/*
* 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 "GrGLSLBlend.h"
#include "glsl/GrGLSLFragmentShaderBuilder.h"
#include "glsl/GrGLSLProgramBuilder.h"
#include "SkBlendModePriv.h"
//////////////////////////////////////////////////////////////////////////////
// Advanced (non-coeff) blend helpers
//////////////////////////////////////////////////////////////////////////////
static void hard_light(GrGLSLFragmentBuilder* 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(GrGLSLFragmentBuilder* fsBuilder,
const char* final,
const char* src,
const char* dst,
const char component) {
const char* divisorGuard = "";
const GrShaderCaps* shaderCaps = fsBuilder->getProgramBuilder()->shaderCaps();
if (shaderCaps->mustGuardDivisionEvenAfterExplicitZeroCheck()) {
divisorGuard = "+ 0.00000001";
}
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("half 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 %s));",
dst, dst, component, src, divisorGuard);
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(GrGLSLFragmentBuilder* fsBuilder,
const char* final,
const char* src,
const char* dst,
const char component) {
const char* divisorGuard = "";
const GrShaderCaps* shaderCaps = fsBuilder->getProgramBuilder()->shaderCaps();
if (shaderCaps->mustGuardDivisionEvenAfterExplicitZeroCheck()) {
divisorGuard = "+ 0.00000001";
}
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("half d = max(0.0, %s.a - (%s.a - %s.%c) * %s.a / (%s.%c %s));",
dst, dst, dst, component, src, src, component, divisorGuard);
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(GrGLSLFragmentBuilder* fsBuilder,
const char* final,
const char* src,
const char* dst,
const char component) {
const char* divisorGuard = "";
const GrShaderCaps* shaderCaps = fsBuilder->getProgramBuilder()->shaderCaps();
if (shaderCaps->mustGuardDivisionEvenAfterExplicitZeroCheck()) {
divisorGuard = "+ 0.00000001";
}
// 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 %s) +"
"(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, divisorGuard, 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("half DSqd = %s.%c * %s.%c;",
dst, component, dst, component);
fsBuilder->codeAppendf("half DCub = DSqd * %s.%c;", dst, component);
fsBuilder->codeAppendf("half DaSqd = %s.a * %s.a;", dst, dst);
fsBuilder->codeAppendf("half 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 ="
"(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) -"
" DaCub*%s.%c) / (DaSqd %s);",
final, component, src, component, dst, component,
src, src, component, dst, src, src, component, src, src,
component, src, component, divisorGuard);
fsBuilder->codeAppendf("} else {");
// -sqrt(Da * D) (Sa-2 S)-Da S+D (Sa-2 S+1)+S
fsBuilder->codeAppendf("%s.%c = %s.%c*(%s.a - 2.0*%s.%c + 1.0) + %s.%c -"
" sqrt(%s.a*%s.%c)*(%s.a - 2.0*%s.%c) - %s.a*%s.%c;",
final, component, dst, component, src, src, component, src, component,
dst, dst, component, src, src, component, dst, 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:
// float3 set_luminance(float3 hueSatColor, float alpha, float3 lumColor).
static void add_lum_function(GrGLSLFragmentBuilder* fsBuilder, SkString* setLumFunction) {
// Emit a helper that gets the luminance of a color.
SkString getFunction;
GrShaderVar getLumArgs[] = {
GrShaderVar("color", kHalf3_GrSLType),
};
SkString getLumBody("return dot(half3(0.3, 0.59, 0.11), color);");
fsBuilder->emitFunction(kHalf_GrSLType,
"luminance",
SK_ARRAY_COUNT(getLumArgs), getLumArgs,
getLumBody.c_str(),
&getFunction);
// Emit the set luminance function.
GrShaderVar setLumArgs[] = {
GrShaderVar("hueSat", kHalf3_GrSLType),
GrShaderVar("alpha", kHalf_GrSLType),
GrShaderVar("lumColor", kHalf3_GrSLType),
};
SkString setLumBody;
setLumBody.printf("half diff = %s(lumColor - hueSat);", getFunction.c_str());
setLumBody.append("half3 outColor = hueSat + diff;");
setLumBody.appendf("half outLum = %s(outColor);", getFunction.c_str());
setLumBody.append("half minComp = min(min(outColor.r, outColor.g), outColor.b);"
"half maxComp = max(max(outColor.r, outColor.g), outColor.b);"
"if (minComp < 0.0 && outLum != minComp) {"
"outColor = outLum + ((outColor - half3(outLum, outLum, outLum)) * outLum) /"
"(outLum - minComp);"
"}"
"if (maxComp > alpha && maxComp != outLum) {"
"outColor = outLum +"
"((outColor - half3(outLum, outLum, outLum)) * (alpha - outLum)) /"
"(maxComp - outLum);"
"}"
"return outColor;");
fsBuilder->emitFunction(kHalf3_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(float3 hueLumColor, float3 satColor)
static void add_sat_function(GrGLSLFragmentBuilder* fsBuilder, SkString* setSatFunction) {
// Emit a helper that gets the saturation of a color
SkString getFunction;
GrShaderVar getSatArgs[] = { GrShaderVar("color", kHalf3_GrSLType) };
SkString getSatBody;
getSatBody.printf("return max(max(color.r, color.g), color.b) - "
"min(min(color.r, color.g), color.b);");
fsBuilder->emitFunction(kHalf_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 float3 where r, g ,b are the
// adjusted min, mid, and max inputs, respectively.
