aa814fe4a1
Review URL: http://codereview.appspot.com/5488048/ git-svn-id: http://skia.googlecode.com/svn/trunk@2854 2bbb7eff-a529-9590-31e7-b0007b416f81
236 lines
7.9 KiB
C++
236 lines
7.9 KiB
C++
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/*
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* Copyright 2010 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef GrSamplerState_DEFINED
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#define GrSamplerState_DEFINED
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#include "GrTypes.h"
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#include "GrMatrix.h"
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#define MAX_KERNEL_WIDTH 25
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class GrSamplerState {
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public:
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enum Filter {
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/**
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* Read the closest src texel to the sample position
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*/
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kNearest_Filter,
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/**
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* Blend between closest 4 src texels to sample position (tent filter)
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*/
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kBilinear_Filter,
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/**
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* Average of 4 bilinear filterings spaced +/- 1 texel from sample
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* position in x and y. Intended for averaging 16 texels in a downsample
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* pass. (rasterizing such that texture samples fall exactly halfway
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* between texels in x and y spaced 4 texels apart.) Only supported
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* on shader backends.
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*/
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k4x4Downsample_Filter,
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/**
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* Apply a separable convolution kernel.
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*/
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kConvolution_Filter,
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kDefault_Filter = kNearest_Filter
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};
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/**
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* The intepretation of the texture matrix depends on the sample mode. The
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* texture matrix is applied both when the texture coordinates are explicit
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* and when vertex positions are used as texture coordinates. In the latter
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* case the texture matrix is applied to the pre-view-matrix position
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* values.
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*
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* kNormal_SampleMode
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* The post-matrix texture coordinates are in normalize space with (0,0) at
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* the top-left and (1,1) at the bottom right.
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* kRadial_SampleMode
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* The matrix specifies the radial gradient parameters.
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* (0,0) in the post-matrix space is center of the radial gradient.
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* kRadial2_SampleMode
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* Matrix transforms to space where first circle is centered at the
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* origin. The second circle will be centered (x, 0) where x may be
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* 0 and is provided by setRadial2Params. The post-matrix space is
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* normalized such that 1 is the second radius - first radius.
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* kSweepSampleMode
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* The angle from the origin of texture coordinates in post-matrix space
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* determines the gradient value.
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*/
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enum SampleMode {
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kNormal_SampleMode, //!< sample color directly
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kRadial_SampleMode, //!< treat as radial gradient
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kRadial2_SampleMode, //!< treat as 2-point radial gradient
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kSweep_SampleMode, //!< treat as sweep gradient
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kDefault_SampleMode = kNormal_SampleMode
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};
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/**
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* Describes how a texture is sampled when coordinates are outside the
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* texture border
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*/
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enum WrapMode {
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kClamp_WrapMode,
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kRepeat_WrapMode,
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kMirror_WrapMode,
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kDefault_WrapMode = kClamp_WrapMode
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};
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/**
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* Default sampler state is set to clamp, use normal sampling mode, be
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* unfiltered, and use identity matrix.
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*/
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GrSamplerState()
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: fRadial2CenterX1()
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, fRadial2Radius0()
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, fRadial2PosRoot() {
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this->reset();
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}
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WrapMode getWrapX() const { return fWrapX; }
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WrapMode getWrapY() const { return fWrapY; }
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SampleMode getSampleMode() const { return fSampleMode; }
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const GrMatrix& getMatrix() const { return fMatrix; }
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const GrRect& getTextureDomain() const { return fTextureDomain; }
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bool hasTextureDomain() const {return SkIntToScalar(0) != fTextureDomain.right();}
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Filter getFilter() const { return fFilter; }
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int getKernelWidth() const { return fKernelWidth; }
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const float* getKernel() const { return fKernel; }
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const float* getImageIncrement() const { return fImageIncrement; }
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bool swapsRAndB() const { return fSwapRAndB; }
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bool isGradient() const {
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return kRadial_SampleMode == fSampleMode ||
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kRadial2_SampleMode == fSampleMode ||
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kSweep_SampleMode == fSampleMode;
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}
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void setWrapX(WrapMode mode) { fWrapX = mode; }
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void setWrapY(WrapMode mode) { fWrapY = mode; }
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void setSampleMode(SampleMode mode) { fSampleMode = mode; }
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/**
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* Access the sampler's matrix. See SampleMode for explanation of
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* relationship between the matrix and sample mode.
