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 "src/gpu/ccpr/GrCCPathProcessor.h"
9
10#include "src/gpu/GrOnFlushResourceProvider.h"
11#include "src/gpu/GrOpsRenderPass.h"
12#include "src/gpu/GrTexture.h"
13#include "src/gpu/GrTexturePriv.h"
14#include "src/gpu/ccpr/GrCCPerFlushResources.h"
15#include "src/gpu/glsl/GrGLSLFragmentShaderBuilder.h"
16#include "src/gpu/glsl/GrGLSLGeometryProcessor.h"
17#include "src/gpu/glsl/GrGLSLProgramBuilder.h"
18#include "src/gpu/glsl/GrGLSLVarying.h"
19
20// Paths are drawn as octagons. Each point on the octagon is the intersection of two lines: one edge
21// from the path's bounding box and one edge from its 45-degree bounding box. The selectors
22// below indicate one corner from the bounding box, paired with a corner from the 45-degree bounding
23// box. The octagon vertex is the point that lies between these two corners, found by intersecting
24// their edges.
25static constexpr float kOctoEdgeNorms[8*4] = {
26 // bbox // bbox45
27 0,0, 0,0,
28 0,0, 1,0,
29 1,0, 1,0,
30 1,0, 1,1,
31 1,1, 1,1,
32 1,1, 0,1,
33 0,1, 0,1,
34 0,1, 0,0,
35};
36
37GR_DECLARE_STATIC_UNIQUE_KEY(gVertexBufferKey);
38
39sk_sp<const GrGpuBuffer> GrCCPathProcessor::FindVertexBuffer(GrOnFlushResourceProvider* onFlushRP) {
40 GR_DEFINE_STATIC_UNIQUE_KEY(gVertexBufferKey);
41 return onFlushRP->findOrMakeStaticBuffer(GrGpuBufferType::kVertex, sizeof(kOctoEdgeNorms),
42 kOctoEdgeNorms, gVertexBufferKey);
43}
44
45static constexpr uint16_t kRestartStrip = 0xffff;
46
47static constexpr uint16_t kOctoIndicesAsStrips[] = {
48 3, 4, 2, 0, 1, kRestartStrip, // First half.
49 7, 0, 6, 4, 5 // Second half.
50};
51
52static constexpr uint16_t kOctoIndicesAsTris[] = {
53 // First half.
54 3, 4, 2,
55 4, 0, 2,
56 2, 0, 1,
57
58 // Second half.
59 7, 0, 6,
60 0, 4, 6,
61 6, 4, 5,
62};
63
64GR_DECLARE_STATIC_UNIQUE_KEY(gIndexBufferKey);
65
66constexpr GrPrimitiveProcessor::Attribute GrCCPathProcessor::kInstanceAttribs[];
67constexpr GrPrimitiveProcessor::Attribute GrCCPathProcessor::kCornersAttrib;
68
69sk_sp<const GrGpuBuffer> GrCCPathProcessor::FindIndexBuffer(GrOnFlushResourceProvider* onFlushRP) {
70 GR_DEFINE_STATIC_UNIQUE_KEY(gIndexBufferKey);
71 if (onFlushRP->caps()->usePrimitiveRestart()) {
72 return onFlushRP->findOrMakeStaticBuffer(GrGpuBufferType::kIndex,
73 sizeof(kOctoIndicesAsStrips), kOctoIndicesAsStrips,
74 gIndexBufferKey);
75 } else {
76 return onFlushRP->findOrMakeStaticBuffer(GrGpuBufferType::kIndex,
77 sizeof(kOctoIndicesAsTris), kOctoIndicesAsTris,
78 gIndexBufferKey);
79 }
80}
81
82GrCCPathProcessor::GrCCPathProcessor(CoverageMode coverageMode, const GrTexture* atlasTexture,
83 const GrSwizzle& swizzle, GrSurfaceOrigin atlasOrigin,
84 const SkMatrix& viewMatrixIfUsingLocalCoords)
85 : INHERITED(kGrCCPathProcessor_ClassID)
86 , fCoverageMode(coverageMode)
87 , fAtlasAccess(GrSamplerState::Filter::kNearest, atlasTexture->backendFormat(), swizzle)
88 , fAtlasDimensions(atlasTexture->dimensions())
89 , fAtlasOrigin(atlasOrigin) {
90 // TODO: Can we just assert that atlas has GrCCAtlas::kTextureOrigin and remove fAtlasOrigin?
