michael@0: /* michael@0: * Copyright 2013 Google Inc. michael@0: * michael@0: * Use of this source code is governed by a BSD-style license that can be michael@0: * found in the LICENSE file. michael@0: */ michael@0: michael@0: #include "GrDistanceFieldTextureEffect.h" michael@0: #include "gl/GrGLEffect.h" michael@0: #include "gl/GrGLSL.h" michael@0: #include "gl/GrGLTexture.h" michael@0: #include "gl/GrGLVertexEffect.h" michael@0: #include "GrTBackendEffectFactory.h" michael@0: #include "GrTexture.h" michael@0: michael@0: // The distance field is constructed as unsigned char values, so that the zero value is at 128, michael@0: // and the range is [-4, 4 - 1/255). Hence our multiplier is 8 - 1/32 and zero threshold is 128/255. michael@0: #define MULTIPLIER "7.96875" michael@0: #define THRESHOLD "0.50196078431" michael@0: michael@0: class GrGLDistanceFieldTextureEffect : public GrGLVertexEffect { michael@0: public: michael@0: GrGLDistanceFieldTextureEffect(const GrBackendEffectFactory& factory, michael@0: const GrDrawEffect& drawEffect) michael@0: : INHERITED (factory) michael@0: , fTextureSize(SkSize::Make(-1.f,-1.f)) {} michael@0: michael@0: virtual void emitCode(GrGLFullShaderBuilder* builder, michael@0: const GrDrawEffect& drawEffect, michael@0: EffectKey key, michael@0: const char* outputColor, michael@0: const char* inputColor, michael@0: const TransformedCoordsArray&, michael@0: const TextureSamplerArray& samplers) SK_OVERRIDE { michael@0: SkASSERT(1 == drawEffect.castEffect().numVertexAttribs()); michael@0: michael@0: SkAssertResult(builder->enableFeature(GrGLShaderBuilder::kStandardDerivatives_GLSLFeature)); michael@0: michael@0: SkString fsCoordName; michael@0: const char* vsCoordName; michael@0: const char* fsCoordNamePtr; michael@0: builder->addVarying(kVec2f_GrSLType, "textureCoords", &vsCoordName, &fsCoordNamePtr); michael@0: fsCoordName = fsCoordNamePtr; michael@0: michael@0: const char* attrName0 = michael@0: builder->getEffectAttributeName(drawEffect.getVertexAttribIndices()[0])->c_str(); michael@0: builder->vsCodeAppendf("\t%s = %s;\n", vsCoordName, attrName0); michael@0: michael@0: const char* textureSizeUniName = NULL; michael@0: fTextureSizeUni = builder->addUniform(GrGLShaderBuilder::kFragment_Visibility, michael@0: kVec2f_GrSLType, "TextureSize", michael@0: &textureSizeUniName); michael@0: michael@0: builder->fsCodeAppend("\tvec4 texColor = "); michael@0: builder->fsAppendTextureLookup(samplers[0], michael@0: fsCoordName.c_str(), michael@0: kVec2f_GrSLType); michael@0: builder->fsCodeAppend(";\n"); michael@0: builder->fsCodeAppend("\tfloat distance = " MULTIPLIER "*(texColor.r - " THRESHOLD ");\n"); michael@0: michael@0: // we adjust for the effect of the transformation on the distance by using michael@0: // the length of the gradient of the texture coordinates. We use st coordinates michael@0: // to ensure we're mapping 1:1 from texel space to pixel space. michael@0: builder->fsCodeAppendf("\tvec2 st = %s*%s;\n", fsCoordName.c_str(), textureSizeUniName); michael@0: builder->fsCodeAppend("\tvec2 Jdx = dFdx(st);\n"); michael@0: builder->fsCodeAppend("\tvec2 Jdy = dFdy(st);\n"); michael@0: builder->fsCodeAppend("\tvec2 st_grad = normalize(st);\n"); michael@0: builder->fsCodeAppend("\tvec2 grad = vec2(st_grad.x*Jdx.x + st_grad.y*Jdy.x,\n"); michael@0: builder->fsCodeAppend("\t st_grad.x*Jdx.y + st_grad.y*Jdy.y);\n"); michael@0: michael@0: // this gives us a smooth step across approximately one fragment michael@0: // (assuming a radius of the diagonal of the fragment, hence a factor of sqrt(2)/2) michael@0: builder->fsCodeAppend("\tfloat afwidth = 0.7071*length(grad);\n"); michael@0: