/*
* Copyright 2014 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "GrBicubicEffect.h"
#include "GrTexture.h"
#include "glsl/GrGLSLFragmentShaderBuilder.h"
#include "glsl/GrGLSLProgramDataManager.h"
#include "glsl/GrGLSLUniformHandler.h"
class GrGLBicubicEffect : public GrGLSLFragmentProcessor {
public:
void emitCode(EmitArgs&) override;
static inline void GenKey(const GrProcessor& effect, const GrShaderCaps&,
GrProcessorKeyBuilder* b) {
const GrBicubicEffect& bicubicEffect = effect.cast<GrBicubicEffect>();
b->add32(GrTextureDomain::GLDomain::DomainKey(bicubicEffect.domain()));
}
protected:
void onSetData(const GrGLSLProgramDataManager&, const GrFragmentProcessor&) override;
private:
typedef GrGLSLProgramDataManager::UniformHandle UniformHandle;
UniformHandle fImageIncrementUni;
GrTextureDomain::GLDomain fDomain;
typedef GrGLSLFragmentProcessor INHERITED;
};
void GrGLBicubicEffect::emitCode(EmitArgs& args) {
const GrBicubicEffect& bicubicEffect = args.fFp.cast<GrBicubicEffect>();
GrGLSLUniformHandler* uniformHandler = args.fUniformHandler;
fImageIncrementUni = uniformHandler->addUniform(kFragment_GrShaderFlag, kHalf2_GrSLType,
"ImageIncrement");
const char* imgInc = uniformHandler->getUniformCStr(fImageIncrementUni);
GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
SkString coords2D = fragBuilder->ensureCoords2D(args.fTransformedCoords[0]);
/*
* Filter weights come from Don Mitchell & Arun Netravali's 'Reconstruction Filters in Computer
* Graphics', ACM SIGGRAPH Computer Graphics 22, 4 (Aug. 1988).
* ACM DL: http://dl.acm.org/citation.cfm?id=378514
* Free : http://www.cs.utexas.edu/users/fussell/courses/cs384g/lectures/mitchell/Mitchell.pdf
*
* The authors define a family of cubic filters with two free parameters (B and C):
*
* { (12 - 9B - 6C)|x|^3 + (-18 + 12B + 6C)|x|^2 + (6 - 2B) if |x| < 1
* k(x) = 1/6 { (-B - 6C)|x|^3 + (6B + 30C)|x|^2 + (-12B - 48C)|x| + (8B + 24C) if 1 <= |x| < 2
* { 0 otherwise
*
* Various well-known cubic splines can be generated, and the authors select (1/3, 1/3) as their
* favorite overall spline - this is now commonly known as the Mitchell filter, and is the
* source of the specific weights below.
*
* This is GLSL, so the matrix is column-major (transposed from standard matrix notation).
*/
fragBuilder->codeAppend("half4x4 kMitchellCoefficients = half4x4("
" 1.0 / 18.0, 16.0 / 18.0, 1.0 / 18.0, 0.0 / 18.0,"
"-9.0 / 18.0, 0.0 / 18.0, 9.0 / 18.0, 0.0 / 18.0,"
"15.0 / 18.0, -36.0 / 18.0, 27.0 / 18.0, -6.0 / 18.0,"
"-7.0 / 18.0, 21.0 / 18.0, -21.0 / 18.0, 7.0 / 18.0);");
fragBuilder->codeAppendf("float2 coord = %s - %s * float2(0.5);", coords2D.c_str(), imgInc);
// We unnormalize the coord in order to determine our fractional offset (f) within the texel
// We then snap coord to a texel center and renormalize. The snap prevents cases where the
// starting coords are near a texel boundary and accumulations of imgInc would cause us to skip/
// double hit a texel.
fragBuilder->codeAppendf("coord /= %s;", imgInc);
fragBuilder->codeAppend("float2 f = fract(coord);");
fragBuilder->codeAppendf("coord = (coord - f + float2(0.5)) * %s;", imgInc);
fragBuilder->codeAppend("half4 wx = kMitchellCoefficients * half4(1.0, f.x, f.x * f.x, f.x * f.x * f.x);");
fragBuilder->codeAppend("half4 wy = kMitchellCoefficients * half4(1.0, f.y, f.y * f.y, f.y * f.y * f.y);");
fragBuilder->codeAppend("half4 rowColors[4];");
for (int y = 0; y < 4; ++y) {
for (int x = 0; x < 4; ++x) {
SkString coord;
coord.printf("coord + %s * float2(%d, %d)", imgInc, x - 1, y - 1);
SkString sampleVar;
sampleVar.printf("rowColors[%d]", x);
fDomain.sampleTexture(fragBuilder,
args.fUniformHandler,
args.fShaderCaps,
bicubicEffect.domain(),
sampleVar.c_str(),
coord,
args.fTexSamplers[0]);
}
fragBuilder->codeAppendf(
"half4 s%d = wx.x * rowColors[0] + wx.y * rowColors[1] + wx.z * rowColors[2] + wx.w * rowColors[3];",
y);
}
SkString bicubicColor("(wy.x * s0 + wy.y * s1 + wy.z * s2 + wy.w * s3)");
fragBuilder->codeAppendf("%s = %s * %s;", args.fOutputColor, bicubicColor.c_str(),
args.fInputColor);
}
void GrGLBicubicEffect::onSetData(const GrGLSLProgramDataManager& pdman,
const GrFragmentProcessor& processor) {
