1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/gfx/skia/trunk/src/gpu/effects/GrDistanceFieldTextureEffect.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,155 @@
1.4 +/*
1.5 + * Copyright 2013 Google Inc.
1.6 + *
1.7 + * Use of this source code is governed by a BSD-style license that can be
1.8 + * found in the LICENSE file.
1.9 + */
1.10 +
1.11 +#include "GrDistanceFieldTextureEffect.h"
1.12 +#include "gl/GrGLEffect.h"
1.13 +#include "gl/GrGLSL.h"
1.14 +#include "gl/GrGLTexture.h"
1.15 +#include "gl/GrGLVertexEffect.h"
1.16 +#include "GrTBackendEffectFactory.h"
1.17 +#include "GrTexture.h"
1.18 +
1.19 +// The distance field is constructed as unsigned char values, so that the zero value is at 128,
1.20 +// and the range is [-4, 4 - 1/255). Hence our multiplier is 8 - 1/32 and zero threshold is 128/255.
1.21 +#define MULTIPLIER "7.96875"
1.22 +#define THRESHOLD "0.50196078431"
1.23 +
1.24 +class GrGLDistanceFieldTextureEffect : public GrGLVertexEffect {
1.25 +public:
1.26 + GrGLDistanceFieldTextureEffect(const GrBackendEffectFactory& factory,
1.27 + const GrDrawEffect& drawEffect)
1.28 + : INHERITED (factory)
1.29 + , fTextureSize(SkSize::Make(-1.f,-1.f)) {}
1.30 +
1.31 + virtual void emitCode(GrGLFullShaderBuilder* builder,
1.32 + const GrDrawEffect& drawEffect,
1.33 + EffectKey key,
1.34 + const char* outputColor,
1.35 + const char* inputColor,
1.36 + const TransformedCoordsArray&,
1.37 + const TextureSamplerArray& samplers) SK_OVERRIDE {
1.38 + SkASSERT(1 == drawEffect.castEffect<GrDistanceFieldTextureEffect>().numVertexAttribs());
1.39 +
1.40 + SkAssertResult(builder->enableFeature(GrGLShaderBuilder::kStandardDerivatives_GLSLFeature));
1.41 +
1.42 + SkString fsCoordName;
1.43 + const char* vsCoordName;
1.44 + const char* fsCoordNamePtr;
1.45 + builder->addVarying(kVec2f_GrSLType, "textureCoords", &vsCoordName, &fsCoordNamePtr);
1.46 + fsCoordName = fsCoordNamePtr;
1.47 +
1.48 + const char* attrName0 =
1.49 + builder->getEffectAttributeName(drawEffect.getVertexAttribIndices()[0])->c_str();
1.50 + builder->vsCodeAppendf("\t%s = %s;\n", vsCoordName, attrName0);
1.51 +
1.52 + const char* textureSizeUniName = NULL;
1.53 + fTextureSizeUni = builder->addUniform(GrGLShaderBuilder::kFragment_Visibility,
1.54 + kVec2f_GrSLType, "TextureSize",
1.55 + &textureSizeUniName);
1.56 +
1.57 + builder->fsCodeAppend("\tvec4 texColor = ");
1.58 + builder->fsAppendTextureLookup(samplers[0],
1.59 + fsCoordName.c_str(),
1.60 + kVec2f_GrSLType);
1.61 + builder->fsCodeAppend(";\n");
1.62 + builder->fsCodeAppend("\tfloat distance = " MULTIPLIER "*(texColor.r - " THRESHOLD ");\n");
1.63 +
1.64 + // we adjust for the effect of the transformation on the distance by using
1.65 + // the length of the gradient of the texture coordinates. We use st coordinates
1.66 + // to ensure we're mapping 1:1 from texel space to pixel space.
