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