/src/skia/src/gpu/tessellate/GrStrokeHardwareTessellator.cpp
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1 | | /* |
2 | | * Copyright 2020 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/tessellate/GrStrokeHardwareTessellator.h" |
9 | | |
10 | | #include "src/core/SkMathPriv.h" |
11 | | #include "src/core/SkPathPriv.h" |
12 | | #include "src/gpu/GrMeshDrawTarget.h" |
13 | | #include "src/gpu/GrRecordingContextPriv.h" |
14 | | #include "src/gpu/GrVx.h" |
15 | | #include "src/gpu/geometry/GrPathUtils.h" |
16 | | #include "src/gpu/geometry/GrWangsFormula.h" |
17 | | #include "src/gpu/tessellate/GrCullTest.h" |
18 | | |
19 | | namespace { |
20 | | |
21 | 0 | static float num_combined_segments(float numParametricSegments, float numRadialSegments) { |
22 | | // The first and last edges are shared by both the parametric and radial sets of edges, so |
23 | | // the total number of edges is: |
24 | | // |
25 | | // numCombinedEdges = numParametricEdges + numRadialEdges - 2 |
26 | | // |
27 | | // It's also important to differentiate between the number of edges and segments in a strip: |
28 | | // |
29 | | // numCombinedSegments = numCombinedEdges - 1 |
30 | | // |
31 | | // So the total number of segments in the combined strip is: |
32 | | // |
33 | | // numCombinedSegments = numParametricEdges + numRadialEdges - 2 - 1 |
34 | | // = numParametricSegments + 1 + numRadialSegments + 1 - 2 - 1 |
35 | | // = numParametricSegments + numRadialSegments - 1 |
36 | | // |
37 | 0 | return numParametricSegments + numRadialSegments - 1; |
38 | 0 | } |
39 | | |
40 | 0 | static grvx::float2 pow4(grvx::float2 x) { |
41 | 0 | auto xx = x*x; |
42 | 0 | return xx*xx; |
43 | 0 | } |
44 | | |
45 | | class PatchWriter { |
46 | | public: |
47 | | using ShaderFlags = GrStrokeTessellator::ShaderFlags; |
48 | | |
49 | | enum class JoinType { |
50 | | kMiter = SkPaint::kMiter_Join, |
51 | | kRound = SkPaint::kRound_Join, |
52 | | kBevel = SkPaint::kBevel_Join, |
53 | | kBowtie = SkPaint::kLast_Join + 1 // Double sided round join. |
54 | | }; |
55 | | |
56 | | PatchWriter(ShaderFlags shaderFlags, GrMeshDrawTarget* target, |
57 | | const SkRect& strokeCullBounds, const SkMatrix& viewMatrix, float matrixMaxScale, |
58 | | GrVertexChunkArray* patchChunks, size_t patchStride, int minPatchesPerChunk) |
59 | | : fShaderFlags(shaderFlags) |
60 | | , fCullTest(strokeCullBounds, viewMatrix) |
61 | | , fChunkBuilder(target, patchChunks, patchStride, minPatchesPerChunk) |
62 | | // Subtract 2 because the tessellation shader chops every cubic at two locations, and |
63 | | // each chop has the potential to introduce an extra segment. |
64 | | , fMaxTessellationSegments(target->caps().shaderCaps()->maxTessellationSegments() - 2) |
65 | 0 | , fParametricPrecision(GrStrokeTolerances::CalcParametricPrecision(matrixMaxScale)) { |
66 | 0 | } |
67 | | |
68 | | // This is the precision value, adjusted for the view matrix, to use with Wang's formulas when |
69 | | // determining how many parametric segments a curve will require. |
70 | 0 | float parametricPrecision() const { |
71 | 0 | return fParametricPrecision; |
72 | 0 | } |
73 | | // Will a line and worst-case previous join both fit in a single patch together? |
74 | 0 | bool lineFitsInPatch_withJoin() { |
75 | 0 | return fMaxCombinedSegments_withJoin >= 1; |
76 | 0 | } |
77 | | // Will a stroke with the given number of parametric segments and a worst-case rotation of 180 |
78 | | // degrees fit in a single patch? |
79 | 0 | bool stroke180FitsInPatch(float numParametricSegments_pow4) { |
80 | 0 | return numParametricSegments_pow4 <= fMaxParametricSegments_pow4[0]; |
81 | 0 | } |
82 | | // Will a worst-case 180-degree stroke with the given number of parametric segments, and a |
83 | | // worst-case join fit in a single patch together? |
84 | 0 | bool stroke180FitsInPatch_withJoin(float numParametricSegments_pow4) { |
85 | 0 | return numParametricSegments_pow4 <= fMaxParametricSegments_pow4_withJoin[0]; |
86 | 0 | } |
87 | | // Will a stroke with the given number of parametric segments and a worst-case rotation of 360 |
88 | | // degrees fit in a single patch? |
89 | 0 | bool stroke360FitsInPatch(float numParametricSegments_pow4) { |
90 | 0 | return numParametricSegments_pow4 <= fMaxParametricSegments_pow4[1]; |
91 | 0 | } |
92 | | // Will a worst-case 360-degree stroke with the given number of parametric segments, and a |
93 | | // worst-case join fit in a single patch together? |
94 | 0 | bool stroke360FitsInPatch_withJoin(float numParametricSegments_pow4) { |
95 | 0 | return numParametricSegments_pow4 <= fMaxParametricSegments_pow4_withJoin[1]; |
96 | 0 | } |
97 | | |
98 | 0 | void updateTolerances(float numRadialSegmentsPerRadian, SkPaint::Join joinType) { |
99 | 0 | using grvx::float2; |
100 | |
|
101 | 0 | fNumRadialSegmentsPerRadian = numRadialSegmentsPerRadian; |
102 | | |
103 | | // Calculate the worst-case numbers of parametric segments our hardware can support for the |
104 | | // current stroke radius, in the event that there are also enough radial segments to rotate |
105 | | // 180 and 360 degrees respectively. These are used for "quick accepts" that allow us to |
106 | | // send almost all curves directly to the hardware without having to chop. |
107 | 0 | float2 numRadialSegments_180_360 = skvx::max(skvx::ceil( |
108 | 0 | float2{SK_ScalarPI, 2*SK_ScalarPI} * fNumRadialSegmentsPerRadian), 1); |
109 | | // numEdges = numSegments + 1. See num_combined_segments(). |
110 | 0 | float maxTotalEdges = fMaxTessellationSegments + 1; |
111 | | // numParametricSegments = numTotalEdges - numRadialSegments. See num_combined_segments(). |
112 | 0 | float2 maxParametricSegments = skvx::max(maxTotalEdges - numRadialSegments_180_360, 0); |
113 | 0 | float2 maxParametricSegments_pow4 = pow4(maxParametricSegments); |
114 | 0 | maxParametricSegments_pow4.store(fMaxParametricSegments_pow4); |
115 | | |
116 | | // Find the worst-case numbers of parametric segments if we are to integrate a join into the |
117 | | // same patch as the curve. |
