1 /* 2 * Copyright 2015 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 "GrTessellator.h" 9 10 #include "GrDefaultGeoProcFactory.h" 11 #include "GrPathUtils.h" 12 #include "GrVertexWriter.h" 13 14 #include "SkArenaAlloc.h" 15 #include "SkGeometry.h" 16 #include "SkPath.h" 17 #include "SkPointPriv.h" 18 #include "SkTDPQueue.h" 19 20 #include <algorithm> 21 #include <cstdio> 22 #include <utility> 23 24 /* 25 * There are six stages to the basic algorithm: 26 * 27 * 1) Linearize the path contours into piecewise linear segments (path_to_contours()). 28 * 2) Build a mesh of edges connecting the vertices (build_edges()). 29 * 3) Sort the vertices in Y (and secondarily in X) (merge_sort()). 30 * 4) Simplify the mesh by inserting new vertices at intersecting edges (simplify()). 31 * 5) Tessellate the simplified mesh into monotone polygons (tessellate()). 32 * 6) Triangulate the monotone polygons directly into a vertex buffer (polys_to_triangles()). 33 * 34 * For screenspace antialiasing, the algorithm is modified as follows: 35 * 36 * Run steps 1-5 above to produce polygons. 37 * 5b) Apply fill rules to extract boundary contours from the polygons (extract_boundaries()). 38 * 5c) Simplify boundaries to remove "pointy" vertices that cause inversions (simplify_boundary()). 39 * 5d) Displace edges by half a pixel inward and outward along their normals. Intersect to find 40 * new vertices, and set zero alpha on the exterior and one alpha on the interior. Build a new 41 * antialiased mesh from those vertices (stroke_boundary()). 42 * Run steps 3-6 above on the new mesh, and produce antialiased triangles. 43 * 44 * The vertex sorting in step (3) is a merge sort, since it plays well with the linked list 45 * of vertices (and the necessity of inserting new vertices on intersection). 46 * 47 * Stages (4) and (5) use an active edge list -- a list of all edges for which the 48 * sweep line has crossed the top vertex, but not the bottom vertex. It's sorted 49 * left-to-right based on the point where both edges are active (when both top vertices 50 * have been seen, so the "lower" top vertex of the two). If the top vertices are equal 51 * (shared), it's sorted based on the last point where both edges are active, so the 52 * "upper" bottom vertex. 53 * 54 * The most complex step is the simplification (4). It's based on the Bentley-Ottman 55 * line-sweep algorithm, but due to floating point inaccuracy, the intersection points are 56 * not exact and may violate the mesh topology or active edge list ordering. We 57 * accommodate this by adjusting the topology of the mesh and AEL to match the intersection 58 * points. This occurs in two ways: 59 * 60 * A) Intersections may cause a shortened edge to no longer be ordered with respect to its 61 * neighbouring edges at the top or bottom vertex. This is handled by merging the 62 * edges (merge_collinear_edges()). 63 * B) Intersections may cause an edge to violate the left-to-right ordering of the 64 * active edge list. This is handled by detecting potential violations and rewinding 65 * the active edge list to the vertex before they occur (rewind() during merging, 66 * rewind_if_necessary() during splitting). 67 * 68 * The tessellation steps (5) and (6) are based on "Triangulating Simple Polygons and 69 * Equivalent Problems" (Fournier and Montuno); also a line-sweep algorithm. Note that it 70 * currently uses a linked list for the active edge list, rather than a 2-3 tree as the 71 * paper describes. The 2-3 tree gives O(lg N) lookups, but insertion and removal also 72 * become O(lg N). In all the test cases, it was found that the cost of frequent O(lg N) 73 * insertions and removals was greater than the cost of infrequent O(N) lookups with the 74 * linked list implementation. With the latter, all removals are O(1), and most insertions 75 * are O(1), since we know the adjacent edge in the active edge list based on the topology. 76 * Only type 2 vertices (see paper) require the O(N) lookups, and these are much less 77 * frequent. There may be other data structures worth investigating, however. 78 * 79 * Note that the orientation of the line sweep algorithms is determined by the aspect ratio of the 80 * path bounds. When the path is taller than it is wide, we sort vertices based on increasing Y 81 * coordinate, and secondarily by increasing X coordinate. When the path is wider than it is tall, 82 * we sort by increasing X coordinate, but secondarily by *decreasing* Y coordinate. This is so 83 * that the "left" and "right" orientation in the code remains correct (edges to the left are 84 * increasing in Y; edges to the right are decreasing in Y). That is, the setting rotates 90 85 * degrees counterclockwise, rather that transposing. 86 */ 87 88 #define LOGGING_ENABLED 0 89 90 #if LOGGING_ENABLED 91 #define LOG printf 92 #else 93 #define LOG(...) 94 #endif 95 96 namespace { 97 98 const int kArenaChunkSize = 16 * 1024; 99 const float kCosMiterAngle = 0.97f; // Corresponds to an angle of ~14 degrees. 100 101 struct Vertex; 102 struct Edge; 103 struct Event; 104 struct Poly; 105 106 template <class T, T* T::*Prev, T* T::*Next> 107 void list_insert(T* t, T* prev, T* next, T** head, T** tail) { 108 t->*Prev = prev; 109 t->*Next = next; 110 if (prev) { 111 prev->*Next = t; 112 } else if (head) { 113 *head = t; 114 } 115 if (next) { 116 next->*Prev = t; 117 } else if (tail) { 118 *tail = t; 119 } 120 } 121 122 template <class T, T* T::*Prev, T* T::*Next> 123 void list_remove(T* t, T** head, T** tail) { 124 if (t->*Prev) { 125 t->*Prev->*Next = t->*Next; 126 } else if (head) { 127 *head = t->*Next; 128 } 129 if (t->*Next) { 130 t->*Next->*Prev = t->*Prev; 131 } else if (tail) { 132 *tail = t->*Prev; 133 } 134 t->*Prev = t->*Next = nullptr; 135 } 136 137 /** 138 * Vertices are used in three ways: first, the path contours are converted into a 139 * circularly-linked list of Vertices for each contour. After edge construction, the same Vertices 140 * are re-ordered by the merge sort according to the sweep_lt comparator (usually, increasing 141 * in Y) using the same fPrev/fNext pointers that were used for the contours, to avoid 142 * reallocation. Finally, MonotonePolys are built containing a circularly-linked list of 143 * Vertices. (Currently, those Vertices are newly-allocated for the MonotonePolys, since 144 * an individual Vertex from the path mesh may belong to multiple 145 * MonotonePolys, so the original Vertices cannot be re-used. 146 */ 147 148 struct Vertex { 149 Vertex(const SkPoint& point, uint8_t alpha) 150 : fPoint(point), fPrev(nullptr), fNext(nullptr) 151 , fFirstEdgeAbove(nullptr), fLastEdgeAbove(nullptr) 152 , fFirstEdgeBelow(nullptr), fLastEdgeBelow(nullptr) 153 , fLeftEnclosingEdge(nullptr), fRightEnclosingEdge(nullptr) 154 , fPartner(nullptr) 155 , fAlpha(alpha) 156 #if LOGGING_ENABLED 157 , fID (-1.0f) 158 #endif 159 {} 160 SkPoint fPoint; // Vertex position 161 Vertex* fPrev; // Linked list of contours, then Y-sorted vertices. 162 Vertex* fNext; // " 163 Edge* fFirstEdgeAbove; // Linked list of edges above this vertex. 164 Edge* fLastEdgeAbove; // " 165 Edge* fFirstEdgeBelow; // Linked list of edges below this vertex. 166 Edge* fLastEdgeBelow; // " 167 Edge* fLeftEnclosingEdge; // Nearest edge in the AEL left of this vertex. 168 Edge* fRightEnclosingEdge; // Nearest edge in the AEL right of this vertex. 169 Vertex* fPartner; // Corresponding inner or outer vertex (for AA). 170 uint8_t fAlpha; 171 #if LOGGING_ENABLED 172 float fID; // Identifier used for logging. 