Implement instanced rendering for simple shapes

src/gpu/GrInstancedRenderingTypes.h

+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrInstancedRenderingTypes_DEFINED
+#define GrInstancedRenderingTypes_DEFINED
+
+#include "GrTypes.h"
+#include "SkRRect.h"
+
+/**
+ * Internal structs and enums for classes involved in instanced rendering. This class is intended
+ * to be inherited non-publicly.
+ */
+class GrInstancedRenderingTypes {
+public:
+    /**
+     * Per-vertex data. These values get fed into normal vertex attribs.
+     */
+    struct ShapeVertex {
+        float     fX, fY;  //!< Shape coordinates.
+        int32_t   fAttrs;  //!< Shape-specific vertex attributes, if needed.
+    };
+
+    /**
+     * Per-instance data. These values get fed into instanced vertex attribs.
+     */
+    struct Instance {
+        uint32_t   fInfo;               //!< Packed info about the instance. See InfoBits.
+        float      fShapeMatrix2x3[6];  //!< Maps canonical shape coords -> device space coords.
+        uint32_t   fColor;              //!< Color to be written out by the primitive processor.
+        float      fLocalRect[4];       //!< Local coords rect that spans [-1, +1] in shape coords.
+    };
+
+    /**
+     * Additional parameters required by some instances (e.g. round rect radii, perspective column,
+     * local matrix). These are accessed via texel buffer.
+     */
+    struct ParamsTexel {
+        union {
+            struct { float fX, fY, fZ, fW; };
+            float fValues[4];
+        };
+    };
+
+    GR_STATIC_ASSERT(0 == offsetof(ParamsTexel, fX));
+    GR_STATIC_ASSERT(4 * 4 == sizeof(ParamsTexel));
+
+    enum AttribIdx {
+        kShapeCoords_AttribIdx,
+        kVertexAttrs_AttribIdx,
+        kInstanceInfo_AttribIdx,
+        kShapeMatrixX_AttribIdx,
+        kShapeMatrixY_AttribIdx,
+        kColor_AttribIdx,
+        kLocalRect_AttribIdx,
+
+        kNumVertexAttribs
+    };
+
+    enum AntialiasMode {
+        kNone_AntialiasMode,
+        kCoverage_AntialiasMode,
+        kMSAA_AntialiasMode,
+        kMixedSamples_AntialiasMode,
+
+        kLast_AntialiasMode = kMixedSamples_AntialiasMode
+    };
+
+    enum AntialiasFlags {
+        kNone_AntialiasFlag          = (1 << kNone_AntialiasMode),
+        kCoverage_AntialiasFlag      = (1 << kCoverage_AntialiasMode),
+        kMSAA_AntialiasFlag          = (1 << kMSAA_AntialiasMode),
+        kMixedSamples_AntialiasFlag  = (1 << kMixedSamples_AntialiasMode)
+    };
+
+    enum ShapeType {
+        kRect_ShapeType,
+        kOval_ShapeType,
+        kSimpleRRect_ShapeType,
+        kNinePatch_ShapeType,
+        kComplexRRect_ShapeType,
+
+        kLast_ShapeType = kComplexRRect_ShapeType
+    };
+
+    static ShapeType RRectShapeType(const SkRRect& rrect) {
+        SkASSERT(rrect.getType() >= SkRRect::kRect_Type &&
+                 rrect.getType() <= SkRRect::kComplex_Type);
+        return static_cast<ShapeType>(rrect.getType() - 1);
+
+        GR_STATIC_ASSERT(kRect_ShapeType == SkRRect::kRect_Type - 1);
+        GR_STATIC_ASSERT(kOval_ShapeType == SkRRect::kOval_Type - 1);
+        GR_STATIC_ASSERT(kSimpleRRect_ShapeType == SkRRect::kSimple_Type - 1);
+        GR_STATIC_ASSERT(kNinePatch_ShapeType == SkRRect::kNinePatch_Type - 1);
+        GR_STATIC_ASSERT(kComplexRRect_ShapeType == SkRRect::kComplex_Type - 1);
+        GR_STATIC_ASSERT(kLast_ShapeType == SkRRect::kComplex_Type - 1);
+    }
+
+    enum ShapeFlag {
+        kRect_ShapeFlag          = (1 << kRect_ShapeType),
+        kOval_ShapeFlag          = (1 << kOval_ShapeType),
+        kSimpleRRect_ShapeFlag   = (1 << kSimpleRRect_ShapeType),
+        kNinePatch_ShapeFlag     = (1 << kNinePatch_ShapeType),
+        kComplexRRect_ShapeFlag  = (1 << kComplexRRect_ShapeType),
+
+        kRRect_ShapesMask = kSimpleRRect_ShapeFlag | kNinePatch_ShapeFlag | kComplexRRect_ShapeFlag
+    };
+
+    /**
+     * Defines what data is stored at which bits in the fInfo field of the instanced data.
