blob: 1fdd3b781ff93c2c8d5b660b3700547535779ad6 [file] [log] [blame]
/*
* Copyright 2015 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "effects/GrCustomXfermode.h"
#include "effects/GrCustomXfermodePriv.h"
#include "GrCoordTransform.h"
#include "GrContext.h"
#include "GrFragmentProcessor.h"
#include "GrInvariantOutput.h"
#include "GrProcessor.h"
#include "GrTexture.h"
#include "GrTextureAccess.h"
#include "SkXfermode.h"
#include "gl/GrGLCaps.h"
#include "gl/GrGLGpu.h"
#include "gl/GrGLProcessor.h"
#include "gl/GrGLProgramDataManager.h"
#include "gl/builders/GrGLProgramBuilder.h"
bool GrCustomXfermode::IsSupportedMode(SkXfermode::Mode mode) {
return mode > SkXfermode::kLastCoeffMode && mode <= SkXfermode::kLastMode;
}
///////////////////////////////////////////////////////////////////////////////
// Static helpers
///////////////////////////////////////////////////////////////////////////////
static GrBlendEquation hw_blend_equation(SkXfermode::Mode mode) {
enum { kOffset = kOverlay_GrBlendEquation - SkXfermode::kOverlay_Mode };
return static_cast<GrBlendEquation>(mode + kOffset);
GR_STATIC_ASSERT(kOverlay_GrBlendEquation == SkXfermode::kOverlay_Mode + kOffset);
GR_STATIC_ASSERT(kDarken_GrBlendEquation == SkXfermode::kDarken_Mode + kOffset);
GR_STATIC_ASSERT(kLighten_GrBlendEquation == SkXfermode::kLighten_Mode + kOffset);
GR_STATIC_ASSERT(kColorDodge_GrBlendEquation == SkXfermode::kColorDodge_Mode + kOffset);
GR_STATIC_ASSERT(kColorBurn_GrBlendEquation == SkXfermode::kColorBurn_Mode + kOffset);
GR_STATIC_ASSERT(kHardLight_GrBlendEquation == SkXfermode::kHardLight_Mode + kOffset);
GR_STATIC_ASSERT(kSoftLight_GrBlendEquation == SkXfermode::kSoftLight_Mode + kOffset);
GR_STATIC_ASSERT(kDifference_GrBlendEquation == SkXfermode::kDifference_Mode + kOffset);
GR_STATIC_ASSERT(kExclusion_GrBlendEquation == SkXfermode::kExclusion_Mode + kOffset);
GR_STATIC_ASSERT(kMultiply_GrBlendEquation == SkXfermode::kMultiply_Mode + kOffset);
GR_STATIC_ASSERT(kHSLHue_GrBlendEquation == SkXfermode::kHue_Mode + kOffset);
GR_STATIC_ASSERT(kHSLSaturation_GrBlendEquation == SkXfermode::kSaturation_Mode + kOffset);
GR_STATIC_ASSERT(kHSLColor_GrBlendEquation == SkXfermode::kColor_Mode + kOffset);
GR_STATIC_ASSERT(kHSLLuminosity_GrBlendEquation == SkXfermode::kLuminosity_Mode + kOffset);
GR_STATIC_ASSERT(kGrBlendEquationCnt == SkXfermode::kLastMode + 1 + kOffset);
}
static void hard_light(GrGLFragmentBuilder* fsBuilder,
const char* final,
const char* src,
const char* dst) {
static const char kComponents[] = {'r', 'g', 'b'};
for (size_t i = 0; i < SK_ARRAY_COUNT(kComponents); ++i) {
char component = kComponents[i];
fsBuilder->codeAppendf("if (2.0 * %s.%c <= %s.a) {", src, component, src);
fsBuilder->codeAppendf("%s.%c = 2.0 * %s.%c * %s.%c;",
final, component, src, component, dst, component);
fsBuilder->codeAppend("} else {");
fsBuilder->codeAppendf("%s.%c = %s.a * %s.a - 2.0 * (%s.a - %s.%c) * (%s.a - %s.%c);",
final, component, src, dst, dst, dst, component, src, src,
component);
fsBuilder->codeAppend("}");
}
fsBuilder->codeAppendf("%s.rgb += %s.rgb * (1.0 - %s.a) + %s.rgb * (1.0 - %s.a);",
final, src, dst, dst, src);
}
// Does one component of color-dodge
static void color_dodge_component(GrGLFragmentBuilder* fsBuilder,
const char* final,
const char* src,
const char* dst,
const char component) {
fsBuilder->codeAppendf("if (0.0 == %s.%c) {", dst, component);
fsBuilder->codeAppendf("%s.%c = %s.%c * (1.0 - %s.a);",
final, component, src, component, dst);
fsBuilder->codeAppend("} else {");
fsBuilder->codeAppendf("float d = %s.a - %s.%c;", src, src, component);
fsBuilder->codeAppend("if (0.0 == d) {");