173 #endif 174 }; 175 176 /***************************************************************************************/ 177 178 typedef bool (*CompareFunc)(const SkPoint& a, const SkPoint& b); 179 180 bool sweep_lt_horiz(const SkPoint& a, const SkPoint& b) { 181 return a.fX < b.fX || (a.fX == b.fX && a.fY > b.fY); 182 } 183 184 bool sweep_lt_vert(const SkPoint& a, const SkPoint& b) { 185 return a.fY < b.fY || (a.fY == b.fY && a.fX < b.fX); 186 } 187 188 struct Comparator { 189 enum class Direction { kVertical, kHorizontal }; 190 Comparator(Direction direction) : fDirection(direction) {} 191 bool sweep_lt(const SkPoint& a, const SkPoint& b) const { 192 return fDirection == Direction::kHorizontal ? sweep_lt_horiz(a, b) : sweep_lt_vert(a, b); 193 } 194 Direction fDirection; 195 }; 196 197 inline void* emit_vertex(Vertex* v, bool emitCoverage, void* data) { 198 GrVertexWriter verts{data}; 199 verts.write(v->fPoint); 200 201 if (emitCoverage) { 202 verts.write(GrNormalizeByteToFloat(v->fAlpha)); 203 } 204 205 return verts.fPtr; 206 } 207 208 void* emit_triangle(Vertex* v0, Vertex* v1, Vertex* v2, bool emitCoverage, void* data) { 209 LOG("emit_triangle %g (%g, %g) %d\n", v0->fID, v0->fPoint.fX, v0->fPoint.fY, v0->fAlpha); 210 LOG(" %g (%g, %g) %d\n", v1->fID, v1->fPoint.fX, v1->fPoint.fY, v1->fAlpha); 211 LOG(" %g (%g, %g) %d\n", v2->fID, v2->fPoint.fX, v2->fPoint.fY, v2->fAlpha); 212 #if TESSELLATOR_WIREFRAME 213 data = emit_vertex(v0, emitCoverage, data); 214 data = emit_vertex(v1, emitCoverage, data); 215 data = emit_vertex(v1, emitCoverage, data); 216 data = emit_vertex(v2, emitCoverage, data); 217 data = emit_vertex(v2, emitCoverage, data); 218 data = emit_vertex(v0, emitCoverage, data); 219 #else 220 data = emit_vertex(v0, emitCoverage, data); 221 data = emit_vertex(v1, emitCoverage, data); 222 data = emit_vertex(v2, emitCoverage, data); 223 #endif 224 return data; 225 } 226 227 struct VertexList { 228 VertexList() : fHead(nullptr), fTail(nullptr) {} 229 VertexList(Vertex* head, Vertex* tail) : fHead(head), fTail(tail) {} 230 Vertex* fHead; 231 Vertex* fTail; 232 void insert(Vertex* v, Vertex* prev, Vertex* next) { 233 list_insert<Vertex, &Vertex::fPrev, &Vertex::fNext>(v, prev, next, &fHead, &fTail); 234 } 235 void append(Vertex* v) { 236 insert(v, fTail, nullptr); 237 } 238 void append(const VertexList& list) { 239 if (!list.fHead) { 240 return; 241 } 242 if (fTail) { 243 fTail->fNext = list.fHead; 244 list.fHead->fPrev = fTail; 245 } else { 246 fHead = list.fHead; 247 } 248 fTail = list.fTail; 249 } 250 void prepend(Vertex* v) { 251 insert(v, nullptr, fHead); 252 } 253 void remove(Vertex* v) { 254 list_remove<Vertex, &Vertex::fPrev, &Vertex::fNext>(v, &fHead, &fTail); 255 } 256 void close() { 257 if (fHead && fTail) { 258 fTail->fNext = fHead; 259 fHead->fPrev = fTail; 260 } 261 } 262 }; 263 264 // Round to nearest quarter-pixel. This is used for screenspace tessellation. 265 266 inline void round(SkPoint* p) { 267 p->fX = SkScalarRoundToScalar(p->fX * SkFloatToScalar(4.0f)) * SkFloatToScalar(0.25f); 268 p->fY = SkScalarRoundToScalar(p->fY * SkFloatToScalar(4.0f)) * SkFloatToScalar(0.25f); 269 } 270 271 inline SkScalar double_to_clamped_scalar(double d) { 272 return SkDoubleToScalar(std::min((double) SK_ScalarMax, std::max(d, (double) -SK_ScalarMax))); 273 } 274 275 // A line equation in implicit form. fA * x + fB * y + fC = 0, for all points (x, y) on the line. 276 struct Line { 277 Line(double a, double b, double c) : fA(a), fB(b), fC(c) {} 278 Line(Vertex* p, Vertex* q) : Line(p->fPoint, q->fPoint) {} 279 Line(const SkPoint& p, const SkPoint& q) 280 : fA(static_cast<double>(q.fY) - p.fY) // a = dY 281 , fB(static_cast<double>(p.fX) - q.fX) // b = -dX 282 , fC(static_cast<double>(p.fY) * q.fX - // c = cross(q, p) 283 static_cast<double>(p.fX) * q.fY) {} 284 double dist(const SkPoint& p) const { 285 return fA * p.fX + fB * p.fY + fC; 286 } 287 Line operator*(double v) const { 288 return Line(fA * v, fB * v, fC * v); 289 } 290 double magSq() const { 291 return fA * fA + fB * fB; 292 } 293 void normalize() { 294 double len = sqrt(this->magSq()); 295 if (len == 0.0) { 296 return; 297 } 298 double scale = 1.0f / len; 299 fA *= scale; 300 fB *= scale; 301 fC *= scale; 302 } 303 bool nearParallel(const Line& o) const { 304 return fabs(o.fA - fA) < 0.00001 && fabs(o.fB - fB) < 0.00001; 305 } 306 307 // Compute the intersection of two (infinite) Lines. 308 bool intersect(const Line& other, SkPoint* point) const { 309 double denom = fA * other.fB - fB * other.fA; 310 if (denom == 0.0) { 311 return false; 312 } 313 double scale = 1.0 / denom; 314 point->fX = double_to_clamped_scalar((fB * other.fC - other.fB * fC) * scale); 315 point->fY = double_to_clamped_scalar((other.fA * fC - fA * other.fC) * scale); 316 round(point); 317 return true; 318 } 319 double fA, fB, fC; 320 }; 321 322 /** 323 * An Edge joins a top Vertex to a bottom Vertex. Edge ordering for the list of "edges above" and 324 * "edge below" a vertex as well as for the active edge list is handled by isLeftOf()/isRightOf(). 325 * Note that an Edge will give occasionally dist() != 0 for its own endpoints (because floating 326 * point). For speed, that case is only tested by the callers that require it (e.g., 327 * rewind_if_necessary()). Edges also handle checking for intersection with other edges. 328 * Currently, this converts the edges to the parametric form, in order to avoid doing a division 329 * until an intersection has been confirmed. This is slightly slower in the "found" case, but 330 * a lot faster in the "not found" case. 331 * 332 * The coefficients of the line equation stored in double precision to avoid catastrphic 333 * cancellation in the isLeftOf() and isRightOf() checks. Using doubles ensures that the result is 334 * correct in float, since it's a polynomial of degree 2. The intersect() function, being 335 * degree 5, is still subject to catastrophic cancellation. We deal with that by assuming its 336 * output may be incorrect, and adjusting the mesh topology to match (see comment at the top of 337 * this file). 338 */ 339 340 struct Edge { 341 enum class Type { kInner, kOuter, kConnector }; 342 Edge(Vertex* top, Vertex* bottom, int winding, Type type) 343 : fWinding(winding) 344 , fTop(top) 345 , fBottom(bottom) 346 , fType(type) 347 , fLeft(nullptr) 348 , fRight(nullptr) 349 , fPrevEdgeAbove(nullptr) 350 , fNextEdgeAbove(nullptr) 351 , fPrevEdgeBelow(nullptr) 352 , fNextEdgeBelow(nullptr) 353 , fLeftPoly(nullptr) 354 , fRightPoly(nullptr) 355 , fEvent(nullptr) 356 , fLeftPolyPrev(nullptr) 357 , fLeftPolyNext(nullptr) 358 , fRightPolyPrev(nullptr) 359 , fRightPolyNext(nullptr) 360 , fOverlap(false) 361 , fUsedInLeftPoly(false) 362 , fUsedInRightPoly(false) 363 , fLine(top, bottom) { 364 } 365 int fWinding; // 1 == edge goes downward; -1 = edge goes upward. 366 Vertex* fTop; // The top vertex in vertex-sort-order (sweep_lt). 367 Vertex* fBottom; // The bottom vertex in vertex-sort-order. 368 Type fType; 369 Edge* fLeft; // The linked list of edges in the active edge list. 370 Edge* fRight; // " 371 Edge* fPrevEdgeAbove; // The linked list of edges in the bottom Vertex's "edges above". 372 Edge* fNextEdgeAbove; // " 373 Edge* fPrevEdgeBelow; // The linked list of edges in the top Vertex's "edges below". 374 Edge* fNextEdgeBelow; // " 375 Poly* fLeftPoly; // The Poly to the left of this edge, if any. 376 Poly* fRightPoly; // The Poly to the right of this edge, if any. 377 Event* fEvent; 378 Edge* fLeftPolyPrev; 379 Edge* fLeftPolyNext; 380 Edge* fRightPolyPrev; 381 Edge* fRightPolyNext; 382 bool fOverlap; // True if there's an overlap region adjacent to this edge. 383 bool fUsedInLeftPoly; 384 bool fUsedInRightPoly; 385 Line fLine; 386 double dist(const SkPoint& p) const { 387 return fLine.dist(p); 388 } 389 bool isRightOf(Vertex* v) const { 390 return fLine.dist(v->fPoint) < 0.0; 391 } 392 bool isLeftOf(Vertex* v) const { 393 return fLine.dist(v->fPoint) > 0.0; 394 } 395 void recompute() { 396 fLine = Line(fTop, fBottom); 397 } 398 bool intersect(const Edge& other, SkPoint* p, uint8_t* alpha = nullptr) const { 399 LOG("intersecting %g -> %g with %g -> %g\n", 400 fTop->fID, fBottom->fID, 401 other.fTop->fID, other.fBottom->fID); 402 if (fTop == other.fTop || fBottom == other.fBottom) { 403 return false; 404 } 405 double denom = fLine.fA * other.fLine.fB - fLine.fB * other.fLine.fA; 406 if (denom == 0.0) { 407 return false; 408 } 409 double dx = static_cast<double>(other.fTop->fPoint.fX) - fTop->fPoint.fX; 410 double dy = static_cast<double>(other.fTop->fPoint.fY) - fTop->fPoint.fY; 411 double sNumer = dy * other.fLine.fB + dx * other.fLine.fA; 412 double tNumer = dy * fLine.fB + dx * fLine.fA; 413 // If (sNumer / denom) or (tNumer / denom) is not in [0..1], exit early. 414 // This saves us doing the divide below unless absolutely necessary. 