Refugee from Dead Machine 13: New version of the convex AA tessellator

src/gpu/GrAAConvexPathRenderer.cpp

Index: src/gpu/GrAAConvexPathRenderer.cpp
diff --git a/src/gpu/GrAAConvexPathRenderer.cpp b/src/gpu/GrAAConvexPathRenderer.cpp
index f031f7f61b93e572783cbcddb9aa0645474e882a..e5b642d17e39a8bfafb8f9e5f23c14a9901800b7 100644
--- a/src/gpu/GrAAConvexPathRenderer.cpp
+++ b/src/gpu/GrAAConvexPathRenderer.cpp
@@ -8,10 +8,12 @@
 
 #include "GrAAConvexPathRenderer.h"
 
+#include "GrAAConvexTessellator.h"
 #include "GrBatch.h"
 #include "GrBatchTarget.h"
 #include "GrBufferAllocPool.h"
 #include "GrContext.h"
+#include "GrDefaultGeoProcFactory.h"
 #include "GrDrawTargetCaps.h"
 #include "GrGeometryProcessor.h"
 #include "GrInvariantOutput.h"
@@ -704,6 +706,50 @@ bool GrAAConvexPathRenderer::canDrawPath(const GrDrawTarget* target,
             stroke.isFillStyle() && !path.isInverseFillType() && path.isConvex());
 }
 
+static void extract_verts(const GrAAConvexTessellator& tess,
+                          void* vertices,
+                          size_t vertexStride,
+                          GrColor color,
+                          uint16_t* idxs,
+                          bool tweakAlphaForCoverage) {
+    intptr_t verts = reinterpret_cast<intptr_t>(vertices);
+
+    for (int i = 0; i < tess.numPts(); ++i) {
+        *((SkPoint*)((intptr_t)verts + i * vertexStride)) = tess.point(i);
+    }
+
+    // Make 'verts' point to the colors
+    verts += sizeof(SkPoint);
+    for (int i = 0; i < tess.numPts(); ++i) {
+        if (tweakAlphaForCoverage) {
+            SkASSERT(tess.depth(i) >= -0.5f);
+            SkASSERT(SkScalarRoundToInt(255.0f * (tess.depth(i) + 0.5f)) <= 255);
+            unsigned scale = SkScalarRoundToInt(255.0f * (tess.depth(i) + 0.5f));
+            GrColor scaledColor = (0xff == scale) ? color : SkAlphaMulQ(color, scale);
+            *reinterpret_cast<GrColor*>(verts + i * vertexStride) = scaledColor;
+        } else {
+            *reinterpret_cast<GrColor*>(verts + i * vertexStride) = color;
+            *reinterpret_cast<float*>(verts + i * vertexStride + sizeof(GrColor)) = 
+                                                                    tess.depth(i) + 0.5f;
+        }
+    }
+
+    for (int i = 0; i < tess.numIndices(); ++i) {
+        idxs[i] = tess.index(i);
+    }
+}
+
+static const GrGeometryProcessor* create_fill_gp(bool tweakAlphaForCoverage,
+                                                 const SkMatrix& localMatrix) {
+    uint32_t flags = GrDefaultGeoProcFactory::kColor_GPType;
+    if (!tweakAlphaForCoverage) {
+        flags |= GrDefaultGeoProcFactory::kCoverage_GPType;
+    }
+
+    return  GrDefaultGeoProcFactory::Create(flags, GrColor_WHITE, SkMatrix::I(), localMatrix,
+                                            false, 0xff);
+}
+
 class AAConvexPathBatch : public GrBatch {
 public:
     struct Geometry {
@@ -739,9 +785,105 @@ public:
         fBatch.fColor = fGeoData[0].fColor;
         fBatch.fUsesLocalCoords = init.fUsesLocalCoords;
         fBatch.fCoverageIgnored = init.fCoverageIgnored;
+        fBatch.fLinesOnly = SkPath::kLine_SegmentMask == fGeoData[0].fPath.getSegmentMasks();
+        fBatch.fCanTweakAlphaForCoverage = init.fCanTweakAlphaForCoverage;
+    }
+
+    void generateGeometryLinesOnly(GrBatchTarget* batchTarget, const GrPipeline* pipeline) {
+        bool canTweakAlphaForCoverage = this->canTweakAlphaForCoverage();
+
+        SkMatrix invert;
+        if (this->usesLocalCoords() && !this->viewMatrix().invert(&invert)) {
+            SkDebugf("Could not invert viewmatrix\n");
+            return;
+        }
+
+        // Setup GrGeometryProcessor
+        SkAutoTUnref<const GrGeometryProcessor> gp(create_fill_gp(canTweakAlphaForCoverage, 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);
+
+        size_t vertexStride = gp->getVertexStride();
+
+        SkASSERT(canTweakAlphaForCoverage ?
+                 vertexStride == sizeof(GrDefaultGeoProcFactory::PositionColorAttr) :
+                 vertexStride == sizeof(GrDefaultGeoProcFactory::PositionColorCoverageAttr));
+
+        GrAAConvexTessellator tess;
+
+        int instanceCount = fGeoData.count();
+
+        for (int i = 0; i < instanceCount; i++) {
+            tess.rewind();
+
+            Geometry& args = fGeoData[i];
+
+            // We use the fact that SkPath::transform path does subdivision based on
+            // perspective. Otherwise, we apply the view matrix when copying to the
+            // segment representation.
+            const SkMatrix* viewMatrix = &args.fViewMatrix;
+            if (viewMatrix->hasPerspective()) {
+                args.fPath.transform(*viewMatrix);
+                viewMatrix = &SkMatrix::I();
+            }
+
+            if (!tess.tessellate(*viewMatrix, args.fPath)) {
+                continue;
+            }
+
+            const GrVertexBuffer* vertexBuffer;
+            int firstVertex;
+
+            void* verts = batchTarget->vertexPool()->makeSpace(vertexStride,
+                                                               tess.numPts(),
+                                                               &vertexBuffer,
+                                                               &firstVertex);
+            if (!verts) {
+                SkDebugf("Could not allocate vertices\n");
+                return;
+            }
+
+            const GrIndexBuffer* indexBuffer;
+            int firstIndex;
+
+            void* indices = batchTarget->indexPool()->makeSpace(tess.numIndices(),
+                                                                &indexBuffer,
+                                                                &firstIndex);
+            if (!indices) {
+                SkDebugf("Could not allocate indices\n");
+                return;
+            }
+
+            uint16_t* idxs = reinterpret_cast<uint16_t*>(indices);
+
+            extract_verts(tess, verts, vertexStride, args.fColor, idxs, canTweakAlphaForCoverage);
+
+            GrDrawTarget::DrawInfo info;
+            info.setPrimitiveType(kTriangles_GrPrimitiveType);
+            info.setStartVertex(firstVertex);
+            info.setStartIndex(firstIndex);
+            info.setVertexBuffer(vertexBuffer);
+            info.setIndexBuffer(indexBuffer);
+            info.setVertexCount(tess.numPts());
+            info.setIndexCount(tess.numIndices());
+            batchTarget->draw(info);
+        }
     }
 