118 | 0 | float numRadialSegments180 = numRadialSegments_180_360[0]; |
119 | 0 | float worstCaseNumSegmentsInJoin; |
120 | 0 | switch (joinType) { |
121 | 0 | case SkPaint::kBevel_Join: worstCaseNumSegmentsInJoin = 1; break; |
122 | 0 | case SkPaint::kMiter_Join: worstCaseNumSegmentsInJoin = 2; break; |
123 | 0 | case SkPaint::kRound_Join: worstCaseNumSegmentsInJoin = numRadialSegments180; break; |
124 | 0 | } |
125 | | |
126 | | // Now calculate the worst-case numbers of parametric segments if we also want to combine a |
127 | | // join with the patch. Subtract an extra 1 off the end because when we integrate a join, |
128 | | // the tessellator has to add a redundant edge between the join and curve. |
129 | 0 | float2 maxParametricSegments_pow4_withJoin = pow4(skvx::max( |
130 | 0 | maxParametricSegments - worstCaseNumSegmentsInJoin - 1, 0)); |
131 | 0 | maxParametricSegments_pow4_withJoin.store(fMaxParametricSegments_pow4_withJoin); |
132 | |
|
133 | 0 | fMaxCombinedSegments_withJoin = fMaxTessellationSegments - worstCaseNumSegmentsInJoin - 1; |
134 | 0 | fSoloRoundJoinAlwaysFitsInPatch = (numRadialSegments180 <= fMaxTessellationSegments); |
135 | 0 | fStrokeJoinType = JoinType(joinType); |
136 | 0 | } |
137 | | |
138 | 0 | void updateDynamicStroke(const SkStrokeRec& stroke) { |
139 | 0 | SkASSERT(fShaderFlags & ShaderFlags::kDynamicStroke); |
140 | 0 | fDynamicStroke.set(stroke); |
141 | 0 | } Unexecuted instantiation: GrStrokeHardwareTessellator.cpp:(anonymous namespace)::PatchWriter::updateDynamicStroke(SkStrokeRec const&) Unexecuted instantiation: GrStrokeHardwareTessellator.cpp:(anonymous namespace)::PatchWriter::updateDynamicStroke(SkStrokeRec const&) |
142 | | |
143 | 0 | void updateDynamicColor(const SkPMColor4f& color) { |
144 | 0 | SkASSERT(fShaderFlags & ShaderFlags::kDynamicColor); |
145 | 0 | bool wideColor = fShaderFlags & ShaderFlags::kWideColor; |
146 | 0 | SkASSERT(wideColor || color.fitsInBytes()); |
147 | 0 | fDynamicColor.set(color, wideColor); |
148 | 0 | } Unexecuted instantiation: GrStrokeHardwareTessellator.cpp:(anonymous namespace)::PatchWriter::updateDynamicColor(SkRGBA4f<(SkAlphaType)2> const&) Unexecuted instantiation: GrStrokeHardwareTessellator.cpp:(anonymous namespace)::PatchWriter::updateDynamicColor(SkRGBA4f<(SkAlphaType)2> const&) |
149 | | |
150 | 0 | void moveTo(SkPoint pt) { |
151 | 0 | fCurrContourStartPoint = pt; |
152 | 0 | fHasLastControlPoint = false; |
153 | 0 | } |
154 | | |
155 | | // Writes out the given line, possibly chopping its previous join until the segments fit in |
156 | | // tessellation patches. |
157 | 0 | void writeLineTo(SkPoint p0, SkPoint p1) { |
158 | 0 | this->writeLineTo(fStrokeJoinType, p0, p1); |
159 | 0 | } |
160 | 0 | void writeLineTo(JoinType prevJoinType, SkPoint p0, SkPoint p1) { |
161 | | // Zero-length paths need special treatment because they are spec'd to behave differently. |
162 | 0 | if (p0 == p1) { |
163 | 0 | return; |
164 | 0 | } |
165 | 0 | SkPoint asPatch[4] = {p0, p0, p1, p1}; |
166 | 0 | this->internalPatchTo(prevJoinType, this->lineFitsInPatch_withJoin(), asPatch, p1); |
167 | 0 | } |
168 | | |
169 | | // Recursively chops the given conic and its previous join until the segments fit in |
170 | | // tessellation patches. |
171 | 0 | void writeConicPatchesTo(const SkPoint p[3], float w) { |
172 | 0 | this->internalConicPatchesTo(fStrokeJoinType, p, w); |
173 | 0 | } |
174 | | |
175 | | // Chops the given cubic at points of inflection and 180-degree rotation, and then recursively |
176 | | // chops the previous join and cubic sections as necessary until the segments fit in |
177 | | // tessellation patches. |
178 | 0 | void writeCubicConvex180PatchesTo(const SkPoint p[4]) { |
179 | 0 | SkPoint chops[10]; |
180 | 0 | float chopT[2]; |
181 | 0 | bool areCusps; |
182 | 0 | int numChops = GrPathUtils::findCubicConvex180Chops(p, chopT, &areCusps); |
183 | 0 | if (numChops == 0) { |
184 | | // The curve is already convex and rotates no more than 180 degrees. |
185 | 0 | this->internalCubicConvex180PatchesTo(fStrokeJoinType, p); |
186 | 0 | } else if (numChops == 1) { |
187 | 0 | SkChopCubicAt(p, chops, chopT[0]); |
188 | 0 | if (areCusps) { |
189 | | // When chopping on a perfect cusp, these 3 points will be equal. |
190 | 0 | chops[2] = chops[4] = chops[3]; |
191 | 0 | } |
192 | 0 | this->internalCubicConvex180PatchesTo(fStrokeJoinType, chops); |
193 | 0 | this->internalCubicConvex180PatchesTo(JoinType::kBowtie, chops + 3); |
194 | 0 | } else { |
195 | 0 | SkASSERT(numChops == 2); |
196 | 0 | SkChopCubicAt(p, chops, chopT[0], chopT[1]); |
197 | | // Two cusps are only possible on a flat line with two 180-degree turnarounds. |
198 | 0 | if (areCusps) { |
199 | 0 | this->writeLineTo(chops[0], chops[3]); |
200 | 0 | this->writeLineTo(JoinType::kBowtie, chops[3], chops[6]); |
201 | 0 | this->writeLineTo(JoinType::kBowtie, chops[6], chops[9]); |
202 | 0 | return; |
203 | 0 | } |
204 | 0 | this->internalCubicConvex180PatchesTo(fStrokeJoinType, chops); |
205 | 0 | this->internalCubicConvex180PatchesTo(JoinType::kBowtie, chops + 3); |
206 | 0 | this->internalCubicConvex180PatchesTo(JoinType::kBowtie, chops + 6); |
207 | 0 | } |
208 | 0 | } Unexecuted instantiation: GrStrokeHardwareTessellator.cpp:(anonymous namespace)::PatchWriter::writeCubicConvex180PatchesTo(SkPoint const*) Unexecuted instantiation: GrStrokeHardwareTessellator.cpp:(anonymous namespace)::PatchWriter::writeCubicConvex180PatchesTo(SkPoint const*) |
209 | | |
210 | | // Writes out the given stroke patch exactly as provided, without chopping or checking the |
211 | | // number of segments. Possibly chops its previous join until the segments fit in tessellation |
212 | | // patches. |
213 | | SK_ALWAYS_INLINE void writePatchTo(bool prevJoinFitsInPatch, const SkPoint p[4], |
214 | 0 | SkPoint endControlPoint) { |
215 | 0 | SkASSERT(fStrokeJoinType != JoinType::kBowtie); |
216 | |
|
217 | 0 | if (!fHasLastControlPoint) { |
218 | | // The first stroke doesn't have a previous join (yet). If the current contour ends up |