const GrBicubicEffect& bicubicEffect = processor.cast<GrBicubicEffect>();
GrTextureProxy* proxy = processor.textureSampler(0).proxy();
GrTexture* texture = proxy->peekTexture();
float imageIncrement[2];
imageIncrement[0] = 1.0f / texture->width();
imageIncrement[1] = 1.0f / texture->height();
pdman.set2fv(fImageIncrementUni, 1, imageIncrement);
fDomain.setData(pdman, bicubicEffect.domain(), proxy,
processor.textureSampler(0).samplerState());
}
GrBicubicEffect::GrBicubicEffect(sk_sp<GrTextureProxy> proxy,
const SkMatrix& matrix,
const GrSamplerState::WrapMode wrapModes[2],
GrTextureDomain::Mode modeX, GrTextureDomain::Mode modeY)
: INHERITED{kGrBicubicEffect_ClassID,
ModulateForSamplerOptFlags(proxy->config(),
GrTextureDomain::IsDecalSampled(wrapModes, modeX,modeY))}
, fCoordTransform(matrix, proxy.get())
, fDomain(proxy.get(),
GrTextureDomain::MakeTexelDomain(
SkIRect::MakeWH(proxy->width(), proxy->height()), modeX, modeY),
modeX, modeY)
, fTextureSampler(std::move(proxy),
GrSamplerState(wrapModes, GrSamplerState::Filter::kNearest)) {
this->addCoordTransform(&fCoordTransform);
this->setTextureSamplerCnt(1);
}
GrBicubicEffect::GrBicubicEffect(sk_sp<GrTextureProxy> proxy,
const SkMatrix& matrix,
const SkRect& domain)
: INHERITED(kGrBicubicEffect_ClassID, ModulateForClampedSamplerOptFlags(proxy->config()))
, fCoordTransform(matrix, proxy.get())
, fDomain(proxy.get(), domain, GrTextureDomain::kClamp_Mode, GrTextureDomain::kClamp_Mode)
, fTextureSampler(std::move(proxy)) {
// Make sure the sampler's ctor uses the clamp wrap mode
SkASSERT(fTextureSampler.samplerState().wrapModeX() == GrSamplerState::WrapMode::kClamp &&
fTextureSampler.samplerState().wrapModeY() == GrSamplerState::WrapMode::kClamp);
this->addCoordTransform(&fCoordTransform);
this->setTextureSamplerCnt(1);
}
GrBicubicEffect::GrBicubicEffect(const GrBicubicEffect& that)
: INHERITED(kGrBicubicEffect_ClassID, that.optimizationFlags())
, fCoordTransform(that.fCoordTransform)
, fDomain(that.fDomain)
, fTextureSampler(that.fTextureSampler) {
this->addCoordTransform(&fCoordTransform);
this->setTextureSamplerCnt(1);
}
void GrBicubicEffect::onGetGLSLProcessorKey(const GrShaderCaps& caps,
GrProcessorKeyBuilder* b) const {
GrGLBicubicEffect::GenKey(*this, caps, b);
}
GrGLSLFragmentProcessor* GrBicubicEffect::onCreateGLSLInstance() const {
return new GrGLBicubicEffect;
}
bool GrBicubicEffect::onIsEqual(const GrFragmentProcessor& sBase) const {
const GrBicubicEffect& s = sBase.cast<GrBicubicEffect>();
return fDomain == s.fDomain;
}
GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrBicubicEffect);
#if GR_TEST_UTILS
std::unique_ptr<GrFragmentProcessor> GrBicubicEffect::TestCreate(GrProcessorTestData* d) {
int texIdx = d->fRandom->nextBool() ? GrProcessorUnitTest::kSkiaPMTextureIdx
: GrProcessorUnitTest::kAlphaTextureIdx;
static const GrSamplerState::WrapMode kClampClamp[] = {GrSamplerState::WrapMode::kClamp,
GrSamplerState::WrapMode::kClamp};
return GrBicubicEffect::Make(d->textureProxy(texIdx), SkMatrix::I(), kClampClamp);
}
#endif
//////////////////////////////////////////////////////////////////////////////
bool GrBicubicEffect::ShouldUseBicubic(const SkMatrix& matrix, GrSamplerState::Filter* filterMode) {
if (matrix.isIdentity()) {
*filterMode = GrSamplerState::Filter::kNearest;
return false;
}
SkScalar scales[2];
if (!matrix.getMinMaxScales(scales) || scales[0] < SK_Scalar1) {
// Bicubic doesn't handle arbitrary minimization well, as src texels can be skipped
// entirely,
*filterMode = GrSamplerState::Filter::kMipMap;
return false;
}
// At this point if scales[1] == SK_Scalar1 then the matrix doesn't do any scaling.
if (scales[1] == SK_Scalar1) {
if (matrix.rectStaysRect() && SkScalarIsInt(matrix.getTranslateX()) &&
SkScalarIsInt(matrix.getTranslateY())) {
*filterMode = GrSamplerState::Filter::kNearest;
} else {
// Use bilerp to handle rotation or fractional translation.
*filterMode = GrSamplerState::Filter::kBilerp;
}
return false;
}
// When we use the bicubic filtering effect each sample is read from the texture using
// nearest neighbor sampling.
*filterMode = GrSamplerState::Filter::kNearest;
return true;
}