2 * Copyright 2014 Google Inc.
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
8 #ifndef GrConvexPolyEffect_DEFINED
9 #define GrConvexPolyEffect_DEFINED
11 #include "GrDrawTargetCaps.h"
12 #include "GrProcessor.h"
13 #include "GrTypesPriv.h"
15 class GrGLConvexPolyEffect;
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.
23 class GrConvexPolyEffect : public GrFragmentProcessor {
30 * edges is a set of n edge equations where n is limited to kMaxEdges. It contains 3*n values.
31 * The edges should form a convex polygon. The positive half-plane is considered to be the
32 * inside. The equations should be normalized such that the first two coefficients are a unit
35 * Currently the edges are specified in device space. In the future we may prefer to specify
36 * them in src space. There are a number of ways this could be accomplished but we'd probably
37 * have to modify the effect/shaderbuilder interface to make it possible (e.g. give access
38 * to the view matrix or untransformed positions in the fragment shader).
40 static GrFragmentProcessor* Create(GrPrimitiveEdgeType edgeType, int n,
41 const SkScalar edges[]) {
42 if (n <= 0 || n > kMaxEdges || kHairlineAA_GrProcessorEdgeType == edgeType) {
45 return SkNEW_ARGS(GrConvexPolyEffect, (edgeType, n, edges));
49 * Creates an effect that clips against the path. If the path is not a convex polygon, is
50 * inverse filled, or has too many edges, this will return NULL. If offset is non-NULL, then
51 * the path is translated by the vector.
53 static GrFragmentProcessor* Create(GrPrimitiveEdgeType, const SkPath&,
54 const SkVector* offset = NULL);
57 * Creates an effect that fills inside the rect with AA edges..
59 static GrFragmentProcessor* Create(GrPrimitiveEdgeType, const SkRect&);
61 virtual ~GrConvexPolyEffect();
63 static const char* Name() { return "ConvexPoly"; }
65 GrPrimitiveEdgeType getEdgeType() const { return fEdgeType; }
67 int getEdgeCount() const { return fEdgeCount; }
69 const SkScalar* getEdges() const { return fEdges; }
71 typedef GrGLConvexPolyEffect GLProcessor;
73 virtual const GrBackendFragmentProcessorFactory& getFactory() const SK_OVERRIDE;
76 GrConvexPolyEffect(GrPrimitiveEdgeType edgeType, int n, const SkScalar edges[]);
78 virtual bool onIsEqual(const GrFragmentProcessor& other) const SK_OVERRIDE;
80 virtual void onComputeInvariantOutput(InvariantOutput* inout) const SK_OVERRIDE;
82 GrPrimitiveEdgeType fEdgeType;
84 SkScalar fEdges[3 * kMaxEdges];
86 GR_DECLARE_FRAGMENT_PROCESSOR_TEST;
88 typedef GrFragmentProcessor INHERITED;