91 this->setInstanceAttributes(kInstanceAttribs, SK_ARRAY_COUNT(kInstanceAttribs));
92 SkASSERT(this->instanceStride() == sizeof(Instance));
93
94 this->setVertexAttributes(&kCornersAttrib, 1);
95 this->setTextureSamplerCnt(1);
96
97 if (!viewMatrixIfUsingLocalCoords.invert(&fLocalMatrix)) {
98 fLocalMatrix.setIdentity();
99 }
100}
101
102class GrCCPathProcessor::Impl : public GrGLSLGeometryProcessor {
103public:
104 void onEmitCode(EmitArgs& args, GrGPArgs* gpArgs) override;
105
106private:
107 void setData(const GrGLSLProgramDataManager& pdman, const GrPrimitiveProcessor& primProc,
108 const CoordTransformRange& transformRange) override {
109 const auto& proc = primProc.cast<GrCCPathProcessor>();
110 pdman.set2f(fAtlasAdjustUniform,
111 1.0f / proc.fAtlasDimensions.fWidth,
112 1.0f / proc.fAtlasDimensions.fHeight);
113 this->setTransformDataHelper(proc.fLocalMatrix, pdman, transformRange);
114 }
115
116 GrGLSLUniformHandler::UniformHandle fAtlasAdjustUniform;
117
118 typedef GrGLSLGeometryProcessor INHERITED;
119};
120
121GrGLSLPrimitiveProcessor* GrCCPathProcessor::createGLSLInstance(const GrShaderCaps&) const {
122 return new Impl();
123}
124
125void GrCCPathProcessor::drawPaths(GrOpFlushState* flushState, const GrPipeline& pipeline,
126 const GrSurfaceProxy& atlasProxy,
127 const GrCCPerFlushResources& resources, int baseInstance,
128 int endInstance, const SkRect& bounds) const {
129 const GrCaps& caps = flushState->caps();
130 GrPrimitiveType primitiveType = caps.usePrimitiveRestart()
131 ? GrPrimitiveType::kTriangleStrip
132 : GrPrimitiveType::kTriangles;
133 int numIndicesPerInstance = caps.usePrimitiveRestart()
134 ? SK_ARRAY_COUNT(kOctoIndicesAsStrips)
135 : SK_ARRAY_COUNT(kOctoIndicesAsTris);
136 auto enablePrimitiveRestart = GrPrimitiveRestart(flushState->caps().usePrimitiveRestart());
137
138 GrRenderTargetProxy* rtProxy = flushState->proxy();
139 GrProgramInfo programInfo(rtProxy->numSamples(), rtProxy->numStencilSamples(),
140 rtProxy->backendFormat(), flushState->writeView()->origin(),
141 &pipeline, this, primitiveType);
142
143 flushState->bindPipelineAndScissorClip(programInfo, bounds);
144 flushState->bindTextures(*this, atlasProxy, pipeline);
145 flushState->bindBuffers(resources.indexBuffer(), resources.instanceBuffer(),
146 resources.vertexBuffer(), enablePrimitiveRestart);
147 flushState->drawIndexedInstanced(numIndicesPerInstance, 0, endInstance - baseInstance,
148 baseInstance, 0);
149}
150
151void GrCCPathProcessor::Impl::onEmitCode(EmitArgs& args, GrGPArgs* gpArgs) {
152 using Interpolation = GrGLSLVaryingHandler::Interpolation;
153
154 const GrCCPathProcessor& proc = args.fGP.cast<GrCCPathProcessor>();
155 GrGLSLUniformHandler* uniHandler = args.fUniformHandler;
156 GrGLSLVaryingHandler* varyingHandler = args.fVaryingHandler;
157 bool isCoverageCount = (CoverageMode::kCoverageCount == proc.fCoverageMode);
158
159 const char* atlasAdjust;
160 fAtlasAdjustUniform = uniHandler->addUniform(
161 nullptr, kVertex_GrShaderFlag, kFloat2_GrSLType, "atlas_adjust", &atlasAdjust);
162
163 varyingHandler->emitAttributes(proc);
164
165 GrGLSLVarying texcoord((isCoverageCount) ? kFloat3_GrSLType : kFloat2_GrSLType);
166 varyingHandler->addVarying("texcoord", &texcoord);
167
168 GrGLSLVarying color(kHalf4_GrSLType);
169 varyingHandler->addPassThroughAttribute(
170 kInstanceAttribs[kColorAttribIdx], args.fOutputColor, Interpolation::kCanBeFlat);
171
172 // The vertex shader bloats and intersects the devBounds and devBounds45 rectangles, in order to
173 // find an octagon that circumscribes the (bloated) path.
