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/*
* Copyright 2017 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef GrAtlasedShaderHelpers_DEFINED
#define GrAtlasedShaderHelpers_DEFINED
#include "GrShaderCaps.h"
#include "glsl/GrGLSLPrimitiveProcessor.h"
#include "glsl/GrGLSLFragmentShaderBuilder.h"
#include "glsl/GrGLSLVarying.h"
#include "glsl/GrGLSLVertexGeoBuilder.h"
static void append_index_uv_varyings(GrGLSLPrimitiveProcessor::EmitArgs& args,
const char* inTexCoordsName,
const char* atlasSizeInvName,
GrGLSLVarying *uv,
GrGLSLVarying *texIdx,
GrGLSLVarying *st) {
using Interpolation = GrGLSLVaryingHandler::Interpolation;
// This extracts the texture index and texel coordinates from the same variable
// Packing structure: texel coordinates are multiplied by 2 (or shifted left 1)
// texture index is stored as lower bits of both x and y
if (args.fShaderCaps->integerSupport()) {
args.fVertBuilder->codeAppendf("int2 signedCoords = int2(%s.x, %s.y);",
inTexCoordsName, inTexCoordsName);
args.fVertBuilder->codeAppend("int texIdx = 2*(signedCoords.x & 0x1) + (signedCoords.y & 0x1);");
args.fVertBuilder->codeAppend("float2 unormTexCoords = float2(signedCoords.x/2, signedCoords.y/2);");
} else {
args.fVertBuilder->codeAppendf("float2 indexTexCoords = float2(%s.x, %s.y);",
inTexCoordsName, inTexCoordsName);
args.fVertBuilder->codeAppend("float2 unormTexCoords = floor(0.5*indexTexCoords);");
args.fVertBuilder->codeAppend("float2 diff = indexTexCoords - 2.0*unormTexCoords;");
args.fVertBuilder->codeAppend("float texIdx = 2.0*diff.x + diff.y;");
}
// Multiply by 1/atlasSize to get normalized texture coordinates
args.fVaryingHandler->addVarying("TextureCoords", uv);
args.fVertBuilder->codeAppendf("%s = unormTexCoords * %s;", uv->vsOut(), atlasSizeInvName);
args.fVaryingHandler->addVarying("TexIndex", texIdx, args.fShaderCaps->integerSupport()
? Interpolation::kMustBeFlat
: Interpolation::kCanBeFlat);
args.fVertBuilder->codeAppendf("%s = texIdx;", texIdx->vsOut());
if (st) {
args.fVaryingHandler->addVarying("IntTextureCoords", st);
args.fVertBuilder->codeAppendf("%s = unormTexCoords;", st->vsOut());
}
}
static void append_multitexture_lookup(GrGLSLPrimitiveProcessor::EmitArgs& args,
int numTextureSamplers,
const GrGLSLVarying &texIdx,
const char* coordName,
const char* colorName) {
// conditionally load from the indexed texture sampler
for (int i = 0; i < numTextureSamplers-1; ++i) {
args.fFragBuilder->codeAppendf("if (%s == %d) { %s = ", texIdx.fsIn(), i, colorName);
args.fFragBuilder->appendTextureLookup(args.fTexSamplers[i], coordName,
kFloat2_GrSLType);
args.fFragBuilder->codeAppend("; } else ");
}
args.fFragBuilder->codeAppendf("{ %s = ", colorName);
args.fFragBuilder->appendTextureLookup(args.fTexSamplers[numTextureSamplers-1], coordName,
kFloat2_GrSLType);
args.fFragBuilder->codeAppend("; }");
}
#endif
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