415 if (denom > 0.0 ? (sNumer < 0.0 || sNumer > denom || tNumer < 0.0 || tNumer > denom) 416 : (sNumer > 0.0 || sNumer < denom || tNumer > 0.0 || tNumer < denom)) { 417 return false; 418 } 419 double s = sNumer / denom; 420 SkASSERT(s >= 0.0 && s <= 1.0); 421 p->fX = SkDoubleToScalar(fTop->fPoint.fX - s * fLine.fB); 422 p->fY = SkDoubleToScalar(fTop->fPoint.fY + s * fLine.fA); 423 if (alpha) { 424 if (fType == Type::kConnector) { 425 *alpha = (1.0 - s) * fTop->fAlpha + s * fBottom->fAlpha; 426 } else if (other.fType == Type::kConnector) { 427 double t = tNumer / denom; 428 *alpha = (1.0 - t) * other.fTop->fAlpha + t * other.fBottom->fAlpha; 429 } else if (fType == Type::kOuter && other.fType == Type::kOuter) { 430 *alpha = 0; 431 } else { 432 *alpha = 255; 433 } 434 } 435 return true; 436 } 437 }; 438 439 struct EdgeList { 440 EdgeList() : fHead(nullptr), fTail(nullptr) {} 441 Edge* fHead; 442 Edge* fTail; 443 void insert(Edge* edge, Edge* prev, Edge* next) { 444 list_insert<Edge, &Edge::fLeft, &Edge::fRight>(edge, prev, next, &fHead, &fTail); 445 } 446 void append(Edge* e) { 447 insert(e, fTail, nullptr); 448 } 449 void remove(Edge* edge) { 450 list_remove<Edge, &Edge::fLeft, &Edge::fRight>(edge, &fHead, &fTail); 451 } 452 void removeAll() { 453 while (fHead) { 454 this->remove(fHead); 455 } 456 } 457 void close() { 458 if (fHead && fTail) { 459 fTail->fRight = fHead; 460 fHead->fLeft = fTail; 461 } 462 } 463 bool contains(Edge* edge) const { 464 return edge->fLeft || edge->fRight || fHead == edge; 465 } 466 }; 467 468 struct Event { 469 Event(Edge* edge, bool isOuterBoundary, const SkPoint& point, uint8_t alpha) 470 : fEdge(edge), fIsOuterBoundary(isOuterBoundary), fPoint(point), fAlpha(alpha) 471 , fPrev(nullptr), fNext(nullptr) { 472 } 473 Edge* fEdge; 474 bool fIsOuterBoundary; 475 SkPoint fPoint; 476 uint8_t fAlpha; 477 Event* fPrev; 478 Event* fNext; 479 void apply(VertexList* mesh, Comparator& c, SkArenaAlloc& alloc); 480 }; 481 482 bool compare(Event* const& e1, Event* const& e2) { 483 return e1->fAlpha > e2->fAlpha; 484 } 485 486 struct EventList : public SkTDPQueue<Event*, &compare> {}; 487 488 void create_event(Edge* e, bool isOuterBoundary, EventList* events, SkArenaAlloc& alloc) { 489 Edge bisector1(e->fTop, e->fTop->fPartner, 1, Edge::Type::kConnector); 490 Edge bisector2(e->fBottom, e->fBottom->fPartner, 1, Edge::Type::kConnector); 491 SkPoint p; 492 uint8_t alpha; 493 if (bisector1.intersect(bisector2, &p, &alpha)) { 494 LOG("found overlap edge %g -> %g, will collapse to %g,%g alpha %d\n", 495 e->fTop->fID, e->fBottom->fID, p.fX, p.fY, alpha); 496 e->fEvent = alloc.make<Event>(e, isOuterBoundary, p, alpha); 497 events->insert(e->fEvent); 498 } 499 } 500 501 /***************************************************************************************/ 502 503 struct Poly { 504 Poly(Vertex* v, int winding) 505 : fFirstVertex(v) 506 , fWinding(winding) 507 , fHead(nullptr) 508 , fTail(nullptr) 509 , fNext(nullptr) 510 , fPartner(nullptr) 511 , fCount(0) 512 { 513 #if LOGGING_ENABLED 514 static int gID = 0; 515 fID = gID++; 516 LOG("*** created Poly %d\n", fID); 517 #endif 518 } 519 typedef enum { kLeft_Side, kRight_Side } Side; 520 struct MonotonePoly { 521 MonotonePoly(Edge* edge, Side side) 522 : fSide(side) 523 , fFirstEdge(nullptr) 524 , fLastEdge(nullptr) 525 , fPrev(nullptr) 526 , fNext(nullptr) { 527 this->addEdge(edge); 528 } 529 Side fSide; 530 Edge* fFirstEdge; 531 Edge* fLastEdge; 532 MonotonePoly* fPrev; 533 MonotonePoly* fNext; 534 void addEdge(Edge* edge) { 535 if (fSide == kRight_Side) { 536 SkASSERT(!edge->fUsedInRightPoly); 537 list_insert<Edge, &Edge::fRightPolyPrev, &Edge::fRightPolyNext>( 538 edge, fLastEdge, nullptr, &fFirstEdge, &fLastEdge); 539 edge->fUsedInRightPoly = true; 540 } else { 541 SkASSERT(!edge->fUsedInLeftPoly); 542 list_insert<Edge, &Edge::fLeftPolyPrev, &Edge::fLeftPolyNext>( 543 edge, fLastEdge, nullptr, &fFirstEdge, &fLastEdge); 544 edge->fUsedInLeftPoly = true; 545 } 546 } 547 548 void* emit(bool emitCoverage, void* data) { 549 Edge* e = fFirstEdge; 550 VertexList vertices; 551 vertices.append(e->fTop); 552 int count = 1; 553 while (e != nullptr) { 554 if (kRight_Side == fSide) { 555 vertices.append(e->fBottom); 556 e = e->fRightPolyNext; 557 } else { 558 vertices.prepend(e->fBottom); 559 e = e->fLeftPolyNext; 560 } 561 count++; 562 } 563 Vertex* first = vertices.fHead; 564 Vertex* v = first->fNext; 565 while (v != vertices.fTail) { 566 SkASSERT(v && v->fPrev && v->fNext); 567 Vertex* prev = v->fPrev; 568 Vertex* curr = v; 569 Vertex* next = v->fNext; 570 if (count == 3) { 571 return emit_triangle(prev, curr, next, emitCoverage, data); 572 } 573 double ax = static_cast<double>(curr->fPoint.fX) - prev->fPoint.fX; 574 double ay = static_cast<double>(curr->fPoint.fY) - prev->fPoint.fY; 575 double bx = static_cast<double>(next->fPoint.fX) - curr->fPoint.fX; 576 double by = static_cast<double>(next->fPoint.fY) - curr->fPoint.fY; 577 if (ax * by - ay * bx >= 0.0) { 578 data = emit_triangle(prev, curr, next, emitCoverage, data); 579 v->fPrev->fNext = v->fNext; 580 v->fNext->fPrev = v->fPrev; 581 count--; 582 if (v->fPrev == first) { 583 v = v->fNext; 584 } else { 585 v = v->fPrev; 586 } 587 } else { 588 v = v->fNext; 589 } 590 } 591 return data; 592 } 593 }; 594 Poly* addEdge(Edge* e, Side side, SkArenaAlloc& alloc) { 595 LOG("addEdge (%g -> %g) to poly %d, %s side\n", 596 e->fTop->fID, e->fBottom->fID, fID, side == kLeft_Side ? "left" : "right"); 597 Poly* partner = fPartner; 598 Poly* poly = this; 599 if (side == kRight_Side) { 600 if (e->fUsedInRightPoly) { 601 return this; 602 } 603 } else { 604 if (e->fUsedInLeftPoly) { 605 return this; 606 } 607 } 608 if (partner) { 609 fPartner = partner->fPartner = nullptr; 610 } 611 if (!fTail) { 612 fHead = fTail = alloc.make<MonotonePoly>(e, side); 613 fCount += 2; 614 } else if (e->fBottom == fTail->fLastEdge->fBottom) { 615 return poly; 616 } else if (side == fTail->fSide) { 617 fTail->addEdge(e); 618 fCount++; 619 } else { 620 e = alloc.make<Edge>(fTail->fLastEdge->fBottom, e->fBottom, 1, Edge::Type::kInner); 621 fTail->addEdge(e); 622 fCount++; 623 if (partner) { 624 partner->addEdge(e, side, alloc); 625 poly = partner; 626 } else { 627 MonotonePoly* m = alloc.make<MonotonePoly>(e, side); 628 m->fPrev = fTail; 629 fTail->fNext = m; 630 fTail = m; 631 } 632 } 633 return poly; 634 } 635 void* emit(bool emitCoverage, void *data) { 636 if (fCount < 3) { 637 return data; 638 } 639 LOG("emit() %d, size %d\n", fID, fCount); 640 for (MonotonePoly* m = fHead; m != nullptr; m = m->fNext) { 641 data = m->emit(emitCoverage, data); 642 } 643 return data; 644 } 645 Vertex* lastVertex() const { return fTail ? fTail->fLastEdge->fBottom : fFirstVertex; } 646 Vertex* fFirstVertex; 647 int fWinding; 648 MonotonePoly* fHead; 649 MonotonePoly* fTail; 650 Poly* fNext; 651 Poly* fPartner; 652 int fCount; 653 #if LOGGING_ENABLED 654 int fID; 655 #endif 656 }; 657 658 /***************************************************************************************/ 659 660 bool coincident(const SkPoint& a, const SkPoint& b) { 661 return a == b; 662 } 663 664 Poly* new_poly(Poly** head, Vertex* v, int winding, SkArenaAlloc& alloc) { 665 Poly* poly = alloc.make<Poly>(v, winding); 666 poly->fNext = *head; 667 *head = poly; 668 return poly; 669 } 670 671 void append_point_to_contour(const SkPoint& p, VertexList* contour, SkArenaAlloc& alloc) { 672 Vertex* v = alloc.make<Vertex>(p, 255); 673 #if LOGGING_ENABLED 674 static float gID = 0.0f; 675 v->fID = gID++; 676 #endif 677 contour->append(v); 678 } 679 680 SkScalar quad_error_at(const SkPoint pts[3], SkScalar t, SkScalar u) { 681 SkQuadCoeff quad(pts); 682 SkPoint p0 = to_point(quad.eval(t - 0.5f * u)); 683 SkPoint mid = to_point(quad.eval(t)); 684 SkPoint p1 = to_point(quad.eval(t + 0.5f * u)); 685 if (!p0.isFinite() || !mid.isFinite() || !p1.isFinite()) { 686 return 0; 687 } 688 return SkPointPriv::DistanceToLineSegmentBetweenSqd(mid, p0, p1); 689 } 690 691 void append_quadratic_to_contour(const SkPoint pts[3], SkScalar toleranceSqd, VertexList* contour, 692 SkArenaAlloc& alloc) { 693 SkQuadCoeff quad(pts); 694 Sk2s aa = quad.fA * quad.fA; 695 SkScalar denom = 2.0f * (aa[0] + aa[1]); 696 Sk2s ab = quad.fA * quad.fB; 697 SkScalar t = denom ? (-ab[0] - ab[1]) / denom : 0.0f; 698 int nPoints = 1; 699 SkScalar u = 1.0f; 700 // Test possible subdivision values only at the point of maximum curvature. 701 // If it passes the flatness metric there, it'll pass everywhere. 