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*/
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GrMatrix* matrix() { return &fMatrix; }
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/**
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* Sets the sampler's texture coordinate domain to a
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* custom rectangle, rather than the default (0,1).
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* This option is currently only supported with kClamp_WrapMode
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*/
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void setTextureDomain(const GrRect& textureDomain) { fTextureDomain = textureDomain; }
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/**
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* Swaps the R and B components when reading from the texture. Has no effect
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* if the texture is alpha only.
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*/
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void setRAndBSwap(bool swap) { fSwapRAndB = swap; }
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/**
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* Multiplies the current sampler matrix a matrix
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*
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* After this call M' = M*m where M is the old matrix, m is the parameter
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* to this function, and M' is the new matrix. (We consider points to
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* be column vectors so tex cood vector t is transformed by matrix X as
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* t' = X*t.)
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*
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* @param matrix the matrix used to modify the matrix.
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*/
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void preConcatMatrix(const GrMatrix& matrix) { fMatrix.preConcat(matrix); }
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/**
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* Sets filtering type.
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* @param filter type of filtering to apply
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*/
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void setFilter(Filter filter) { fFilter = filter; }
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void reset(WrapMode wrapXAndY,
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Filter filter,
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const GrMatrix& matrix) {
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fWrapX = wrapXAndY;
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fWrapY = wrapXAndY;
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fSampleMode = kDefault_SampleMode;
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fFilter = filter;
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fMatrix = matrix;
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fTextureDomain.setEmpty();
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fSwapRAndB = false;
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}
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void reset(WrapMode wrapXAndY,
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Filter filter) {
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this->reset(wrapXAndY, filter, GrMatrix::I());
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}
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void reset(const GrMatrix& matrix) {
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this->reset(kDefault_WrapMode, kDefault_Filter, matrix);
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}
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void reset() {
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this->reset(kDefault_WrapMode, kDefault_Filter, GrMatrix::I());
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}
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GrScalar getRadial2CenterX1() const { return fRadial2CenterX1; }
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GrScalar getRadial2Radius0() const { return fRadial2Radius0; }
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bool isRadial2PosRoot() const { return SkToBool(fRadial2PosRoot); }
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// do the radial gradient params lead to a linear (rather than quadratic)
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// equation.
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bool radial2IsDegenerate() const { return GR_Scalar1 == fRadial2CenterX1; }
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/**
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* Sets the parameters for kRadial2_SampleMode. The texture
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* matrix must be set so that the first point is at (0,0) and the second
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* point lies on the x-axis. The second radius minus the first is 1 unit.
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* The additional parameters to define the gradient are specified by this
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* function.
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*/
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void setRadial2Params(GrScalar centerX1, GrScalar radius0, bool posRoot) {
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fRadial2CenterX1 = centerX1;
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fRadial2Radius0 = radius0;
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fRadial2PosRoot = posRoot;
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}
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void setConvolutionParams(int kernelWidth, const float* kernel, float imageIncrement[2]) {
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GrAssert(kernelWidth >= 0 && kernelWidth <= MAX_KERNEL_WIDTH);
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fKernelWidth = kernelWidth;
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if (NULL != kernel) {
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memcpy(fKernel, kernel, kernelWidth * sizeof(float));
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}
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if (NULL != imageIncrement) {
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memcpy(fImageIncrement, imageIncrement, sizeof(fImageIncrement));
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} else {
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memset(fImageIncrement, 0, sizeof(fImageIncrement));
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}
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}
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private:
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WrapMode fWrapX : 8;
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WrapMode fWrapY : 8;
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SampleMode fSampleMode : 8;
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Filter fFilter : 8;
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GrMatrix fMatrix;
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bool fSwapRAndB;
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GrRect fTextureDomain;
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// these are undefined unless fSampleMode == kRadial2_SampleMode
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GrScalar fRadial2CenterX1;
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GrScalar fRadial2Radius0;
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SkBool8 fRadial2PosRoot;
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// These are undefined unless fFilter == kConvolution_Filter
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uint8_t fKernelWidth;
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float fImageIncrement[2];
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float fKernel[MAX_KERNEL_WIDTH];
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};
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#endif
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