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 #include "GrCCPathProcessor.h"
9
10 #include "GrOnFlushResourceProvider.h"
11 #include "GrTexture.h"
12 #include "glsl/GrGLSLFragmentShaderBuilder.h"
13 #include "glsl/GrGLSLGeometryProcessor.h"
14 #include "glsl/GrGLSLProgramBuilder.h"
15 #include "glsl/GrGLSLVarying.h"
16
17 // Slightly undershoot an AA bloat radius of 0.5 so vertices that fall on integer boundaries don't
18 // accidentally reach into neighboring path masks within the atlas.
19 constexpr float kAABloatRadius = 0.491111f;
20
21 // Paths are drawn as octagons. Each point on the octagon is the intersection of two lines: one edge
22 // from the path's bounding box and one edge from its 45-degree bounding box. The below inputs
23 // define a vertex by the two edges that need to be intersected. Normals point out of the octagon,
24 // and the bounding boxes are sent in as instance attribs.
25 static constexpr float kOctoEdgeNorms[8 * 4] = {
26 // bbox // bbox45
27 -1, 0, -1,+1,
28 -1, 0, -1,-1,
29 0,-1, -1,-1,
30 0,-1, +1,-1,
31 +1, 0, +1,-1,
32 +1, 0, +1,+1,
33 0,+1, +1,+1,
34 0,+1, -1,+1,
35 };
36
37 GR_DECLARE_STATIC_UNIQUE_KEY(gVertexBufferKey);
38
FindVertexBuffer(GrOnFlushResourceProvider * onFlushRP)39 sk_sp<const GrBuffer> GrCCPathProcessor::FindVertexBuffer(GrOnFlushResourceProvider* onFlushRP) {
40 GR_DEFINE_STATIC_UNIQUE_KEY(gVertexBufferKey);
41 return onFlushRP->findOrMakeStaticBuffer(kVertex_GrBufferType, sizeof(kOctoEdgeNorms),
42 kOctoEdgeNorms, gVertexBufferKey);
43 }
44
45 static constexpr uint16_t kRestartStrip = 0xffff;
46
47 static constexpr uint16_t kOctoIndicesAsStrips[] = {
48 1, 0, 2, 4, 3, kRestartStrip, // First half.
49 5, 4, 6, 0, 7 // Second half.
50 };
51
52 static constexpr uint16_t kOctoIndicesAsTris[] = {
53 // First half.
54 1, 0, 2,
55 0, 4, 2,
56 2, 4, 3,
57
58 // Second half.
59 5, 4, 6,
60 4, 0, 6,
61 6, 0, 7,
62 };
63
64 GR_DECLARE_STATIC_UNIQUE_KEY(gIndexBufferKey);
65
FindIndexBuffer(GrOnFlushResourceProvider * onFlushRP)66 sk_sp<const GrBuffer> GrCCPathProcessor::FindIndexBuffer(GrOnFlushResourceProvider* onFlushRP) {
67 GR_DEFINE_STATIC_UNIQUE_KEY(gIndexBufferKey);
68 if (onFlushRP->caps()->usePrimitiveRestart()) {
69 return onFlushRP->findOrMakeStaticBuffer(kIndex_GrBufferType, sizeof(kOctoIndicesAsStrips),
70 kOctoIndicesAsStrips, gIndexBufferKey);
71 } else {
72 return onFlushRP->findOrMakeStaticBuffer(kIndex_GrBufferType, sizeof(kOctoIndicesAsTris),
73 kOctoIndicesAsTris, gIndexBufferKey);
74 }
75 }
76
NumIndicesPerInstance(const GrCaps & caps)77 int GrCCPathProcessor::NumIndicesPerInstance(const GrCaps& caps) {
78 return caps.usePrimitiveRestart() ? SK_ARRAY_COUNT(kOctoIndicesAsStrips)
79 : SK_ARRAY_COUNT(kOctoIndicesAsTris);
80 }
81
GrCCPathProcessor(GrResourceProvider * resourceProvider,sk_sp<GrTextureProxy> atlas,SkPath::FillType fillType)82 GrCCPathProcessor::GrCCPathProcessor(GrResourceProvider* resourceProvider,
83 sk_sp<GrTextureProxy> atlas, SkPath::FillType fillType)
84 : INHERITED(kGrCCPathProcessor_ClassID)
85 , fFillType(fillType)
86 , fAtlasAccess(std::move(atlas), GrSamplerState::Filter::kNearest,
87 GrSamplerState::WrapMode::kClamp, kFragment_GrShaderFlag) {
88 this->addInstanceAttrib("devbounds", kFloat4_GrVertexAttribType);
89 this->addInstanceAttrib("devbounds45", kFloat4_GrVertexAttribType);
90 this->addInstanceAttrib("view_matrix", kFloat4_GrVertexAttribType);
91 this->addInstanceAttrib("view_translate", kFloat2_GrVertexAttribType);
92 this->addInstanceAttrib("atlas_offset", kShort2_GrVertexAttribType);