702 while (nPoints < GrPathUtils::kMaxPointsPerCurve) { 703 u = 1.0f / nPoints; 704 if (quad_error_at(pts, t, u) < toleranceSqd) { 705 break; 706 } 707 nPoints++; 708 } 709 for (int j = 1; j <= nPoints; j++) { 710 append_point_to_contour(to_point(quad.eval(j * u)), contour, alloc); 711 } 712 } 713 714 void generate_cubic_points(const SkPoint& p0, 715 const SkPoint& p1, 716 const SkPoint& p2, 717 const SkPoint& p3, 718 SkScalar tolSqd, 719 VertexList* contour, 720 int pointsLeft, 721 SkArenaAlloc& alloc) { 722 SkScalar d1 = SkPointPriv::DistanceToLineSegmentBetweenSqd(p1, p0, p3); 723 SkScalar d2 = SkPointPriv::DistanceToLineSegmentBetweenSqd(p2, p0, p3); 724 if (pointsLeft < 2 || (d1 < tolSqd && d2 < tolSqd) || 725 !SkScalarIsFinite(d1) || !SkScalarIsFinite(d2)) { 726 append_point_to_contour(p3, contour, alloc); 727 return; 728 } 729 const SkPoint q[] = { 730 { SkScalarAve(p0.fX, p1.fX), SkScalarAve(p0.fY, p1.fY) }, 731 { SkScalarAve(p1.fX, p2.fX), SkScalarAve(p1.fY, p2.fY) }, 732 { SkScalarAve(p2.fX, p3.fX), SkScalarAve(p2.fY, p3.fY) } 733 }; 734 const SkPoint r[] = { 735 { SkScalarAve(q[0].fX, q[1].fX), SkScalarAve(q[0].fY, q[1].fY) }, 736 { SkScalarAve(q[1].fX, q[2].fX), SkScalarAve(q[1].fY, q[2].fY) } 737 }; 738 const SkPoint s = { SkScalarAve(r[0].fX, r[1].fX), SkScalarAve(r[0].fY, r[1].fY) }; 739 pointsLeft >>= 1; 740 generate_cubic_points(p0, q[0], r[0], s, tolSqd, contour, pointsLeft, alloc); 741 generate_cubic_points(s, r[1], q[2], p3, tolSqd, contour, pointsLeft, alloc); 742 } 743 744 // Stage 1: convert the input path to a set of linear contours (linked list of Vertices). 745 746 void path_to_contours(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 747 VertexList* contours, SkArenaAlloc& alloc, bool *isLinear) { 748 SkScalar toleranceSqd = tolerance * tolerance; 749 750 SkPoint pts[4]; 751 *isLinear = true; 752 VertexList* contour = contours; 753 SkPath::Iter iter(path, false); 754 if (path.isInverseFillType()) { 755 SkPoint quad[4]; 756 clipBounds.toQuad(quad); 757 for (int i = 3; i >= 0; i--) { 758 append_point_to_contour(quad[i], contours, alloc); 759 } 760 contour++; 761 } 762 SkAutoConicToQuads converter; 763 SkPath::Verb verb; 764 while ((verb = iter.next(pts, false)) != SkPath::kDone_Verb) { 765 switch (verb) { 766 case SkPath::kConic_Verb: { 767 SkScalar weight = iter.conicWeight(); 768 const SkPoint* quadPts = converter.computeQuads(pts, weight, toleranceSqd); 769 for (int i = 0; i < converter.countQuads(); ++i) { 770 append_quadratic_to_contour(quadPts, toleranceSqd, contour, alloc); 771 quadPts += 2; 772 } 773 *isLinear = false; 774 break; 775 } 776 case SkPath::kMove_Verb: 777 if (contour->fHead) { 778 contour++; 779 } 780 append_point_to_contour(pts[0], contour, alloc); 781 break; 782 case SkPath::kLine_Verb: { 783 append_point_to_contour(pts[1], contour, alloc); 784 break; 785 } 786 case SkPath::kQuad_Verb: { 787 append_quadratic_to_contour(pts, toleranceSqd, contour, alloc); 788 *isLinear = false; 789 break; 790 } 791 case SkPath::kCubic_Verb: { 792 int pointsLeft = GrPathUtils::cubicPointCount(pts, tolerance); 793 generate_cubic_points(pts[0], pts[1], pts[2], pts[3], toleranceSqd, contour, 794 pointsLeft, alloc); 795 *isLinear = false; 796 break; 797 } 798 case SkPath::kClose_Verb: 799 case SkPath::kDone_Verb: 800 break; 801 } 802 } 803 } 804 805 inline bool apply_fill_type(SkPath::FillType fillType, int winding) { 806 switch (fillType) { 807 case SkPath::kWinding_FillType: 808 return winding != 0; 809 case SkPath::kEvenOdd_FillType: 810 return (winding & 1) != 0; 811 case SkPath::kInverseWinding_FillType: 812 return winding == 1; 813 case SkPath::kInverseEvenOdd_FillType: 814 return (winding & 1) == 1; 815 default: 816 SkASSERT(false); 817 return false; 818 } 819 } 820 821 inline bool apply_fill_type(SkPath::FillType fillType, Poly* poly) { 822 return poly && apply_fill_type(fillType, poly->fWinding); 823 } 824 825 Edge* new_edge(Vertex* prev, Vertex* next, Edge::Type type, Comparator& c, SkArenaAlloc& alloc) { 826 int winding = c.sweep_lt(prev->fPoint, next->fPoint) ? 1 : -1; 827 Vertex* top = winding < 0 ? next : prev; 828 Vertex* bottom = winding < 0 ? prev : next; 829 return alloc.make<Edge>(top, bottom, winding, type); 830 } 831 832 void remove_edge(Edge* edge, EdgeList* edges) { 833 LOG("removing edge %g -> %g\n", edge->fTop->fID, edge->fBottom->fID); 834 SkASSERT(edges->contains(edge)); 835 edges->remove(edge); 836 } 837 838 void insert_edge(Edge* edge, Edge* prev, EdgeList* edges) { 839 LOG("inserting edge %g -> %g\n", edge->fTop->fID, edge->fBottom->fID); 840 SkASSERT(!edges->contains(edge)); 841 Edge* next = prev ? prev->fRight : edges->fHead; 842 edges->insert(edge, prev, next); 843 } 844 845 void find_enclosing_edges(Vertex* v, EdgeList* edges, Edge** left, Edge** right) { 846 if (v->fFirstEdgeAbove && v->fLastEdgeAbove) { 847 *left = v->fFirstEdgeAbove->fLeft; 848 *right = v->fLastEdgeAbove->fRight; 849 return; 850 } 851 Edge* next = nullptr; 852 Edge* prev; 853 for (prev = edges->fTail; prev != nullptr; prev = prev->fLeft) { 854 if (prev->isLeftOf(v)) { 855 break; 856 } 857 next = prev; 858 } 859 *left = prev; 860 *right = next; 861 } 862 863 void insert_edge_above(Edge* edge, Vertex* v, Comparator& c) { 864 if (edge->fTop->fPoint == edge->fBottom->fPoint || 865 c.sweep_lt(edge->fBottom->fPoint, edge->fTop->fPoint)) { 866 return; 867 } 868 LOG("insert edge (%g -> %g) above vertex %g\n", edge->fTop->fID, edge->fBottom->fID, v->fID); 869 Edge* prev = nullptr; 870 Edge* next; 871 for (next = v->fFirstEdgeAbove; next; next = next->fNextEdgeAbove) { 872 if (next->isRightOf(edge->fTop)) { 873 break; 874 } 875 prev = next; 876 } 877 list_insert<Edge, &Edge::fPrevEdgeAbove, &Edge::fNextEdgeAbove>( 878 edge, prev, next, &v->fFirstEdgeAbove, &v->fLastEdgeAbove); 879 } 880 881 void insert_edge_below(Edge* edge, Vertex* v, Comparator& c) { 882 if (edge->fTop->fPoint == edge->fBottom->fPoint || 883 c.sweep_lt(edge->fBottom->fPoint, edge->fTop->fPoint)) { 884 return; 885 } 886 LOG("insert edge (%g -> %g) below vertex %g\n", edge->fTop->fID, edge->fBottom->fID, v->fID); 887 Edge* prev = nullptr; 888 Edge* next; 889 for (next = v->fFirstEdgeBelow; next; next = next->fNextEdgeBelow) { 890 if (next->isRightOf(edge->fBottom)) { 891 break; 892 } 893 prev = next; 894 } 895 list_insert<Edge, &Edge::fPrevEdgeBelow, &Edge::fNextEdgeBelow>( 896 edge, prev, next, &v->fFirstEdgeBelow, &v->fLastEdgeBelow); 897 } 898 899 void remove_edge_above(Edge* edge) { 900 SkASSERT(edge->fTop && edge->fBottom); 901 LOG("removing edge (%g -> %g) above vertex %g\n", edge->fTop->fID, edge->fBottom->fID, 902 edge->fBottom->fID); 903 list_remove<Edge, &Edge::fPrevEdgeAbove, &Edge::fNextEdgeAbove>( 904 edge, &edge->fBottom->fFirstEdgeAbove, &edge->fBottom->fLastEdgeAbove); 905 } 906 907 void remove_edge_below(Edge* edge) { 908 SkASSERT(edge->fTop && edge->fBottom); 909 LOG("removing edge (%g -> %g) below vertex %g\n", edge->fTop->fID, edge->fBottom->fID, 910 edge->fTop->fID); 911 list_remove<Edge, &Edge::fPrevEdgeBelow, &Edge::fNextEdgeBelow>( 912 edge, &edge->fTop->fFirstEdgeBelow, &edge->fTop->fLastEdgeBelow); 913 } 914 915 void disconnect(Edge* edge) 916 { 917 remove_edge_above(edge); 918 remove_edge_below(edge); 919 } 920 921 void merge_collinear_edges(Edge* edge, EdgeList* activeEdges, Vertex** current, Comparator& c); 922 923 void rewind(EdgeList* activeEdges, Vertex** current, Vertex* dst, Comparator& c) { 924 if (!current || *current == dst || c.sweep_lt((*current)->fPoint, dst->fPoint)) { 925 return; 926 } 927 Vertex* v = *current; 928 LOG("rewinding active edges from vertex %g to vertex %g\n", v->fID, dst->fID); 929 while (v != dst) { 930 v = v->fPrev; 931 for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { 932 remove_edge(e, activeEdges); 933 } 934 Edge* leftEdge = v->fLeftEnclosingEdge; 935 for (Edge* e = v->fFirstEdgeAbove; e; e = e->fNextEdgeAbove) { 936 insert_edge(e, leftEdge, activeEdges); 937 leftEdge = e; 938 } 939 } 940 *current = v; 941 } 942 943 void rewind_if_necessary(Edge* edge, EdgeList* activeEdges, Vertex** current, Comparator& c) { 944 if (!activeEdges || !current) { 945 return; 946 } 947 Vertex* top = edge->fTop; 948 Vertex* bottom = edge->fBottom; 949 if (edge->fLeft) { 950 Vertex* leftTop = edge->fLeft->fTop; 951 Vertex* leftBottom = edge->fLeft->fBottom; 952 if (c.sweep_lt(leftTop->fPoint, top->fPoint) && !edge->fLeft->isLeftOf(top)) { 953 rewind(activeEdges, current, leftTop, c); 954 } else if (c.sweep_lt(top->fPoint, leftTop->fPoint) && !edge->isRightOf(leftTop)) { 955 rewind(activeEdges, current, top, c); 956 } else if (c.sweep_lt(bottom->fPoint, leftBottom->fPoint) && 957 !edge->fLeft->isLeftOf(bottom)) { 958 rewind(activeEdges, current, leftTop, c); 959 } else if (c.sweep_lt(leftBottom->fPoint, bottom->fPoint) && !edge->isRightOf(leftBottom)) { 960 rewind(activeEdges, current, top, c); 961 } 962 } 963 if (edge->fRight) { 964 Vertex* rightTop = edge->fRight->fTop; 965 Vertex* rightBottom = edge->fRight->fBottom; 966 if (c.sweep_lt(rightTop->fPoint, top->fPoint) && !edge->fRight->isRightOf(top)) { 967 rewind(activeEdges, current, rightTop, c); 968 } else if (c.sweep_lt(top->fPoint, rightTop->fPoint) && !edge->isLeftOf(rightTop)) { 969 rewind(activeEdges, current, top, c); 970 } else if (c.sweep_lt(bottom->fPoint, rightBottom->fPoint) && 971 !edge->fRight->isRightOf(bottom)) { 972 rewind(activeEdges, current, rightTop, c); 973 } else if (c.sweep_lt(rightBottom->fPoint, bottom->fPoint) && 974 !edge->isLeftOf(rightBottom)) { 975 rewind(activeEdges, current, top, c); 976 } 977 } 978 } 979 980 void set_top(Edge* edge, Vertex* v, EdgeList* activeEdges, Vertex** current, Comparator& c) { 981 remove_edge_below(edge); 982 edge->fTop = v; 983 edge->recompute(); 984 insert_edge_below(edge, v, c); 985 rewind_if_necessary(edge, activeEdges, current, c); 986 merge_collinear_edges(edge, activeEdges, current, c); 987 } 988 989 void set_bottom(Edge* edge, Vertex* v, EdgeList* activeEdges, Vertex** current, Comparator& c) { 990 remove_edge_above(edge); 991 edge->fBottom = v; 992 edge->recompute(); 993 insert_edge_above(edge, v, c); 994 rewind_if_necessary(edge, activeEdges, current, c); 995 merge_collinear_edges(edge, activeEdges, current, c); 996 } 997 998 void merge_edges_above(Edge* edge, Edge* other, EdgeList* activeEdges, Vertex** current, 999 Comparator& c) { 1000 if (coincident(edge->fTop->fPoint, other->fTop->fPoint)) { 1001 LOG("merging coincident above edges (%g, %g) -> (%g, %g)\n", 1002 edge->fTop->fPoint.fX, edge->fTop->fPoint.fY, 1003 edge->fBottom->fPoint.fX, edge->fBottom->fPoint.fY); 1004 rewind(activeEdges, current, edge->fTop, c); 1005 other->fWinding += edge->fWinding; 1006 disconnect(edge); 1007 edge->fTop = edge->fBottom = nullptr; 1008 } else if (c.sweep_lt(edge->fTop->fPoint, other->fTop->fPoint)) { 1009 rewind(activeEdges, current, edge->fTop, c); 1010 other->fWinding += edge->fWinding; 1011 set_bottom(edge, other->fTop, activeEdges, current, c); 1012 } else { 1013 rewind(activeEdges, current, other->fTop, c); 1014 edge->fWinding += other->fWinding; 1015 set_bottom(other, edge->fTop, activeEdges, current, c); 1016 } 1017 } 1018 1019 void merge_edges_below(Edge* edge, Edge* other, EdgeList* activeEdges, Vertex** current, 1020 Comparator& c) { 1021 if (coincident(edge->fBottom->fPoint, other->fBottom->fPoint)) { 1022 LOG("merging coincident below edges (%g, %g) -> (%g, %g)\n", 1023 edge->fTop->fPoint.fX, edge->fTop->fPoint.fY, 1024 edge->fBottom->fPoint.fX, edge->fBottom->fPoint.fY); 1025 rewind(activeEdges, current, edge->fTop, c); 1026 other->fWinding += edge->fWinding; 1027 disconnect(edge); 1028 edge->fTop = edge->fBottom = nullptr; 1029 } else if (c.sweep_lt(edge->fBottom->fPoint, other->fBottom->fPoint)) { 1030 rewind(activeEdges, current, other->fTop, c); 1031 edge->fWinding += other->fWinding; 1032 set_top(other, edge->fBottom, activeEdges, current, c); 1033 } else { 1034 rewind(activeEdges, current, edge->fTop, c); 1035 other->fWinding += edge->fWinding; 1036 set_top(edge, other->fBottom, activeEdges, current, c); 1037 } 1038 } 1039 1040 bool top_collinear(Edge* left, Edge* right) { 1041 if (!left || !right) { 1042 return false; 1043 } 1044 return left->fTop->fPoint == right->fTop->fPoint || 1045 !left->isLeftOf(right->fTop) || !right->isRightOf(left->fTop); 1046 } 1047 1048 bool bottom_collinear(Edge* left, Edge* right) { 1049 if (!left || !right) { 1050 return false; 1051 } 1052 return left->fBottom->fPoint == right->fBottom->fPoint || 1053 !left->isLeftOf(right->fBottom) || !right->isRightOf(left->fBottom); 1054 } 1055 1056 void merge_collinear_edges(Edge* edge, EdgeList* activeEdges, Vertex** current, Comparator& c) { 1057 for (;;) { 1058 if (top_collinear(edge->fPrevEdgeAbove, edge)) { 1059 merge_edges_above(edge->fPrevEdgeAbove, edge, activeEdges, current, c); 1060 } else if (top_collinear(edge, edge->fNextEdgeAbove)) { 1061 merge_edges_above(edge->fNextEdgeAbove, edge, activeEdges, current, c); 1062 } else if (bottom_collinear(edge->fPrevEdgeBelow, edge)) { 1063 merge_edges_below(edge->fPrevEdgeBelow, edge, activeEdges, current, c); 1064 } else if (bottom_collinear(edge, edge->fNextEdgeBelow)) { 1065 merge_edges_below(edge->fNextEdgeBelow, edge, activeEdges, current, c); 1066 } else { 1067 break; 1068 } 1069 } 1070 SkASSERT(!top_collinear(edge->fPrevEdgeAbove, edge)); 1071 SkASSERT(!top_collinear(edge, edge->fNextEdgeAbove)); 1072 SkASSERT(!bottom_collinear(edge->fPrevEdgeBelow, edge)); 1073 SkASSERT(!bottom_collinear(edge, edge->fNextEdgeBelow)); 1074 } 1075 1076 bool split_edge(Edge* edge, Vertex* v, EdgeList* activeEdges, Vertex** current, Comparator& c, 1077 SkArenaAlloc& alloc) { 1078 if (!edge->fTop || !edge->fBottom || v == edge->fTop || v == edge->fBottom) { 1079 return false; 1080 } 1081 LOG("splitting edge (%g -> %g) at vertex %g (%g, %g)\n", 1082 edge->fTop->fID, edge->fBottom->fID, 1083 v->fID, v->fPoint.fX, v->fPoint.fY); 1084 Vertex* top; 1085 Vertex* bottom; 1086 int winding = edge->fWinding; 1087 if (c.sweep_lt(v->fPoint, edge->fTop->fPoint)) { 1088 top = v; 1089 bottom = edge->fTop; 1090 set_top(edge, v, activeEdges, current, c); 1091 } else if (c.sweep_lt(edge->fBottom->fPoint, v->fPoint)) { 1092 top = edge->fBottom; 1093 bottom = v; 1094 set_bottom(edge, v, activeEdges, current, c); 1095 } else { 1096 top = v; 1097 bottom = edge->fBottom; 1098 set_bottom(edge, v, activeEdges, current, c); 1099 } 1100 Edge* newEdge = alloc.make<Edge>(top, bottom, winding, edge->fType); 1101 insert_edge_below(newEdge, top, c); 1102 insert_edge_above(newEdge, bottom, c); 1103 merge_collinear_edges(newEdge, activeEdges, current, c); 1104 return true; 1105 } 1106 1107 bool intersect_edge_pair(Edge* left, Edge* right, EdgeList* activeEdges, Vertex** current, Comparator& c, SkArenaAlloc& alloc) { 1108 if (!left->fTop || !left->fBottom || !right->fTop || !right->fBottom) { 1109 return false; 1110 } 1111 if (left->fTop == right->fTop || left->fBottom == right->fBottom) { 1112 return false; 1113 } 1114 if (c.sweep_lt(left->fTop->fPoint, right->fTop->fPoint)) { 1115 if (!left->isLeftOf(right->fTop)) { 1116 rewind(activeEdges, current, right->fTop, c); 1117 return split_edge(left, right->fTop, activeEdges, current, c, alloc); 1118 } 1119 } else { 1120 if (!right->isRightOf(left->fTop)) { 1121 rewind(activeEdges, current, left->fTop, c); 1122 return split_edge(right, left->fTop, activeEdges, current, c, alloc); 1123 } 1124 } 1125 if (c.sweep_lt(right->fBottom->fPoint, left->fBottom->fPoint)) { 1126 if (!left->isLeftOf(right->fBottom)) { 1127 rewind(activeEdges, current, right->fBottom, c); 1128 return split_edge(left, right->fBottom, activeEdges, current, c, alloc); 1129 } 1130 } else { 1131 if (!right->isRightOf(left->fBottom)) { 1132 rewind(activeEdges, current, left->fBottom, c); 1133 return split_edge(right, left->fBottom, activeEdges, current, c, alloc); 1134 } 1135 } 1136 return false; 1137 } 1138 1139 Edge* connect(Vertex* prev, Vertex* next, Edge::Type type, Comparator& c, SkArenaAlloc& alloc, 1140 int winding_scale = 1) { 1141 if (!prev || !next || prev->fPoint == next->fPoint) { 1142 return nullptr; 1143 } 1144 Edge* edge = new_edge(prev, next, type, c, alloc); 1145 insert_edge_below(edge, edge->fTop, c); 1146 insert_edge_above(edge, edge->fBottom, c); 1147 edge->fWinding *= winding_scale; 1148 merge_collinear_edges(edge, nullptr, nullptr, c); 1149 return edge; 1150 } 1151 1152 void merge_vertices(Vertex* src, Vertex* dst, VertexList* mesh, Comparator& c, 1153 SkArenaAlloc& alloc) { 1154 LOG("found coincident verts at %g, %g; merging %g into %g\n", src->fPoint.fX, src->fPoint.fY, 1155 src->fID, dst->fID); 1156 dst->fAlpha = SkTMax(src->fAlpha, dst->fAlpha); 1157 if (src->fPartner) { 1158 src->fPartner->fPartner = dst; 1159 } 1160 while (Edge* edge = src->fFirstEdgeAbove) { 1161 set_bottom(edge, dst, nullptr, nullptr, c); 1162 } 1163 while (Edge* edge = src->fFirstEdgeBelow) { 1164 set_top(edge, dst, nullptr, nullptr, c); 1165 } 1166 mesh->remove(src); 1167 } 1168 1169 Vertex* create_sorted_vertex(const SkPoint& p, uint8_t alpha, VertexList* mesh, 1170 Vertex* reference, Comparator& c, SkArenaAlloc& alloc) { 1171 Vertex* prevV = reference; 1172 while (prevV && c.sweep_lt(p, prevV->fPoint)) { 1173 prevV = prevV->fPrev; 1174 } 1175 Vertex* nextV = prevV ? prevV->fNext : mesh->fHead; 1176 while (nextV && c.sweep_lt(nextV->fPoint, p)) { 1177 prevV = nextV; 1178 nextV = nextV->fNext; 1179 } 1180 Vertex* v; 1181 if (prevV && coincident(prevV->fPoint, p)) { 