fsBuilder->codeAppendf("%s.%c = %s.a * %s.a + %s.%c * (1.0 - %s.a) + %s.%c * (1.0 - %s.a);",
final, component, src, dst, src, component, dst, dst, component,
src);
fsBuilder->codeAppend("} else {");
fsBuilder->codeAppendf("d = min(%s.a, %s.%c * %s.a / d);",
dst, dst, component, src);
fsBuilder->codeAppendf("%s.%c = d * %s.a + %s.%c * (1.0 - %s.a) + %s.%c * (1.0 - %s.a);",
final, component, src, src, component, dst, dst, component, src);
fsBuilder->codeAppend("}");
fsBuilder->codeAppend("}");
}
// Does one component of color-burn
static void color_burn_component(GrGLFragmentBuilder* fsBuilder,
const char* final,
const char* src,
const char* dst,
const char component) {
fsBuilder->codeAppendf("if (%s.a == %s.%c) {", dst, dst, component);
fsBuilder->codeAppendf("%s.%c = %s.a * %s.a + %s.%c * (1.0 - %s.a) + %s.%c * (1.0 - %s.a);",
final, component, src, dst, src, component, dst, dst, component,
src);
fsBuilder->codeAppendf("} else if (0.0 == %s.%c) {", src, component);
fsBuilder->codeAppendf("%s.%c = %s.%c * (1.0 - %s.a);",
final, component, dst, component, src);
fsBuilder->codeAppend("} else {");
fsBuilder->codeAppendf("float d = max(0.0, %s.a - (%s.a - %s.%c) * %s.a / %s.%c);",
dst, dst, dst, component, src, src, component);
fsBuilder->codeAppendf("%s.%c = %s.a * d + %s.%c * (1.0 - %s.a) + %s.%c * (1.0 - %s.a);",
final, component, src, src, component, dst, dst, component, src);
fsBuilder->codeAppend("}");
}
// Does one component of soft-light. Caller should have already checked that dst alpha > 0.
static void soft_light_component_pos_dst_alpha(GrGLFragmentBuilder* fsBuilder,
const char* final,
const char* src,
const char* dst,
const char component) {
// if (2S < Sa)
fsBuilder->codeAppendf("if (2.0 * %s.%c <= %s.a) {", src, component, src);
// (D^2 (Sa-2 S))/Da+(1-Da) S+D (-Sa+2 S+1)
fsBuilder->codeAppendf("%s.%c = (%s.%c*%s.%c*(%s.a - 2.0*%s.%c)) / %s.a +"
"(1.0 - %s.a) * %s.%c + %s.%c*(-%s.a + 2.0*%s.%c + 1.0);",
final, component, dst, component, dst, component, src, src,
component, dst, dst, src, component, dst, component, src, src,
component);
// else if (4D < Da)
fsBuilder->codeAppendf("} else if (4.0 * %s.%c <= %s.a) {",
dst, component, dst);
fsBuilder->codeAppendf("float DSqd = %s.%c * %s.%c;",
dst, component, dst, component);
fsBuilder->codeAppendf("float DCub = DSqd * %s.%c;", dst, component);
fsBuilder->codeAppendf("float DaSqd = %s.a * %s.a;", dst, dst);
fsBuilder->codeAppendf("float DaCub = DaSqd * %s.a;", dst);
// (Da^3 (-S)+Da^2 (S-D (3 Sa-6 S-1))+12 Da D^2 (Sa-2 S)-16 D^3 (Sa-2 S))/Da^2
fsBuilder->codeAppendf("%s.%c ="
"(-DaCub*%s.%c + DaSqd*(%s.%c - %s.%c * (3.0*%s.a - 6.0*%s.%c - 1.0)) +"
" 12.0*%s.a*DSqd*(%s.a - 2.0*%s.%c) - 16.0*DCub * (%s.a - 2.0*%s.%c)) /"
"DaSqd;",
final, component, src, component, src, component, dst, component,
src, src, component, dst, src, src, component, src, src,
component);
fsBuilder->codeAppendf("} else {");
// -sqrt(Da * D) (Sa-2 S)-Da S+D (Sa-2 S+1)+S
fsBuilder->codeAppendf("%s.%c = -sqrt(%s.a*%s.%c)*(%s.a - 2.0*%s.%c) - %s.a*%s.%c +"
"%s.%c*(%s.a - 2.0*%s.%c + 1.0) + %s.%c;",
final, component, dst, dst, component, src, src, component, dst,
src, component, dst, component, src, src, component, src,
component);
fsBuilder->codeAppendf("}");
}
// Adds a function that takes two colors and an alpha as input. It produces a color with the
// hue and saturation of the first color, the luminosity of the second color, and the input
// alpha. It has this signature:
// vec3 set_luminance(vec3 hueSatColor, float alpha, vec3 lumColor).
static void add_lum_function(GrGLFragmentBuilder* fsBuilder, SkString* setLumFunction) {
// Emit a helper that gets the luminance of a color.