93 this->addInstanceAttrib("color", kUByte4_norm_GrVertexAttribType);
94
95 SkASSERT(offsetof(Instance, fDevBounds) ==
96 this->getInstanceAttrib(InstanceAttribs::kDevBounds).fOffsetInRecord);
97 SkASSERT(offsetof(Instance, fDevBounds45) ==
98 this->getInstanceAttrib(InstanceAttribs::kDevBounds45).fOffsetInRecord);
99 SkASSERT(offsetof(Instance, fViewMatrix) ==
100 this->getInstanceAttrib(InstanceAttribs::kViewMatrix).fOffsetInRecord);
101 SkASSERT(offsetof(Instance, fViewTranslate) ==
102 this->getInstanceAttrib(InstanceAttribs::kViewTranslate).fOffsetInRecord);
103 SkASSERT(offsetof(Instance, fAtlasOffset) ==
104 this->getInstanceAttrib(InstanceAttribs::kAtlasOffset).fOffsetInRecord);
105 SkASSERT(offsetof(Instance, fColor) ==
106 this->getInstanceAttrib(InstanceAttribs::kColor).fOffsetInRecord);
107 SkASSERT(sizeof(Instance) == this->getInstanceStride());
108
109 GR_STATIC_ASSERT(6 == kNumInstanceAttribs);
110
111 this->addVertexAttrib("edge_norms", kFloat4_GrVertexAttribType);
112
113 fAtlasAccess.instantiate(resourceProvider);
114 this->addTextureSampler(&fAtlasAccess);
115
116 if (resourceProvider->caps()->usePrimitiveRestart()) {
117 this->setWillUsePrimitiveRestart();
118 }
119 }
120
getGLSLProcessorKey(const GrShaderCaps &,GrProcessorKeyBuilder * b) const121 void GrCCPathProcessor::getGLSLProcessorKey(const GrShaderCaps&, GrProcessorKeyBuilder* b) const {
122 b->add32((fFillType << 16) | this->atlasProxy()->origin());
123 }
124
125 class GLSLPathProcessor : public GrGLSLGeometryProcessor {
126 public:
127 void onEmitCode(EmitArgs& args, GrGPArgs* gpArgs) override;
128
129 private:
setData(const GrGLSLProgramDataManager & pdman,const GrPrimitiveProcessor & primProc,FPCoordTransformIter && transformIter)130 void setData(const GrGLSLProgramDataManager& pdman, const GrPrimitiveProcessor& primProc,
131 FPCoordTransformIter&& transformIter) override {
132 const GrCCPathProcessor& proc = primProc.cast<GrCCPathProcessor>();
133 pdman.set2f(fAtlasAdjustUniform, 1.0f / proc.atlas()->width(),
134 1.0f / proc.atlas()->height());
135 this->setTransformDataHelper(SkMatrix::I(), pdman, &transformIter);
136 }
137
138 GrGLSLUniformHandler::UniformHandle fAtlasAdjustUniform;
139
140 typedef GrGLSLGeometryProcessor INHERITED;
141 };
142
createGLSLInstance(const GrShaderCaps &) const143 GrGLSLPrimitiveProcessor* GrCCPathProcessor::createGLSLInstance(const GrShaderCaps&) const {
144 return new GLSLPathProcessor();
145 }
146
onEmitCode(EmitArgs & args,GrGPArgs * gpArgs)147 void GLSLPathProcessor::onEmitCode(EmitArgs& args, GrGPArgs* gpArgs) {
148 using InstanceAttribs = GrCCPathProcessor::InstanceAttribs;
149 using Interpolation = GrGLSLVaryingHandler::Interpolation;
150
151 const GrCCPathProcessor& proc = args.fGP.cast<GrCCPathProcessor>();
152 GrGLSLUniformHandler* uniHandler = args.fUniformHandler;
153 GrGLSLVaryingHandler* varyingHandler = args.fVaryingHandler;
154
155 const char* atlasAdjust;
156 fAtlasAdjustUniform = uniHandler->addUniform(
157 kVertex_GrShaderFlag,
158 kFloat2_GrSLType, "atlas_adjust", &atlasAdjust);
159
160 varyingHandler->emitAttributes(proc);
161
162 GrGLSLVarying texcoord(kFloat2_GrSLType);
163 GrGLSLVarying color(kHalf4_GrSLType);
164 varyingHandler->addVarying("texcoord", &texcoord);
165 varyingHandler->addPassThroughAttribute(&proc.getInstanceAttrib(InstanceAttribs::kColor),
166 args.fOutputColor, Interpolation::kCanBeFlat);
167
168 // The vertex shader bloats and intersects the devBounds and devBounds45 rectangles, in order to
169 // find an octagon that circumscribes the (bloated) path.
