1 /*
2 * Copyright 2017 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8 #ifndef GrAtlasedShaderHelpers_DEFINED
9 #define GrAtlasedShaderHelpers_DEFINED
10
11 #include "GrShaderCaps.h"
12 #include "glsl/GrGLSLPrimitiveProcessor.h"
13 #include "glsl/GrGLSLFragmentShaderBuilder.h"
14 #include "glsl/GrGLSLVarying.h"
15 #include "glsl/GrGLSLVertexGeoBuilder.h"
16
append_index_uv_varyings(GrGLSLPrimitiveProcessor::EmitArgs & args,const char * inTexCoordsName,const char * atlasSizeInvName,GrGLSLVarying * uv,GrGLSLVarying * texIdx,GrGLSLVarying * st)17 static void append_index_uv_varyings(GrGLSLPrimitiveProcessor::EmitArgs& args,
18 const char* inTexCoordsName,
19 const char* atlasSizeInvName,
20 GrGLSLVarying *uv,
21 GrGLSLVarying *texIdx,
22 GrGLSLVarying *st) {
23 using Interpolation = GrGLSLVaryingHandler::Interpolation;
24
25 // This extracts the texture index and texel coordinates from the same variable
26 // Packing structure: texel coordinates are multiplied by 2 (or shifted left 1)
27 // texture index is stored as lower bits of both x and y
28 if (args.fShaderCaps->integerSupport()) {
29 args.fVertBuilder->codeAppendf("int2 signedCoords = int2(%s.x, %s.y);",
30 inTexCoordsName, inTexCoordsName);
31 args.fVertBuilder->codeAppend("int texIdx = 2*(signedCoords.x & 0x1) + (signedCoords.y & 0x1);");
32 args.fVertBuilder->codeAppend("float2 unormTexCoords = float2(signedCoords.x/2, signedCoords.y/2);");
33 } else {
34 args.fVertBuilder->codeAppendf("float2 indexTexCoords = float2(%s.x, %s.y);",
35 inTexCoordsName, inTexCoordsName);
36 args.fVertBuilder->codeAppend("float2 unormTexCoords = floor(0.5*indexTexCoords);");
37 args.fVertBuilder->codeAppend("float2 diff = indexTexCoords - 2.0*unormTexCoords;");
38 args.fVertBuilder->codeAppend("float texIdx = 2.0*diff.x + diff.y;");
39 }
40
41 // Multiply by 1/atlasSize to get normalized texture coordinates
42 args.fVaryingHandler->addVarying("TextureCoords", uv);
43 args.fVertBuilder->codeAppendf("%s = unormTexCoords * %s;", uv->vsOut(), atlasSizeInvName);
44
45 args.fVaryingHandler->addVarying("TexIndex", texIdx, args.fShaderCaps->integerSupport()
46 ? Interpolation::kMustBeFlat
47 : Interpolation::kCanBeFlat);
48 args.fVertBuilder->codeAppendf("%s = texIdx;", texIdx->vsOut());
49
50 if (st) {
51 args.fVaryingHandler->addVarying("IntTextureCoords", st);
52 args.fVertBuilder->codeAppendf("%s = unormTexCoords;", st->vsOut());
53 }
54 }
55
append_multitexture_lookup(GrGLSLPrimitiveProcessor::EmitArgs & args,int numTextureSamplers,const GrGLSLVarying & texIdx,const char * coordName,const char * colorName)56 static void append_multitexture_lookup(GrGLSLPrimitiveProcessor::EmitArgs& args,
57 int numTextureSamplers,
58 const GrGLSLVarying &texIdx,
59 const char* coordName,
60 const char* colorName) {
61 // conditionally load from the indexed texture sampler
62 for (int i = 0; i < numTextureSamplers-1; ++i) {
63 args.fFragBuilder->codeAppendf("if (%s == %d) { %s = ", texIdx.fsIn(), i, colorName);
64 args.fFragBuilder->appendTextureLookup(args.fTexSamplers[i], coordName,
65 kFloat2_GrSLType);
66 args.fFragBuilder->codeAppend("; } else ");
67 }
68 args.fFragBuilder->codeAppendf("{ %s = ", colorName);
69 args.fFragBuilder->appendTextureLookup(args.fTexSamplers[numTextureSamplers-1], coordName,
70 kFloat2_GrSLType);
71 args.fFragBuilder->codeAppend("; }");
72 }
73
74 #endif
75