commit-bot@chromium.org | c3fe549 | 2014-01-30 18:15:51 +0000 | [diff] [blame] | 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 coverage effect. |
| 20 | * Bounding geometry is rendered and the effect computes coverage based on the fragment'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, |
skia.committer@gmail.com | 4c18e9f | 2014-01-31 03:01:59 +0000 | [diff] [blame] | 30 | |
commit-bot@chromium.org | c3fe549 | 2014-01-30 18:15:51 +0000 | [diff] [blame] | 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 contains 3*n values. |
| 41 | * The edges should form a convex polygon. The positive half-plane is considered to be the |
| 42 | * inside. The equations should be normalized such that the first two coefficients are a unit |
| 43 | * 2d vector. |
| 44 | * |
| 45 | * Currently the edges are specified in device space. In the future we may prefer 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 convex 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 |