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/*
* Copyright 2010 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef GrSamplerState_DEFINED
#define GrSamplerState_DEFINED
#include "GrTypes.h"
#include "GrMatrix.h"
#define MAX_KERNEL_WIDTH 25
class GrSamplerState {
public:
enum Filter {
/**
* Read the closest src texel to the sample position
*/
kNearest_Filter,
/**
* Blend between closest 4 src texels to sample position (tent filter)
*/
kBilinear_Filter,
/**
* Average of 4 bilinear filterings spaced +/- 1 texel from sample
* position in x and y. Intended for averaging 16 texels in a downsample
* pass. (rasterizing such that texture samples fall exactly halfway
* between texels in x and y spaced 4 texels apart.) Only supported
* on shader backends.
*/
k4x4Downsample_Filter,
/**
* Apply a separable convolution kernel.
*/
kConvolution_Filter,
kDefault_Filter = kNearest_Filter
};
/**
* The intepretation of the texture matrix depends on the sample mode. The
* texture matrix is applied both when the texture coordinates are explicit
* and when vertex positions are used as texture coordinates. In the latter
* case the texture matrix is applied to the pre-view-matrix position
* values.
*
* kNormal_SampleMode
* The post-matrix texture coordinates are in normalize space with (0,0) at
* the top-left and (1,1) at the bottom right.
* kRadial_SampleMode
* The matrix specifies the radial gradient parameters.
* (0,0) in the post-matrix space is center of the radial gradient.
* kRadial2_SampleMode
* Matrix transforms to space where first circle is centered at the
* origin. The second circle will be centered (x, 0) where x may be
* 0 and is provided by setRadial2Params. The post-matrix space is
* normalized such that 1 is the second radius - first radius.
* kSweepSampleMode
* The angle from the origin of texture coordinates in post-matrix space
* determines the gradient value.
*/
enum SampleMode {
kNormal_SampleMode, //!< sample color directly
kRadial_SampleMode, //!< treat as radial gradient
kRadial2_SampleMode, //!< treat as 2-point radial gradient
kSweep_SampleMode, //!< treat as sweep gradient
kDefault_SampleMode = kNormal_SampleMode
};
/**
* Describes how a texture is sampled when coordinates are outside the
* texture border
*/
enum WrapMode {
kClamp_WrapMode,
kRepeat_WrapMode,
kMirror_WrapMode,
kDefault_WrapMode = kClamp_WrapMode
};
/**
* Default sampler state is set to clamp, use normal sampling mode, be
* unfiltered, and use identity matrix.
*/
GrSamplerState()
: fRadial2CenterX1()
, fRadial2Radius0()
, fRadial2PosRoot() {
this->reset();
}
WrapMode getWrapX() const { return fWrapX; }
WrapMode getWrapY() const { return fWrapY; }
SampleMode getSampleMode() const { return fSampleMode; }
const GrMatrix& getMatrix() const { return fMatrix; }
const GrRect& getTextureDomain() const { return fTextureDomain; }
bool hasTextureDomain() const {return SkIntToScalar(0) != fTextureDomain.right();}
Filter getFilter() const { return fFilter; }
int getKernelWidth() const { return fKernelWidth; }
const float* getKernel() const { return fKernel; }
const float* getImageIncrement() const { return fImageIncrement; }
bool swapsRAndB() const { return fSwapRAndB; }
bool isGradient() const {
return kRadial_SampleMode == fSampleMode ||
kRadial2_SampleMode == fSampleMode ||
kSweep_SampleMode == fSampleMode;
}
void setWrapX(WrapMode mode) { fWrapX = mode; }
void setWrapY(WrapMode mode) { fWrapY = mode; }
void setSampleMode(SampleMode mode) { fSampleMode = mode; }
/**
* Access the sampler's matrix. See SampleMode for explanation of
* relationship between the matrix and sample mode.