219 | | // closing itself, we will add that join as its own patch. TODO: Consider deferring the |
220 | | // first stroke until we know whether the contour will close. This will allow us to use |
221 | | // the closing join as the first patch's previous join. |
222 | 0 | fHasLastControlPoint = true; |
223 | 0 | fCurrContourFirstControlPoint = (p[1] != p[0]) ? p[1] : p[2]; |
224 | 0 | fLastControlPoint = p[0]; // Disables the join section of this patch. |
225 | 0 | } else if (!prevJoinFitsInPatch) { |
226 | | // There aren't enough guaranteed segments to fold the previous join into this patch. |
227 | | // Emit the join in its own separate patch. |
228 | 0 | this->internalJoinTo(fStrokeJoinType, p[0], (p[1] != p[0]) ? p[1] : p[2]); |
229 | 0 | fLastControlPoint = p[0]; // Disables the join section of this patch. |
230 | 0 | } |
231 | |
|
232 | 0 | if (GrVertexWriter patchWriter = fChunkBuilder.appendVertex()) { |
233 | 0 | patchWriter.write(fLastControlPoint); |
234 | 0 | patchWriter.writeArray(p, 4); |
235 | 0 | this->writeDynamicAttribs(&patchWriter); |
236 | 0 | } |
237 | |
|
238 | 0 | fLastControlPoint = endControlPoint; |
239 | 0 | } Unexecuted instantiation: GrStrokeHardwareTessellator.cpp:(anonymous namespace)::PatchWriter::writePatchTo(bool, SkPoint const*, SkPoint) Unexecuted instantiation: GrStrokeHardwareTessellator.cpp:(anonymous namespace)::PatchWriter::writePatchTo(bool, SkPoint const*, SkPoint) |
240 | | |
241 | | void writeClose(SkPoint contourEndpoint, const SkMatrix& viewMatrix, |
242 | 0 | const SkStrokeRec& stroke) { |
243 | 0 | if (!fHasLastControlPoint) { |
244 | | // Draw caps instead of closing if the subpath is zero length: |
245 | | // |
246 | | // "Any zero length subpath ... shall be stroked if the 'stroke-linecap' property has |
247 | | // a value of round or square producing respectively a circle or a square." |
248 | | // |
249 | | // (https://www.w3.org/TR/SVG11/painting.html#StrokeProperties) |
250 | | // |
251 | 0 | this->writeCaps(contourEndpoint, viewMatrix, stroke); |
252 | 0 | return; |
253 | 0 | } |
254 | | |
255 | | // Draw a line back to the beginning. (This will be discarded if |
256 | | // contourEndpoint == fCurrContourStartPoint.) |
257 | 0 | this->writeLineTo(contourEndpoint, fCurrContourStartPoint); |
258 | 0 | this->internalJoinTo(fStrokeJoinType, fCurrContourStartPoint, fCurrContourFirstControlPoint); |
259 | |
|
260 | 0 | fHasLastControlPoint = false; |
261 | 0 | } |
262 | | |
263 | 0 | void writeCaps(SkPoint contourEndpoint, const SkMatrix& viewMatrix, const SkStrokeRec& stroke) { |
264 | 0 | if (!fHasLastControlPoint) { |
265 | | // We don't have any control points to orient the caps. In this case, square and round |
266 | | // caps are specified to be drawn as an axis-aligned square or circle respectively. |
267 | | // Assign default control points that achieve this. |
268 | 0 | SkVector outset; |
269 | 0 | if (!stroke.isHairlineStyle()) { |
270 | 0 | outset = {1, 0}; |
271 | 0 | } else { |
272 | | // If the stroke is hairline, orient the square on the post-transform x-axis |
273 | | // instead. We don't need to worry about the vector length since it will be |
274 | | // normalized later. Since the matrix cannot have perspective, the below is |
275 | | // equivalent to: |
276 | | // |
277 | | // outset = inverse(|a b|) * |1| * arbitrary_scale |
278 | | // |c d| |0| |
279 | | // |
280 | | // == 1/det * | d -b| * |1| * arbitrary_scale |
281 | | // |-c a| |0| |
282 | | // |
283 | | // == 1/det * | d| * arbitrary_scale |
284 | | // |-c| |
285 | | // |
286 | | // == | d| |
287 | | // |-c| |
288 | | // |
289 | 0 | SkASSERT(!viewMatrix.hasPerspective()); |
290 | 0 | float c=viewMatrix.getSkewY(), d=viewMatrix.getScaleY(); |
291 | 0 | outset = {d, -c}; |
292 | 0 | } |
293 | 0 | fCurrContourFirstControlPoint = fCurrContourStartPoint - outset; |
294 | 0 | fLastControlPoint = fCurrContourStartPoint + outset; |
295 | 0 | fHasLastControlPoint = true; |
296 | 0 | contourEndpoint = fCurrContourStartPoint; |
297 | 0 | } |
298 | |
|
299 | 0 | switch (stroke.getCap()) { |
300 | 0 | case SkPaint::kButt_Cap: |
301 | 0 | break; |
302 | 0 | case SkPaint::kRound_Cap: { |
303 | | // A round cap is the same thing as a 180-degree round join. |
304 | | // If our join type isn't round we can alternatively use a bowtie. |
305 | 0 | JoinType roundCapJoinType = (stroke.getJoin() == SkPaint::kRound_Join) |
306 | 0 | ? JoinType::kRound : JoinType::kBowtie; |
307 | 0 | this->internalJoinTo(roundCapJoinType, contourEndpoint, fLastControlPoint); |
308 | 0 | this->internalMoveTo(fCurrContourStartPoint, fCurrContourFirstControlPoint); |
309 | 0 | this->internalJoinTo(roundCapJoinType, fCurrContourStartPoint, |
310 | 0 | fCurrContourFirstControlPoint); |
311 | 0 | break; |
312 | 0 | } |
313 | 0 | case SkPaint::kSquare_Cap: { |
314 | | // A square cap is the same as appending lineTos. |
315 | 0 | auto strokeJoinType = JoinType(stroke.getJoin()); |
316 | 0 | SkVector lastTangent = contourEndpoint - fLastControlPoint; |
317 | 0 | if (!stroke.isHairlineStyle()) { |
318 | | // Extend the cap by 1/2 stroke width. |
319 | 0 | lastTangent *= (.5f * stroke.getWidth()) / lastTangent.length(); |
320 | 0 | } else { |
321 | | // Extend the cap by what will be 1/2 pixel after transformation. |
322 | 0 | lastTangent *= |
323 | 0 | .5f / viewMatrix.mapVector(lastTangent.fX, lastTangent.fY).length(); |
324 | 0 | } |
325 | 0 | this->writeLineTo(strokeJoinType, contourEndpoint, contourEndpoint + lastTangent); |
326 | 0 | this->internalMoveTo(fCurrContourStartPoint, fCurrContourFirstControlPoint); |
327 | 0 | SkVector firstTangent = fCurrContourFirstControlPoint - fCurrContourStartPoint; |
328 | 0 | if (!stroke.isHairlineStyle()) { |
329 | | // Set the the cap back by 1/2 stroke width. |
330 | 0 | firstTangent *= (-.5f * stroke.getWidth()) / firstTangent.length(); |
331 | 0 | } else { |
332 | | // Set the cap back by what will be 1/2 pixel after transformation. |
333 | 0 | firstTangent *= |
