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| 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 "GrDrawTargetCaps.h" |
| 12 #include "GrEffect.h" |
| 13 #include "GrVertexEffect.h" |
| 14 |
| 15 class GrGLConvexPolyEffect; |
| 16 class SkPath; |
| 17 |
| 18 /** |
| 19 * An effect that renders a convex polygon. It is intended to be used as a cover
age effect. |
| 20 * Bounding geometry is rendered and the effect computes coverage based on the f
ragment's |
| 21 * position relative to the polygon. |
| 22 */ |
| 23 class GrConvexPolyEffect : public GrEffect { |
| 24 public: |
| 25 /** This could be expanded to include a AA hairline mode. If so, unify with
GrBezierEffect's |
| 26 enum. */ |
| 27 enum EdgeType { |
| 28 kFillNoAA_EdgeType, |
| 29 kFillAA_EdgeType, |
| 30 |
| 31 kLastEdgeType = kFillAA_EdgeType, |
| 32 }; |
| 33 |
| 34 enum { |
| 35 kEdgeTypeCnt = kLastEdgeType + 1, |
| 36 kMaxEdges = 8, |
| 37 }; |
| 38 |
| 39 /** |
| 40 * edges is a set of n edge equations where n is limited to kMaxEdges. It co
ntains 3*n values. |
| 41 * The edges should form a convex polygon. The positive half-plane is consid
ered to be the |
| 42 * inside. The equations should be normalized such that the first two coeffi
cients are a unit |
| 43 * 2d vector. |
| 44 * |
| 45 * Currently the edges are specified in device space. In the future we may p
refer to specify |
| 46 * them in src space. There are a number of ways this could be accomplished
but we'd probably |
| 47 * have to modify the effect/shaderbuilder interface to make it possible (e.
g. give access |
| 48 * to the view matrix or untransformed positions in the fragment shader). |
| 49 */ |
| 50 static GrEffectRef* Create(EdgeType edgeType, int n, const SkScalar edges[])
{ |
| 51 if (n <= 0 || n > kMaxEdges) { |
| 52 return NULL; |
| 53 } |
| 54 return CreateEffectRef(AutoEffectUnref(SkNEW_ARGS(GrConvexPolyEffect, |
| 55 (edgeType, n, edges)))
); |
| 56 } |
| 57 |
| 58 /** |
| 59 * Creates an effect that clips against the path. If the path is not a conve
x polygon, is |
| 60 * inverse filled, or has too many edges, this will return NULL. |
| 61 */ |
| 62 static GrEffectRef* Create(EdgeType, const SkPath&); |
| 63 |
| 64 virtual ~GrConvexPolyEffect(); |
| 65 |
| 66 static const char* Name() { return "ConvexPoly"; } |
| 67 |
| 68 EdgeType getEdgeType() const { return fEdgeType; } |
| 69 |
| 70 int getEdgeCount() const { return fEdgeCount; } |
| 71 |
| 72 const SkScalar* getEdges() const { return fEdges; } |
| 73 |
| 74 typedef GrGLConvexPolyEffect GLEffect; |
| 75 |
| 76 virtual void getConstantColorComponents(GrColor* color, uint32_t* validFlags
) const SK_OVERRIDE; |
| 77 |
| 78 virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE; |
| 79 |
| 80 private: |
| 81 GrConvexPolyEffect(EdgeType edgeType, int n, const SkScalar edges[]); |
| 82 |
| 83 virtual bool onIsEqual(const GrEffect& other) const SK_OVERRIDE; |
| 84 |
| 85 EdgeType fEdgeType; |
| 86 int fEdgeCount; |
| 87 SkScalar fEdges[3 * kMaxEdges]; |
| 88 |
| 89 GR_DECLARE_EFFECT_TEST; |
| 90 |
| 91 typedef GrEffect INHERITED; |
| 92 }; |
| 93 |
| 94 |
| 95 #endif |
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