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 "src/gpu/GrDrawOpAtlas.h"
12 #include "src/gpu/GrShaderCaps.h"
13 #include "src/gpu/glsl/GrGLSLFragmentShaderBuilder.h"
14 #include "src/gpu/glsl/GrGLSLGeometryProcessor.h"
15 #include "src/gpu/glsl/GrGLSLVarying.h"
16 #include "src/gpu/glsl/GrGLSLVertexGeoBuilder.h"
17
append_index_uv_varyings(GrGLSLGeometryProcessor::EmitArgs & args,int numTextureSamplers,const char * inTexCoordsName,const char * atlasDimensionsInvName,GrGLSLVarying * uv,GrGLSLVarying * texIdx,GrGLSLVarying * st)18 static void append_index_uv_varyings(GrGLSLGeometryProcessor::EmitArgs& args,
19 int numTextureSamplers,
20 const char* inTexCoordsName,
21 const char* atlasDimensionsInvName,
22 GrGLSLVarying* uv,
23 GrGLSLVarying* texIdx,
24 GrGLSLVarying* st) {
25 using Interpolation = GrGLSLVaryingHandler::Interpolation;
26 // This extracts the texture index and texel coordinates from the same variable
27 // Packing structure: texel coordinates have the 2-bit texture page encoded in bits 13 & 14 of
28 // the x coordinate. It would be nice to use bits 14 and 15, but iphone6 has problem with those
29 // bits when in gles. Iphone6 works fine with bits 14 and 15 in metal.
30 if (args.fShaderCaps->integerSupport()) {
31 if (numTextureSamplers <= 1) {
32 args.fVertBuilder->codeAppendf(R"code(
33 int texIdx = 0;
34 float2 unormTexCoords = float2(%s.x, %s.y);
35 )code", inTexCoordsName, inTexCoordsName);
36 } else {
37 args.fVertBuilder->codeAppendf(R"code(
38 int2 coords = int2(%s.x, %s.y);
39 int texIdx = coords.x >> 13;
40 float2 unormTexCoords = float2(coords.x & 0x1FFF, coords.y);
41 )code", inTexCoordsName, inTexCoordsName);
42 }
43 } else {
44 if (numTextureSamplers <= 1) {
45 args.fVertBuilder->codeAppendf(R"code(
46 float texIdx = 0;
47 float2 unormTexCoords = float2(%s.x, %s.y);
48 )code", inTexCoordsName, inTexCoordsName);
49 } else {
50 args.fVertBuilder->codeAppendf(R"code(
51 float2 coord = float2(%s.x, %s.y);
52 float texIdx = floor(coord.x * exp2(-13));
53 float2 unormTexCoords = float2(coord.x - texIdx * exp2(13), coord.y);
54 )code", inTexCoordsName, inTexCoordsName);
55 }
56 }
57
58 // Multiply by 1/atlasDimensions to get normalized texture coordinates
59 uv->reset(kFloat2_GrSLType);
60 args.fVaryingHandler->addVarying("TextureCoords", uv);
61 args.fVertBuilder->codeAppendf(
62 "%s = unormTexCoords * %s;", uv->vsOut(), atlasDimensionsInvName);
63
64 // On ANGLE there is a significant cost to using an int varying. We don't know of any case where
65 // it is worse to use a float so for now we always do.
66 texIdx->reset(kFloat_GrSLType);
67 // If we computed the local var "texIdx" as an int we will need to cast it to float
68 const char* cast = args.fShaderCaps->integerSupport() ? "float" : "";
69 args.fVaryingHandler->addVarying("TexIndex", texIdx, Interpolation::kCanBeFlat);
70 args.fVertBuilder->codeAppendf("%s = %s(texIdx);", texIdx->vsOut(), cast);
71
72 if (st) {
73 st->reset(kFloat2_GrSLType);
74 args.fVaryingHandler->addVarying("IntTextureCoords", st);
75 args.fVertBuilder->codeAppendf("%s = unormTexCoords;", st->vsOut());
76 }
77 }
78
append_multitexture_lookup(GrGLSLGeometryProcessor::EmitArgs & args,int numTextureSamplers,const GrGLSLVarying & texIdx,const char * coordName,const char * colorName)79 static void append_multitexture_lookup(GrGLSLGeometryProcessor::EmitArgs& args,
80 int numTextureSamplers,
81 const GrGLSLVarying &texIdx,
82 const char* coordName,
83 const char* colorName) {
84 SkASSERT(numTextureSamplers > 0);
85 // This shouldn't happen, but will avoid a crash if it does
86 if (numTextureSamplers <= 0) {
87 args.fFragBuilder->codeAppendf("%s = float4(1, 1, 1, 1);", colorName);
88 return;
89 }
90
91 // conditionally load from the indexed texture sampler
92 for (int i = 0; i < numTextureSamplers-1; ++i) {
93 args.fFragBuilder->codeAppendf("if (%s == %d) { %s = ", texIdx.fsIn(), i, colorName);
94 args.fFragBuilder->appendTextureLookup(args.fTexSamplers[i], coordName);
95 args.fFragBuilder->codeAppend("; } else ");
96 }
97 args.fFragBuilder->codeAppendf("{ %s = ", colorName);
98 args.fFragBuilder->appendTextureLookup(args.fTexSamplers[numTextureSamplers - 1], coordName);
99 args.fFragBuilder->codeAppend("; }");
100 }
101
102 #endif
103