Move GrTBatchTesselator to its own file

src/gpu/batches/GrTBatchTesselator.h

+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrTBatchTesselator_DEFINED
+#define GrTBatchTesselator_DEFINED
+
+#include "GrVertexBatch.h"
+
+#include "GrBatchFlushState.h"
+
+/*

[bsalomon, 2015/08/18 15:01:46]

/** (I think the double * is needed for doxygen to recognize this)

+ * GrTBatchTesselator is an optional template to help with writing batches
+ * To use this template, an implementation must define the following static functions:

[bsalomon, 2015/08/18 15:01:46]

referring to Base?

Base is a confusing name... it's not really a base of anything.


I was kind of confused when we talked about the name (my fault). If this class
is the batch maybe it should be GrTInstancedBatch? And Base becomes TESS,
TESSELLATOR, IMPL, ...?

+ *     A Geometry struct
+ *
+ *     const char* Name()
+ *
+ *     bool CanCombine(const Geometry& mine, const Geometry& theirs,
+ *                     const GrPipelineOptimizations&)
+ *
+ *     const GrGeometryProcessor* CreateGP(const Geometry& seedGeometry,
+ *                                         const GrPipelineOptimizations& opts)
+ *
+ *     const GrIndexBuffer* GetIndexBuffer(GrResourceProvider*)
+ *
+ *     Tesselate(intptr_t vertices, size_t vertexStride, const Geometry& geo,
+ *               const GrPipelineOptimizations& opts)
+ */
+template <typename Base, int kVertsPerInstance, int kIndicesPerInstance>
+class GrTBatchTesselator : public GrVertexBatch {
+public:
+    typedef typename Base::Geometry Geometry;
+
+    static GrTBatchTesselator* Create() {
+        return SkNEW(GrTBatchTesselator);
+    }
+
+    const char* name() const override { return Base::Name(); }
+
+    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();
+    }
+
+    void initBatchTracker(const GrPipelineOptimizations& opt) override {
+        opt.getOverrideColorIfSet(&fGeoData[0].fColor);
+        fOpts = opt;
+    }
+
+    SkSTArray<1, Geometry, true>* geoData() { return &fGeoData; }
+
+    // to avoid even the initial copy of the struct, we have a getter for the first item which
+    // is used to seed the batch with its initial geometry.  After seeding, the client should call
+    // init() so the Batch can initialize itself
+    Geometry* geometry() { return &fGeoData[0]; }
+    void init() {
+        const Geometry& geo = fGeoData[0];
+        this->setBounds(geo.fDevRect);
+    }
+
+private:
+    GrTBatchTesselator() {
+        this->initClassID<GrTBatchTesselator<Base, kVertsPerInstance, kIndicesPerInstance>>();
+
+        // Push back an initial geometry
+        fGeoData.push_back();
+    }
+
+    void onPrepareDraws(Target* target) override {
+        SkAutoTUnref<const GrGeometryProcessor> gp(Base::CreateGP(this->seedGeometry(), fOpts));
+        if (!gp) {
+            SkDebugf("Couldn't create GrGeometryProcessor\n");
+            return;
+        }
+
+        target->initDraw(gp, this->pipeline());
+
+        size_t vertexStride = gp->getVertexStride();
+        int instanceCount = fGeoData.count();
+
+        SkAutoTUnref<const GrIndexBuffer> indexBuffer(
+                Base::GetIndexBuffer(target->resourceProvider()));
+        InstancedHelper helper;
+        void* vertices = helper.init(target, kTriangles_GrPrimitiveType, vertexStride,
+                                     indexBuffer, kVertsPerInstance, kIndicesPerInstance,
+                                     instanceCount);
+        if (!vertices || !indexBuffer) {
+            SkDebugf("Could not allocate vertices\n");
+            return;
+        }
+
+        for (int i = 0; i < instanceCount; i++) {
+            intptr_t verts = reinterpret_cast<intptr_t>(vertices) +
+                             i * kVertsPerInstance * vertexStride;
+            Base::Tesselate(verts, vertexStride, fGeoData[i], fOpts);
+        }
+        helper.recordDraw(target);
+    }
+
+    const Geometry& seedGeometry() const { return fGeoData[0]; }
+
+    bool onCombineIfPossible(GrBatch* t, const GrCaps& caps) override {
+        GrTBatchTesselator* that = t->cast<GrTBatchTesselator>();
+        if (!GrPipeline::CanCombine(*this->pipeline(), this->bounds(), *that->pipeline(),
+                                    that->bounds(), caps)) {
+            return false;
+        }
+
+        if (!Base::CanCombine(this->seedGeometry(), that->seedGeometry(), fOpts)) {
+            return false;
+        }
+
+        // In the event of two batches, one who can tweak, one who cannot, we just fall back to
+        // not tweaking
+        if (fOpts.canTweakAlphaForCoverage() && !that->fOpts.canTweakAlphaForCoverage()) {
+            fOpts = that->fOpts;
+        }
+
+        fGeoData.push_back_n(that->geoData()->count(), that->geoData()->begin());
+        this->joinBounds(that->bounds());
+        return true;
+    }
+
+    GrPipelineOptimizations fOpts;
+    SkSTArray<1, Geometry, true> fGeoData;
+};
+
+#endif