Enable blend optimizations with instanced draws

src/gpu/instanced/GLInstancedRendering.cpp

Index: src/gpu/instanced/GLInstancedRendering.cpp
diff --git a/src/gpu/instanced/GLInstancedRendering.cpp b/src/gpu/instanced/GLInstancedRendering.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..7df39f07df15de889149110bb2889a9019764181
--- /dev/null
+++ b/src/gpu/instanced/GLInstancedRendering.cpp
@@ -0,0 +1,301 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "GLInstancedRendering.h"
+
+#include "GrResourceProvider.h"
+#include "gl/GrGLGpu.h"
+#include "instanced/InstanceProcessor.h"
+
+#define GL_CALL(X) GR_GL_CALL(this->glGpu()->glInterface(), X)
+
+namespace gr_instanced {
+
+class GLInstancedRendering::GLBatch : public InstancedRendering::Batch {
+public:
+    DEFINE_BATCH_CLASS_ID
+
+    GLBatch(GLInstancedRendering* instRendering) : INHERITED(ClassID(), instRendering) {}
+    int numGLCommands() const { return 1 + fNumChangesInGeometry; }
+
+private:
+    int fEmulatedBaseInstance;
+    int fGLDrawCmdsIdx;
+
+    friend class GLInstancedRendering;
+
+    typedef Batch INHERITED;
+};
+
+GLInstancedRendering* GLInstancedRendering::CreateIfSupported(GrGLGpu* gpu) {
+#ifndef SK_BUILD_FOR_MAC
+    // Only whitelisting on Mac for now. Once we've been able to work through the various issues on
+    // other platforms we can enable more generally.
+    return nullptr;
+#endif
+    const GrGLCaps& glCaps = gpu->glCaps();
+    AntialiasMode lastSupportedAAMode;
+    if (!glCaps.vertexArrayObjectSupport() ||
+        !glCaps.drawIndirectSupport() ||
+        !InstanceProcessor::IsSupported(*glCaps.glslCaps(), glCaps, &lastSupportedAAMode)) {
+        return nullptr;
+    }
+    return new GLInstancedRendering(gpu, lastSupportedAAMode);
+}
+
+GLInstancedRendering::GLInstancedRendering(GrGLGpu* gpu, AntialiasMode lastSupportedAAMode)
+    : INHERITED(gpu, lastSupportedAAMode, gpu->glCaps().canDrawIndirectToFloat()),
+      fVertexArrayID(0),
+      fGLDrawCmdsInfo(0),
+      fInstanceAttribsBufferUniqueId(SK_InvalidUniqueID) {
+}
+
+GLInstancedRendering::~GLInstancedRendering() {
+    if (fVertexArrayID) {
+        GL_CALL(DeleteVertexArrays(1, &fVertexArrayID));
+        this->glGpu()->notifyVertexArrayDelete(fVertexArrayID);
+    }
+}
+
+inline GrGLGpu* GLInstancedRendering::glGpu() const {
+    return static_cast<GrGLGpu*>(this->gpu());
+}
+
+InstancedRendering::Batch* GLInstancedRendering::createBatch() {
+    return new GLBatch(this);
+}
+
+void GLInstancedRendering::onBeginFlush(GrResourceProvider* rp) {
+    // Count what there is to draw.
+    BatchList::Iter iter;
+    iter.init(this->trackedBatches(), BatchList::Iter::kHead_IterStart);
+    int numGLInstances = 0;
+    int numGLDrawCmds = 0;
+    while (Batch* b = iter.get()) {
+        GLBatch* batch = static_cast<GLBatch*>(b);
+        iter.next();
+
+        numGLInstances += batch->fNumDraws;
+        numGLDrawCmds += batch->numGLCommands();
+    }
+    if (!numGLDrawCmds) {
+        return;
+    }
+    SkASSERT(numGLInstances);
+
+    // Lazily create a vertex array object.
