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