334 | 0 | -.5f / viewMatrix.mapVector(firstTangent.fX, firstTangent.fY).length(); |
335 | 0 | } |
336 | 0 | this->writeLineTo(strokeJoinType, fCurrContourStartPoint, |
337 | 0 | fCurrContourStartPoint + firstTangent); |
338 | 0 | break; |
339 | 0 | } |
340 | 0 | } |
341 | | |
342 | 0 | fHasLastControlPoint = false; |
343 | 0 | } Unexecuted instantiation: GrStrokeHardwareTessellator.cpp:(anonymous namespace)::PatchWriter::writeCaps(SkPoint, SkMatrix const&, SkStrokeRec const&) Unexecuted instantiation: GrStrokeHardwareTessellator.cpp:(anonymous namespace)::PatchWriter::writeCaps(SkPoint, SkMatrix const&, SkStrokeRec const&) |
344 | | |
345 | | private: |
346 | 0 | void internalMoveTo(SkPoint pt, SkPoint lastControlPoint) { |
347 | 0 | fCurrContourStartPoint = pt; |
348 | 0 | fCurrContourFirstControlPoint = fLastControlPoint = lastControlPoint; |
349 | 0 | fHasLastControlPoint = true; |
350 | 0 | } |
351 | | |
352 | | // Recursively chops the given conic and its previous join until the segments fit in |
353 | | // tessellation patches. |
354 | | void internalConicPatchesTo(JoinType prevJoinType, const SkPoint p[3], float w, |
355 | 0 | int maxDepth = -1) { |
356 | 0 | if (!fCullTest.areVisible3(p)) { |
357 | | // The stroke is out of view. Discard it. |
358 | 0 | this->discardStroke(p, 3); |
359 | 0 | return; |
360 | 0 | } |
361 | | // Zero-length paths need special treatment because they are spec'd to behave differently. |
362 | | // If the control point is colocated on an endpoint then this might end up being the case. |
363 | | // Fall back on a lineTo and let it make the final check. |
364 | 0 | if (p[1] == p[0] || p[1] == p[2] || w == 0) { |
365 | 0 | this->writeLineTo(prevJoinType, p[0], p[2]); |
366 | 0 | return; |
367 | 0 | } |
368 | | |
369 | | // Convert to a patch. |
370 | 0 | SkPoint asPatch[4]; |
371 | 0 | if (w == 1) { |
372 | 0 | GrPathUtils::convertQuadToCubic(p, asPatch); |
373 | 0 | } else { |
374 | 0 | GrTessellationShader::WriteConicPatch(p, w, asPatch); |
375 | 0 | } |
376 | |
|
377 | 0 | float numParametricSegments_pow4; |
378 | 0 | if (w == 1) { |
379 | 0 | numParametricSegments_pow4 = GrWangsFormula::quadratic_pow4(fParametricPrecision, p); |
380 | 0 | } else { |
381 | 0 | float n = GrWangsFormula::conic_pow2(fParametricPrecision, p, w); |
382 | 0 | numParametricSegments_pow4 = n*n; |
383 | 0 | } |
384 | 0 | if (this->stroke180FitsInPatch(numParametricSegments_pow4) || maxDepth == 0) { |
385 | 0 | this->internalPatchTo(prevJoinType, |
386 | 0 | this->stroke180FitsInPatch_withJoin(numParametricSegments_pow4), |
387 | 0 | asPatch, p[2]); |
388 | 0 | return; |
389 | 0 | } |
390 | | |
391 | | // We still might have enough tessellation segments to render the curve. Check again with |
392 | | // the actual rotation. |
393 | 0 | float numRadialSegments = SkMeasureQuadRotation(p) * fNumRadialSegmentsPerRadian; |
394 | 0 | numRadialSegments = std::max(std::ceil(numRadialSegments), 1.f); |
395 | 0 | float numParametricSegments = GrWangsFormula::root4(numParametricSegments_pow4); |
396 | 0 | numParametricSegments = std::max(std::ceil(numParametricSegments), 1.f); |
397 | 0 | float numCombinedSegments = num_combined_segments(numParametricSegments, numRadialSegments); |
398 | 0 | if (numCombinedSegments > fMaxTessellationSegments) { |
399 | | // The hardware doesn't support enough segments for this curve. Chop and recurse. |
400 | 0 | if (maxDepth < 0) { |
401 | | // Decide on an extremely conservative upper bound for when to quit chopping. This |
402 | | // is solely to protect us from infinite recursion in instances where FP error |
403 | | // prevents us from chopping at the correct midtangent. |
404 | 0 | maxDepth = sk_float_nextlog2(numParametricSegments) + |
405 | 0 | sk_float_nextlog2(numRadialSegments) + 1; |
406 | 0 | maxDepth = std::max(maxDepth, 1); |
407 | 0 | } |
408 | 0 | if (w == 1) { |
409 | 0 | SkPoint chops[5]; |
410 | 0 | if (numParametricSegments >= numRadialSegments) { |
411 | 0 | SkChopQuadAtHalf(p, chops); |
412 | 0 | } else { |
413 | 0 | SkChopQuadAtMidTangent(p, chops); |
414 | 0 | } |
415 | 0 | this->internalConicPatchesTo(prevJoinType, chops, 1, maxDepth - 1); |
416 | 0 | this->internalConicPatchesTo(JoinType::kBowtie, chops + 2, 1, maxDepth - 1); |
417 | 0 | } else { |
418 | 0 | SkConic conic(p, w); |
419 | 0 | float chopT = (numParametricSegments >= numRadialSegments) ? .5f |
420 | 0 | : conic.findMidTangent(); |
421 | 0 | SkConic chops[2]; |
422 | 0 | if (conic.chopAt(chopT, chops)) { |
423 | 0 | this->internalConicPatchesTo(prevJoinType, chops[0].fPts, chops[0].fW, |
424 | 0 | maxDepth - 1); |
425 | 0 | this->internalConicPatchesTo(JoinType::kBowtie, chops[1].fPts, chops[1].fW, |
426 | 0 | maxDepth - 1); |
427 | 0 | } |
428 | 0 | } |
429 | 0 | return; |
430 | 0 | } |
431 | | |
432 | 0 | this->internalPatchTo(prevJoinType, (numCombinedSegments <= fMaxCombinedSegments_withJoin), |
433 | 0 | asPatch, p[2]); |
434 | 0 | } |
435 | | |
436 | | // Recursively chops the given cubic and its previous join until the segments fit in |
437 | | // tessellation patches. The cubic must be convex and must not rotate more than 180 degrees. |
438 | | void internalCubicConvex180PatchesTo(JoinType prevJoinType, const SkPoint p[4], |
439 | 0 | int maxDepth = -1) { |
440 | 0 | if (!fCullTest.areVisible4(p)) { |
441 | | // The stroke is out of view. Discard it. |
442 | 0 | this->discardStroke(p, 4); |
443 | 0 | return; |
444 | 0 | } |
445 | | // The stroke tessellation shader assigns special meaning to p0==p1==p2 and p1==p2==p3. If |
446 | | // this is the case then we need to rewrite the cubic. |
447 | 0 | if (p[1] == p[2] && (p[1] == p[0] || p[1] == p[3])) { |
448 | 0 | this->writeLineTo(prevJoinType, p[0], p[3]); |
449 | 0 | return; |
450 | 0 | } |
451 | | |
452 | 0 | float numParametricSegments_pow4 = GrWangsFormula::cubic_pow4(fParametricPrecision, p); |
453 | 0 | if (this->stroke180FitsInPatch(numParametricSegments_pow4) || maxDepth == 0) { |
454 | 0 | this->internalPatchTo(prevJoinType, |