+    if (!fVertexArrayID) {
+        GL_CALL(GenVertexArrays(1, &fVertexArrayID));
+        if (!fVertexArrayID) {
+            return;
+        }
+        this->glGpu()->bindVertexArray(fVertexArrayID);
+
+        // Attach our index buffer to the vertex array.
+        GL_CALL(BindBuffer(GR_GL_ELEMENT_ARRAY_BUFFER,
+                           static_cast<const GrGLBuffer*>(this->indexBuffer())->bufferID()));
+
+        // Set up the non-instanced attribs.
+        this->glGpu()->bindBuffer(kVertex_GrBufferType,
+                                  static_cast<const GrGLBuffer*>(this->vertexBuffer()));
+        GL_CALL(EnableVertexAttribArray((int)Attrib::kShapeCoords));
+        GL_CALL(VertexAttribPointer((int)Attrib::kShapeCoords, 2, GR_GL_FLOAT, GR_GL_FALSE,
+                                    sizeof(ShapeVertex), (void*) offsetof(ShapeVertex, fX)));
+        GL_CALL(EnableVertexAttribArray((int)Attrib::kVertexAttrs));
+        GL_CALL(VertexAttribIPointer((int)Attrib::kVertexAttrs, 1, GR_GL_INT, sizeof(ShapeVertex),
+                                     (void*) offsetof(ShapeVertex, fAttrs)));
+
+        SkASSERT(SK_InvalidUniqueID == fInstanceAttribsBufferUniqueId);
+    }
+
+    // Create and map instance and draw-indirect buffers.
+    SkASSERT(!fInstanceBuffer);
+    fInstanceBuffer.reset(static_cast<GrGLBuffer*>(
+        rp->createBuffer(sizeof(Instance) * numGLInstances, kVertex_GrBufferType,
+                         kDynamic_GrAccessPattern, GrResourceProvider::kNoPendingIO_Flag)));
+    if (!fInstanceBuffer) {
+        return;
+    }
+
+    SkASSERT(!fDrawIndirectBuffer);
+    fDrawIndirectBuffer.reset(static_cast<GrGLBuffer*>(
+        rp->createBuffer(sizeof(GrGLDrawElementsIndirectCommand) * numGLDrawCmds,
+                         kDrawIndirect_GrBufferType, kDynamic_GrAccessPattern,
+                         GrResourceProvider::kNoPendingIO_Flag)));
+    if (!fDrawIndirectBuffer) {
+        return;
+    }
+
+    Instance* glMappedInstances = static_cast<Instance*>(fInstanceBuffer->map());
+    int glInstancesIdx = 0;
+
+    auto* glMappedCmds = static_cast<GrGLDrawElementsIndirectCommand*>(fDrawIndirectBuffer->map());
+    int glDrawCmdsIdx = 0;
+
+    bool baseInstanceSupport = this->glGpu()->glCaps().baseInstanceSupport();
+
+    if (GR_GL_LOG_INSTANCED_BATCHES || !baseInstanceSupport) {
+        fGLDrawCmdsInfo.reset(numGLDrawCmds);
+    }
+
+    // Generate the instance and draw-indirect buffer contents based on the tracked batches.