SkString helperFunction;
GrShaderVar helperArgs[] = {
GrShaderVar("minComp", kHalf_GrSLType),
GrShaderVar("midComp", kHalf_GrSLType),
GrShaderVar("maxComp", kHalf_GrSLType),
GrShaderVar("sat", kHalf_GrSLType),
};
static const char kHelperBody[] = "if (minComp < maxComp) {"
"half3 result;"
"result.r = 0.0;"
"result.g = sat * (midComp - minComp) / (maxComp - minComp);"
"result.b = sat;"
"return result;"
"} else {"
"return half3(0, 0, 0);"
"}";
fsBuilder->emitFunction(kHalf3_GrSLType,
"set_saturation_helper",
SK_ARRAY_COUNT(helperArgs), helperArgs,
kHelperBody,
&helperFunction);
GrShaderVar setSatArgs[] = {
GrShaderVar("hueLumColor", kHalf3_GrSLType),
GrShaderVar("satColor", kHalf3_GrSLType),
};
const char* helpFunc = helperFunction.c_str();
SkString setSatBody;
setSatBody.appendf("half 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(kHalf3_GrSLType,
"set_saturation",
SK_ARRAY_COUNT(setSatArgs), setSatArgs,
setSatBody.c_str(),
setSatFunction);
}
static void emit_advanced_xfermode_code(GrGLSLFragmentBuilder* fsBuilder, const char* srcColor,
const char* dstColor, const char* outputColor,
SkBlendMode mode) {
SkASSERT(srcColor);
SkASSERT(dstColor);
SkASSERT(outputColor);
// These all perform src-over on the alpha channel.
fsBuilder->codeAppendf("%s.a = %s.a + (1.0 - %s.a) * %s.a;",
outputColor, srcColor, srcColor, dstColor);
switch (mode) {
case SkBlendMode::kOverlay:
// Overlay is Hard-Light with the src and dst reversed
hard_light(fsBuilder, outputColor, dstColor, srcColor);
break;
case SkBlendMode::kDarken:
fsBuilder->codeAppendf("%s.rgb = min((1.0 - %s.a) * %s.rgb + %s.rgb, "
"(1.0 - %s.a) * %s.rgb + %s.rgb);",
outputColor,
srcColor, dstColor, srcColor,
dstColor, srcColor, dstColor);
break;
case SkBlendMode::kLighten:
fsBuilder->codeAppendf("%s.rgb = max((1.0 - %s.a) * %s.rgb + %s.rgb, "
"(1.0 - %s.a) * %s.rgb + %s.rgb);",
outputColor,
srcColor, dstColor, srcColor,
dstColor, srcColor, dstColor);
break;
case SkBlendMode::kColorDodge:
color_dodge_component(fsBuilder, outputColor, srcColor, dstColor, 'r');
color_dodge_component(fsBuilder, outputColor, srcColor, dstColor, 'g');
color_dodge_component(fsBuilder, outputColor, srcColor, dstColor, 'b');
break;
case SkBlendMode::kColorBurn:
color_burn_component(fsBuilder, outputColor, srcColor, dstColor, 'r');
color_burn_component(fsBuilder, outputColor, srcColor, dstColor, 'g');
color_burn_component(fsBuilder, outputColor, srcColor, dstColor, 'b');
break;
case SkBlendMode::kHardLight:
hard_light(fsBuilder, outputColor, srcColor, dstColor);
break;
case SkBlendMode::kSoftLight:
fsBuilder->codeAppendf("if (0.0 == %s.a) {", dstColor);
fsBuilder->codeAppendf("%s.rgba = %s;", outputColor, srcColor);
fsBuilder->codeAppendf("} else {");
soft_light_component_pos_dst_alpha(fsBuilder, outputColor, srcColor, dstColor, 'r');
soft_light_component_pos_dst_alpha(fsBuilder, outputColor, srcColor, dstColor, 'g');
soft_light_component_pos_dst_alpha(fsBuilder, outputColor, srcColor, dstColor, 'b');
fsBuilder->codeAppendf("}");
break;
case SkBlendMode::kDifference:
fsBuilder->codeAppendf("%s.rgb = %s.rgb + %s.rgb -"