174 GrGLSLVertexBuilder* v = args.fVertBuilder;
175
176 // Are we clockwise? (Positive wind => nonzero fill rule.)
177 // Or counter-clockwise? (negative wind => even/odd fill rule.)
178 v->codeAppendf("float wind = sign(devbounds.z - devbounds.x);");
179
180 // Find our reference corner from the device-space bounding box.
181 v->codeAppendf("float2 refpt = mix(devbounds.xy, devbounds.zw, corners.xy);");
182
183 // Find our reference corner from the 45-degree bounding box.
184 v->codeAppendf("float2 refpt45 = mix(devbounds45.xy, devbounds45.zw, corners.zw);");
185 // Transform back to device space.
186 v->codeAppendf("refpt45 *= float2x2(+1, +1, -wind, +wind) * .5;");
187
188 // Find the normals to each edge, then intersect them to find our octagon vertex.
189 v->codeAppendf("float2x2 N = float2x2("
190 "corners.z + corners.w - 1, corners.w - corners.z, "
191 "corners.xy*2 - 1);");
192 v->codeAppendf("N = float2x2(wind, 0, 0, 1) * N;");
193 v->codeAppendf("float2 K = float2(dot(N[0], refpt), dot(N[1], refpt45));");
194 v->codeAppendf("float2 octocoord = K * inverse(N);");
195
196 // Round the octagon out to ensure we rasterize every pixel the path might touch. (Positive
197 // bloatdir means we should take the "ceil" and negative means to take the "floor".)
198 //
199 // NOTE: If we were just drawing a rect, ceil/floor would be enough. But since there are also
200 // diagonals in the octagon that cross through pixel centers, we need to outset by another
201 // quarter px to ensure those pixels get rasterized.
202 v->codeAppendf("float2 bloatdir = (0 != N[0].x) "
203 "? float2(N[0].x, N[1].y)"
204 ": float2(N[1].x, N[0].y);");
205 v->codeAppendf("octocoord = (ceil(octocoord * bloatdir - 1e-4) + 0.25) * bloatdir;");
206 v->codeAppendf("float2 atlascoord = octocoord + float2(dev_to_atlas_offset);");
207
208 // Convert to atlas coordinates in order to do our texture lookup.
209 if (kTopLeft_GrSurfaceOrigin == proc.fAtlasOrigin) {
210 v->codeAppendf("%s.xy = atlascoord * %s;", texcoord.vsOut(), atlasAdjust);
211 } else {
212 SkASSERT(kBottomLeft_GrSurfaceOrigin == proc.fAtlasOrigin);
213 v->codeAppendf("%s.xy = float2(atlascoord.x * %s.x, 1 - atlascoord.y * %s.y);",
214 texcoord.vsOut(), atlasAdjust, atlasAdjust);
215 }
216 if (isCoverageCount) {
217 v->codeAppendf("%s.z = wind * .5;", texcoord.vsOut());
218 }
219
220 gpArgs->fPositionVar.set(kFloat2_GrSLType, "octocoord");
221 this->emitTransforms(v, varyingHandler, uniHandler, gpArgs->fPositionVar, proc.fLocalMatrix,
222 args.fFPCoordTransformHandler);
223
224 // Fragment shader.
225 GrGLSLFPFragmentBuilder* f = args.fFragBuilder;
226
227 // Look up coverage in the atlas.
228 f->codeAppendf("half coverage = ");
229 f->appendTextureLookup(args.fTexSamplers[0], SkStringPrintf("%s.xy", texcoord.fsIn()).c_str());
230 f->codeAppendf(".a;");
231
232 if (isCoverageCount) {
233 f->codeAppendf("coverage = abs(coverage);");
234
235 // Scale coverage count by .5. Make it negative for even-odd paths and positive for
236 // winding ones. Clamp winding coverage counts at 1.0 (i.e. min(coverage/2, .5)).
237 f->codeAppendf("coverage = min(abs(coverage) * half(%s.z), .5);", texcoord.fsIn());
238
239 // For negative values, this finishes the even-odd sawtooth function. Since positive
240 // (winding) values were clamped at "coverage/2 = .5", this only undoes the previous
241 // multiply by .5.
242 f->codeAppend ("coverage = 1 - abs(fract(coverage) * 2 - 1);");
243 }
244
245 f->codeAppendf("%s = half4(coverage);", args.fOutputCoverage);
246}
247