GrBatchPrototype

src/gpu/GrBatch.h

Index: src/gpu/GrBatch.h
diff --git a/src/gpu/GrBatch.h b/src/gpu/GrBatch.h
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index 0000000000000000000000000000000000000000..b1837abd7d4115f04345b8f2853a6f973484a338
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+++ b/src/gpu/GrBatch.h
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+/*
+ * 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 GrBatch_DEFINED
+#define GrBatch_DEFINED
+
+#include <new>
+// TODO remove this header when we move entirely to batch
+#include "GrGeometryProcessor.h"
+#include "SkRefCnt.h"
+#include "SkThread.h"
+#include "SkTypes.h"
+
+class GrBatchBuffer;
+class GrGpu;
+class GrIndexBufferAllocPool;
+class GrInitInvariantOutput;
+class GrOptDrawState;
+class GrVertexBufferAllocPool;
+
+/*
+ * GrBatch is the base class for all Ganesh deferred geometry generators.  To facilitate
+ * reorderable batching, Ganesh does not generate geometry inline with draw calls.  Instead, it
+ * captures the arguments to the draw and then generates the geometry on demand.  This gives GrBatch
+ * subclasses complete freedom to decide how / what they can batch.
+ *
+ * Batches are created generally in renderers, but they cannot be reused.  Instead, they are owned

[bsalomon, 2015/01/21 21:39:29]

How about

"Batches are created when GrContext processes a draw call. Batches of the same
subclass may be merged using canMakeEqual/MakeEqual. When two batches merge, one
takes on the union of the data and the other is left empty. The merged batch
becomes responsible for drawing the data from both the original batches."

also looks like these were renamed from equal to combine.

+ * by a GrDrawTarget subclass after being passed into BatchDraw.  Two GrBatches may be batched.  The
+ * canMakeEqual and MakeEqual calls below are used to determine if two batches can batch.  MakeEqual
+ * can be destructive.
+ *
+ * GrBatches are always drawn with a GrOptDrawState.  Of the GrOptDrawState determines any

[bsalomon, 2015/01/21 21:39:29]

The second sentence is confusing. Also, this might make more sense after the
third para.

+ * pipeline optimizations are possible, it will communicate this information to the GrBatch through
+ * GrBatchOpt.
+ *
+ * Finally, generateGeometry is called with a GrOptDrawState, and a GrBatchBuffer.  GrBatchBuffer

[bsalomon, 2015/01/21 21:39:29]

Can you just explain it directly in terms of GrBatchBuffer rather than in terms
of something that a reader might now be familiar with?

+ * can be treated somewhat like a Gpu, and though it guarantees in order playback to a real gpu, it
+ * may delay flushing to the gpu for performance reasons.
+ */
+
+struct GrBatchOpt {
+  bool fCanTweakAlphaForCoverage;
+};
+
+class GrBatch : public SkRefCnt {
+public:
+    SK_DECLARE_INST_COUNT(GrBatch)
+    GrBatch() { SkDEBUGCODE(fUsed = false;) }
+    virtual ~GrBatch() {}
+    virtual const char* name() const = 0;
+    virtual void getInvariantOutputColor(GrInitInvariantOutput* out,
+                                         const GrBatchOpt&) const = 0;
+    virtual void getInvariantOutputCoverage(GrInitInvariantOutput* out,
+                                            const GrBatchOpt&) const = 0;
+
+    virtual void initBatchOpt(const GrBatchOpt&) = 0;
+    virtual void initBatchTracker(const GrGeometryProcessor::InitBT& init) = 0;
+
+    bool combineIfPossible(GrBatch* that) {
+        if (this->classID() != that->classID()) {
+            return false;
+        }
+
+        return onCombineIfPossible(that);
+    }
+
+    virtual bool onCombineIfPossible(GrBatch*) = 0;
+
+    virtual void generateGeometry(GrBatchBuffer*, const GrOptDrawState*) = 0;
+
+    void* operator new(size_t size);
+    void operator delete(void* target);
+
+    void* operator new(size_t size, void* placement) {
+        return ::operator new(size, placement);
+    }
+    void operator delete(void* target, void* placement) {
+        ::operator delete(target, placement);
+    }
+
+    /**
+      * Helper for down-casting to a GrBatch subclass
+      */
+    template <typename T> const T& cast() const { return *static_cast<const T*>(this); }
+    template <typename T> T* cast() { return static_cast<T*>(this); }
+
+    uint32_t classID() const { SkASSERT(kIllegalBatchClassID != fClassID); return fClassID; }
+
+    // TODO no GrPrimitiveProcessors yet read fragment position
+    bool willReadFragmentPosition() const { return false; }
+
+    SkDEBUGCODE(bool isUsed() const { return fUsed; })
+
+protected:
+    template <typename PROC_SUBCLASS> void initClassID() {
+         static uint32_t kClassID = GenClassID();
+         fClassID = kClassID;
+    }
+
+    uint32_t fClassID;
+
+private:
+    static uint32_t GenClassID() {
+        // fCurrProcessorClassID has been initialized to kIllegalProcessorClassID. The
+        // atomic inc returns the old value not the incremented value. So we add
+        // 1 to the returned value.
+        uint32_t id = static_cast<uint32_t>(sk_atomic_inc(&gCurrBatchClassID)) + 1;
+        if (!id) {
+            SkFAIL("This should never wrap as it should only be called once for each GrBatch "
+                   "subclass.");
+        }
+        return id;
+    }
+
+    enum {
+        kIllegalBatchClassID = 0,
+    };
+    static int32_t gCurrBatchClassID;
+
+    SkDEBUGCODE(bool fUsed;)
+
+    typedef SkRefCnt INHERITED;
+};
+
+#endif