SkString getFunction;
GrGLShaderVar getLumArgs[] = {
GrGLShaderVar("color", kVec3f_GrSLType),
};
SkString getLumBody("return dot(vec3(0.3, 0.59, 0.11), color);");
fsBuilder->emitFunction(kFloat_GrSLType,
"luminance",
SK_ARRAY_COUNT(getLumArgs), getLumArgs,
getLumBody.c_str(),
&getFunction);
// Emit the set luminance function.
GrGLShaderVar setLumArgs[] = {
GrGLShaderVar("hueSat", kVec3f_GrSLType),
GrGLShaderVar("alpha", kFloat_GrSLType),
GrGLShaderVar("lumColor", kVec3f_GrSLType),
};
SkString setLumBody;
setLumBody.printf("float diff = %s(lumColor - hueSat);", getFunction.c_str());
setLumBody.append("vec3 outColor = hueSat + diff;");
setLumBody.appendf("float outLum = %s(outColor);", getFunction.c_str());
setLumBody.append("float minComp = min(min(outColor.r, outColor.g), outColor.b);"
"float maxComp = max(max(outColor.r, outColor.g), outColor.b);"
"if (minComp < 0.0 && outLum != minComp) {"
"outColor = outLum + ((outColor - vec3(outLum, outLum, outLum)) * outLum) /"
"(outLum - minComp);"
"}"
"if (maxComp > alpha && maxComp != outLum) {"
"outColor = outLum +"
"((outColor - vec3(outLum, outLum, outLum)) * (alpha - outLum)) /"
"(maxComp - outLum);"
"}"
"return outColor;");
fsBuilder->emitFunction(kVec3f_GrSLType,
"set_luminance",
SK_ARRAY_COUNT(setLumArgs), setLumArgs,
setLumBody.c_str(),
setLumFunction);
}
// Adds a function that creates a color with the hue and luminosity of one input color and
// the saturation of another color. It will have this signature:
// float set_saturation(vec3 hueLumColor, vec3 satColor)
static void add_sat_function(GrGLFragmentBuilder* fsBuilder, SkString* setSatFunction) {
// Emit a helper that gets the saturation of a color
SkString getFunction;
GrGLShaderVar getSatArgs[] = { GrGLShaderVar("color", kVec3f_GrSLType) };
SkString getSatBody;
getSatBody.printf("return max(max(color.r, color.g), color.b) - "
"min(min(color.r, color.g), color.b);");
fsBuilder->emitFunction(kFloat_GrSLType,
"saturation",
SK_ARRAY_COUNT(getSatArgs), getSatArgs,
getSatBody.c_str(),
&getFunction);
// Emit a helper that sets the saturation given sorted input channels. This used
// to use inout params for min, mid, and max components but that seems to cause
// problems on PowerVR drivers. So instead it returns a vec3 where r, g ,b are the
// adjusted min, mid, and max inputs, respectively.
SkString helperFunction;
GrGLShaderVar helperArgs[] = {
GrGLShaderVar("minComp", kFloat_GrSLType),
GrGLShaderVar("midComp", kFloat_GrSLType),
GrGLShaderVar("maxComp", kFloat_GrSLType),
GrGLShaderVar("sat", kFloat_GrSLType),
};
static const char kHelperBody[] = "if (minComp < maxComp) {"
"vec3 result;"
"result.r = 0.0;"
"result.g = sat * (midComp - minComp) / (maxComp - minComp);"
"result.b = sat;"
"return result;"
"} else {"
"return vec3(0, 0, 0);"
"}";
fsBuilder->emitFunction(kVec3f_GrSLType,
"set_saturation_helper",
SK_ARRAY_COUNT(helperArgs), helperArgs,
kHelperBody,
&helperFunction);
GrGLShaderVar setSatArgs[] = {
GrGLShaderVar("hueLumColor", kVec3f_GrSLType),
GrGLShaderVar("satColor", kVec3f_GrSLType),
};
const char* helpFunc = helperFunction.c_str();
SkString setSatBody;
setSatBody.appendf("float sat = %s(satColor);"
"if (hueLumColor.r <= hueLumColor.g) {"
"if (hueLumColor.g <= hueLumColor.b) {"
"hueLumColor.rgb = %s(hueLumColor.r, hueLumColor.g, hueLumColor.b, sat);"
"} else if (hueLumColor.r <= hueLumColor.b) {"
"hueLumColor.rbg = %s(hueLumColor.r, hueLumColor.b, hueLumColor.g, sat);"
"} else {"
"hueLumColor.brg = %s(hueLumColor.b, hueLumColor.r, hueLumColor.g, sat);"
"}"
"} else if (hueLumColor.r <= hueLumColor.b) {"
"hueLumColor.grb = %s(hueLumColor.g, hueLumColor.r, hueLumColor.b, sat);"
"} else if (hueLumColor.g <= hueLumColor.b) {"
"hueLumColor.gbr = %s(hueLumColor.g, hueLumColor.b, hueLumColor.r, sat);"
"} else {"
"hueLumColor.bgr = %s(hueLumColor.b, hueLumColor.g, hueLumColor.r, sat);"
"}"
"return hueLumColor;",
getFunction.c_str(), helpFunc, helpFunc, helpFunc, helpFunc,
helpFunc, helpFunc);
fsBuilder->emitFunction(kVec3f_GrSLType,
"set_saturation",
SK_ARRAY_COUNT(setSatArgs), setSatArgs,
setSatBody.c_str(),
setSatFunction);
}
static void emit_custom_xfermode_code(SkXfermode::Mode mode,
GrGLFragmentBuilder* fsBuilder,
const char* outputColor,
const char* inputColor,
const char* dstColor) {
// We don't try to optimize for this case at all
if (NULL == inputColor) {
fsBuilder->codeAppendf("const vec4 ones = vec4(1);");
inputColor = "ones";
}
fsBuilder->codeAppendf("// SkXfermode::Mode: %s\n", SkXfermode::ModeName(mode));
// These all perform src-over on the alpha channel.