455 | 0 | this->stroke180FitsInPatch_withJoin(numParametricSegments_pow4), |
456 | 0 | p, p[3]); |
457 | 0 | return; |
458 | 0 | } |
459 | | |
460 | | // We still might have enough tessellation segments to render the curve. Check again with |
461 | | // its actual rotation. |
462 | 0 | float numRadialSegments = SkMeasureNonInflectCubicRotation(p) * fNumRadialSegmentsPerRadian; |
463 | 0 | numRadialSegments = std::max(std::ceil(numRadialSegments), 1.f); |
464 | 0 | float numParametricSegments = GrWangsFormula::root4(numParametricSegments_pow4); |
465 | 0 | numParametricSegments = std::max(std::ceil(numParametricSegments), 1.f); |
466 | 0 | float numCombinedSegments = num_combined_segments(numParametricSegments, numRadialSegments); |
467 | 0 | if (numCombinedSegments > fMaxTessellationSegments) { |
468 | | // The hardware doesn't support enough segments for this curve. Chop and recurse. |
469 | 0 | SkPoint chops[7]; |
470 | 0 | if (maxDepth < 0) { |
471 | | // Decide on an extremely conservative upper bound for when to quit chopping. This |
472 | | // is solely to protect us from infinite recursion in instances where FP error |
473 | | // prevents us from chopping at the correct midtangent. |
474 | 0 | maxDepth = sk_float_nextlog2(numParametricSegments) + |
475 | 0 | sk_float_nextlog2(numRadialSegments) + 1; |
476 | 0 | maxDepth = std::max(maxDepth, 1); |
477 | 0 | } |
478 | 0 | if (numParametricSegments >= numRadialSegments) { |
479 | 0 | SkChopCubicAtHalf(p, chops); |
480 | 0 | } else { |
481 | 0 | SkChopCubicAtMidTangent(p, chops); |
482 | 0 | } |
483 | 0 | this->internalCubicConvex180PatchesTo(prevJoinType, chops, maxDepth - 1); |
484 | 0 | this->internalCubicConvex180PatchesTo(JoinType::kBowtie, chops + 3, maxDepth - 1); |
485 | 0 | return; |
486 | 0 | } |
487 | | |
488 | 0 | this->internalPatchTo(prevJoinType, (numCombinedSegments <= fMaxCombinedSegments_withJoin), |
489 | 0 | p, p[3]); |
490 | 0 | } |
491 | | |
492 | | // Writes out the given stroke patch exactly as provided, without chopping or checking the |
493 | | // number of segments. Possibly chops its previous join until the segments fit in tessellation |
494 | | // patches. It is valid for prevJoinType to be kBowtie. |
495 | | void internalPatchTo(JoinType prevJoinType, bool prevJoinFitsInPatch, const SkPoint p[4], |
496 | 0 | SkPoint endPt) { |
497 | 0 | if (prevJoinType == JoinType::kBowtie) { |
498 | 0 | SkASSERT(fHasLastControlPoint); |
499 | | // Bowtie joins are only used on internal chops, and internal chops almost always have |
500 | | // continuous tangent angles (i.e., the ending tangent of the first chop and the |
501 | | // beginning tangent of the second both point in the same direction). The tangents will |
502 | | // only ever not point in the same direction if we chopped at a cusp point, so that's |
503 | | // the only time we actually need a bowtie. |
504 | 0 | SkPoint nextControlPoint = (p[1] == p[0]) ? p[2] : p[1]; |
505 | 0 | SkVector a = p[0] - fLastControlPoint; |
506 | 0 | SkVector b = nextControlPoint - p[0]; |
507 | 0 | float ab_cosTheta = a.dot(b); |
508 | 0 | float ab_pow2 = a.dot(a) * b.dot(b); |
509 | | // To check if tangents 'a' and 'b' do not point in the same direction, any of the |
510 | | // following formulas work: |
511 | | // |
512 | | // 0 != theta |
513 | | // 1 != cosTheta |
514 | | // 1 != cosTheta * abs(cosTheta) [Still false when cosTheta == -1] |
515 | | // |
516 | | // Introducing a slop term for fuzzy equality gives: |
517 | | // |
518 | | // 1 !~= cosTheta * abs(cosTheta) [tolerance = epsilon] |
519 | | // (ab)^2 !~= (ab)^2 * cosTheta * abs(cosTheta) [tolerance = (ab)^2 * epsilon] |
520 | | // (ab)^2 !~= (ab * cosTheta) * (ab * abs(cosTheta)) [tolerance = (ab)^2 * epsilon] |
521 | | // (ab)^2 !~= (ab * cosTheta) * abs(ab * cosTheta) [tolerance = (ab)^2 * epsilon] |
522 | | // |
523 | | // Since we also scale the tolerance, the formula is unaffected by the magnitude of the |
524 | | // tangent vectors. (And we can fold "ab" in to the abs() because it's always positive.) |
525 | 0 | if (!SkScalarNearlyEqual(ab_pow2, ab_cosTheta * fabsf(ab_cosTheta), |
526 | 0 | ab_pow2 * SK_ScalarNearlyZero)) { |
527 | 0 | this->internalJoinTo(JoinType::kBowtie, p[0], nextControlPoint); |
528 | 0 | fLastControlPoint = p[0]; // Disables the join section of this patch. |
529 | 0 | prevJoinFitsInPatch = true; |
530 | 0 | } |
531 | 0 | } |
532 | |
|
533 | 0 | this->writePatchTo(prevJoinFitsInPatch, p, (p[2] != endPt) ? p[2] : p[1]); |
534 | 0 | } Unexecuted instantiation: GrStrokeHardwareTessellator.cpp:(anonymous namespace)::PatchWriter::internalPatchTo((anonymous namespace)::PatchWriter::JoinType, bool, SkPoint const*, SkPoint) Unexecuted instantiation: GrStrokeHardwareTessellator.cpp:(anonymous namespace)::PatchWriter::internalPatchTo((anonymous namespace)::PatchWriter::JoinType, bool, SkPoint const*, SkPoint) |
535 | | |
536 | | // Recursively chops the given join until the segments fit in tessellation patches. |
537 | | void internalJoinTo(JoinType joinType, SkPoint junctionPoint, SkPoint nextControlPoint, |
538 | 0 | int maxDepth = -1) { |
539 | 0 | if (!fHasLastControlPoint) { |
540 | | // The first stroke doesn't have a previous join. |
541 | 0 | return; |
542 | 0 | } |
543 | | |
544 | 0 | if (!fSoloRoundJoinAlwaysFitsInPatch && maxDepth != 0 && |
545 | 0 | (joinType == JoinType::kRound || joinType == JoinType::kBowtie)) { |
546 | 0 | SkVector tan0 = junctionPoint - fLastControlPoint; |
547 | 0 | SkVector tan1 = nextControlPoint - junctionPoint; |
548 | 0 | float rotation = SkMeasureAngleBetweenVectors(tan0, tan1); |
549 | 0 | float numRadialSegments = rotation * fNumRadialSegmentsPerRadian; |
550 | 0 | if (numRadialSegments > fMaxTessellationSegments) { |
551 | | // This is a round join that requires more segments than the tessellator supports. |
552 | | // Split it and recurse. |
553 | 0 | if (maxDepth < 0) { |
554 | | // Decide on an upper bound for when to quit chopping. This is solely to protect |
555 | | // us from infinite recursion due to FP precision issues. |
