blob: 4d96cd9c979f99afa27156f1c533b29051caa01d [file] [log] [blame]
/*
* 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 "GrProcessor.h"
#include "SkMatrix.h"
#include "GrTexture.h"
#include "GrTypes.h"
#include "GrShaderVar.h"
/**
* Coordinates available to GrProcessor subclasses for requesting transformations. Transformed
* coordinates are made available in the the portion of fragment shader emitted by the effect.
*
* The precision of the shader var that interpolates the transformed coordinates can be specified.
*/
enum GrCoordSet {
/**
* The user-space coordinates that map to the fragment being rendered. This is the space in
* which SkShader operates. It is usually the space in which geometry passed to SkCanvas is
* specified (before the view matrix is applied). However, some draw calls take explicit local
* coords that map onto the geometry (e.g. drawVertices, drawBitmapRectToRect).
*/
kLocal_GrCoordSet,
/**
* The device space position of the fragment being shaded.
*/
kDevice_GrCoordSet,
};
/**
* A class representing a linear transformation from one of the built-in coordinate sets (local or
* position). GrProcessors 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() : fSourceCoords(kLocal_GrCoordSet) { SkDEBUGCODE(fInProcessor = false); }
/**
* Create a transformation that maps [0, 1] to a texture's boundaries. The precision is inferred
* from the texture size and filter. The texture origin also implies whether a y-reversal should
* be performed.
*/
GrCoordTransform(GrCoordSet sourceCoords,
const GrTexture* texture,
GrTextureParams::FilterMode filter) {
SkASSERT(texture);
SkDEBUGCODE(fInProcessor = false);
this->reset(sourceCoords, texture, filter);
}
/**
* Create a transformation from a matrix. The precision is inferred from the texture size and
* filter. The texture origin also implies whether a y-reversal should be performed.
*/
GrCoordTransform(GrCoordSet sourceCoords, const SkMatrix& m,
const GrTexture* texture, GrTextureParams::FilterMode filter) {
SkDEBUGCODE(fInProcessor = false);
SkASSERT(texture);
this->reset(sourceCoords, m, texture, filter);
}
/**
* Create a transformation that applies the matrix to a coord set.
*/
GrCoordTransform(GrCoordSet sourceCoords, const SkMatrix& m,
GrSLPrecision precision = kDefault_GrSLPrecision) {
SkDEBUGCODE(fInProcessor = false);
this->reset(sourceCoords, m, precision);
}
void reset(GrCoordSet sourceCoords, const GrTexture* texture,
GrTextureParams::FilterMode filter) {
SkASSERT(!fInProcessor);
SkASSERT(texture);
this->reset(sourceCoords, MakeDivByTextureWHMatrix(texture), texture, filter);
}
void reset(GrCoordSet, const SkMatrix&, const GrTexture*, GrTextureParams::FilterMode filter);
void reset(GrCoordSet sourceCoords, const SkMatrix& m,
GrSLPrecision precision = kDefault_GrSLPrecision);
GrCoordTransform& operator= (const GrCoordTransform& that) {
SkASSERT(!fInProcessor);
fSourceCoords = that.fSourceCoords;
fMatrix = that.fMatrix;
fReverseY = that.fReverseY;
fPrecision = that.fPrecision;
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(!fInProcessor);
return &fMatrix;
}
bool operator==(const GrCoordTransform& that) const {
return fSourceCoords == that.fSourceCoords &&
fMatrix.cheapEqualTo(that.fMatrix) &&
fReverseY == that.fReverseY &&
fPrecision == that.fPrecision;
}
bool operator!=(const GrCoordTransform& that) const { return !(*this == that); }
GrCoordSet sourceCoords() const { return fSourceCoords; }
const SkMatrix& getMatrix() const { return fMatrix; }
bool reverseY() const { return fReverseY; }
GrSLPrecision precision() const { return fPrecision; }
/** 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(texture);
SkMatrix mat;
(void)mat.setIDiv(texture->width(), texture->height());
return mat;
}
private:
GrCoordSet fSourceCoords;
SkMatrix fMatrix;
bool fReverseY;
GrSLPrecision fPrecision;
typedef SkNoncopyable INHERITED;
#ifdef SK_DEBUG
public:
void setInProcessor() const { fInProcessor = true; }
private:
mutable bool fInProcessor;
#endif
};
#endif