170 GrGLSLVertexBuilder* v = args.fVertBuilder;
171
172 // Each vertex is the intersection of one edge from devBounds and one from devBounds45.
173 // 'N' holds the normals to these edges as column vectors.
174 //
175 // NOTE: "float2x2(float4)" is valid and equivalent to "float2x2(float4.xy, float4.zw)",
176 // however Intel compilers crash when we use the former syntax in this shader.
177 v->codeAppendf("float2x2 N = float2x2(%s.xy, %s.zw);",
178 proc.getEdgeNormsAttrib().fName, proc.getEdgeNormsAttrib().fName);
179
180 // N[0] is the normal for the edge we are intersecting from the regular bounding box, pointing
181 // out of the octagon.
182 v->codeAppendf("float2 refpt = float2[2](%s.xy, %s.zw)[sk_VertexID >> 2];",
183 proc.getInstanceAttrib(InstanceAttribs::kDevBounds).fName,
184 proc.getInstanceAttrib(InstanceAttribs::kDevBounds).fName);
185 v->codeAppendf("refpt += N[0] * %f;", kAABloatRadius); // bloat for AA.
186
187 // N[1] is the normal for the edge we are intersecting from the 45-degree bounding box, pointing
188 // out of the octagon.
189 v->codeAppendf("float2 refpt45 = float2[2](%s.xy, %s.zw)[((sk_VertexID + 1) >> 2) & 1];",
190 proc.getInstanceAttrib(InstanceAttribs::kDevBounds45).fName,
191 proc.getInstanceAttrib(InstanceAttribs::kDevBounds45).fName);
192 v->codeAppendf("refpt45 *= float2x2(.5,.5,-.5,.5);"); // transform back to device space.
193 v->codeAppendf("refpt45 += N[1] * %f;", kAABloatRadius); // bloat for AA.
194
195 v->codeAppend ("float2 K = float2(dot(N[0], refpt), dot(N[1], refpt45));");
196 v->codeAppendf("float2 octocoord = K * inverse(N);");
197
198 gpArgs->fPositionVar.set(kFloat2_GrSLType, "octocoord");
199
200 // Convert to atlas coordinates in order to do our texture lookup.
201 v->codeAppendf("float2 atlascoord = octocoord + float2(%s);",
202 proc.getInstanceAttrib(InstanceAttribs::kAtlasOffset).fName);
203 if (kTopLeft_GrSurfaceOrigin == proc.atlasProxy()->origin()) {
204 v->codeAppendf("%s = atlascoord * %s;", texcoord.vsOut(), atlasAdjust);
205 } else {
206 SkASSERT(kBottomLeft_GrSurfaceOrigin == proc.atlasProxy()->origin());
207 v->codeAppendf("%s = float2(atlascoord.x * %s.x, 1 - atlascoord.y * %s.y);",
208 texcoord.vsOut(), atlasAdjust, atlasAdjust);
209 }
210
211 // Convert to path/local cordinates.
212 v->codeAppendf("float2x2 viewmatrix = float2x2(%s.xy, %s.zw);", // float2x2(float4) busts Intel.
213 proc.getInstanceAttrib(InstanceAttribs::kViewMatrix).fName,
214 proc.getInstanceAttrib(InstanceAttribs::kViewMatrix).fName);
215 v->codeAppendf("float2 pathcoord = inverse(viewmatrix) * (octocoord - %s);",
216 proc.getInstanceAttrib(InstanceAttribs::kViewTranslate).fName);
217
218 this->emitTransforms(v, varyingHandler, uniHandler, GrShaderVar("pathcoord", kFloat2_GrSLType),
219 args.fFPCoordTransformHandler);
220
221 // Fragment shader.
222 GrGLSLFPFragmentBuilder* f = args.fFragBuilder;
223
224 f->codeAppend ("half coverage_count = ");
225 f->appendTextureLookup(args.fTexSamplers[0], texcoord.fsIn(), kFloat2_GrSLType);
226 f->codeAppend (".a;");
227
228 if (SkPath::kWinding_FillType == proc.fillType()) {
229 f->codeAppendf("%s = half4(min(abs(coverage_count), 1));", args.fOutputCoverage);
230 } else {
231 SkASSERT(SkPath::kEvenOdd_FillType == proc.fillType());
232 f->codeAppend ("half t = mod(abs(coverage_count), 2);");
233 f->codeAppendf("%s = half4(1 - abs(t - 1));", args.fOutputCoverage);
234 }
235 }
236