1 /*
2 * Copyright 2022 Google LLC
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 #include "src/gpu/graphite/render/SDFTextRenderStep.h"
9
10 #include "include/core/SkM44.h"
11 #include "include/core/SkRefCnt.h"
12 #include "include/core/SkSamplingOptions.h"
13 #include "include/core/SkSize.h"
14 #include "include/core/SkTileMode.h"
15 #include "include/gpu/graphite/Recorder.h"
16 #include "include/private/base/SkAssert.h"
17 #include "include/private/base/SkDebug.h"
18 #include "src/base/SkEnumBitMask.h"
19 #include "src/core/SkSLTypeShared.h"
20 #include "src/gpu/graphite/AtlasProvider.h"
21 #include "src/gpu/graphite/Attribute.h"
22 #include "src/gpu/graphite/ContextUtils.h"
23 #include "src/gpu/graphite/DrawOrder.h"
24 #include "src/gpu/graphite/DrawParams.h"
25 #include "src/gpu/graphite/DrawTypes.h"
26 #include "src/gpu/graphite/PipelineData.h"
27 #include "src/gpu/graphite/RecorderPriv.h"
28 #include "src/gpu/graphite/TextureProxy.h"
29 #include "src/gpu/graphite/geom/Geometry.h"
30 #include "src/gpu/graphite/geom/SubRunData.h"
31 #include "src/gpu/graphite/geom/Transform_graphite.h"
32 #include "src/gpu/graphite/render/CommonDepthStencilSettings.h"
33 #include "src/gpu/graphite/text/TextAtlasManager.h"
34 #include "src/sksl/SkSLString.h"
35 #include "src/text/gpu/SubRunContainer.h"
36 #include "src/text/gpu/VertexFiller.h"
37
38 #include <string_view>
39
40 #if defined(SK_GAMMA_APPLY_TO_A8)
41 #include "include/private/base/SkCPUTypes.h"
42 #include "src/core/SkMaskGamma.h"
43 #include "src/text/gpu/DistanceFieldAdjustTable.h"
44 #endif
45
46 namespace skgpu::graphite {
47
48 namespace {
49
50 // We are expecting to sample from up to 4 textures
51 constexpr int kNumSDFAtlasTextures = 4;
52
53 } // namespace
54
SDFTextRenderStep()55 SDFTextRenderStep::SDFTextRenderStep()
56 : RenderStep("SDFTextRenderStep",
57 "",
58 Flags::kPerformsShading | Flags::kHasTextures | Flags::kEmitsCoverage,
59 /*uniforms=*/{{"subRunDeviceMatrix", SkSLType::kFloat4x4},
60 {"deviceToLocal", SkSLType::kFloat4x4},
61 {"atlasSizeInv", SkSLType::kFloat2},
62 {"gammaParams", SkSLType::kHalf2}},
63 PrimitiveType::kTriangleStrip,
64 kDirectDepthGEqualPass,
65 /*vertexAttrs=*/ {},
66 /*instanceAttrs=*/
67 {{"size", VertexAttribType::kUShort2, SkSLType::kUShort2},
68 {"uvPos", VertexAttribType::kUShort2, SkSLType::kUShort2},
69 {"xyPos", VertexAttribType::kFloat2, SkSLType::kFloat2},
70 {"indexAndFlags", VertexAttribType::kUShort2, SkSLType::kUShort2},
71 {"strikeToSourceScale", VertexAttribType::kFloat, SkSLType::kFloat},
72 {"depth", VertexAttribType::kFloat, SkSLType::kFloat},
73 {"ssboIndices", VertexAttribType::kUInt2, SkSLType::kUInt2}},
74 /*varyings=*/
75 {{"unormTexCoords", SkSLType::kFloat2},
76 {"textureCoords", SkSLType::kFloat2},
77 {"texIndex", SkSLType::kFloat}}) {}
78
~SDFTextRenderStep()79 SDFTextRenderStep::~SDFTextRenderStep() {}
80
vertexSkSL() const81 std::string SDFTextRenderStep::vertexSkSL() const {
82 // Returns the body of a vertex function, which must define a float4 devPosition variable and
83 // must write to an already-defined float2 stepLocalCoords variable.