+     */
+    enum InfoBits {
+        kShapeType_InfoBit       = 29,
+        kInnerShapeType_InfoBit  = 27,
+        kPerspective_InfoBit     = 26,
+        kLocalMatrix_InfoBit     = 25,
+        kParamsIdx_InfoBit       =  0
+    };
+
+    enum InfoMasks {
+        kShapeType_InfoMask       = 0u - (1 << kShapeType_InfoBit),
+        kInnerShapeType_InfoMask  = (1 << kShapeType_InfoBit) - (1 << kInnerShapeType_InfoBit),
+        kPerspective_InfoFlag     = (1 << kPerspective_InfoBit),
+        kLocalMatrix_InfoFlag     = (1 << kLocalMatrix_InfoBit),
+        kParamsIdx_InfoMask       = (1 << kLocalMatrix_InfoBit) - 1
+    };
+
+    GR_STATIC_ASSERT(kLast_ShapeType <= (uint32_t)kShapeType_InfoMask >> kShapeType_InfoBit);
+    GR_STATIC_ASSERT(kSimpleRRect_ShapeType <= kInnerShapeType_InfoMask >> kInnerShapeType_InfoBit);
+
+    /**
+     * Tracks all information needed in order to draw a batch of instances. This struct also serves
+     * as an all-in-one shader key for the batch.
+     */
+    struct BatchInfo {
+        BatchInfo() : fData(0) {}
+
+        bool isSimpleRects() const {
+            return !((fShapeTypes & ~kRect_ShapeFlag) | fInnerShapeTypes);
+        }
+
+        bool canJoin(BatchInfo that) const {
+            if (fAntialiasMode != that.fAntialiasMode) {
+                return false;
+            }
+            if (SkToBool(fInnerShapeTypes) != SkToBool(that.fInnerShapeTypes)) {
+                // GrInstanceProcessor can't currently combine draws with and without inner shapes.
+                return false;
+            }
+            if (fCannotDiscard != that.fCannotDiscard) {
+                // For stencil draws, the use of discard can be a requirement.
+                return false;
+            }
+            return true;
+        }
+
+        void join(BatchInfo that) {
+            SkASSERT(this->canJoin(that));
+            fData |= that.fData;
+        }
+
+        union {
+            struct {
+                AntialiasMode   fAntialiasMode                : 8;
+                uint8_t         fShapeTypes;
+                uint8_t         fInnerShapeTypes;
+                bool            fHasPerspective               : 1;
+                bool            fHasLocalMatrix               : 1;
+                bool            fHasParams                    : 1;
+                bool            fNonSquare                    : 1;
+                bool            fUsesLocalCoords              : 1;
+                bool            fCannotTweakAlphaForCoverage  : 1;
+                bool            fCannotDiscard                : 1;
+            };
+            uint32_t fData;
+        };
+    };
+
+    // This is required since all the data must fit into 32 bits of a shader key.
+    GR_STATIC_ASSERT(sizeof(uint32_t) == sizeof(BatchInfo));
+    GR_STATIC_ASSERT(kLast_ShapeType <= 8);
+};
+
+#endif