fsBuilder->codeAppendf("%s.a = %s.a + (1.0 - %s.a) * %s.a;",
outputColor, inputColor, inputColor, dstColor);
switch (mode) {
case SkXfermode::kOverlay_Mode:
// Overlay is Hard-Light with the src and dst reversed
hard_light(fsBuilder, outputColor, dstColor, inputColor);
break;
case SkXfermode::kDarken_Mode:
fsBuilder->codeAppendf("%s.rgb = min((1.0 - %s.a) * %s.rgb + %s.rgb, "
"(1.0 - %s.a) * %s.rgb + %s.rgb);",
outputColor,
inputColor, dstColor, inputColor,
dstColor, inputColor, dstColor);
break;
case SkXfermode::kLighten_Mode:
fsBuilder->codeAppendf("%s.rgb = max((1.0 - %s.a) * %s.rgb + %s.rgb, "
"(1.0 - %s.a) * %s.rgb + %s.rgb);",
outputColor,
inputColor, dstColor, inputColor,
dstColor, inputColor, dstColor);
break;
case SkXfermode::kColorDodge_Mode:
color_dodge_component(fsBuilder, outputColor, inputColor, dstColor, 'r');
color_dodge_component(fsBuilder, outputColor, inputColor, dstColor, 'g');
color_dodge_component(fsBuilder, outputColor, inputColor, dstColor, 'b');
break;
case SkXfermode::kColorBurn_Mode:
color_burn_component(fsBuilder, outputColor, inputColor, dstColor, 'r');
color_burn_component(fsBuilder, outputColor, inputColor, dstColor, 'g');
color_burn_component(fsBuilder, outputColor, inputColor, dstColor, 'b');
break;
case SkXfermode::kHardLight_Mode:
hard_light(fsBuilder, outputColor, inputColor, dstColor);
break;
case SkXfermode::kSoftLight_Mode:
fsBuilder->codeAppendf("if (0.0 == %s.a) {", dstColor);
fsBuilder->codeAppendf("%s.rgba = %s;", outputColor, inputColor);
fsBuilder->codeAppendf("} else {");
soft_light_component_pos_dst_alpha(fsBuilder, outputColor, inputColor, dstColor, 'r');
soft_light_component_pos_dst_alpha(fsBuilder, outputColor, inputColor, dstColor, 'g');
soft_light_component_pos_dst_alpha(fsBuilder, outputColor, inputColor, dstColor, 'b');
fsBuilder->codeAppendf("}");
break;
case SkXfermode::kDifference_Mode:
fsBuilder->codeAppendf("%s.rgb = %s.rgb + %s.rgb -"
"2.0 * min(%s.rgb * %s.a, %s.rgb * %s.a);",
outputColor, inputColor, dstColor, inputColor, dstColor,
dstColor, inputColor);
break;
case SkXfermode::kExclusion_Mode:
fsBuilder->codeAppendf("%s.rgb = %s.rgb + %s.rgb - "
"2.0 * %s.rgb * %s.rgb;",
outputColor, dstColor, inputColor, dstColor, inputColor);
break;
case SkXfermode::kMultiply_Mode:
fsBuilder->codeAppendf("%s.rgb = (1.0 - %s.a) * %s.rgb + "
"(1.0 - %s.a) * %s.rgb + "
"%s.rgb * %s.rgb;",
outputColor, inputColor, dstColor, dstColor, inputColor,
inputColor, dstColor);
break;
case SkXfermode::kHue_Mode: {
// SetLum(SetSat(S * Da, Sat(D * Sa)), Sa*Da, D*Sa) + (1 - Sa) * D + (1 - Da) * S
SkString setSat, setLum;
add_sat_function(fsBuilder, &setSat);
add_lum_function(fsBuilder, &setLum);
fsBuilder->codeAppendf("vec4 dstSrcAlpha = %s * %s.a;",
dstColor, inputColor);
fsBuilder->codeAppendf("%s.rgb = %s(%s(%s.rgb * %s.a, dstSrcAlpha.rgb),"
"dstSrcAlpha.a, dstSrcAlpha.rgb);",
outputColor, setLum.c_str(), setSat.c_str(), inputColor,
dstColor);
fsBuilder->codeAppendf("%s.rgb += (1.0 - %s.a) * %s.rgb + (1.0 - %s.a) * %s.rgb;",
outputColor, inputColor, dstColor, dstColor, inputColor);
break;
}
case SkXfermode::kSaturation_Mode: {
