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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 "src/gpu/GrDrawOpAtlas.h"
#include "src/gpu/GrShaderCaps.h"
#include "src/gpu/glsl/GrGLSLFragmentShaderBuilder.h"
#include "src/gpu/glsl/GrGLSLVarying.h"
#include "src/gpu/glsl/GrGLSLVertexGeoBuilder.h"
static void append_index_uv_varyings(GrGeometryProcessor::ProgramImpl::EmitArgs& args,
int numTextureSamplers,
const char* inTexCoordsName,
const char* atlasDimensionsInvName,
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 have the 2-bit texture page encoded in bits 13 & 14 of
// the x coordinate. It would be nice to use bits 14 and 15, but iphone6 has problem with those
// bits when in gles. Iphone6 works fine with bits 14 and 15 in metal.
if (args.fShaderCaps->integerSupport()) {
if (numTextureSamplers <= 1) {
args.fVertBuilder->codeAppendf(R"code(
int texIdx = 0;
float2 unormTexCoords = float2(%s.x, %s.y);
)code", inTexCoordsName, inTexCoordsName);
} else {
args.fVertBuilder->codeAppendf(R"code(
int2 coords = int2(%s.x, %s.y);
int texIdx = coords.x >> 13;
float2 unormTexCoords = float2(coords.x & 0x1FFF, coords.y);
)code", inTexCoordsName, inTexCoordsName);
}
} else {
if (numTextureSamplers <= 1) {
args.fVertBuilder->codeAppendf(R"code(
float texIdx = 0;
float2 unormTexCoords = float2(%s.x, %s.y);
)code", inTexCoordsName, inTexCoordsName);
} else {
args.fVertBuilder->codeAppendf(R"code(
float2 coord = float2(%s.x, %s.y);
float texIdx = floor(coord.x * exp2(-13));
float2 unormTexCoords = float2(coord.x - texIdx * exp2(13), coord.y);
)code", inTexCoordsName, inTexCoordsName);
}
}
// Multiply by 1/atlasDimensions to get normalized texture coordinates
uv->reset(SkSLType::kFloat2);
args.fVaryingHandler->addVarying("TextureCoords", uv);
args.fVertBuilder->codeAppendf(
"%s = unormTexCoords * %s;", uv->vsOut(), atlasDimensionsInvName);
// On ANGLE there is a significant cost to using an int varying. We don't know of any case where
// it is worse to use a float so for now we always do.
texIdx->reset(SkSLType::kFloat);
// If we computed the local var "texIdx" as an int we will need to cast it to float
const char* cast = args.fShaderCaps->integerSupport() ? "float" : "";
args.fVaryingHandler->addVarying("TexIndex", texIdx, Interpolation::kCanBeFlat);
args.fVertBuilder->codeAppendf("%s = %s(texIdx);", texIdx->vsOut(), cast);
if (st) {
st->reset(SkSLType::kFloat2);
args.fVaryingHandler->addVarying("IntTextureCoords", st);
args.fVertBuilder->codeAppendf("%s = unormTexCoords;", st->vsOut());
}
}
static void append_multitexture_lookup(GrGeometryProcessor::ProgramImpl::EmitArgs& args,
int numTextureSamplers,
const GrGLSLVarying& texIdx,
const char* coordName,
const char* colorName) {
SkASSERT(numTextureSamplers > 0);
// This shouldn't happen, but will avoid a crash if it does
if (numTextureSamplers <= 0) {
args.fFragBuilder->codeAppendf("%s = float4(1, 1, 1, 1);", colorName);
return;
}
// 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);
args.fFragBuilder->codeAppend("; } else ");
}
args.fFragBuilder->codeAppendf("{ %s = ", colorName);
args.fFragBuilder->appendTextureLookup(args.fTexSamplers[numTextureSamplers - 1], coordName);
args.fFragBuilder->codeAppend("; }");
}
#endif