1182 v = prevV; 1183 } else if (nextV && coincident(nextV->fPoint, p)) { 1184 v = nextV; 1185 } else { 1186 v = alloc.make<Vertex>(p, alpha); 1187 #if LOGGING_ENABLED 1188 if (!prevV) { 1189 v->fID = mesh->fHead->fID - 1.0f; 1190 } else if (!nextV) { 1191 v->fID = mesh->fTail->fID + 1.0f; 1192 } else { 1193 v->fID = (prevV->fID + nextV->fID) * 0.5f; 1194 } 1195 #endif 1196 mesh->insert(v, prevV, nextV); 1197 } 1198 return v; 1199 } 1200 1201 // If an edge's top and bottom points differ only by 1/2 machine epsilon in the primary 1202 // sort criterion, it may not be possible to split correctly, since there is no point which is 1203 // below the top and above the bottom. This function detects that case. 1204 bool nearly_flat(Comparator& c, Edge* edge) { 1205 SkPoint diff = edge->fBottom->fPoint - edge->fTop->fPoint; 1206 float primaryDiff = c.fDirection == Comparator::Direction::kHorizontal ? diff.fX : diff.fY; 1207 return fabs(primaryDiff) < std::numeric_limits<float>::epsilon() && primaryDiff != 0.0f; 1208 } 1209 1210 SkPoint clamp(SkPoint p, SkPoint min, SkPoint max, Comparator& c) { 1211 if (c.sweep_lt(p, min)) { 1212 return min; 1213 } else if (c.sweep_lt(max, p)) { 1214 return max; 1215 } else { 1216 return p; 1217 } 1218 } 1219 1220 bool check_for_intersection(Edge* left, Edge* right, EdgeList* activeEdges, Vertex** current, 1221 VertexList* mesh, Comparator& c, SkArenaAlloc& alloc) { 1222 if (!left || !right) { 1223 return false; 1224 } 1225 SkPoint p; 1226 uint8_t alpha; 1227 if (left->intersect(*right, &p, &alpha) && p.isFinite()) { 1228 Vertex* v; 1229 LOG("found intersection, pt is %g, %g\n", p.fX, p.fY); 1230 Vertex* top = *current; 1231 // If the intersection point is above the current vertex, rewind to the vertex above the 1232 // intersection. 1233 while (top && c.sweep_lt(p, top->fPoint)) { 1234 top = top->fPrev; 1235 } 1236 if (!nearly_flat(c, left)) { 1237 p = clamp(p, left->fTop->fPoint, left->fBottom->fPoint, c); 1238 } 1239 if (!nearly_flat(c, right)) { 1240 p = clamp(p, right->fTop->fPoint, right->fBottom->fPoint, c); 1241 } 1242 if (p == left->fTop->fPoint) { 1243 v = left->fTop; 1244 } else if (p == left->fBottom->fPoint) { 1245 v = left->fBottom; 1246 } else if (p == right->fTop->fPoint) { 1247 v = right->fTop; 1248 } else if (p == right->fBottom->fPoint) { 1249 v = right->fBottom; 1250 } else { 1251 v = create_sorted_vertex(p, alpha, mesh, top, c, alloc); 1252 if (left->fTop->fPartner) { 1253 Line line1 = left->fLine; 1254 Line line2 = right->fLine; 1255 int dir = left->fType == Edge::Type::kOuter ? -1 : 1; 1256 line1.fC += sqrt(left->fLine.magSq()) * (left->fWinding > 0 ? 1 : -1) * dir; 1257 line2.fC += sqrt(right->fLine.magSq()) * (right->fWinding > 0 ? 1 : -1) * dir; 1258 SkPoint p; 1259 if (line1.intersect(line2, &p)) { 1260 LOG("synthesizing partner (%g,%g) for intersection vertex %g\n", 1261 p.fX, p.fY, v->fID); 1262 v->fPartner = alloc.make<Vertex>(p, 255 - v->fAlpha); 1263 } 1264 } 1265 } 1266 rewind(activeEdges, current, top ? top : v, c); 1267 split_edge(left, v, activeEdges, current, c, alloc); 1268 split_edge(right, v, activeEdges, current, c, alloc); 1269 v->fAlpha = SkTMax(v->fAlpha, alpha); 1270 return true; 1271 } 1272 return intersect_edge_pair(left, right, activeEdges, current, c, alloc); 1273 } 1274 1275 void sanitize_contours(VertexList* contours, int contourCnt, bool approximate) { 1276 for (VertexList* contour = contours; contourCnt > 0; --contourCnt, ++contour) { 1277 SkASSERT(contour->fHead); 1278 Vertex* prev = contour->fTail; 1279 if (approximate) { 1280 round(&prev->fPoint); 1281 } 1282 for (Vertex* v = contour->fHead; v;) { 1283 if (approximate) { 1284 round(&v->fPoint); 1285 } 1286 Vertex* next = v->fNext; 1287 Vertex* nextWrap = next ? next : contour->fHead; 1288 if (coincident(prev->fPoint, v->fPoint)) { 1289 LOG("vertex %g,%g coincident; removing\n", v->fPoint.fX, v->fPoint.fY); 1290 contour->remove(v); 1291 } else if (!v->fPoint.isFinite()) { 1292 LOG("vertex %g,%g non-finite; removing\n", v->fPoint.fX, v->fPoint.fY); 1293 contour->remove(v); 1294 } else if (Line(prev->fPoint, nextWrap->fPoint).dist(v->fPoint) == 0.0) { 1295 LOG("vertex %g,%g collinear; removing\n", v->fPoint.fX, v->fPoint.fY); 1296 contour->remove(v); 1297 } else { 1298 prev = v; 1299 } 1300 v = next; 1301 } 1302 } 1303 } 1304 1305 bool merge_coincident_vertices(VertexList* mesh, Comparator& c, SkArenaAlloc& alloc) { 1306 if (!mesh->fHead) { 1307 return false; 1308 } 1309 bool merged = false; 1310 for (Vertex* v = mesh->fHead->fNext; v;) { 1311 Vertex* next = v->fNext; 1312 if (c.sweep_lt(v->fPoint, v->fPrev->fPoint)) { 1313 v->fPoint = v->fPrev->fPoint; 1314 } 1315 if (coincident(v->fPrev->fPoint, v->fPoint)) { 1316 merge_vertices(v, v->fPrev, mesh, c, alloc); 1317 merged = true; 1318 } 1319 v = next; 1320 } 1321 return merged; 1322 } 1323 1324 // Stage 2: convert the contours to a mesh of edges connecting the vertices. 1325 1326 void build_edges(VertexList* contours, int contourCnt, VertexList* mesh, Comparator& c, 1327 SkArenaAlloc& alloc) { 1328 for (VertexList* contour = contours; contourCnt > 0; --contourCnt, ++contour) { 1329 Vertex* prev = contour->fTail; 1330 for (Vertex* v = contour->fHead; v;) { 1331 Vertex* next = v->fNext; 1332 connect(prev, v, Edge::Type::kInner, c, alloc); 1333 mesh->append(v); 1334 prev = v; 1335 v = next; 1336 } 1337 } 1338 } 1339 1340 void connect_partners(VertexList* mesh, Comparator& c, SkArenaAlloc& alloc) { 1341 for (Vertex* outer = mesh->fHead; outer; outer = outer->fNext) { 1342 if (Vertex* inner = outer->fPartner) { 1343 if ((inner->fPrev || inner->fNext) && (outer->fPrev || outer->fNext)) { 1344 // Connector edges get zero winding, since they're only structural (i.e., to ensure 1345 // no 0-0-0 alpha triangles are produced), and shouldn't affect the poly winding 1346 // number. 1347 connect(outer, inner, Edge::Type::kConnector, c, alloc, 0); 1348 inner->fPartner = outer->fPartner = nullptr; 1349 } 1350 } 1351 } 1352 } 1353 1354 template <CompareFunc sweep_lt> 1355 void sorted_merge(VertexList* front, VertexList* back, VertexList* result) { 1356 Vertex* a = front->fHead; 1357 Vertex* b = back->fHead; 1358 while (a && b) { 1359 if (sweep_lt(a->fPoint, b->fPoint)) { 1360 front->remove(a); 1361 result->append(a); 1362 a = front->fHead; 1363 } else { 1364 back->remove(b); 1365 result->append(b); 1366 b = back->fHead; 1367 } 1368 } 1369 result->append(*front); 1370 result->append(*back); 1371 } 1372 1373 void sorted_merge(VertexList* front, VertexList* back, VertexList* result, Comparator& c) { 1374 if (c.fDirection == Comparator::Direction::kHorizontal) { 1375 sorted_merge<sweep_lt_horiz>(front, back, result); 1376 } else { 1377 sorted_merge<sweep_lt_vert>(front, back, result); 1378 } 1379 #if LOGGING_ENABLED 1380 float id = 0.0f; 1381 for (Vertex* v = result->fHead; v; v = v->fNext) { 1382 v->fID = id++; 1383 } 1384 #endif 1385 } 1386 1387 // Stage 3: sort the vertices by increasing sweep direction. 1388 1389 template <CompareFunc sweep_lt> 1390 void merge_sort(VertexList* vertices) { 1391 Vertex* slow = vertices->fHead; 1392 if (!slow) { 1393 return; 1394 } 1395 Vertex* fast = slow->fNext; 1396 if (!fast) { 1397 return; 1398 } 1399 do { 1400 fast = fast->fNext; 1401 if (fast) { 1402 fast = fast->fNext; 1403 slow = slow->fNext; 1404 } 1405 } while (fast); 1406 VertexList front(vertices->fHead, slow); 1407 VertexList back(slow->fNext, vertices->fTail); 1408 front.fTail->fNext = back.fHead->fPrev = nullptr; 1409 1410 merge_sort<sweep_lt>(&front); 1411 merge_sort<sweep_lt>(&back); 1412 1413 vertices->fHead = vertices->fTail = nullptr; 1414 sorted_merge<sweep_lt>(&front, &back, vertices); 1415 } 1416 1417 void dump_mesh(const VertexList& mesh) { 1418 #if LOGGING_ENABLED 1419 for (Vertex* v = mesh.fHead; v; v = v->fNext) { 1420 LOG("vertex %g (%g, %g) alpha %d", v->fID, v->fPoint.fX, v->fPoint.fY, v->fAlpha); 1421 if (Vertex* p = v->fPartner) { 1422 LOG(", partner %g (%g, %g) alpha %d\n", p->fID, p->fPoint.fX, p->fPoint.fY, p->fAlpha); 1423 } else { 1424 LOG(", null partner\n"); 1425 } 1426 for (Edge* e = v->fFirstEdgeAbove; e; e = e->fNextEdgeAbove) { 1427 LOG(" edge %g -> %g, winding %d\n", e->fTop->fID, e->fBottom->fID, e->fWinding); 1428 } 1429 for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { 1430 LOG(" edge %g -> %g, winding %d\n", e->fTop->fID, e->fBottom->fID, e->fWinding); 1431 } 1432 } 1433 #endif 1434 } 1435 1436 #ifdef SK_DEBUG 1437 void validate_edge_pair(Edge* left, Edge* right, Comparator& c) { 1438 if (!left || !right) { 1439 return; 1440 } 1441 if (left->fTop == right->fTop) { 1442 SkASSERT(left->isLeftOf(right->fBottom)); 1443 SkASSERT(right->isRightOf(left->fBottom)); 1444 } else if (c.sweep_lt(left->fTop->fPoint, right->fTop->fPoint)) { 1445 SkASSERT(left->isLeftOf(right->fTop)); 1446 } else { 1447 SkASSERT(right->isRightOf(left->fTop)); 1448 } 1449 if (left->fBottom == right->fBottom) { 1450 SkASSERT(left->isLeftOf(right->fTop)); 1451 SkASSERT(right->isRightOf(left->fTop)); 1452 } else if (c.sweep_lt(right->fBottom->fPoint, left->fBottom->fPoint)) { 1453 SkASSERT(left->isLeftOf(right->fBottom)); 1454 } else { 1455 SkASSERT(right->isRightOf(left->fBottom)); 1456 } 1457 } 1458 1459 void validate_edge_list(EdgeList* edges, Comparator& c) { 1460 Edge* left = edges->fHead; 1461 if (!left) { 1462 return; 1463 } 1464 for (Edge* right = left->fRight; right; right = right->fRight) { 1465 validate_edge_pair(left, right, c); 1466 left = right; 1467 } 1468 } 1469 #endif 1470 1471 // Stage 4: Simplify the mesh by inserting new vertices at intersecting edges. 