// SetLum(SetSat(D * Sa, Sat(S * Da)), Sa*Da, D*Sa)) + (1 - Sa) * D + (1 - Da) * S
SkString setSat, setLum;
add_sat_function(fsBuilder, &setSat);
add_lum_function(fsBuilder, &setLum);
fsBuilder->codeAppendf("vec4 dstSrcAlpha = %s * %s.a;",
dstColor, inputColor);
fsBuilder->codeAppendf("%s.rgb = %s(%s(dstSrcAlpha.rgb, %s.rgb * %s.a),"
"dstSrcAlpha.a, dstSrcAlpha.rgb);",
outputColor, setLum.c_str(), setSat.c_str(), inputColor,
dstColor);
fsBuilder->codeAppendf("%s.rgb += (1.0 - %s.a) * %s.rgb + (1.0 - %s.a) * %s.rgb;",
outputColor, inputColor, dstColor, dstColor, inputColor);
break;
}
case SkXfermode::kColor_Mode: {
// SetLum(S * Da, Sa* Da, D * Sa) + (1 - Sa) * D + (1 - Da) * S
SkString setLum;
add_lum_function(fsBuilder, &setLum);
fsBuilder->codeAppendf("vec4 srcDstAlpha = %s * %s.a;",
inputColor, dstColor);
fsBuilder->codeAppendf("%s.rgb = %s(srcDstAlpha.rgb, srcDstAlpha.a, %s.rgb * %s.a);",
outputColor, setLum.c_str(), dstColor, inputColor);
fsBuilder->codeAppendf("%s.rgb += (1.0 - %s.a) * %s.rgb + (1.0 - %s.a) * %s.rgb;",
outputColor, inputColor, dstColor, dstColor, inputColor);
break;
}
case SkXfermode::kLuminosity_Mode: {
// SetLum(D * Sa, Sa* Da, S * Da) + (1 - Sa) * D + (1 - Da) * S
SkString setLum;
add_lum_function(fsBuilder, &setLum);
fsBuilder->codeAppendf("vec4 srcDstAlpha = %s * %s.a;",
inputColor, dstColor);
fsBuilder->codeAppendf("%s.rgb = %s(%s.rgb * %s.a, srcDstAlpha.a, srcDstAlpha.rgb);",
outputColor, setLum.c_str(), dstColor, inputColor);
fsBuilder->codeAppendf("%s.rgb += (1.0 - %s.a) * %s.rgb + (1.0 - %s.a) * %s.rgb;",
outputColor, inputColor, dstColor, dstColor, inputColor);
break;
}
default:
SkFAIL("Unknown Custom Xfer mode.");
break;
}
}
///////////////////////////////////////////////////////////////////////////////
// Fragment Processor
///////////////////////////////////////////////////////////////////////////////
GrFragmentProcessor* GrCustomXfermode::CreateFP(SkXfermode::Mode mode, GrTexture* background) {
if (!GrCustomXfermode::IsSupportedMode(mode)) {
return NULL;
} else {
return SkNEW_ARGS(GrCustomXferFP, (mode, background));
}
}
///////////////////////////////////////////////////////////////////////////////
class GLCustomXferFP : public GrGLFragmentProcessor {
public:
GLCustomXferFP(const GrFragmentProcessor&) {}
~GLCustomXferFP() override {};
void emitCode(GrGLFPBuilder* builder,
const GrFragmentProcessor& fp,
const char* outputColor,
const char* inputColor,
const TransformedCoordsArray& coords,
const TextureSamplerArray& samplers) override {
SkXfermode::Mode mode = fp.cast<GrCustomXferFP>().mode();
GrGLFragmentBuilder* fsBuilder = builder->getFragmentShaderBuilder();
const char* dstColor = "bgColor";
fsBuilder->codeAppendf("vec4 %s = ", dstColor);
fsBuilder->appendTextureLookup(samplers[0], coords[0].c_str(), coords[0].getType());
fsBuilder->codeAppendf(";");
emit_custom_xfermode_code(mode, fsBuilder, outputColor, inputColor, dstColor);
}
void setData(const GrGLProgramDataManager&, const GrProcessor&) override {}
static void GenKey(const GrFragmentProcessor& proc, const GrGLSLCaps&, GrProcessorKeyBuilder* b) {
// The background may come from the dst or from a texture.
