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/ganesh/GrDrawOpAtlas.h"
12 #include "src/gpu/ganesh/GrShaderCaps.h"
13 #include "src/gpu/ganesh/glsl/GrGLSLFragmentShaderBuilder.h"
14 #include "src/gpu/ganesh/glsl/GrGLSLVarying.h"
15 #include "src/gpu/ganesh/glsl/GrGLSLVertexGeoBuilder.h"
16
append_index_uv_varyings(GrGeometryProcessor::ProgramImpl::EmitArgs & args,int numTextureSamplers,const char * inTexCoordsName,const char * atlasDimensionsInvName,GrGLSLVarying * uv,GrGLSLVarying * texIdx,GrGLSLVarying * st)17 static inline void append_index_uv_varyings(GrGeometryProcessor::ProgramImpl::EmitArgs& args,
18 int numTextureSamplers,
19 const char* inTexCoordsName,
20 const char* atlasDimensionsInvName,
21 GrGLSLVarying* uv,
22 GrGLSLVarying* texIdx,
23 GrGLSLVarying* st) {
24 using Interpolation = GrGLSLVaryingHandler::Interpolation;
25 // This extracts the texture index and texel coordinates from the same variable
26 // Packing structure: texel coordinates have the 2-bit texture page encoded in bits 13 & 14 of
27 // the x coordinate. It would be nice to use bits 14 and 15, but iphone6 has problem with those
28 // bits when in gles. Iphone6 works fine with bits 14 and 15 in metal.
29 if (args.fShaderCaps->fIntegerSupport) {
30 if (numTextureSamplers <= 1) {
31 args.fVertBuilder->codeAppendf(
32 "int texIdx = 0;"
33 "float2 unormTexCoords = float2(%s.x, %s.y);"
34 , inTexCoordsName, inTexCoordsName);
35 } else {
36 args.fVertBuilder->codeAppendf(
37 "int2 coords = int2(%s.x, %s.y);"
38 "int texIdx = coords.x >> 13;"
39 "float2 unormTexCoords = float2(coords.x & 0x1FFF, coords.y);"
40 , inTexCoordsName, inTexCoordsName);
41 }
42 } else {
43 if (numTextureSamplers <= 1) {
44 args.fVertBuilder->codeAppendf(
45 "float texIdx = 0;"
46 "float2 unormTexCoords = float2(%s.x, %s.y);"
47 , inTexCoordsName, inTexCoordsName);
48 } else {
49 args.fVertBuilder->codeAppendf(
50 "float2 coord = float2(%s.x, %s.y);"
51 "float texIdx = floor(coord.x * exp2(-13));"
52 "float2 unormTexCoords = float2(coord.x - texIdx * exp2(13), coord.y);"
53 , inTexCoordsName, inTexCoordsName);
54 }
55 }
56
57 // Multiply by 1/atlasDimensions to get normalized texture coordinates
58 uv->reset(SkSLType::kFloat2);
59 args.fVaryingHandler->addVarying("TextureCoords", uv);
60 args.fVertBuilder->codeAppendf(
61 "%s = unormTexCoords * %s;", uv->vsOut(), atlasDimensionsInvName);
62
63 // On ANGLE there is a significant cost to using an int varying. We don't know of any case where
64 // it is worse to use a float so for now we always do.