     void generateGeometry(GrBatchTarget* batchTarget, const GrPipeline* pipeline) override {
+        if (this->linesOnly()) {
+            this->generateGeometryLinesOnly(batchTarget, pipeline);
+            return;
+        }
+
         int instanceCount = fGeoData.count();
 
         SkMatrix invert;
@@ -861,12 +1003,24 @@ private:
             return false;
         }
 
+        if (this->linesOnly() != that->linesOnly()) {
+            return false;
+        }
+
+        // In the event of two batches, one who can tweak, one who cannot, we just fall back to
+        // not tweaking
+        if (this->canTweakAlphaForCoverage() != that->canTweakAlphaForCoverage()) {
+            fBatch.fCanTweakAlphaForCoverage = false;
+        }
+
         fGeoData.push_back_n(that->geoData()->count(), that->geoData()->begin());
         return true;
     }
 
     GrColor color() const { return fBatch.fColor; }
+    bool linesOnly() const { return fBatch.fLinesOnly; }
     bool usesLocalCoords() const { return fBatch.fUsesLocalCoords; }
+    bool canTweakAlphaForCoverage() const { return fBatch.fCanTweakAlphaForCoverage; }
     const SkMatrix& viewMatrix() const { return fGeoData[0].fViewMatrix; }
 
     struct BatchTracker {
@@ -874,6 +1028,8 @@ private:
         bool fUsesLocalCoords;
         bool fColorIgnored;
         bool fCoverageIgnored;
+        bool fLinesOnly;
+        bool fCanTweakAlphaForCoverage;
     };
 
     BatchTracker fBatch;