+    iter.init(this->trackedBatches(), BatchList::Iter::kHead_IterStart);
+    while (Batch* b = iter.get()) {
+        GLBatch* batch = static_cast<GLBatch*>(b);
+        iter.next();
+
+        batch->fEmulatedBaseInstance = baseInstanceSupport ? 0 : glInstancesIdx;
+        batch->fGLDrawCmdsIdx = glDrawCmdsIdx;
+
+        const Batch::Draw* draw = batch->fHeadDraw;
+        SkASSERT(draw);
+        do {
+            int instanceCount = 0;
+            IndexRange geometry = draw->fGeometry;
+            SkASSERT(!geometry.isEmpty());
+
+            do {
+                glMappedInstances[glInstancesIdx + instanceCount++] = draw->fInstance;
+                draw = draw->fNext;
+            } while (draw && draw->fGeometry == geometry);
+
+            GrGLDrawElementsIndirectCommand& glCmd = glMappedCmds[glDrawCmdsIdx];
+            glCmd.fCount = geometry.fCount;
+            glCmd.fInstanceCount = instanceCount;
+            glCmd.fFirstIndex = geometry.fStart;
+            glCmd.fBaseVertex = 0;
+            glCmd.fBaseInstance = baseInstanceSupport ? glInstancesIdx : 0;
+
+            if (GR_GL_LOG_INSTANCED_BATCHES || !baseInstanceSupport) {
+                fGLDrawCmdsInfo[glDrawCmdsIdx].fInstanceCount = instanceCount;
+#if GR_GL_LOG_INSTANCED_BATCHES
+                fGLDrawCmdsInfo[glDrawCmdsIdx].fGeometry = geometry;
+#endif
+            }
+
+            glInstancesIdx += instanceCount;
+            ++glDrawCmdsIdx;
+        } while (draw);
+    }
+
+    SkASSERT(glDrawCmdsIdx == numGLDrawCmds);
+    fDrawIndirectBuffer->unmap();
+
+    SkASSERT(glInstancesIdx == numGLInstances);
+    fInstanceBuffer->unmap();
+}
+
+void GLInstancedRendering::onDraw(const GrPipeline& pipeline, const InstanceProcessor& instProc,
+                                  const Batch* baseBatch) {
+    if (!fDrawIndirectBuffer) {
+        return; // beginFlush was not successful.
+    }
+    if (!this->glGpu()->flushGLState(pipeline, instProc)) {
+        return;
+    }
+
+    this->glGpu()->bindBuffer(kDrawIndirect_GrBufferType, fDrawIndirectBuffer.get());
+
+    const GrGLCaps& glCaps = this->glGpu()->glCaps();
+    const GLBatch* batch = static_cast<const GLBatch*>(baseBatch);
+    int numCommands = batch->numGLCommands();
+
+#if GR_GL_LOG_INSTANCED_BATCHES
+    SkASSERT(fGLDrawCmdsInfo);
+    SkDebugf("Instanced batch: [");
+    for (int i = 0; i < numCommands; ++i) {
+        int glCmdIdx = batch->fGLDrawCmdsIdx + i;
+        SkDebugf("%s%i * %s", (i ? ",  " : ""), fGLDrawCmdsInfo[glCmdIdx].fInstanceCount,
+                 InstanceProcessor::GetNameOfIndexRange(fGLDrawCmdsInfo[glCmdIdx].fGeometry));
+    }
+    SkDebugf("]\n");
+#else
+    SkASSERT(SkToBool(fGLDrawCmdsInfo) == !glCaps.baseInstanceSupport());
+#endif
+
+    if (1 == numCommands || !glCaps.baseInstanceSupport() || !glCaps.multiDrawIndirectSupport()) {
+        int emulatedBaseInstance = batch->fEmulatedBaseInstance;
+        for (int i = 0; i < numCommands; ++i) {
+            int glCmdIdx = batch->fGLDrawCmdsIdx + i;
+            this->flushInstanceAttribs(emulatedBaseInstance);
+            GL_CALL(DrawElementsIndirect(GR_GL_TRIANGLES, GR_GL_UNSIGNED_BYTE,
+                                         (GrGLDrawElementsIndirectCommand*) nullptr + glCmdIdx));
+            if (!glCaps.baseInstanceSupport()) {
+                emulatedBaseInstance += fGLDrawCmdsInfo[glCmdIdx].fInstanceCount;
+            }
+        }
+    } else {
+        int glCmdsIdx = batch->fGLDrawCmdsIdx;
+        this->flushInstanceAttribs(batch->fEmulatedBaseInstance);
+        GL_CALL(MultiDrawElementsIndirect(GR_GL_TRIANGLES, GR_GL_UNSIGNED_BYTE,
+                                          (GrGLDrawElementsIndirectCommand*) nullptr + glCmdsIdx,
+                                          numCommands, 0));
+    }
+}
+
+void GLInstancedRendering::flushInstanceAttribs(int baseInstance) {
+    SkASSERT(fVertexArrayID);
+    this->glGpu()->bindVertexArray(fVertexArrayID);
+
+    SkASSERT(fInstanceBuffer);
+    if (fInstanceAttribsBufferUniqueId != fInstanceBuffer->getUniqueID() ||
+        fInstanceAttribsBaseInstance != baseInstance) {
+        Instance* offsetInBuffer = (Instance*) nullptr + baseInstance;
+
+        this->glGpu()->bindBuffer(kVertex_GrBufferType, fInstanceBuffer.get());
+
+        // Info attrib.