uint32_t key = proc.numTextures();
SkASSERT(key <= 1);
key |= proc.cast<GrCustomXferFP>().mode() << 1;
b->add32(key);
}
private:
typedef GrGLFragmentProcessor INHERITED;
};
///////////////////////////////////////////////////////////////////////////////
GrCustomXferFP::GrCustomXferFP(SkXfermode::Mode mode, GrTexture* background)
: fMode(mode) {
this->initClassID<GrCustomXferFP>();
SkASSERT(background);
fBackgroundTransform.reset(kLocal_GrCoordSet, background,
GrTextureParams::kNone_FilterMode);
this->addCoordTransform(&fBackgroundTransform);
fBackgroundAccess.reset(background);
this->addTextureAccess(&fBackgroundAccess);
}
void GrCustomXferFP::getGLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const {
GLCustomXferFP::GenKey(*this, caps, b);
}
GrGLFragmentProcessor* GrCustomXferFP::createGLInstance() const {
return SkNEW_ARGS(GLCustomXferFP, (*this));
}
bool GrCustomXferFP::onIsEqual(const GrFragmentProcessor& other) const {
const GrCustomXferFP& s = other.cast<GrCustomXferFP>();
return fMode == s.fMode;
}
void GrCustomXferFP::onComputeInvariantOutput(GrInvariantOutput* inout) const {
inout->setToUnknown(GrInvariantOutput::kWill_ReadInput);
}
GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrCustomXferFP);
GrFragmentProcessor* GrCustomXferFP::TestCreate(SkRandom* rand,
GrContext*,
const GrDrawTargetCaps&,
GrTexture* textures[]) {
int mode = rand->nextRangeU(SkXfermode::kLastCoeffMode + 1, SkXfermode::kLastSeparableMode);
return SkNEW_ARGS(GrCustomXferFP, (static_cast<SkXfermode::Mode>(mode), textures[0]));
}
///////////////////////////////////////////////////////////////////////////////
// Xfer Processor
///////////////////////////////////////////////////////////////////////////////
class CustomXP : public GrXferProcessor {
public:
static GrXferProcessor* Create(SkXfermode::Mode mode, const GrDeviceCoordTexture* dstCopy,
bool willReadDstColor) {
if (!GrCustomXfermode::IsSupportedMode(mode)) {
return NULL;
} else {
return SkNEW_ARGS(CustomXP, (mode, dstCopy, willReadDstColor));
}
}
~CustomXP() override {};
const char* name() const override { return "Custom Xfermode"; }
GrGLXferProcessor* createGLInstance() const override;
bool hasSecondaryOutput() const override { return false; }
SkXfermode::Mode mode() const { return fMode; }
bool hasHWBlendEquation() const { return -1 != static_cast<int>(fHWBlendEquation); }
GrBlendEquation hwBlendEquation() const {
SkASSERT(this->hasHWBlendEquation());
return fHWBlendEquation;
}
private:
CustomXP(SkXfermode::Mode mode, const GrDeviceCoordTexture* dstCopy, bool willReadDstColor);
GrXferProcessor::OptFlags onGetOptimizations(const GrProcOptInfo& colorPOI,
const GrProcOptInfo& coveragePOI,
bool doesStencilWrite,
GrColor* overrideColor,
const GrDrawTargetCaps& caps) override;
void onGetGLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const override;
bool onWillNeedXferBarrier(const GrRenderTarget* rt,
const GrDrawTargetCaps& caps,
GrXferBarrierType* outBarrierType) const override;
void onGetBlendInfo(BlendInfo*) const override;
bool onIsEqual(const GrXferProcessor& xpBase) const override;
SkXfermode::Mode fMode;
GrBlendEquation fHWBlendEquation;
typedef GrXferProcessor INHERITED;
};
///////////////////////////////////////////////////////////////////////////////
GrXPFactory* GrCustomXfermode::CreateXPFactory(SkXfermode::Mode mode) {
if (!GrCustomXfermode::IsSupportedMode(mode)) {
return NULL;
} else {
return SkNEW_ARGS(GrCustomXPFactory, (mode));
}
}
///////////////////////////////////////////////////////////////////////////////
class GLCustomXP : public GrGLXferProcessor {
public:
GLCustomXP(const GrXferProcessor&) {}
~GLCustomXP() override {}
static void GenKey(const GrXferProcessor& p, const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) {
const CustomXP& xp = p.cast<CustomXP>();
uint32_t key = xp.numTextures();
SkASSERT(key <= 1);
key |= xp.readsCoverage() << 1;
if (xp.hasHWBlendEquation()) {
SkASSERT(caps.advBlendEqInteraction() > 0); // 0 will mean !xp.hasHWBlendEquation().
key |= caps.advBlendEqInteraction() << 2;
}
if (!xp.hasHWBlendEquation() || caps.mustEnableSpecificAdvBlendEqs()) {
GR_STATIC_ASSERT(GrGLSLCaps::kLast_AdvBlendEqInteraction < 4);
key |= xp.mode() << 4;
}
b->add32(key);
}
private:
void onEmitCode(const EmitArgs& args) override {
const CustomXP& xp = args.fXP.cast<CustomXP>();
GrGLXPFragmentBuilder* fsBuilder = args.fPB->getFragmentShaderBuilder();
if (xp.hasHWBlendEquation()) {
// The blend mode will be implemented in hardware; only output the src color.
fsBuilder->enableAdvancedBlendEquationIfNeeded(xp.hwBlendEquation());
if (xp.readsCoverage()) {
// Do coverage modulation by multiplying it into the src color before blending.
