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/*
* Copyright 2013 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef GrCoordTransform_DEFINED
#define GrCoordTransform_DEFINED
#include "GrEffect.h"
#include "SkMatrix.h"
#include "GrTexture.h"
#include "GrTypes.h"
/**
* Coordinates available to GrEffect subclasses for requesting transformations. Transformed
* coordinates are made available in the the portion of fragment shader emitted by the effect.
*/
enum GrCoordSet {
/**
* The user-space coordinates that map to the fragment being rendered. These coords account for
* any change of coordinate system done on the CPU by GrContext before rendering, and also are
* correct for draws that take explicit local coords rather than inferring them from the
* primitive's positions (e.g. drawVertices). These are usually the coords a GrEffect wants.
*/
kLocal_GrCoordSet,
/**
* The actual vertex position. Note that GrContext may not draw using the original view matrix
* specified by the caller, as it may have transformed vertices into another space. These are
* usually not the coordinates a GrEffect wants.
*/
kPosition_GrCoordSet
};
/**
* A class representing a linear transformation from one of the built-in coordinate sets (local or
* position). GrEffects just define these transformations, and the framework does the rest of the
* work to make the transformed coordinates available in their fragment shader.
*/
class GrCoordTransform : SkNoncopyable {
public:
GrCoordTransform() { SkDEBUGCODE(fInEffect = false); }
/**
* Create a transformation that maps [0, 1] to a texture's boundaries.
*/
GrCoordTransform(GrCoordSet sourceCoords, const GrTexture* texture) {
SkDEBUGCODE(fInEffect = false);
this->reset(sourceCoords, texture);
}
/**
* Create a transformation from a matrix. The optional texture parameter is used to infer if the
* framework should internally do a y reversal to account for it being upside down by Skia's
* coord convention.
*/
GrCoordTransform(GrCoordSet sourceCoords, const SkMatrix& m, const GrTexture* texture = NULL) {
SkDEBUGCODE(fInEffect = false);
this->reset(sourceCoords, m, texture);
}
void reset(GrCoordSet sourceCoords, const GrTexture* texture) {
SkASSERT(!fInEffect);
SkASSERT(NULL != texture);
this->reset(sourceCoords, MakeDivByTextureWHMatrix(texture), texture);
}
void reset(GrCoordSet sourceCoords, const SkMatrix& m, const GrTexture* texture = NULL) {
SkASSERT(!fInEffect);
fSourceCoords = sourceCoords;
fMatrix = m;
fReverseY = NULL != texture && kBottomLeft_GrSurfaceOrigin == texture->origin();
}
GrCoordTransform& operator= (const GrCoordTransform& other) {
SkASSERT(!fInEffect);
fSourceCoords = other.fSourceCoords;
fMatrix = other.fMatrix;
fReverseY = other.fReverseY;
return *this;
}
/**
* Access the matrix for editing. Note, this must be done before adding the transform to an
* effect, since effects are immutable.
*/
SkMatrix* accessMatrix() {
SkASSERT(!fInEffect);
return &fMatrix;
}
bool operator== (const GrCoordTransform& other) const {
return fSourceCoords == other.fSourceCoords &&
fMatrix.cheapEqualTo(other.fMatrix) &&
fReverseY == other.fReverseY;
}
GrCoordSet sourceCoords() const { return fSourceCoords; }
const SkMatrix& getMatrix() const { return fMatrix; }
bool reverseY() const { return fReverseY; }
/** Useful for effects that want to insert a texture matrix that is implied by the texture
dimensions */
static inline SkMatrix MakeDivByTextureWHMatrix(const GrTexture* texture) {
SkASSERT(NULL != texture);
SkMatrix mat;
mat.setIDiv(texture->width(), texture->height());
return mat;
}
private:
GrCoordSet fSourceCoords;
SkMatrix fMatrix;
bool fReverseY;
typedef SkNoncopyable INHERITED;
#ifdef SK_DEBUG
public:
void setInEffect() const { fInEffect = true; }
private:
mutable bool fInEffect;
#endif
};
#endif
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