1 /* 2 * Copyright 2014 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 GrConvexPolyEffect_DEFINED 9 #define GrConvexPolyEffect_DEFINED 10 11 #include "include/private/GrTypesPriv.h" 12 #include "src/gpu/GrCaps.h" 13 #include "src/gpu/GrFragmentProcessor.h" 14 #include "src/gpu/GrProcessor.h" 15 16 class GrInvariantOutput; 17 class SkPath; 18 19 /** 20 * An effect that renders a convex polygon. It is intended to be used as a coverage effect. 21 * Bounding geometry is rendered and the effect computes coverage based on the fragment's 22 * position relative to the polygon. 23 */ 24 class GrConvexPolyEffect : public GrFragmentProcessor { 25 public: 26 inline static constexpr int kMaxEdges = 8; 27 28 /** 29 * edges is a set of n edge equations where n is limited to kMaxEdges. It contains 3*n values. 30 * The edges should form a convex polygon. The positive half-plane is considered to be the 31 * inside. The equations should be normalized such that the first two coefficients are a unit 32 * 2d vector. 33 * 34 * Currently the edges are specified in device space. In the future we may prefer to specify 35 * them in src space. There are a number of ways this could be accomplished but we'd probably 36 * have to modify the effect/shaderbuilder interface to make it possible (e.g. give access 37 * to the view matrix or untransformed positions in the fragment shader). 38 */ Make(std::unique_ptr<GrFragmentProcessor> inputFP,GrClipEdgeType edgeType,int n,const float edges[])39 static GrFPResult Make(std::unique_ptr<GrFragmentProcessor> inputFP, 40 GrClipEdgeType edgeType, 41 int n, 42 const float edges[]) { 43 if (n <= 0 || n > kMaxEdges) { 44 return GrFPFailure(std::move(inputFP)); 45 } 46 47 return GrFPSuccess(std::unique_ptr<GrFragmentProcessor>( 48 new GrConvexPolyEffect(std::move(inputFP), edgeType, n, edges))); 49 } 50 51 /** 52 * Creates an effect that clips against the path. If the path is not a convex polygon, is 53 * inverse filled, or has too many edges, creation will fail. 54 */ 55 static GrFPResult Make(std::unique_ptr<GrFragmentProcessor>, GrClipEdgeType, const SkPath&); 56 57 ~GrConvexPolyEffect() override; 58 name()59 const char* name() const override { return "ConvexPoly"; } 60 std::unique_ptr<GrFragmentProcessor> clone() const override; 61 62 private: 63 GrConvexPolyEffect(std::unique_ptr<GrFragmentProcessor> inputFP, 64 GrClipEdgeType edgeType, 65 int n, const SkScalar edges[]); 66 GrConvexPolyEffect(const GrConvexPolyEffect&); 67 68 std::unique_ptr<ProgramImpl> onMakeProgramImpl() const override; 69 70 void onAddToKey(const GrShaderCaps&, GrProcessorKeyBuilder*) const override; 71 72 bool onIsEqual(const GrFragmentProcessor& other) const override; 73 74 GrClipEdgeType fEdgeType; 75 int fEdgeCount; 76 std::array<float, 3*kMaxEdges> fEdges; 77 78 GR_DECLARE_FRAGMENT_PROCESSOR_TEST 79 80 using INHERITED = GrFragmentProcessor; 81 }; 82 83 84 #endif 85