556 | 0 | maxDepth = sk_float_nextlog2(numRadialSegments / fMaxTessellationSegments); |
557 | 0 | maxDepth = std::max(maxDepth, 1); |
558 | 0 | } |
559 | | // Find the bisector so we can split the join in half. |
560 | 0 | SkPoint bisector = SkFindBisector(tan0, tan1); |
561 | | // c0 will be the "next" control point for the first join half, and c1 will be the |
562 | | // "previous" control point for the second join half. |
563 | 0 | SkPoint c0, c1; |
564 | | // FIXME(skia:11347): This hack ensures "c0 - junctionPoint" gives the exact same |
565 | | // ieee fp32 vector as "-(c1 - junctionPoint)". Tessellated stroking is becoming |
566 | | // less experimental, so t's time to think of a cleaner method to avoid T-junctions |
567 | | // when we chop joins. |
568 | 0 | int maxAttempts = 10; |
569 | 0 | do { |
570 | 0 | bisector = (junctionPoint + bisector) - (junctionPoint - bisector); |
571 | 0 | c0 = junctionPoint + bisector; |
572 | 0 | c1 = junctionPoint - bisector; |
573 | 0 | } while (c0 - junctionPoint != -(c1 - junctionPoint) && --maxAttempts); |
574 | | // First join half. |
575 | 0 | this->internalJoinTo(joinType, junctionPoint, c0, maxDepth - 1); |
576 | 0 | fLastControlPoint = c1; |
577 | | // Second join half. |
578 | 0 | this->internalJoinTo(joinType, junctionPoint, nextControlPoint, maxDepth - 1); |
579 | 0 | return; |
580 | 0 | } |
581 | 0 | } |
582 | | |
583 | | // We should never write out joins before the first curve. |
584 | 0 | SkASSERT(fHasLastControlPoint); |
585 | |
|
586 | 0 | if (GrVertexWriter patchWriter = fChunkBuilder.appendVertex()) { |
587 | 0 | patchWriter.write(fLastControlPoint, junctionPoint); |
588 | 0 | if (joinType == JoinType::kBowtie) { |
589 | | // {prevControlPoint, [p0, p0, p0, p3]} is a reserved patch pattern that means this |
590 | | // patch is a bowtie. The bowtie is anchored on p0 and its tangent angles go from |
591 | | // (p0 - prevControlPoint) to (p3 - p0). |
592 | 0 | patchWriter.write(junctionPoint, junctionPoint); |
593 | 0 | } else { |
594 | | // {prevControlPoint, [p0, p3, p3, p3]} is a reserved patch pattern that means this |
595 | | // patch is a join only (no curve sections in the patch). The join is anchored on p0 |
596 | | // and its tangent angles go from (p0 - prevControlPoint) to (p3 - p0). |
597 | 0 | patchWriter.write(nextControlPoint, nextControlPoint); |
598 | 0 | } |
599 | 0 | patchWriter.write(nextControlPoint); |
600 | 0 | this->writeDynamicAttribs(&patchWriter); |
601 | 0 | } |
602 | |
|
603 | 0 | fLastControlPoint = nextControlPoint; |
604 | 0 | } Unexecuted instantiation: GrStrokeHardwareTessellator.cpp:(anonymous namespace)::PatchWriter::internalJoinTo((anonymous namespace)::PatchWriter::JoinType, SkPoint, SkPoint, int) Unexecuted instantiation: GrStrokeHardwareTessellator.cpp:(anonymous namespace)::PatchWriter::internalJoinTo((anonymous namespace)::PatchWriter::JoinType, SkPoint, SkPoint, int) |
605 | | |
606 | 0 | SK_ALWAYS_INLINE void writeDynamicAttribs(GrVertexWriter* patchWriter) { |
607 | 0 | if (fShaderFlags & ShaderFlags::kDynamicStroke) { |
608 | 0 | patchWriter->write(fDynamicStroke); |
609 | 0 | } |
610 | 0 | if (fShaderFlags & ShaderFlags::kDynamicColor) { |
611 | 0 | patchWriter->write(fDynamicColor); |
612 | 0 | } |
613 | 0 | } |
614 | | |
615 | 0 | void discardStroke(const SkPoint p[], int numPoints) { |
616 | 0 | if (!fHasLastControlPoint) { |
617 | | // This disables the first join, if any. (The first join gets added as a standalone |
618 | | // patch during close(), but setting fCurrContourFirstControlPoint to p[0] causes us to |
619 | | // skip that join if we attempt to add it later.) |
620 | 0 | fCurrContourFirstControlPoint = p[0]; |
621 | 0 | fHasLastControlPoint = true; |
622 | 0 | } |
623 | | // Set fLastControlPoint to the next stroke's p0 (which will be equal to the final point of |
624 | | // this stroke). This has the effect of disabling the next stroke's join. |
625 | 0 | fLastControlPoint = p[numPoints - 1]; |
626 | 0 | } |
627 | | |
628 | | const ShaderFlags fShaderFlags; |
629 | | const GrCullTest fCullTest; |
630 | | GrVertexChunkBuilder fChunkBuilder; |
631 | | |
632 | | // The maximum number of tessellation segments the hardware can emit for a single patch. |
633 | | const int fMaxTessellationSegments; |
634 | | |
635 | | // This is the precision value, adjusted for the view matrix, to use with Wang's formulas when |
636 | | // determining how many parametric segments a curve will require. |
637 | | const float fParametricPrecision; |
638 | | |
639 | | // Number of radial segments required for each radian of rotation in order to look smooth with |
640 | | // the current stroke radius. |
641 | | float fNumRadialSegmentsPerRadian; |
642 | | |
643 | | // These arrays contain worst-case numbers of parametric segments, raised to the 4th power, that |
644 | | // our hardware can support for the current stroke radius. They assume curve rotations of 180 |
645 | | // and 360 degrees respectively. These are used for "quick accepts" that allow us to send almost |
646 | | // all curves directly to the hardware without having to chop. We raise to the 4th power because |
647 | | // the "pow4" variants of Wang's formula are the quickest to evaluate. |
648 | | float fMaxParametricSegments_pow4[2]; // Values for strokes that rotate 180 and 360 degrees. |
649 | | float fMaxParametricSegments_pow4_withJoin[2]; // For strokes that rotate 180 and 360 degrees. |
650 | | |
651 | | // Maximum number of segments we can allocate for a stroke if we are stuffing it in a patch |
652 | | // together with a worst-case join. |
653 | | float fMaxCombinedSegments_withJoin; |
654 | | |
655 | | // Additional info on the current stroke radius/join type. |
656 | | bool fSoloRoundJoinAlwaysFitsInPatch; |
657 | | JoinType fStrokeJoinType; |
658 | | |
659 | | // Variables related to the specific contour that we are currently iterating during |
660 | | // prepareBuffers(). |
661 | | bool fHasLastControlPoint = false; |
662 | | SkPoint fCurrContourStartPoint; |