+        GL_CALL(EnableVertexAttribArray((int)Attrib::kInstanceInfo));
+        GL_CALL(VertexAttribIPointer((int)Attrib::kInstanceInfo, 1, GR_GL_UNSIGNED_INT,
+                                     sizeof(Instance), &offsetInBuffer->fInfo));
+        GL_CALL(VertexAttribDivisor((int)Attrib::kInstanceInfo, 1));
+
+        // Shape matrix attrib.
+        GL_CALL(EnableVertexAttribArray((int)Attrib::kShapeMatrixX));
+        GL_CALL(EnableVertexAttribArray((int)Attrib::kShapeMatrixY));
+        GL_CALL(VertexAttribPointer((int)Attrib::kShapeMatrixX, 3, GR_GL_FLOAT, GR_GL_FALSE,
+                                    sizeof(Instance), &offsetInBuffer->fShapeMatrix2x3[0]));
+        GL_CALL(VertexAttribPointer((int)Attrib::kShapeMatrixY, 3, GR_GL_FLOAT, GR_GL_FALSE,
+                                    sizeof(Instance), &offsetInBuffer->fShapeMatrix2x3[3]));
+        GL_CALL(VertexAttribDivisor((int)Attrib::kShapeMatrixX, 1));
+        GL_CALL(VertexAttribDivisor((int)Attrib::kShapeMatrixY, 1));
+
+        // Color attrib.
+        GL_CALL(EnableVertexAttribArray((int)Attrib::kColor));
+        GL_CALL(VertexAttribPointer((int)Attrib::kColor, 4, GR_GL_UNSIGNED_BYTE, GR_GL_TRUE,
+                                    sizeof(Instance), &offsetInBuffer->fColor));
+        GL_CALL(VertexAttribDivisor((int)Attrib::kColor, 1));
+
+        // Local rect attrib.
+        GL_CALL(EnableVertexAttribArray((int)Attrib::kLocalRect));
+        GL_CALL(VertexAttribPointer((int)Attrib::kLocalRect, 4, GR_GL_FLOAT, GR_GL_FALSE,
+                                    sizeof(Instance), &offsetInBuffer->fLocalRect));
+        GL_CALL(VertexAttribDivisor((int)Attrib::kLocalRect, 1));
+
+        fInstanceAttribsBufferUniqueId = fInstanceBuffer->getUniqueID();
+        fInstanceAttribsBaseInstance = baseInstance;
+    }
+}
+
+void GLInstancedRendering::onEndFlush() {
+    fInstanceBuffer.reset();
+    fDrawIndirectBuffer.reset();
+    fGLDrawCmdsInfo.reset(0);
+}
+
+void GLInstancedRendering::onResetGpuResources(ResetType resetType) {
+    if (fVertexArrayID && ResetType::kDestroy == resetType) {
+        GL_CALL(DeleteVertexArrays(1, &fVertexArrayID));
+        this->glGpu()->notifyVertexArrayDelete(fVertexArrayID);
+    }
+    fVertexArrayID = 0;
+    fInstanceBuffer.reset();
+    fDrawIndirectBuffer.reset();
+    fInstanceAttribsBufferUniqueId = SK_InvalidUniqueID;
+}
+
+}