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 "include/private/base/SkAssert.h"
12 #include "src/core/SkSLTypeShared.h"
13 #include "src/gpu/ganesh/GrGeometryProcessor.h"
14 #include "src/gpu/ganesh/GrShaderCaps.h"
15 #include "src/gpu/ganesh/glsl/GrGLSLFragmentShaderBuilder.h"
16 #include "src/gpu/ganesh/glsl/GrGLSLVarying.h"
17 #include "src/gpu/ganesh/glsl/GrGLSLVertexGeoBuilder.h"
18
append_index_uv_varyings(GrGeometryProcessor::ProgramImpl::EmitArgs & args,int numTextureSamplers,const char * inTexCoordsName,const char * atlasDimensionsInvName,GrGLSLVarying * uv,GrGLSLVarying * texIdx,GrGLSLVarying * st)19 static inline void append_index_uv_varyings(GrGeometryProcessor::ProgramImpl::EmitArgs& args,
20 int numTextureSamplers,
21 const char* inTexCoordsName,
22 const char* atlasDimensionsInvName,
23 GrGLSLVarying* uv,
24 GrGLSLVarying* texIdx,
25 GrGLSLVarying* st) {
26 using Interpolation = GrGLSLVaryingHandler::Interpolation;
27 // This extracts the texture index and texel coordinates from the same variable
28 // Packing structure: texel coordinates have the 2-bit texture page encoded in bits 13 & 14 of
29 // the x coordinate. It would be nice to use bits 14 and 15, but iphone6 has problem with those
30 // bits when in gles. Iphone6 works fine with bits 14 and 15 in metal.
31 if (args.fShaderCaps->fIntegerSupport) {
32 if (numTextureSamplers <= 1) {
33 args.fVertBuilder->codeAppendf(
34 "int texIdx = 0;"
35 "float2 unormTexCoords = float2(%s.x, %s.y);"
36 , inTexCoordsName, inTexCoordsName);
37 } else {
38 args.fVertBuilder->codeAppendf(
39 "int2 coords = int2(%s.x, %s.y);"
40 "int texIdx = coords.x >> 13;"
41 "float2 unormTexCoords = float2(coords.x & 0x1FFF, coords.y);"
42 , inTexCoordsName, inTexCoordsName);
43 }
44 } else {
45 if (numTextureSamplers <= 1) {
46 args.fVertBuilder->codeAppendf(
47 "float texIdx = 0;"
48 "float2 unormTexCoords = float2(%s.x, %s.y);"
49 , inTexCoordsName, inTexCoordsName);
50 } else {
51 args.fVertBuilder->codeAppendf(
52 "float2 coord = float2(%s.x, %s.y);"
53 "float texIdx = floor(coord.x * exp2(-13));"
54 "float2 unormTexCoords = float2(coord.x - texIdx * exp2(13), coord.y);"
55 , inTexCoordsName, inTexCoordsName);
56 }
57 }
58
59 // Multiply by 1/atlasDimensions to get normalized texture coordinates
60 uv->reset(SkSLType::kFloat2);
61 args.fVaryingHandler->addVarying("TextureCoords", uv);
62 args.fVertBuilder->codeAppendf(
63 "%s = unormTexCoords * %s;", uv->vsOut(), atlasDimensionsInvName);
64
65 // On ANGLE there is a significant cost to using an int varying. We don't know of any case where
66 // it is worse to use a float so for now we always do.
67 texIdx->reset(SkSLType::kFloat);
68 // If we computed the local var "texIdx" as an int we will need to cast it to float
69 const char* cast = args.fShaderCaps->fIntegerSupport ? "float" : "";
70 args.fVaryingHandler->addVarying("TexIndex", texIdx, Interpolation::kCanBeFlat);
71 args.fVertBuilder->codeAppendf("%s = %s(texIdx);", texIdx->vsOut(), cast);
72
73 if (st) {
74 st->reset(SkSLType::kFloat2);
75 args.fVaryingHandler->addVarying("IntTextureCoords", st);
76 args.fVertBuilder->codeAppendf("%s = unormTexCoords;", st->vsOut());
77 }
78 }
79
append_multitexture_lookup(GrGeometryProcessor::ProgramImpl::EmitArgs & args,int numTextureSamplers,const GrGLSLVarying & texIdx,const char * coordName,const char * colorName)80 static inline void append_multitexture_lookup(GrGeometryProcessor::ProgramImpl::EmitArgs& args,
81 int numTextureSamplers,
82 const GrGLSLVarying& texIdx,
83 const char* coordName,
84 const char* colorName) {
85 SkASSERT(numTextureSamplers > 0);
86 // This shouldn't happen, but will avoid a crash if it does
87 if (numTextureSamplers <= 0) {
88 args.fFragBuilder->codeAppendf("%s = float4(1);", colorName);
89 return;
90 }
91
92 // conditionally load from the indexed texture sampler
93 for (int i = 0; i < numTextureSamplers-1; ++i) {
94 args.fFragBuilder->codeAppendf("if (%s == %d) { %s = ", texIdx.fsIn(), i, colorName);
95 args.fFragBuilder->appendTextureLookup(args.fTexSamplers[i],
96 coordName);
97 args.fFragBuilder->codeAppend("; } else ");
98 }
99 args.fFragBuilder->codeAppendf("{ %s = ", colorName);
100 args.fFragBuilder->appendTextureLookup(args.fTexSamplers[numTextureSamplers - 1],
101 coordName);
102 args.fFragBuilder->codeAppend("; }");
103 }
104
105 // 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)106 static inline void append_multitexture_lookup_lcd(GrGeometryProcessor::ProgramImpl::EmitArgs& args,
107 int numTextureSamplers,
108 const GrGLSLVarying& texIdx,
109 const char* coordName,
110 const char* offsetName,
111 const char* distanceName) {
112 SkASSERT(numTextureSamplers > 0);
113 // This shouldn't happen, but will avoid a crash if it does
114 if (numTextureSamplers <= 0) {
115 args.fFragBuilder->codeAppendf("%s = half3(1);", distanceName);
116 return;
117 }
118
119 // conditionally load from the indexed texture sampler
120 for (int i = 0; i < numTextureSamplers; ++i) {
121 args.fFragBuilder->codeAppendf("if (%s == %d) {", texIdx.fsIn(), i);
122
123 // green is distance to uv center
124 args.fFragBuilder->codeAppendf("%s.y = ", distanceName);
125 args.fFragBuilder->appendTextureLookup(args.fTexSamplers[i], coordName);
126 args.fFragBuilder->codeAppend(".r;");
127
128 // red is distance to left offset
129 args.fFragBuilder->codeAppendf("half2 uv_adjusted = half2(%s) - %s;",
130 coordName, offsetName);
131 args.fFragBuilder->codeAppendf("%s.x = ", distanceName);
132 args.fFragBuilder->appendTextureLookup(args.fTexSamplers[i], "uv_adjusted");
133 args.fFragBuilder->codeAppend(".r;");
134
135 // blue is distance to right offset
136 args.fFragBuilder->codeAppendf("uv_adjusted = half2(%s) + %s;", coordName, offsetName);
137 args.fFragBuilder->codeAppendf("%s.z = ", distanceName);
138 args.fFragBuilder->appendTextureLookup(args.fTexSamplers[i], "uv_adjusted");
139 args.fFragBuilder->codeAppend(".r;");
140
141 if (i < numTextureSamplers-1) {
142 args.fFragBuilder->codeAppend("} else ");
143 } else {
144 args.fFragBuilder->codeAppend("}");
145 }
146 }
147 }
148
149 #endif
150