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/*
* Copyright 2014 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef GrConvexPolyEffect_DEFINED
#define GrConvexPolyEffect_DEFINED
#include "GrDrawTargetCaps.h"
#include "GrEffect.h"
class GrGLConvexPolyEffect;
class SkPath;
/**
* An effect that renders a convex polygon. It is intended to be used as a coverage effect.
* Bounding geometry is rendered and the effect computes coverage based on the fragment's
* position relative to the polygon.
*/
class GrConvexPolyEffect : public GrEffect {
public:
enum EdgeType {
kFillNoAA_EdgeType,
kFillAA_EdgeType,
kInverseFillNoAA_EdgeType,
kInverseFillAA_EdgeType,
kLastEdgeType = kInverseFillAA_EdgeType,
};
enum {
kEdgeTypeCnt = kLastEdgeType + 1,
kMaxEdges = 8,
};
/**
* edges is a set of n edge equations where n is limited to kMaxEdges. It contains 3*n values.
* The edges should form a convex polygon. The positive half-plane is considered to be the
* inside. The equations should be normalized such that the first two coefficients are a unit
* 2d vector.
*
* Currently the edges are specified in device space. In the future we may prefer to specify
* them in src space. There are a number of ways this could be accomplished but we'd probably
* have to modify the effect/shaderbuilder interface to make it possible (e.g. give access
* to the view matrix or untransformed positions in the fragment shader).
*/
static GrEffectRef* Create(EdgeType edgeType, int n, const SkScalar edges[]) {
if (n <= 0 || n > kMaxEdges) {
return NULL;
}
return CreateEffectRef(AutoEffectUnref(SkNEW_ARGS(GrConvexPolyEffect,
(edgeType, n, edges))));
}
/**
* Creates an effect that clips against the path. If the path is not a convex polygon, is
* inverse filled, or has too many edges, this will return NULL. If offset is non-NULL, then
* the path is translated by the vector.
*/
static GrEffectRef* Create(EdgeType, const SkPath&, const SkVector* offset= NULL);
/**
* Creates an effect that fills inside the rect with AA edges..
*/
static GrEffectRef* Create(EdgeType, const SkRect&);
virtual ~GrConvexPolyEffect();
static const char* Name() { return "ConvexPoly"; }
EdgeType getEdgeType() const { return fEdgeType; }
int getEdgeCount() const { return fEdgeCount; }
const SkScalar* getEdges() const { return fEdges; }
typedef GrGLConvexPolyEffect GLEffect;
virtual void getConstantColorComponents(GrColor* color, uint32_t* validFlags) const SK_OVERRIDE;
virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE;
private:
GrConvexPolyEffect(EdgeType edgeType, int n, const SkScalar edges[]);
virtual bool onIsEqual(const GrEffect& other) const SK_OVERRIDE;
EdgeType fEdgeType;
int fEdgeCount;
SkScalar fEdges[3 * kMaxEdges];
GR_DECLARE_EFFECT_TEST;
typedef GrEffect INHERITED;
};
#endif
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