// (See getOptimizations())
fsBuilder->codeAppendf("%s = %s * %s;",
args.fOutputPrimary, args.fInputCoverage, args.fInputColor);
} else {
fsBuilder->codeAppendf("%s = %s;", args.fOutputPrimary, args.fInputColor);
}
} else {
const char* dstColor = fsBuilder->dstColor();
emit_custom_xfermode_code(xp.mode(), fsBuilder, args.fOutputPrimary, args.fInputColor,
dstColor);
if (xp.readsCoverage()) {
fsBuilder->codeAppendf("%s = %s * %s + (vec4(1.0) - %s) * %s;",
args.fOutputPrimary, args.fOutputPrimary,
args.fInputCoverage, args.fInputCoverage, dstColor);
}
}
}
void onSetData(const GrGLProgramDataManager&, const GrXferProcessor&) override {}
typedef GrGLFragmentProcessor INHERITED;
};
///////////////////////////////////////////////////////////////////////////////
CustomXP::CustomXP(SkXfermode::Mode mode, const GrDeviceCoordTexture* dstCopy,
bool willReadDstColor)
: INHERITED(dstCopy, willReadDstColor),
fMode(mode),
fHWBlendEquation(static_cast<GrBlendEquation>(-1)) {
this->initClassID<CustomXP>();
}
void CustomXP::onGetGLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const {
GLCustomXP::GenKey(*this, caps, b);
}
GrGLXferProcessor* CustomXP::createGLInstance() const {
SkASSERT(this->willReadDstColor() != this->hasHWBlendEquation());
return SkNEW_ARGS(GLCustomXP, (*this));
}
bool CustomXP::onIsEqual(const GrXferProcessor& other) const {
const CustomXP& s = other.cast<CustomXP>();
return fMode == s.fMode && fHWBlendEquation == s.fHWBlendEquation;
}
GrXferProcessor::OptFlags CustomXP::onGetOptimizations(const GrProcOptInfo& colorPOI,
const GrProcOptInfo& coveragePOI,
bool doesStencilWrite,
GrColor* overrideColor,
const GrDrawTargetCaps& caps) {
/*
Most the optimizations we do here are based on tweaking alpha for coverage.
The general SVG blend equation is defined in the spec as follows:
Dca' = B(Sc, Dc) * Sa * Da + Y * Sca * (1-Da) + Z * Dca * (1-Sa)
Da' = X * Sa * Da + Y * Sa * (1-Da) + Z * Da * (1-Sa)
(Note that Sca, Dca indicate RGB vectors that are premultiplied by alpha,
and that B(Sc, Dc) is a mode-specific function that accepts non-multiplied
RGB colors.)
For every blend mode supported by this class, i.e. the "advanced" blend
modes, X=Y=Z=1 and this equation reduces to the PDF blend equation.
It can be shown that when X=Y=Z=1, these equations can modulate alpha for
coverage.
== Color ==
We substitute Y=Z=1 and define a blend() function that calculates Dca' in
terms of premultiplied alpha only:
blend(Sca, Dca, Sa, Da) = {Dca : if Sa == 0,
Sca : if Da == 0,
B(Sca/Sa, Dca/Da) * Sa * Da + Sca * (1-Da) + Dca * (1-Sa) : if Sa,Da != 0}
And for coverage modulation, we use a post blend src-over model:
Dca'' = f * blend(Sca, Dca, Sa, Da) + (1-f) * Dca
(Where f is the fractional coverage.)