663 | | SkPoint fCurrContourFirstControlPoint; |
664 | | SkPoint fLastControlPoint; |
665 | | |
666 | | // Values for the current dynamic state (if any) that will get written out with each patch. |
667 | | GrStrokeTessellationShader::DynamicStroke fDynamicStroke; |
668 | | GrVertexColor fDynamicColor; |
669 | | }; |
670 | | |
671 | 0 | SK_ALWAYS_INLINE static bool cubic_has_cusp(const SkPoint p[4]) { |
672 | 0 | using grvx::float2; |
673 | |
|
674 | 0 | float2 p0 = skvx::bit_pun<float2>(p[0]); |
675 | 0 | float2 p1 = skvx::bit_pun<float2>(p[1]); |
676 | 0 | float2 p2 = skvx::bit_pun<float2>(p[2]); |
677 | 0 | float2 p3 = skvx::bit_pun<float2>(p[3]); |
678 | | |
679 | | // See GrPathUtils::findCubicConvex180Chops() for the math. |
680 | 0 | float2 C = p1 - p0; |
681 | 0 | float2 D = p2 - p1; |
682 | 0 | float2 E = p3 - p0; |
683 | 0 | float2 B = D - C; |
684 | 0 | float2 A = grvx::fast_madd<2>(-3, D, E); |
685 | |
|
686 | 0 | float a = grvx::cross(A, B); |
687 | 0 | float b = grvx::cross(A, C); |
688 | 0 | float c = grvx::cross(B, C); |
689 | 0 | float discr = b*b - 4*a*c; |
690 | | |
691 | | // If -cuspThreshold <= discr <= cuspThreshold, it means the two roots are within a distance of |
692 | | // 2^-11 from one another in parametric space. This is close enough for our purposes to take the |
693 | | // slow codepath that knows how to handle cusps. |
694 | 0 | constexpr static float kEpsilon = 1.f / (1 << 11); |
695 | 0 | float cuspThreshold = (2*kEpsilon) * a; |
696 | 0 | cuspThreshold *= cuspThreshold; |
697 | |
|
698 | 0 | return fabsf(discr) <= cuspThreshold && |
699 | | // The most common type of cusp we encounter is when p0==p1 or p2==p3. Unless the curve |
700 | | // is a flat line (a==b==c==0), these don't actually need special treatment because the |
701 | | // cusp occurs at t=0 or t=1. |
702 | 0 | (!(skvx::all(p0 == p1) || skvx::all(p2 == p3)) || (a == 0 && b == 0 && c == 0)); |
703 | 0 | } |
704 | | |
705 | | } // namespace |
706 | | |
707 | | GrStrokeHardwareTessellator::GrStrokeHardwareTessellator(const GrShaderCaps& shaderCaps, |
708 | | ShaderFlags shaderFlags, |
709 | | const SkMatrix& viewMatrix, |
710 | | PathStrokeList* pathStrokeList, |
711 | | std::array<float,2> matrixMinMaxScales, |
712 | | const SkRect& strokeCullBounds) |
713 | | : GrStrokeTessellator(shaderCaps, GrStrokeTessellationShader::Mode::kHardwareTessellation, |
714 | | shaderFlags, SkNextLog2(shaderCaps.maxTessellationSegments()), |
715 | 0 | viewMatrix, pathStrokeList, matrixMinMaxScales, strokeCullBounds) { |
716 | 0 | } |
717 | | |
718 | 0 | void GrStrokeHardwareTessellator::prepare(GrMeshDrawTarget* target, int totalCombinedVerbCnt) { |
719 | 0 | using JoinType = PatchWriter::JoinType; |
720 | | |
721 | | // Over-allocate enough patches for 1 in 4 strokes to chop and for 8 extra caps. |
722 | 0 | int strokePreallocCount = totalCombinedVerbCnt * 5/4; |
723 | 0 | int capPreallocCount = 8; |
724 | 0 | int minPatchesPerChunk = strokePreallocCount + capPreallocCount; |
725 | 0 | PatchWriter patchWriter(fShader.flags(), target, fStrokeCullBounds, fShader.viewMatrix(), |
726 | 0 | fMatrixMinMaxScales[1], &fPatchChunks, fShader.vertexStride(), |
727 | 0 | minPatchesPerChunk); |
728 | |
|
729 | 0 | if (!fShader.hasDynamicStroke()) { |
730 | | // Strokes are static. Calculate tolerances once. |
731 | 0 | const SkStrokeRec& stroke = fPathStrokeList->fStroke; |
732 | 0 | float localStrokeWidth = GrStrokeTolerances::GetLocalStrokeWidth(fMatrixMinMaxScales.data(), |
733 | 0 | stroke.getWidth()); |
734 | 0 | float numRadialSegmentsPerRadian = GrStrokeTolerances::CalcNumRadialSegmentsPerRadian( |
735 | 0 | patchWriter.parametricPrecision(), localStrokeWidth); |
736 | 0 | patchWriter.updateTolerances(numRadialSegmentsPerRadian, stroke.getJoin()); |
737 | 0 | } |
738 | | |
739 | | // Fast SIMD queue that buffers up values for "numRadialSegmentsPerRadian". Only used when we |
740 | | // have dynamic strokes. |
741 | 0 | GrStrokeToleranceBuffer toleranceBuffer(patchWriter.parametricPrecision()); |
742 | |
|
743 | 0 | for (PathStrokeList* pathStroke = fPathStrokeList; pathStroke; pathStroke = pathStroke->fNext) { |
744 | 0 | const SkStrokeRec& stroke = pathStroke->fStroke; |
745 | 0 | if (fShader.hasDynamicStroke()) { |
746 | | // Strokes are dynamic. Update tolerances with every new stroke. |
747 | 0 | patchWriter.updateTolerances(toleranceBuffer.fetchRadialSegmentsPerRadian(pathStroke), |
748 | 0 | stroke.getJoin()); |
749 | 0 | patchWriter.updateDynamicStroke(stroke); |
750 | 0 | } |
751 | 0 | if (fShader.hasDynamicColor()) { |
752 | 0 | patchWriter.updateDynamicColor(pathStroke->fColor); |
753 | 0 | } |
754 | |
|
755 | 0 | const SkPath& path = pathStroke->fPath; |
756 | 0 | bool contourIsEmpty = true; |
757 | 0 | for (auto [verb, p, w] : SkPathPriv::Iterate(path)) { |
758 | 0 | bool prevJoinFitsInPatch; |
759 | 0 | SkPoint scratchPts[4]; |
760 | 0 | const SkPoint* patchPts; |
761 | 0 | SkPoint endControlPoint; |
762 | 0 | switch (verb) { |
763 | 0 | case SkPathVerb::kMove: |
764 | | // "A subpath ... consisting of a single moveto shall not be stroked." |
765 | | // https://www.w3.org/TR/SVG11/painting.html#StrokeProperties |
766 | 0 | if (!contourIsEmpty) { |
767 | 0 | patchWriter.writeCaps(p[-1], fShader.viewMatrix(), stroke); |
768 | 0 | } |
769 | 0 | patchWriter.moveTo(p[0]); |
770 | 0 | contourIsEmpty = true; |
771 | 0 | continue; |
772 | 0 | case SkPathVerb::kClose: |
773 | 0 | patchWriter.writeClose(p[0], fShader.viewMatrix(), stroke); |
774 | 0 | contourIsEmpty = true; |
775 | 0 | continue; |
776 | 0 | case SkPathVerb::kLine: |
777 | | // Set this to false first, before the upcoming continue might disrupt our flow. |
778 | 0 | contourIsEmpty = false; |
779 | 0 | if (p[0] == p[1]) { |
780 | 0 | continue; |
781 | 0 | } |
782 | 0 | prevJoinFitsInPatch = patchWriter.lineFitsInPatch_withJoin(); |
783 | 0 | scratchPts[0] = scratchPts[1] = p[0]; |
784 | 0 | scratchPts[2] = scratchPts[3] = p[1]; |
785 | 0 | patchPts = scratchPts; |
786 | 0 | endControlPoint = p[0]; |
