilder->codeAppendf("xSub = min(fragPosShifted.x - %s.x, 0.0);", inRectParams.fsIn());
         fsBuilder->codeAppendf("xSub += min(%s.z - fragPosShifted.x, 0.0);", inRectParams.fsIn());
         fsBuilder->codeAppendf("ySub = min(fragPosShifted.y - %s.y, 0.0);", inRectParams.fsIn());
         fsBuilder->codeAppendf("ySub += min(%s.w - fragPosShifted.y, 0.0);", inRectParams.fsIn());
         // Now compute coverage in x and y and multiply them to get the fraction of the pixel
         // covered.
         fsBuilder->codeAppendf("float alpha = (1.0 + max(xSub, -1.0)) * (1.0 + max(ySub, -1.0));");
+    } else if (de.aaMode() == kMSAA_DashAAMode) {
+        // For MSAA, we don't modulate the alpha by the Y distance, since MSAA coverage will handle
+        // AA on the the top and bottom edges. The shader is only responsible for intra-dash alpha.
+        fsBuilder->codeAppend("float xSub;");
+        fsBuilder->codeAppendf("xSub = min(fragPosShifted.x - %s.x, 0.0);", inRectParams.fsIn());
+        fsBuilder->codeAppendf("xSub += min(%s.z - fragPosShifted.x, 0.0);", inRectParams.fsIn());
+        // Now compute coverage in x and y and multiply them to get the fraction of the pixel

[egdaniel, 2015/04/20 19:55:13]

not doing y anymore here.

[Stephen White, 2015/04/20 20:20:32]

Done.

+        // covered.
+        fsBuilder->codeAppendf("float alpha = (1.0 + max(xSub, -1.0));");
     } else {
         // Assuming the bounding geometry is tight so no need to check y values
         fsBuilder->codeAppendf("float alpha = 1.0;");
         fsBuilder->codeAppendf("alpha *= (fragPosShifted.x - %s.x) > -0.5 ? 1.0 : 0.0;",
                                inRectParams.fsIn());
         fsBuilder->codeAppendf("alpha *= (%s.z - fragPosShifted.x) >= -0.5 ? 1.0 : 0.0;",
                                inRectParams.fsIn());
     }
     fsBuilder->codeAppendf("%s = vec4(alpha);", args.fOutputCoverage);
 }
@@ skipping 14 matching lines @@
 
 void GLDashingLineEffect::GenKey(const GrGeometryProcessor& gp,
                                  const GrBatchTracker& bt,
                                  const GrGLCaps&,
                                  GrProcessorKeyBuilder* b) {
     const DashingLineBatchTracker& local = bt.cast<DashingLineBatchTracker>();
     const DashingLineEffect& de = gp.cast<DashingLineEffect>();
     uint32_t key = 0;
     key |= local.fUsesLocalCoords && gp.localMatrix().hasPerspective() ? 0x1 : 0x0;
     key |= ComputePosKey(gp.viewMatrix()) << 1;
-    key |= de.getEdgeType() << 8;
+    key |= de.aaMode() << 8;
     b->add32(key << 16 | local.fInputColorType);
 }
 
 //////////////////////////////////////////////////////////////////////////////
 
 GrGeometryProcessor* DashingLineEffect::Create(GrColor color,
-                                               GrPrimitiveEdgeType edgeType,
+                                               DashAAMode aaMode,
                                                const SkMatrix& localMatrix) {
-    return SkNEW_ARGS(DashingLineEffect, (color, edgeType, localMatrix));
+    return SkNEW_ARGS(DashingLineEffect, (color, aaMode, localMatrix));
 }
 
 DashingLineEffect::~DashingLineEffect() {}
 
 void DashingLineEffect::onGetInvariantOutputCoverage(GrInitInvariantOutput* out) const {
     out->setUnknownSingleComponent();
 }
 
 void DashingLineEffect::getGLProcessorKey(const GrBatchTracker& bt,
                                           const GrGLCaps& caps,
                                           GrProcessorKeyBuilder* b) const {
     GLDashingLineEffect::GenKey(*this, bt, caps, b);
 }
 