65 texIdx->reset(SkSLType::kFloat);
66 // If we computed the local var "texIdx" as an int we will need to cast it to float
67 const char* cast = args.fShaderCaps->fIntegerSupport ? "float" : "";
68 args.fVaryingHandler->addVarying("TexIndex", texIdx, Interpolation::kCanBeFlat);
69 args.fVertBuilder->codeAppendf("%s = %s(texIdx);", texIdx->vsOut(), cast);
70
71 if (st) {
72 st->reset(SkSLType::kFloat2);
73 args.fVaryingHandler->addVarying("IntTextureCoords", st);
74 args.fVertBuilder->codeAppendf("%s = unormTexCoords;", st->vsOut());
75 }
76 }
77
append_multitexture_lookup(GrGeometryProcessor::ProgramImpl::EmitArgs & args,int numTextureSamplers,const GrGLSLVarying & texIdx,const char * coordName,const char * colorName)78 static inline void append_multitexture_lookup(GrGeometryProcessor::ProgramImpl::EmitArgs& args,
79 int numTextureSamplers,
80 const GrGLSLVarying& texIdx,
81 const char* coordName,
82 const char* colorName) {
83 SkASSERT(numTextureSamplers > 0);
84 // This shouldn't happen, but will avoid a crash if it does
85 if (numTextureSamplers <= 0) {
86 args.fFragBuilder->codeAppendf("%s = float4(1);", colorName);
87 return;
88 }
89
90 // conditionally load from the indexed texture sampler
91 for (int i = 0; i < numTextureSamplers-1; ++i) {
92 args.fFragBuilder->codeAppendf("if (%s == %d) { %s = ", texIdx.fsIn(), i, colorName);
93 args.fFragBuilder->appendTextureLookup(args.fTexSamplers[i],
94 coordName);
95 args.fFragBuilder->codeAppend("; } else ");
96 }
97 args.fFragBuilder->codeAppendf("{ %s = ", colorName);
98 args.fFragBuilder->appendTextureLookup(args.fTexSamplers[numTextureSamplers - 1],
99 coordName);
100 args.fFragBuilder->codeAppend("; }");
101 }
102
103 // Special lookup function for sdf lcd -- avoids duplicating conditional logic three times
append_multitexture_lookup_lcd(GrGeometryProcessor::ProgramImpl::EmitArgs & args,int numTextureSamplers,const GrGLSLVarying & texIdx,const char * coordName,const char * offsetName,const char * distanceName)104 static inline void append_multitexture_lookup_lcd(GrGeometryProcessor::ProgramImpl::EmitArgs& args,
105 int numTextureSamplers,
106 const GrGLSLVarying& texIdx,
107 const char* coordName,
108 const char* offsetName,
109 const char* distanceName) {
110 SkASSERT(numTextureSamplers > 0);
111 // This shouldn't happen, but will avoid a crash if it does
112 if (numTextureSamplers <= 0) {
113 args.fFragBuilder->codeAppendf("%s = half3(1);", distanceName);
114 return;
115 }
116
117 // conditionally load from the indexed texture sampler
118 for (int i = 0; i < numTextureSamplers; ++i) {
119 args.fFragBuilder->codeAppendf("if (%s == %d) {", texIdx.fsIn(), i);
120
121 // green is distance to uv center
122 args.fFragBuilder->codeAppendf("%s.y = ", distanceName);
123 args.fFragBuilder->appendTextureLookup(args.fTexSamplers[i], coordName);
124 args.fFragBuilder->codeAppend(".r;");
125
126 // red is distance to left offset
127 args.fFragBuilder->codeAppendf("half2 uv_adjusted = half2(%s) - %s;",
128 coordName, offsetName);
129 args.fFragBuilder->codeAppendf("%s.x = ", distanceName);
130 args.fFragBuilder->appendTextureLookup(args.fTexSamplers[i], "uv_adjusted");
131 args.fFragBuilder->codeAppend(".r;");
132
133 // blue is distance to right offset
134 args.fFragBuilder->codeAppendf("uv_adjusted = half2(%s) + %s;", coordName, offsetName);
135 args.fFragBuilder->codeAppendf("%s.z = ", distanceName);
136 args.fFragBuilder->appendTextureLookup(args.fTexSamplers[i], "uv_adjusted");
137 args.fFragBuilder->codeAppend(".r;");
138
139 if (i < numTextureSamplers-1) {
140 args.fFragBuilder->codeAppend("} else ");
141 } else {
142 args.fFragBuilder->codeAppend("}");
143 }
144 }
145 }
146
147 #endif
148