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      1 /*
      2  * Copyright 2017 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #ifndef GrCCPathProcessor_DEFINED
      9 #define GrCCPathProcessor_DEFINED
     10 
     11 #include "GrCaps.h"
     12 #include "GrGeometryProcessor.h"
     13 #include "SkPath.h"
     14 #include <array>
     15 
     16 class GrOnFlushResourceProvider;
     17 
     18 /**
     19  * This class draws AA paths using the coverage count masks produced by GrCCCoverageProcessor.
     20  *
     21  * Paths are drawn as bloated octagons, and coverage is derived from the coverage count mask and
     22  * fill rule.
     23  *
     24  * The caller must set up an instance buffer as detailed below, then draw indexed-instanced
     25  * meshes using the buffers and parameters provided by this class.
     26  */
     27 class GrCCPathProcessor : public GrGeometryProcessor {
     28 public:
     29     enum class InstanceAttribs {
     30         kDevBounds,
     31         kDevBounds45,
     32         kViewMatrix, // FIXME: This causes a lot of duplication. It could move to a texel buffer.
     33         kViewTranslate,
     34         kAtlasOffset,
     35         kColor
     36     };
     37     static constexpr int kNumInstanceAttribs = 1 + (int)InstanceAttribs::kColor;
     38 
     39     struct Instance {
     40         SkRect fDevBounds;
     41         SkRect fDevBounds45; // Bounding box in "| 1  -1 | * devCoords" space.
     42                              //                  | 1   1 |
     43         std::array<float, 4> fViewMatrix;  // {kScaleX, kSkewy, kSkewX, kScaleY}
     44         std::array<float, 2> fViewTranslate;
     45         std::array<int16_t, 2> fAtlasOffset;
     46         uint32_t fColor;
     47 
     48         GR_STATIC_ASSERT(SK_SCALAR_IS_FLOAT);
     49     };
     50 
     51     GR_STATIC_ASSERT(4 * 16 == sizeof(Instance));
     52 
     53     static GrPrimitiveType MeshPrimitiveType(const GrCaps& caps) {
     54         return caps.usePrimitiveRestart() ? GrPrimitiveType::kTriangleStrip
     55                                           : GrPrimitiveType::kTriangles;
     56     }
     57     static sk_sp<const GrBuffer> FindVertexBuffer(GrOnFlushResourceProvider*);
     58     static sk_sp<const GrBuffer> FindIndexBuffer(GrOnFlushResourceProvider*);
     59     static int NumIndicesPerInstance(const GrCaps&);
     60 
     61     GrCCPathProcessor(GrResourceProvider*, sk_sp<GrTextureProxy> atlas, SkPath::FillType);
     62 
     63     const char* name() const override { return "GrCCPathProcessor"; }
     64     const GrSurfaceProxy* atlasProxy() const { return fAtlasAccess.proxy(); }
     65     const GrTexture* atlas() const { return fAtlasAccess.peekTexture(); }
     66     SkPath::FillType fillType() const { return fFillType; }
     67     const Attribute& getInstanceAttrib(InstanceAttribs attribID) const {
     68         const Attribute& attrib = this->getAttrib((int)attribID);
     69         SkASSERT(Attribute::InputRate::kPerInstance == attrib.fInputRate);
     70         return attrib;
     71     }
     72     const Attribute& getEdgeNormsAttrib() const {
     73         SkASSERT(1 + kNumInstanceAttribs == this->numAttribs());
     74         const Attribute& attrib = this->getAttrib(kNumInstanceAttribs);
     75         SkASSERT(Attribute::InputRate::kPerVertex == attrib.fInputRate);
     76         return attrib;
     77     }
     78 
     79     void getGLSLProcessorKey(const GrShaderCaps&, GrProcessorKeyBuilder*) const override;
     80     GrGLSLPrimitiveProcessor* createGLSLInstance(const GrShaderCaps&) const override;
     81 
     82 private:
     83     const SkPath::FillType fFillType;
     84     const TextureSampler fAtlasAccess;
     85 
     86     typedef GrGeometryProcessor INHERITED;
     87 };
     88 
     89 #endif
     90