"2.0 * min(%s.rgb * %s.a, %s.rgb * %s.a);",
outputColor, srcColor, dstColor, srcColor, dstColor,
dstColor, srcColor);
break;
case SkBlendMode::kExclusion:
fsBuilder->codeAppendf("%s.rgb = %s.rgb + %s.rgb - "
"2.0 * %s.rgb * %s.rgb;",
outputColor, dstColor, srcColor, dstColor, srcColor);
break;
case SkBlendMode::kMultiply:
fsBuilder->codeAppendf("%s.rgb = (1.0 - %s.a) * %s.rgb + "
"(1.0 - %s.a) * %s.rgb + "
"%s.rgb * %s.rgb;",
outputColor, srcColor, dstColor, dstColor, srcColor,
srcColor, dstColor);
break;
case SkBlendMode::kHue: {
// 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("half4 dstSrcAlpha = %s * %s.a;",
dstColor, srcColor);
fsBuilder->codeAppendf("%s.rgb = %s(%s(%s.rgb * %s.a, dstSrcAlpha.rgb),"
"dstSrcAlpha.a, dstSrcAlpha.rgb);",
outputColor, setLum.c_str(), setSat.c_str(), srcColor,
dstColor);
fsBuilder->codeAppendf("%s.rgb += (1.0 - %s.a) * %s.rgb + (1.0 - %s.a) * %s.rgb;",
outputColor, srcColor, dstColor, dstColor, srcColor);
break;
}
case SkBlendMode::kSaturation: {
// 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("half4 dstSrcAlpha = %s * %s.a;",
dstColor, srcColor);
fsBuilder->codeAppendf("%s.rgb = %s(%s(dstSrcAlpha.rgb, %s.rgb * %s.a),"
"dstSrcAlpha.a, dstSrcAlpha.rgb);",
outputColor, setLum.c_str(), setSat.c_str(), srcColor,
dstColor);
fsBuilder->codeAppendf("%s.rgb += (1.0 - %s.a) * %s.rgb + (1.0 - %s.a) * %s.rgb;",
outputColor, srcColor, dstColor, dstColor, srcColor);
break;
}
case SkBlendMode::kColor: {
// SetLum(S * Da, Sa* Da, D * Sa) + (1 - Sa) * D + (1 - Da) * S
SkString setLum;
add_lum_function(fsBuilder, &setLum);
fsBuilder->codeAppendf("half4 srcDstAlpha = %s * %s.a;",
srcColor, dstColor);
fsBuilder->codeAppendf("%s.rgb = %s(srcDstAlpha.rgb, srcDstAlpha.a, %s.rgb * %s.a);",
outputColor, setLum.c_str(), dstColor, srcColor);
fsBuilder->codeAppendf("%s.rgb += (1.0 - %s.a) * %s.rgb + (1.0 - %s.a) * %s.rgb;",
outputColor, srcColor, dstColor, dstColor, srcColor);
break;
}
case SkBlendMode::kLuminosity: {
// SetLum(D * Sa, Sa* Da, S * Da) + (1 - Sa) * D + (1 - Da) * S
SkString setLum;
add_lum_function(fsBuilder, &setLum);
fsBuilder->codeAppendf("half4 srcDstAlpha = %s * %s.a;",
srcColor, dstColor);
fsBuilder->codeAppendf("%s.rgb = %s(%s.rgb * %s.a, srcDstAlpha.a, srcDstAlpha.rgb);",
outputColor, setLum.c_str(), dstColor, srcColor);
fsBuilder->codeAppendf("%s.rgb += (1.0 - %s.a) * %s.rgb + (1.0 - %s.a) * %s.rgb;",
outputColor, srcColor, dstColor, dstColor, srcColor);
break;
}
default:
SK_ABORT("Unknown Custom Xfer mode.");
break;
}
}
//////////////////////////////////////////////////////////////////////////////
// Porter-Duff blend helper
//////////////////////////////////////////////////////////////////////////////
static bool append_porterduff_term(GrGLSLFragmentBuilder* fsBuilder, SkBlendModeCoeff coeff,
const char* colorName, const char* srcColorName,
const char* dstColorName, bool hasPrevious) {
if (SkBlendModeCoeff::kZero == coeff) {
return hasPrevious;
} else {
if (hasPrevious) {
fsBuilder->codeAppend(" + ");
}
fsBuilder->codeAppendf("%s", colorName);
switch (coeff) {
case SkBlendModeCoeff::kOne:
break;