 GrGLPrimitiveProcessor* DashingLineEffect::createGLInstance(const GrBatchTracker& bt,
                                                             const GrGLCaps&) const {
     return SkNEW_ARGS(GLDashingLineEffect, (*this, bt));
 }
 
 DashingLineEffect::DashingLineEffect(GrColor color,
-                                     GrPrimitiveEdgeType edgeType,
+                                     DashAAMode aaMode,
                                      const SkMatrix& localMatrix)
-    : INHERITED(color, SkMatrix::I(), localMatrix), fEdgeType(edgeType) {
+    : INHERITED(color, SkMatrix::I(), localMatrix), fAAMode(aaMode) {
     this->initClassID<DashingLineEffect>();
     fInPosition = &this->addVertexAttrib(Attribute("inPosition", kVec2f_GrVertexAttribType));
     fInDashParams = &this->addVertexAttrib(Attribute("inDashParams", kVec3f_GrVertexAttribType));
     fInRectParams = &this->addVertexAttrib(Attribute("inRect", kVec4f_GrVertexAttribType));
 }
 
 bool DashingLineEffect::onIsEqual(const GrGeometryProcessor& other) const {
     const DashingLineEffect& de = other.cast<DashingLineEffect>();
-    return fEdgeType == de.fEdgeType;
+    return fAAMode == de.fAAMode;
 }
 
 void DashingLineEffect::initBatchTracker(GrBatchTracker* bt, const GrPipelineInfo& init) const {
     DashingLineBatchTracker* local = bt->cast<DashingLineBatchTracker>();
     local->fInputColorType = GetColorInputType(&local->fColor, this->color(), init, false);
     local->fUsesLocalCoords = init.fUsesLocalCoords;
 }
 
 bool DashingLineEffect::onCanMakeEqual(const GrBatchTracker& m,
                                        const GrGeometryProcessor& that,
                                        const GrBatchTracker& t) const {
     const DashingLineBatchTracker& mine = m.cast<DashingLineBatchTracker>();
     const DashingLineBatchTracker& theirs = t.cast<DashingLineBatchTracker>();
     return CanCombineLocalMatrices(*this, mine.fUsesLocalCoords,
                                   that, theirs.fUsesLocalCoords) &&
            CanCombineOutput(mine.fInputColorType, mine.fColor,
                             theirs.fInputColorType, theirs.fColor);
 }
 
 GR_DEFINE_GEOMETRY_PROCESSOR_TEST(DashingLineEffect);
 
 GrGeometryProcessor* DashingLineEffect::TestCreate(SkRandom* random,
                                                    GrContext*,
                                                    const GrDrawTargetCaps& caps,
                                                    GrTexture*[]) {
-    GrPrimitiveEdgeType edgeType = static_cast<GrPrimitiveEdgeType>(random->nextULessThan(
-            kGrProcessorEdgeTypeCnt));
-
+    DashAAMode aaMode = static_cast<DashAAMode>(random->nextULessThan(kDashAAModeCnt));
     return DashingLineEffect::Create(GrRandomColor(random),
-                                     edgeType, GrProcessorUnitTest::TestMatrix(random));
+                                     aaMode, GrProcessorUnitTest::TestMatrix(random));
 }
 
 //////////////////////////////////////////////////////////////////////////////
 
 static GrGeometryProcessor* create_dash_gp(GrColor color,
-                                           GrPrimitiveEdgeType edgeType,
+                                           DashAAMode dashAAMode,
                                            DashCap cap,
                                            const SkMatrix& localMatrix) {
     switch (cap) {
         case kRound_DashCap:
-            return DashingCircleEffect::Create(color, edgeType, localMatrix);
+            return DashingCircleEffect::Create(color, dashAAMode, localMatrix);
         case kNonRound_DashCap:
-            return DashingLineEffect::Create(color, edgeType, localMatrix);
+            return DashingLineEffect::Create(color, dashAAMode, localMatrix);
         default:
             SkFAIL("Unexpected dashed cap.");
     }
     return NULL;
 }