builder->fsCodeAppend("\tfloat val = smoothstep(-afwidth, afwidth, distance);\n"); michael@0: michael@0: builder->fsCodeAppendf("\t%s = %s;\n", outputColor, michael@0: (GrGLSLExpr4(inputColor) * GrGLSLExpr1("val")).c_str()); michael@0: } michael@0: michael@0: virtual void setData(const GrGLUniformManager& uman, michael@0: const GrDrawEffect& drawEffect) SK_OVERRIDE { michael@0: SkASSERT(fTextureSizeUni.isValid()); michael@0: const GrDistanceFieldTextureEffect& distanceFieldEffect = michael@0: drawEffect.castEffect(); michael@0: if (distanceFieldEffect.getSize().width() != fTextureSize.width() || michael@0: distanceFieldEffect.getSize().height() != fTextureSize.height()) { michael@0: fTextureSize = distanceFieldEffect.getSize(); michael@0: uman.set2f(fTextureSizeUni, michael@0: distanceFieldEffect.getSize().width(), michael@0: distanceFieldEffect.getSize().height()); michael@0: } michael@0: } michael@0: michael@0: private: michael@0: GrGLUniformManager::UniformHandle fTextureSizeUni; michael@0: SkSize fTextureSize; michael@0: michael@0: typedef GrGLVertexEffect INHERITED; michael@0: }; michael@0: michael@0: /////////////////////////////////////////////////////////////////////////////// michael@0: michael@0: GrDistanceFieldTextureEffect::GrDistanceFieldTextureEffect(GrTexture* texture, michael@0: const GrTextureParams& params, michael@0: const SkISize& size) michael@0: : fTextureAccess(texture, params) michael@0: , fSize(SkSize::Make(SkIntToScalar(size.width()), SkIntToScalar(size.height()))) { michael@0: this->addTextureAccess(&fTextureAccess); michael@0: this->addVertexAttrib(kVec2f_GrSLType); michael@0: } michael@0: michael@0: bool GrDistanceFieldTextureEffect::onIsEqual(const GrEffect& other) const { michael@0: const GrDistanceFieldTextureEffect& cte = CastEffect(other); michael@0: return fTextureAccess == cte.fTextureAccess; michael@0: } michael@0: michael@0: void GrDistanceFieldTextureEffect::getConstantColorComponents(GrColor* color, michael@0: uint32_t* validFlags) const { michael@0: if ((*validFlags & kA_GrColorComponentFlag) && 0xFF == GrColorUnpackA(*color) && michael@0: GrPixelConfigIsOpaque(this->texture(0)->config())) { michael@0: *validFlags = kA_GrColorComponentFlag; michael@0: } else { michael@0: *validFlags = 0; michael@0: } michael@0: } michael@0: michael@0: const GrBackendEffectFactory& GrDistanceFieldTextureEffect::getFactory() const { michael@0: return GrTBackendEffectFactory::getInstance(); michael@0: } michael@0: michael@0: /////////////////////////////////////////////////////////////////////////////// michael@0: michael@0: GR_DEFINE_EFFECT_TEST(GrDistanceFieldTextureEffect); michael@0: michael@0: GrEffectRef* GrDistanceFieldTextureEffect::TestCreate(SkRandom* random, michael@0: GrContext*, michael@0: const GrDrawTargetCaps&, michael@0: GrTexture* textures[]) { michael@0: int texIdx = random->nextBool() ? GrEffectUnitTest::kSkiaPMTextureIdx : michael@0: GrEffectUnitTest::kAlphaTextureIdx; michael@0: static const SkShader::TileMode kTileModes[] = { michael@0: SkShader::kClamp_TileMode, michael@0: SkShader::kRepeat_TileMode, michael@0: SkShader::kMirror_TileMode, michael@0: }; michael@0: SkShader::TileMode tileModes[] = { michael@0: kTileModes[random->nextULessThan(SK_ARRAY_COUNT(kTileModes))], michael@0: kTileModes[random->nextULessThan(SK_ARRAY_COUNT(kTileModes))], michael@0: }; michael@0: GrTextureParams params(tileModes, random->nextBool() ? GrTextureParams::kBilerp_FilterMode : michael@0: GrTextureParams::kNone_FilterMode); michael@0: SkISize size = SkISize::Make(1024, 2048); michael@0: michael@0: return GrDistanceFieldTextureEffect::Create(textures[texIdx], params, size); michael@0: }