787 | 0 | break; |
788 | 0 | case SkPathVerb::kQuad: { |
789 | 0 | contourIsEmpty = false; |
790 | 0 | if (p[1] == p[0] || p[1] == p[2]) { |
791 | | // Zero-length paths need special treatment because they are spec'd to |
792 | | // behave differently. If the control point is colocated on an endpoint then |
793 | | // this might end up being the case. Fall back on a lineTo and let it make |
794 | | // the final check. |
795 | 0 | patchWriter.writeLineTo(p[0], p[2]); |
796 | 0 | continue; |
797 | 0 | } |
798 | 0 | if (GrPathUtils::conicHasCusp(p)) { |
799 | | // Cusps are rare, but the tessellation shader can't handle them. Chop the |
800 | | // curve into segments that the shader can handle. |
801 | 0 | SkPoint cusp = SkEvalQuadAt(p, SkFindQuadMidTangent(p)); |
802 | 0 | patchWriter.writeLineTo(p[0], cusp); |
803 | 0 | patchWriter.writeLineTo(JoinType::kBowtie, cusp, p[2]); |
804 | 0 | continue; |
805 | 0 | } |
806 | 0 | float numParametricSegments_pow4 = |
807 | 0 | GrWangsFormula::quadratic_pow4(patchWriter.parametricPrecision(), p); |
808 | 0 | if (!patchWriter.stroke180FitsInPatch(numParametricSegments_pow4)) { |
809 | | // The curve requires more tessellation segments than the hardware can |
810 | | // support. This is rare. Recursively chop until each sub-curve fits. |
811 | 0 | patchWriter.writeConicPatchesTo(p, 1); |
812 | 0 | continue; |
813 | 0 | } |
814 | | // The curve fits in a single tessellation patch. This is the most common case. |
815 | | // Write it out directly. |
816 | 0 | prevJoinFitsInPatch = patchWriter.stroke180FitsInPatch_withJoin( |
817 | 0 | numParametricSegments_pow4); |
818 | 0 | GrPathUtils::convertQuadToCubic(p, scratchPts); |
819 | 0 | patchPts = scratchPts; |
820 | 0 | endControlPoint = patchPts[2]; |
821 | 0 | break; |
822 | 0 | } |
823 | 0 | case SkPathVerb::kConic: { |
824 | 0 | contourIsEmpty = false; |
825 | 0 | if (p[1] == p[0] || p[1] == p[2]) { |
826 | | // Zero-length paths need special treatment because they are spec'd to |
827 | | // behave differently. If the control point is colocated on an endpoint then |
828 | | // this might end up being the case. Fall back on a lineTo and let it make |
829 | | // the final check. |
830 | 0 | patchWriter.writeLineTo(p[0], p[2]); |
831 | 0 | continue; |
832 | 0 | } |
833 | 0 | if (GrPathUtils::conicHasCusp(p)) { |
834 | | // Cusps are rare, but the tessellation shader can't handle them. Chop the |
835 | | // curve into segments that the shader can handle. |
836 | 0 | SkConic conic(p, *w); |
837 | 0 | SkPoint cusp = conic.evalAt(conic.findMidTangent()); |
838 | 0 | patchWriter.writeLineTo(p[0], cusp); |
839 | 0 | patchWriter.writeLineTo(JoinType::kBowtie, cusp, p[2]); |
840 | 0 | continue; |
841 | 0 | } |
842 | | // For now, the tessellation shader still uses Wang's quadratic formula when it |
843 | | // draws conics. |
844 | | // TODO: Update here when the shader starts using the real conic formula. |
845 | 0 | float n = GrWangsFormula::conic_pow2(patchWriter.parametricPrecision(), p, *w); |
846 | 0 | float numParametricSegments_pow4 = n*n; |
847 | 0 | if (!patchWriter.stroke180FitsInPatch(numParametricSegments_pow4)) { |
848 | | // The curve requires more tessellation segments than the hardware can |
849 | | // support. This is rare. Recursively chop until each sub-curve fits. |
850 | 0 | patchWriter.writeConicPatchesTo(p, *w); |
851 | 0 | continue; |
852 | 0 | } |
853 | | // The curve fits in a single tessellation patch. This is the most common |
854 | | // case. Write it out directly. |
855 | 0 | prevJoinFitsInPatch = patchWriter.stroke180FitsInPatch_withJoin( |
856 | 0 | numParametricSegments_pow4); |
857 | 0 | GrTessellationShader::WriteConicPatch(p, *w, scratchPts); |
858 | 0 | patchPts = scratchPts; |
859 | 0 | endControlPoint = p[1]; |
860 | 0 | break; |
861 | 0 | } |
862 | 0 | case SkPathVerb::kCubic: { |
863 | 0 | contourIsEmpty = false; |
864 | 0 | if (p[1] == p[2] && (p[1] == p[0] || p[1] == p[3])) { |
865 | | // The stroke tessellation shader assigns special meaning to p0==p1==p2 and |
866 | | // p1==p2==p3. If this is the case then we need to rewrite the cubic. |
867 | 0 | patchWriter.writeLineTo(p[0], p[3]); |
868 | 0 | continue; |
869 | 0 | } |
870 | 0 | float numParametricSegments_pow4 = |
871 | 0 | GrWangsFormula::cubic_pow4(patchWriter.parametricPrecision(), p); |
872 | 0 | if (!patchWriter.stroke360FitsInPatch(numParametricSegments_pow4) || |
873 | 0 | cubic_has_cusp(p)) { |
874 | | // Either the curve requires more tessellation segments than the hardware |
875 | | // can support, or it has cusp(s). Either case is rare. Chop it into |
876 | | // sections that rotate 180 degrees or less (which will naturally be the |
877 | | // cusp points if there are any), and then recursively chop each section |
878 | | // until it fits. |
879 | 0 | patchWriter.writeCubicConvex180PatchesTo(p); |
880 | 0 | continue; |
881 | 0 | } |
882 | | // The curve fits in a single tessellation patch. This is the most common case. |
883 | | // Write it out directly. |
884 | 0 | prevJoinFitsInPatch = patchWriter.stroke360FitsInPatch_withJoin( |
885 | 0 | numParametricSegments_pow4); |
886 | 0 | patchPts = p; |
887 | 0 | endControlPoint = (p[2] != p[3]) ? p[2] : p[1]; |
888 | 0 | break; |
889 | 0 | } |
890 | 0 | } |
891 | 0 | patchWriter.writePatchTo(prevJoinFitsInPatch, patchPts, endControlPoint); |
892 | 0 | } |
893 | 0 | if (!contourIsEmpty) { |
894 | 0 | const SkPoint* p = SkPathPriv::PointData(path); |
895 | 0 | patchWriter.writeCaps(p[path.countPoints() - 1], fShader.viewMatrix(), stroke); |
896 | 0 | } |
897 | 0 | } |
898 | 0 | } |
899 | | |
900 | | #if SK_GPU_V1 |
901 | | #include "src/gpu/GrOpFlushState.h" |
902 | | |
903 | 0 | void GrStrokeHardwareTessellator::draw(GrOpFlushState* flushState) const { |
904 | 0 | for (const auto& vertexChunk : fPatchChunks) { |
905 | 0 | flushState->bindBuffers(nullptr, nullptr, vertexChunk.fBuffer); |
906 | 0 | flushState->draw(vertexChunk.fCount, vertexChunk.fBase); |
907 | 0 | } |
908 | 0 | } |
909 | | |
910 | | #endif |