1472 1473 bool simplify(VertexList* mesh, Comparator& c, SkArenaAlloc& alloc) { 1474 LOG("simplifying complex polygons\n"); 1475 EdgeList activeEdges; 1476 bool found = false; 1477 for (Vertex* v = mesh->fHead; v != nullptr; v = v->fNext) { 1478 if (!v->fFirstEdgeAbove && !v->fFirstEdgeBelow) { 1479 continue; 1480 } 1481 Edge* leftEnclosingEdge; 1482 Edge* rightEnclosingEdge; 1483 bool restartChecks; 1484 do { 1485 LOG("\nvertex %g: (%g,%g), alpha %d\n", v->fID, v->fPoint.fX, v->fPoint.fY, v->fAlpha); 1486 restartChecks = false; 1487 find_enclosing_edges(v, &activeEdges, &leftEnclosingEdge, &rightEnclosingEdge); 1488 v->fLeftEnclosingEdge = leftEnclosingEdge; 1489 v->fRightEnclosingEdge = rightEnclosingEdge; 1490 if (v->fFirstEdgeBelow) { 1491 for (Edge* edge = v->fFirstEdgeBelow; edge; edge = edge->fNextEdgeBelow) { 1492 if (check_for_intersection(leftEnclosingEdge, edge, &activeEdges, &v, mesh, c, 1493 alloc)) { 1494 restartChecks = true; 1495 break; 1496 } 1497 if (check_for_intersection(edge, rightEnclosingEdge, &activeEdges, &v, mesh, c, 1498 alloc)) { 1499 restartChecks = true; 1500 break; 1501 } 1502 } 1503 } else { 1504 if (check_for_intersection(leftEnclosingEdge, rightEnclosingEdge, 1505 &activeEdges, &v, mesh, c, alloc)) { 1506 restartChecks = true; 1507 } 1508 1509 } 1510 found = found || restartChecks; 1511 } while (restartChecks); 1512 #ifdef SK_DEBUG 1513 validate_edge_list(&activeEdges, c); 1514 #endif 1515 for (Edge* e = v->fFirstEdgeAbove; e; e = e->fNextEdgeAbove) { 1516 remove_edge(e, &activeEdges); 1517 } 1518 Edge* leftEdge = leftEnclosingEdge; 1519 for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { 1520 insert_edge(e, leftEdge, &activeEdges); 1521 leftEdge = e; 1522 } 1523 } 1524 SkASSERT(!activeEdges.fHead && !activeEdges.fTail); 1525 return found; 1526 } 1527 1528 // Stage 5: Tessellate the simplified mesh into monotone polygons. 1529 1530 Poly* tessellate(const VertexList& vertices, SkArenaAlloc& alloc) { 1531 LOG("\ntessellating simple polygons\n"); 1532 EdgeList activeEdges; 1533 Poly* polys = nullptr; 1534 for (Vertex* v = vertices.fHead; v != nullptr; v = v->fNext) { 1535 if (!v->fFirstEdgeAbove && !v->fFirstEdgeBelow) { 1536 continue; 1537 } 1538 #if LOGGING_ENABLED 1539 LOG("\nvertex %g: (%g,%g), alpha %d\n", v->fID, v->fPoint.fX, v->fPoint.fY, v->fAlpha); 1540 #endif 1541 Edge* leftEnclosingEdge; 1542 Edge* rightEnclosingEdge; 1543 find_enclosing_edges(v, &activeEdges, &leftEnclosingEdge, &rightEnclosingEdge); 1544 Poly* leftPoly; 1545 Poly* rightPoly; 1546 if (v->fFirstEdgeAbove) { 1547 leftPoly = v->fFirstEdgeAbove->fLeftPoly; 1548 rightPoly = v->fLastEdgeAbove->fRightPoly; 1549 } else { 1550 leftPoly = leftEnclosingEdge ? leftEnclosingEdge->fRightPoly : nullptr; 1551 rightPoly = rightEnclosingEdge ? rightEnclosingEdge->fLeftPoly : nullptr; 1552 } 1553 #if LOGGING_ENABLED 1554 LOG("edges above:\n"); 1555 for (Edge* e = v->fFirstEdgeAbove; e; e = e->fNextEdgeAbove) { 1556 LOG("%g -> %g, lpoly %d, rpoly %d\n", e->fTop->fID, e->fBottom->fID, 1557 e->fLeftPoly ? e->fLeftPoly->fID : -1, e->fRightPoly ? e->fRightPoly->fID : -1); 1558 } 1559 LOG("edges below:\n"); 1560 for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { 1561 LOG("%g -> %g, lpoly %d, rpoly %d\n", e->fTop->fID, e->fBottom->fID, 1562 e->fLeftPoly ? e->fLeftPoly->fID : -1, e->fRightPoly ? e->fRightPoly->fID : -1); 1563 } 1564 #endif 1565 if (v->fFirstEdgeAbove) { 1566 if (leftPoly) { 1567 leftPoly = leftPoly->addEdge(v->fFirstEdgeAbove, Poly::kRight_Side, alloc); 1568 } 1569 if (rightPoly) { 1570 rightPoly = rightPoly->addEdge(v->fLastEdgeAbove, Poly::kLeft_Side, alloc); 1571 } 1572 for (Edge* e = v->fFirstEdgeAbove; e != v->fLastEdgeAbove; e = e->fNextEdgeAbove) { 1573 Edge* rightEdge = e->fNextEdgeAbove; 1574 remove_edge(e, &activeEdges); 1575 if (e->fRightPoly) { 1576 e->fRightPoly->addEdge(e, Poly::kLeft_Side, alloc); 1577 } 1578 if (rightEdge->fLeftPoly && rightEdge->fLeftPoly != e->fRightPoly) { 1579 rightEdge->fLeftPoly->addEdge(e, Poly::kRight_Side, alloc); 1580 } 1581 } 1582 remove_edge(v->fLastEdgeAbove, &activeEdges); 1583 if (!v->fFirstEdgeBelow) { 1584 if (leftPoly && rightPoly && leftPoly != rightPoly) { 1585 SkASSERT(leftPoly->fPartner == nullptr && rightPoly->fPartner == nullptr); 1586 rightPoly->fPartner = leftPoly; 1587 leftPoly->fPartner = rightPoly; 1588 } 1589 } 1590 } 1591 if (v->fFirstEdgeBelow) { 1592 if (!v->fFirstEdgeAbove) { 1593 if (leftPoly && rightPoly) { 1594 if (leftPoly == rightPoly) { 1595 if (leftPoly->fTail && leftPoly->fTail->fSide == Poly::kLeft_Side) { 1596 leftPoly = new_poly(&polys, leftPoly->lastVertex(), 1597 leftPoly->fWinding, alloc); 1598 leftEnclosingEdge->fRightPoly = leftPoly; 1599 } else { 1600 rightPoly = new_poly(&polys, rightPoly->lastVertex(), 1601 rightPoly->fWinding, alloc); 1602 rightEnclosingEdge->fLeftPoly = rightPoly; 1603 } 1604 } 1605 Edge* join = alloc.make<Edge>(leftPoly->lastVertex(), v, 1, Edge::Type::kInner); 1606 leftPoly = leftPoly->addEdge(join, Poly::kRight_Side, alloc); 1607 rightPoly = rightPoly->addEdge(join, Poly::kLeft_Side, alloc); 1608 } 1609 } 1610 Edge* leftEdge = v->fFirstEdgeBelow; 1611 leftEdge->fLeftPoly = leftPoly; 1612 insert_edge(leftEdge, leftEnclosingEdge, &activeEdges); 1613 for (Edge* rightEdge = leftEdge->fNextEdgeBelow; rightEdge; 1614 rightEdge = rightEdge->fNextEdgeBelow) { 1615 insert_edge(rightEdge, leftEdge, &activeEdges); 1616 int winding = leftEdge->fLeftPoly ? leftEdge->fLeftPoly->fWinding : 0; 1617 winding += leftEdge->fWinding; 1618 if (winding != 0) { 1619 Poly* poly = new_poly(&polys, v, winding, alloc); 1620 leftEdge->fRightPoly = rightEdge->fLeftPoly = poly; 1621 } 1622 leftEdge = rightEdge; 1623 } 1624 v->fLastEdgeBelow->fRightPoly = rightPoly; 1625 } 1626 #if LOGGING_ENABLED 1627 LOG("\nactive edges:\n"); 1628 for (Edge* e = activeEdges.fHead; e != nullptr; e = e->fRight) { 1629 LOG("%g -> %g, lpoly %d, rpoly %d\n", e->fTop->fID, e->fBottom->fID, 1630 e->fLeftPoly ? e->fLeftPoly->fID : -1, e->fRightPoly ? e->fRightPoly->fID : -1); 1631 } 1632 #endif 1633 } 1634 return polys; 1635 } 1636 1637 void remove_non_boundary_edges(const VertexList& mesh, SkPath::FillType fillType, 1638 SkArenaAlloc& alloc) { 1639 LOG("removing non-boundary edges\n"); 1640 EdgeList activeEdges; 1641 for (Vertex* v = mesh.fHead; v != nullptr; v = v->fNext) { 1642 if (!v->fFirstEdgeAbove && !v->fFirstEdgeBelow) { 1643 continue; 1644 } 1645 Edge* leftEnclosingEdge; 1646 Edge* rightEnclosingEdge; 1647 find_enclosing_edges(v, &activeEdges, &leftEnclosingEdge, &rightEnclosingEdge); 1648 bool prevFilled = leftEnclosingEdge && 1649 apply_fill_type(fillType, leftEnclosingEdge->fWinding); 1650 for (Edge* e = v->fFirstEdgeAbove; e;) { 1651 Edge* next = e->fNextEdgeAbove; 1652 remove_edge(e, &activeEdges); 1653 bool filled = apply_fill_type(fillType, e->fWinding); 1654 if (filled == prevFilled) { 1655 disconnect(e); 1656 } 1657 prevFilled = filled; 1658 e = next; 1659 } 1660 Edge* prev = leftEnclosingEdge; 1661 for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { 1662 if (prev) { 1663 e->fWinding += prev->fWinding; 1664 } 1665 insert_edge(e, prev, &activeEdges); 1666 prev = e; 1667 } 1668 } 1669 } 1670 1671 // Note: this is the normal to the edge, but not necessarily unit length. 