*/
GrMatrix* matrix() { return &fMatrix; }
/**
* Sets the sampler's texture coordinate domain to a
* custom rectangle, rather than the default (0,1).
* This option is currently only supported with kClamp_WrapMode
*/
void setTextureDomain(const GrRect& textureDomain) { fTextureDomain = textureDomain; }
/**
* Swaps the R and B components when reading from the texture. Has no effect
* if the texture is alpha only.
*/
void setRAndBSwap(bool swap) { fSwapRAndB = swap; }
/**
* Multiplies the current sampler matrix a matrix
*
* After this call M' = M*m where M is the old matrix, m is the parameter
* to this function, and M' is the new matrix. (We consider points to
* be column vectors so tex cood vector t is transformed by matrix X as
* t' = X*t.)
*
* @param matrix the matrix used to modify the matrix.
*/
void preConcatMatrix(const GrMatrix& matrix) { fMatrix.preConcat(matrix); }
/**
* Sets filtering type.
* @param filter type of filtering to apply
*/
void setFilter(Filter filter) { fFilter = filter; }
void reset(WrapMode wrapXAndY,
Filter filter,
const GrMatrix& matrix) {
fWrapX = wrapXAndY;
fWrapY = wrapXAndY;
fSampleMode = kDefault_SampleMode;
fFilter = filter;
fMatrix = matrix;
fTextureDomain.setEmpty();
fSwapRAndB = false;
}
void reset(WrapMode wrapXAndY,
Filter filter) {
this->reset(wrapXAndY, filter, GrMatrix::I());
}
void reset(const GrMatrix& matrix) {
this->reset(kDefault_WrapMode, kDefault_Filter, matrix);
}
void reset() {
this->reset(kDefault_WrapMode, kDefault_Filter, GrMatrix::I());
}
GrScalar getRadial2CenterX1() const { return fRadial2CenterX1; }
GrScalar getRadial2Radius0() const { return fRadial2Radius0; }
bool isRadial2PosRoot() const { return SkToBool(fRadial2PosRoot); }
// do the radial gradient params lead to a linear (rather than quadratic)
// equation.
bool radial2IsDegenerate() const { return GR_Scalar1 == fRadial2CenterX1; }
/**
* Sets the parameters for kRadial2_SampleMode. The texture
* matrix must be set so that the first point is at (0,0) and the second
* point lies on the x-axis. The second radius minus the first is 1 unit.
* The additional parameters to define the gradient are specified by this
* function.
*/
void setRadial2Params(GrScalar centerX1, GrScalar radius0, bool posRoot) {
fRadial2CenterX1 = centerX1;
fRadial2Radius0 = radius0;
fRadial2PosRoot = posRoot;
}
void setConvolutionParams(int kernelWidth, const float* kernel, float imageIncrement[2]) {
GrAssert(kernelWidth >= 0 && kernelWidth <= MAX_KERNEL_WIDTH);
fKernelWidth = kernelWidth;
if (NULL != kernel) {
memcpy(fKernel, kernel, kernelWidth * sizeof(float));
}
if (NULL != imageIncrement) {
memcpy(fImageIncrement, imageIncrement, sizeof(fImageIncrement));
} else {
memset(fImageIncrement, 0, sizeof(fImageIncrement));
}
}
private:
WrapMode fWrapX : 8;
WrapMode fWrapY : 8;
SampleMode fSampleMode : 8;
Filter fFilter : 8;
GrMatrix fMatrix;
bool fSwapRAndB;
GrRect fTextureDomain;
// these are undefined unless fSampleMode == kRadial2_SampleMode
GrScalar fRadial2CenterX1;
GrScalar fRadial2Radius0;
SkBool8 fRadial2PosRoot;
// These are undefined unless fFilter == kConvolution_Filter
uint8_t fKernelWidth;
float fImageIncrement[2];
float fKernel[MAX_KERNEL_WIDTH];
};
#endif