84 return "texIndex = half(indexAndFlags.x);"
85 "float4 devPosition = text_vertex_fn(float2(sk_VertexID >> 1, sk_VertexID & 1), "
86 "subRunDeviceMatrix, "
87 "deviceToLocal, "
88 "atlasSizeInv, "
89 "float2(size), "
90 "float2(uvPos), "
91 "xyPos, "
92 "strikeToSourceScale, "
93 "depth, "
94 "textureCoords, "
95 "unormTexCoords, "
96 "stepLocalCoords);";
97 }
98
texturesAndSamplersSkSL(const ResourceBindingRequirements & bindingReqs,int * nextBindingIndex) const99 std::string SDFTextRenderStep::texturesAndSamplersSkSL(
100 const ResourceBindingRequirements& bindingReqs, int* nextBindingIndex) const {
101 std::string result;
102
103 for (unsigned int i = 0; i < kNumSDFAtlasTextures; ++i) {
104 result += EmitSamplerLayout(bindingReqs, nextBindingIndex);
105 SkSL::String::appendf(&result, " sampler2D sdf_atlas_%u;\n", i);
106 }
107
108 return result;
109 }
110
fragmentCoverageSkSL() const111 const char* SDFTextRenderStep::fragmentCoverageSkSL() const {
112 // The returned SkSL must write its coverage into a 'half4 outputCoverage' variable (defined in
113 // the calling code) with the actual coverage splatted out into all four channels.
114
115 // TODO: To minimize the number of shaders generated this is the full affine shader.
116 // For best performance it may be worth creating the uniform scale shader as well,
117 // as that's the most common case.
118 // TODO: Need to add 565 support.
119 // TODO: Need aliased and possibly sRGB support.
120 static_assert(kNumSDFAtlasTextures == 4);
121 return "outputCoverage = sdf_text_coverage_fn(sample_indexed_atlas(textureCoords, "
122 "int(texIndex), "
123 "sdf_atlas_0, "
124 "sdf_atlas_1, "
125 "sdf_atlas_2, "
126 "sdf_atlas_3).r, "
127 "gammaParams, "
128 "unormTexCoords);";
129 }
130
writeVertices(DrawWriter * dw,const DrawParams & params,skvx::uint2 ssboIndices) const131 void SDFTextRenderStep::writeVertices(DrawWriter* dw,
132 const DrawParams& params,
133 skvx::uint2 ssboIndices) const {
134 const SubRunData& subRunData = params.geometry().subRunData();
135 subRunData.subRun()->vertexFiller().fillInstanceData(dw,
136 subRunData.startGlyphIndex(),
137 subRunData.glyphCount(),
138 subRunData.subRun()->instanceFlags(),
139 ssboIndices,
140 subRunData.subRun()->glyphs(),
141 params.order().depthAsFloat());
142 }
143
writeUniformsAndTextures(const DrawParams & params,PipelineDataGatherer * gatherer) const144 void SDFTextRenderStep::writeUniformsAndTextures(const DrawParams& params,
145 PipelineDataGatherer* gatherer) const {
146 SkDEBUGCODE(UniformExpectationsValidator uev(gatherer, this->uniforms());)
147
148 const SubRunData& subRunData = params.geometry().subRunData();
149 unsigned int numProxies;
150 Recorder* recorder = subRunData.recorder();
151 const sk_sp<TextureProxy>* proxies =
152 recorder->priv().atlasProvider()->textAtlasManager()->getProxies(
153 subRunData.subRun()->maskFormat(), &numProxies);
154 SkASSERT(proxies && numProxies > 0);
155
156 // write uniforms
157 gatherer->write(params.transform().matrix()); // subRunDeviceMatrix
158 gatherer->write(subRunData.deviceToLocal());
159 SkV2 atlasDimensionsInverse = {1.f/proxies[0]->dimensions().width(),
160 1.f/proxies[0]->dimensions().height()};
161 gatherer->write(atlasDimensionsInverse);
162
163 float gammaAdjustment = 0;
164 // TODO: generate LCD adjustment
165 #if defined(SK_GAMMA_APPLY_TO_A8)
166 auto dfAdjustTable = sktext::gpu::DistanceFieldAdjustTable::Get();
167 // TODO: don't do this for aliased text
168 U8CPU lum = SkColorSpaceLuminance::computeLuminance(SK_GAMMA_EXPONENT,
169 subRunData.luminanceColor());
170 gammaAdjustment = dfAdjustTable->getAdjustment(lum, subRunData.useGammaCorrectDistanceTable());
171 #endif
172 SkV2 gammaParams = {gammaAdjustment, subRunData.useGammaCorrectDistanceTable() ? 1.f : 0.f};
173 gatherer->writeHalf(gammaParams);
174
175 // write textures and samplers
176 for (unsigned int i = 0; i < numProxies; ++i) {
177 gatherer->add(proxies[i], {SkFilterMode::kLinear, SkTileMode::kClamp});
178 }
179 // If the atlas has less than 4 active proxies we still need to set up samplers for the shader.
180 for (unsigned int i = numProxies; i < kNumSDFAtlasTextures; ++i) {
181 gatherer->add(proxies[0], {SkFilterMode::kLinear, SkTileMode::kClamp});
182 }
183 }
184
185 } // namespace skgpu::graphite
186