1.67 + builder->fsCodeAppendf("\tvec2 st = %s*%s;\n", fsCoordName.c_str(), textureSizeUniName);
1.68 + builder->fsCodeAppend("\tvec2 Jdx = dFdx(st);\n");
1.69 + builder->fsCodeAppend("\tvec2 Jdy = dFdy(st);\n");
1.70 + builder->fsCodeAppend("\tvec2 st_grad = normalize(st);\n");
1.71 + builder->fsCodeAppend("\tvec2 grad = vec2(st_grad.x*Jdx.x + st_grad.y*Jdy.x,\n");
1.72 + builder->fsCodeAppend("\t st_grad.x*Jdx.y + st_grad.y*Jdy.y);\n");
1.73 +
1.74 + // this gives us a smooth step across approximately one fragment
1.75 + // (assuming a radius of the diagonal of the fragment, hence a factor of sqrt(2)/2)
1.76 + builder->fsCodeAppend("\tfloat afwidth = 0.7071*length(grad);\n");
1.77 + builder->fsCodeAppend("\tfloat val = smoothstep(-afwidth, afwidth, distance);\n");
1.78 +
1.79 + builder->fsCodeAppendf("\t%s = %s;\n", outputColor,
1.80 + (GrGLSLExpr4(inputColor) * GrGLSLExpr1("val")).c_str());
1.81 + }
1.82 +
1.83 + virtual void setData(const GrGLUniformManager& uman,
1.84 + const GrDrawEffect& drawEffect) SK_OVERRIDE {
1.85 + SkASSERT(fTextureSizeUni.isValid());
1.86 + const GrDistanceFieldTextureEffect& distanceFieldEffect =
1.87 + drawEffect.castEffect<GrDistanceFieldTextureEffect>();
1.88 + if (distanceFieldEffect.getSize().width() != fTextureSize.width() ||
1.89 + distanceFieldEffect.getSize().height() != fTextureSize.height()) {
1.90 + fTextureSize = distanceFieldEffect.getSize();
1.91 + uman.set2f(fTextureSizeUni,
1.92 + distanceFieldEffect.getSize().width(),
1.93 + distanceFieldEffect.getSize().height());
1.94 + }
1.95 + }
1.96 +
1.97 +private:
1.98 + GrGLUniformManager::UniformHandle fTextureSizeUni;
1.99 + SkSize fTextureSize;
1.100 +
1.101 + typedef GrGLVertexEffect INHERITED;
1.102 +};
1.103 +
1.104 +///////////////////////////////////////////////////////////////////////////////
1.105 +
1.106 +GrDistanceFieldTextureEffect::GrDistanceFieldTextureEffect(GrTexture* texture,
1.107 + const GrTextureParams& params,
1.108 + const SkISize& size)
1.109 + : fTextureAccess(texture, params)
1.110 + , fSize(SkSize::Make(SkIntToScalar(size.width()), SkIntToScalar(size.height()))) {
1.111 + this->addTextureAccess(&fTextureAccess);
1.112 + this->addVertexAttrib(kVec2f_GrSLType);
1.113 +}
1.114 +
1.115 +bool GrDistanceFieldTextureEffect::onIsEqual(const GrEffect& other) const {
1.116 + const GrDistanceFieldTextureEffect& cte = CastEffect<GrDistanceFieldTextureEffect>(other);
1.117 + return fTextureAccess == cte.fTextureAccess;
1.118 +}
1.119 +
1.120 +void GrDistanceFieldTextureEffect::getConstantColorComponents(GrColor* color,
1.121 + uint32_t* validFlags) const {
1.122 + if ((*validFlags & kA_GrColorComponentFlag) && 0xFF == GrColorUnpackA(*color) &&
1.123 + GrPixelConfigIsOpaque(this->texture(0)->config())) {
1.124 + *validFlags = kA_GrColorComponentFlag;
1.125 + } else {
1.126 + *validFlags = 0;
1.127 + }
1.128 +}
1.129 +
1.130 +const GrBackendEffectFactory& GrDistanceFieldTextureEffect::getFactory() const {
1.131 + return GrTBackendEffectFactory<GrDistanceFieldTextureEffect>::getInstance();
1.132 +}
1.133 +
1.134 +///////////////////////////////////////////////////////////////////////////////
1.135 +
1.136 +GR_DEFINE_EFFECT_TEST(GrDistanceFieldTextureEffect);
1.137 +
1.138 +GrEffectRef* GrDistanceFieldTextureEffect::TestCreate(SkRandom* random,
1.139 + GrContext*,
1.140 + const GrDrawTargetCaps&,
1.141 + GrTexture* textures[]) {
1.142 + int texIdx = random->nextBool() ? GrEffectUnitTest::kSkiaPMTextureIdx :
1.143 + GrEffectUnitTest::kAlphaTextureIdx;
1.144 + static const SkShader::TileMode kTileModes[] = {
1.145 + SkShader::kClamp_TileMode,
1.146 + SkShader::kRepeat_TileMode,
1.147 + SkShader::kMirror_TileMode,
1.148 + };
1.149 + SkShader::TileMode tileModes[] = {
1.150 + kTileModes[random->nextULessThan(SK_ARRAY_COUNT(kTileModes))],
1.151 + kTileModes[random->nextULessThan(SK_ARRAY_COUNT(kTileModes))],
1.152 + };
1.153 + GrTextureParams params(tileModes, random->nextBool() ? GrTextureParams::kBilerp_FilterMode :
1.154 + GrTextureParams::kNone_FilterMode);
1.155 + SkISize size = SkISize::Make(1024, 2048);
1.156 +
1.157 + return GrDistanceFieldTextureEffect::Create(textures[texIdx], params, size);
1.158 +}