Next we show that canTweakAlphaForCoverage() is true by proving the
following relationship:
blend(f*Sca, Dca, f*Sa, Da) == f * blend(Sca, Dca, Sa, Da) + (1-f) * Dca
General case (f,Sa,Da != 0):
f * blend(Sca, Dca, Sa, Da) + (1-f) * Dca
= f * (B(Sca/Sa, Dca/Da) * Sa * Da + Sca * (1-Da) + Dca * (1-Sa)) + (1-f) * Dca [Sa,Da != 0, definition of blend()]
= B(Sca/Sa, Dca/Da) * f*Sa * Da + f*Sca * (1-Da) + f*Dca * (1-Sa) + Dca - f*Dca
= B(Sca/Sa, Dca/Da) * f*Sa * Da + f*Sca - f*Sca * Da + f*Dca - f*Dca * Sa + Dca - f*Dca
= B(Sca/Sa, Dca/Da) * f*Sa * Da + f*Sca - f*Sca * Da - f*Dca * Sa + Dca
= B(Sca/Sa, Dca/Da) * f*Sa * Da + f*Sca * (1-Da) - f*Dca * Sa + Dca
= B(Sca/Sa, Dca/Da) * f*Sa * Da + f*Sca * (1-Da) + Dca * (1 - f*Sa)
= B(f*Sca/f*Sa, Dca/Da) * f*Sa * Da + f*Sca * (1-Da) + Dca * (1 - f*Sa) [f!=0]
= blend(f*Sca, Dca, f*Sa, Da) [definition of blend()]
Corner cases (Sa=0, Da=0, and f=0):
Sa=0: f * blend(Sca, Dca, Sa, Da) + (1-f) * Dca
= f * Dca + (1-f) * Dca [Sa=0, definition of blend()]
= Dca
= blend(0, Dca, 0, Da) [definition of blend()]
= blend(f*Sca, Dca, f*Sa, Da) [Sa=0]
Da=0: f * blend(Sca, Dca, Sa, Da) + (1-f) * Dca
= f * Sca + (1-f) * Dca [Da=0, definition of blend()]
= f * Sca [Da=0]
= blend(f*Sca, 0, f*Sa, 0) [definition of blend()]
= blend(f*Sca, Dca, f*Sa, Da) [Da=0]
f=0: f * blend(Sca, Dca, Sa, Da) + (1-f) * Dca
= Dca [f=0]
= blend(0, Dca, 0, Da) [definition of blend()]
= blend(f*Sca, Dca, f*Sa, Da) [f=0]
== Alpha ==
We substitute X=Y=Z=1 and define a blend() function that calculates Da':
blend(Sa, Da) = Sa * Da + Sa * (1-Da) + Da * (1-Sa)
= Sa * Da + Sa - Sa * Da + Da - Da * Sa
= Sa + Da - Sa * Da
We use the same model for coverage modulation as we did with color:
Da'' = f * blend(Sa, Da) + (1-f) * Da
And show that canTweakAlphaForCoverage() is true by proving the following
relationship:
blend(f*Sa, Da) == f * blend(Sa, Da) + (1-f) * Da
f * blend(Sa, Da) + (1-f) * Da
= f * (Sa + Da - Sa * Da) + (1-f) * Da
= f*Sa + f*Da - f*Sa * Da + Da - f*Da
= f*Sa - f*Sa * Da + Da
= f*Sa + Da - f*Sa * Da
= blend(f*Sa, Da)
*/
OptFlags flags = kNone_Opt;
if (colorPOI.allStagesMultiplyInput()) {
flags |= kCanTweakAlphaForCoverage_OptFlag;
}
if (coveragePOI.isSolidWhite()) {
flags |= kIgnoreCoverage_OptFlag;
}
if (caps.advancedBlendEquationSupport() && !coveragePOI.isFourChannelOutput()) {
// This blend mode can be implemented in hardware.
fHWBlendEquation = hw_blend_equation(fMode);
}
return flags;
}
bool CustomXP::onWillNeedXferBarrier(const GrRenderTarget* rt,
const GrDrawTargetCaps& caps,
GrXferBarrierType* outBarrierType) const {
if (this->hasHWBlendEquation() && !caps.advancedCoherentBlendEquationSupport()) {
*outBarrierType = kBlend_GrXferBarrierType;
return true;
}
return false;
}
void CustomXP::onGetBlendInfo(BlendInfo* blendInfo) const {
if (this->hasHWBlendEquation()) {
blendInfo->fEquation = this->hwBlendEquation();
}
}
///////////////////////////////////////////////////////////////////////////////
GrCustomXPFactory::GrCustomXPFactory(SkXfermode::Mode mode)
: fMode(mode) {
this->initClassID<GrCustomXPFactory>();
}
GrXferProcessor*
GrCustomXPFactory::onCreateXferProcessor(const GrDrawTargetCaps& caps,
const GrProcOptInfo& colorPOI,
const GrProcOptInfo& coveragePOI,
const GrDeviceCoordTexture* dstCopy) const {
return CustomXP::Create(fMode, dstCopy, this->willReadDstColor(caps, colorPOI, coveragePOI));
}
bool GrCustomXPFactory::willReadDstColor(const GrDrawTargetCaps& caps,
const GrProcOptInfo& colorPOI,
const GrProcOptInfo& coveragePOI) const {
if (!caps.advancedBlendEquationSupport()) {
// No hardware support for advanced blend equations; we will need to do it in the shader.
return true;
}
if (coveragePOI.isFourChannelOutput()) {
// Advanced blend equations can't tweak alpha for RGB coverage.
return true;
}
return false;
}
void GrCustomXPFactory::getInvariantOutput(const GrProcOptInfo& colorPOI,
const GrProcOptInfo& coveragePOI,
GrXPFactory::InvariantOutput* output) const {
output->fWillBlendWithDst = true;
output->fBlendedColorFlags = 0;
}
GR_DEFINE_XP_FACTORY_TEST(GrCustomXPFactory);
GrXPFactory* GrCustomXPFactory::TestCreate(SkRandom* rand,
GrContext*,
const GrDrawTargetCaps&,
GrTexture*[]) {
int mode = rand->nextRangeU(SkXfermode::kLastCoeffMode + 1, SkXfermode::kLastSeparableMode);
return SkNEW_ARGS(GrCustomXPFactory, (static_cast<SkXfermode::Mode>(mode)));
}