case SkBlendModeCoeff::kSC:
fsBuilder->codeAppendf(" * %s", srcColorName);
break;
case SkBlendModeCoeff::kISC:
fsBuilder->codeAppendf(" * (half4(1.0) - %s)", srcColorName);
break;
case SkBlendModeCoeff::kDC:
fsBuilder->codeAppendf(" * %s", dstColorName);
break;
case SkBlendModeCoeff::kIDC:
fsBuilder->codeAppendf(" * (half4(1.0) - %s)", dstColorName);
break;
case SkBlendModeCoeff::kSA:
fsBuilder->codeAppendf(" * %s.a", srcColorName);
break;
case SkBlendModeCoeff::kISA:
fsBuilder->codeAppendf(" * (1.0 - %s.a)", srcColorName);
break;
case SkBlendModeCoeff::kDA:
fsBuilder->codeAppendf(" * %s.a", dstColorName);
break;
case SkBlendModeCoeff::kIDA:
fsBuilder->codeAppendf(" * (1.0 - %s.a)", dstColorName);
break;
default:
SK_ABORT("Unsupported Blend Coeff");
}
return true;
}
}
//////////////////////////////////////////////////////////////////////////////
void GrGLSLBlend::AppendMode(GrGLSLFragmentBuilder* fsBuilder, const char* srcColor,
const char* dstColor, const char* outColor,
SkBlendMode mode) {
SkBlendModeCoeff srcCoeff, dstCoeff;
if (SkBlendMode_AsCoeff(mode, &srcCoeff, &dstCoeff)) {
// The only coeff mode that can go out of range is plus.
bool clamp = mode == SkBlendMode::kPlus;
fsBuilder->codeAppendf("%s = ", outColor);
if (clamp) {
fsBuilder->codeAppend("clamp(");
}
// append src blend
bool didAppend = append_porterduff_term(fsBuilder, srcCoeff, srcColor, srcColor, dstColor,
false);
// append dst blend
if(!append_porterduff_term(fsBuilder, dstCoeff, dstColor, srcColor, dstColor, didAppend)) {
fsBuilder->codeAppend("half4(0, 0, 0, 0)");
}
if (clamp) {
fsBuilder->codeAppend(", 0, 1);");
}
fsBuilder->codeAppend(";");
} else {
emit_advanced_xfermode_code(fsBuilder, srcColor, dstColor, outColor, mode);
}
}
void GrGLSLBlend::AppendRegionOp(GrGLSLFragmentBuilder* fsBuilder, const char* srcColor,
const char* dstColor, const char* outColor,
SkRegion::Op regionOp) {
SkBlendModeCoeff srcCoeff, dstCoeff;
switch (regionOp) {
case SkRegion::kReplace_Op:
srcCoeff = SkBlendModeCoeff::kOne;
dstCoeff = SkBlendModeCoeff::kZero;
break;
case SkRegion::kIntersect_Op:
srcCoeff = SkBlendModeCoeff::kDC;
dstCoeff = SkBlendModeCoeff::kZero;
break;
case SkRegion::kUnion_Op:
srcCoeff = SkBlendModeCoeff::kOne;
dstCoeff = SkBlendModeCoeff::kISC;
break;
case SkRegion::kXOR_Op:
srcCoeff = SkBlendModeCoeff::kIDC;
dstCoeff = SkBlendModeCoeff::kISC;
break;
case SkRegion::kDifference_Op:
srcCoeff = SkBlendModeCoeff::kZero;
dstCoeff = SkBlendModeCoeff::kISC;
break;
case SkRegion::kReverseDifference_Op:
srcCoeff = SkBlendModeCoeff::kIDC;
dstCoeff = SkBlendModeCoeff::kZero;
break;
default:
SK_ABORT("Unsupported Op");
// We should never get here but to make compiler happy
srcCoeff = SkBlendModeCoeff::kZero;
dstCoeff = SkBlendModeCoeff::kZero;
}
fsBuilder->codeAppendf("%s = ", outColor);
// append src blend
bool didAppend = append_porterduff_term(fsBuilder, srcCoeff, srcColor, srcColor, dstColor,
false);
// append dst blend
if(!append_porterduff_term(fsBuilder, dstCoeff, dstColor, srcColor, dstColor, didAppend)) {
fsBuilder->codeAppend("half4(0, 0, 0, 0)");
}
fsBuilder->codeAppend(";");
}