1672 void get_edge_normal(const Edge* e, SkVector* normal) { 1673 normal->set(SkDoubleToScalar(e->fLine.fA), 1674 SkDoubleToScalar(e->fLine.fB)); 1675 } 1676 1677 void reconnect(Edge* edge, Vertex* src, Vertex* dst, Comparator& c) { 1678 disconnect(edge); 1679 if (src == edge->fTop) { 1680 edge->fTop = dst; 1681 } else { 1682 SkASSERT(src == edge->fBottom); 1683 edge->fBottom = dst; 1684 } 1685 if (edge->fEvent) { 1686 edge->fEvent->fEdge = nullptr; 1687 } 1688 if (edge->fTop == edge->fBottom) { 1689 return; 1690 } 1691 if (c.sweep_lt(edge->fBottom->fPoint, edge->fTop->fPoint)) { 1692 using std::swap; 1693 swap(edge->fTop, edge->fBottom); 1694 edge->fWinding *= -1; 1695 } 1696 edge->recompute(); 1697 insert_edge_below(edge, edge->fTop, c); 1698 insert_edge_above(edge, edge->fBottom, c); 1699 merge_collinear_edges(edge, nullptr, nullptr, c); 1700 } 1701 1702 // Stage 5c: detect and remove "pointy" vertices whose edge normals point in opposite directions 1703 // and whose adjacent vertices are less than a quarter pixel from an edge. These are guaranteed to 1704 // invert on stroking. 1705 1706 void simplify_boundary(EdgeList* boundary, Comparator& c, SkArenaAlloc& alloc) { 1707 Edge* prevEdge = boundary->fTail; 1708 SkVector prevNormal; 1709 get_edge_normal(prevEdge, &prevNormal); 1710 for (Edge* e = boundary->fHead; e != nullptr;) { 1711 Vertex* prev = prevEdge->fWinding == 1 ? prevEdge->fTop : prevEdge->fBottom; 1712 Vertex* next = e->fWinding == 1 ? e->fBottom : e->fTop; 1713 double distPrev = e->dist(prev->fPoint); 1714 double distNext = prevEdge->dist(next->fPoint); 1715 SkVector normal; 1716 get_edge_normal(e, &normal); 1717 constexpr double kQuarterPixelSq = 0.25f * 0.25f; 1718 if (prev != next && prevNormal.dot(normal) < 0.0 && 1719 (distPrev * distPrev <= kQuarterPixelSq || distNext * distNext <= kQuarterPixelSq)) { 1720 Edge* join = new_edge(prev, next, Edge::Type::kInner, c, alloc); 1721 if (prev->fPoint != next->fPoint) { 1722 join->fLine.normalize(); 1723 join->fLine = join->fLine * join->fWinding; 1724 } 1725 insert_edge(join, e, boundary); 1726 remove_edge(prevEdge, boundary); 1727 remove_edge(e, boundary); 1728 if (join->fLeft && join->fRight) { 1729 prevEdge = join->fLeft; 1730 e = join; 1731 } else { 1732 prevEdge = boundary->fTail; 1733 e = boundary->fHead; // join->fLeft ? join->fLeft : join; 1734 } 1735 get_edge_normal(prevEdge, &prevNormal); 1736 } else { 1737 prevEdge = e; 1738 prevNormal = normal; 1739 e = e->fRight; 1740 } 1741 } 1742 } 1743 1744 void reconnect_all_overlap_edges(Vertex* src, Vertex* dst, Edge* current, Comparator& c) { 1745 if (src->fPartner) { 1746 src->fPartner->fPartner = dst; 1747 } 1748 for (Edge* e = src->fFirstEdgeAbove; e; ) { 1749 Edge* next = e->fNextEdgeAbove; 1750 if (e->fOverlap && e != current) { 1751 reconnect(e, src, dst, c); 1752 } 1753 e = next; 1754 } 1755 for (Edge* e = src->fFirstEdgeBelow; e; ) { 1756 Edge* next = e->fNextEdgeBelow; 1757 if (e->fOverlap && e != current) { 1758 reconnect(e, src, dst, c); 1759 } 1760 e = next; 1761 } 1762 } 1763 1764 void Event::apply(VertexList* mesh, Comparator& c, SkArenaAlloc& alloc) { 1765 if (!fEdge || !fEdge->fTop || !fEdge->fBottom) { 1766 return; 1767 } 1768 Vertex* top = fEdge->fTop; 1769 Vertex* bottom = fEdge->fBottom; 1770 Vertex* dest = create_sorted_vertex(fPoint, fAlpha, mesh, fEdge->fTop, c, alloc); 1771 LOG("collapsing edge %g -> %g to %g (%g, %g) alpha %d\n", 1772 top->fID, bottom->fID, dest->fID, fPoint.fX, fPoint.fY, fAlpha); 1773 reconnect_all_overlap_edges(top, dest, fEdge, c); 1774 reconnect_all_overlap_edges(bottom, dest, fEdge, c); 1775 1776 // Since the destination has multiple partners, give it none. 1777 dest->fPartner = nullptr; 1778 1779 // Disconnect all collapsed edges except outer boundaries. 1780 // Those are required to preserve shape coverage and winding correctness. 1781 if (!fIsOuterBoundary) { 1782 disconnect(fEdge); 1783 } else { 1784 LOG("edge %g -> %g is outer boundary; not disconnecting.\n", 1785 fEdge->fTop->fID, fEdge->fBottom->fID); 1786 fEdge->fWinding = fEdge->fWinding >= 0 ? 1 : -1; 1787 } 1788 1789 // If top still has some connected edges, set its partner to dest. 1790 top->fPartner = top->fFirstEdgeAbove || top->fFirstEdgeBelow ? dest : nullptr; 1791 1792 // If bottom still has some connected edges, set its partner to dest. 1793 bottom->fPartner = bottom->fFirstEdgeAbove || bottom->fFirstEdgeBelow ? dest : nullptr; 1794 } 1795 1796 bool is_overlap_edge(Edge* e) { 1797 if (e->fType == Edge::Type::kOuter) { 1798 return e->fWinding != 0 && e->fWinding != 1; 1799 } else if (e->fType == Edge::Type::kInner) { 1800 return e->fWinding != 0 && e->fWinding != -2; 1801 } else { 1802 return false; 1803 } 1804 } 1805 1806 // This is a stripped-down version of tessellate() which computes edges which 1807 // join two filled regions, which represent overlap regions, and collapses them. 1808 bool collapse_overlap_regions(VertexList* mesh, Comparator& c, SkArenaAlloc& alloc) { 1809 LOG("\nfinding overlap regions\n"); 1810 EdgeList activeEdges; 1811 EventList events; 1812 for (Vertex* v = mesh->fHead; v != nullptr; v = v->fNext) { 1813 if (!v->fFirstEdgeAbove && !v->fFirstEdgeBelow) { 1814 continue; 1815 } 1816 Edge* leftEnclosingEdge; 1817 Edge* rightEnclosingEdge; 1818 find_enclosing_edges(v, &activeEdges, &leftEnclosingEdge, &rightEnclosingEdge); 1819 for (Edge* e = v->fLastEdgeAbove; e; e = e->fPrevEdgeAbove) { 1820 Edge* prev = e->fPrevEdgeAbove ? e->fPrevEdgeAbove : leftEnclosingEdge; 1821 remove_edge(e, &activeEdges); 1822 if (prev) { 1823 e->fWinding -= prev->fWinding; 1824 } 1825 } 1826 Edge* prev = leftEnclosingEdge; 1827 for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { 1828 if (prev) { 1829 e->fWinding += prev->fWinding; 1830 e->fOverlap = e->fOverlap || is_overlap_edge(prev); 1831 } 1832 e->fOverlap = e->fOverlap || is_overlap_edge(e); 1833 if (e->fOverlap) { 1834 // If this edge borders a zero-winding area, it's a boundary; don't disconnect it. 1835 bool isOuterBoundary = e->fType == Edge::Type::kOuter && 1836 (!prev || prev->fWinding == 0 || e->fWinding == 0); 1837 create_event(e, isOuterBoundary, &events, alloc); 1838 } 1839 insert_edge(e, prev, &activeEdges); 1840 prev = e; 1841 } 1842 } 1843 LOG("\ncollapsing overlap regions\n"); 1844 if (events.count() == 0) { 1845 return false; 1846 } 1847 while (events.count() > 0) { 1848 Event* event = events.peek(); 1849 events.pop(); 1850 event->apply(mesh, c, alloc); 1851 } 1852 return true; 1853 } 1854 1855 bool inversion(Vertex* prev, Vertex* next, Edge* origEdge, Comparator& c) { 1856 if (!prev || !next) { 1857 return true; 1858 } 1859 int winding = c.sweep_lt(prev->fPoint, next->fPoint) ? 1 : -1; 1860 return winding != origEdge->fWinding; 1861 } 1862 1863 // Stage 5d: Displace edges by half a pixel inward and outward along their normals. Intersect to 1864 // find new vertices, and set zero alpha on the exterior and one alpha on the interior. Build a 1865 // new antialiased mesh from those vertices. 1866 1867 void stroke_boundary(EdgeList* boundary, VertexList* innerMesh, VertexList* outerMesh, 1868 Comparator& c, SkArenaAlloc& alloc) { 1869 LOG("\nstroking boundary\n"); 1870 // A boundary with fewer than 3 edges is degenerate. 1871 if (!boundary->fHead || !boundary->fHead->fRight || !boundary->fHead->fRight->fRight) { 1872 return; 1873 } 1874 Edge* prevEdge = boundary->fTail; 1875 Vertex* prevV = prevEdge->fWinding > 0 ? prevEdge->fTop : prevEdge->fBottom; 1876 SkVector prevNormal; 1877 get_edge_normal(prevEdge, &prevNormal); 1878 double radius = 0.5; 1879 Line prevInner(prevEdge->fLine); 1880 prevInner.fC -= radius; 1881 Line prevOuter(prevEdge->fLine); 1882 prevOuter.fC += radius; 1883 VertexList innerVertices; 1884 VertexList outerVertices; 1885 bool innerInversion = true; 1886 bool outerInversion = true; 1887 for (Edge* e = boundary->fHead; e != nullptr; e = e->fRight) { 1888 Vertex* v = e->fWinding > 0 ? e->fTop : e->fBottom; 1889 SkVector normal; 1890 get_edge_normal(e, &normal); 1891 Line inner(e->fLine); 1892 inner.fC -= radius; 1893 Line outer(e->fLine); 1894 outer.fC += radius; 1895 SkPoint innerPoint, outerPoint; 1896 LOG("stroking vertex %g (%g, %g)\n", v->fID, v->fPoint.fX, v->fPoint.fY); 1897 if (!prevEdge->fLine.nearParallel(e->fLine) && prevInner.intersect(inner, &innerPoint) && 1898 prevOuter.intersect(outer, &outerPoint)) { 1899 float cosAngle = normal.dot(prevNormal); 1900 if (cosAngle < -kCosMiterAngle) { 1901 Vertex* nextV = e->fWinding > 0 ? e->fBottom : e->fTop; 1902 1903 // This is a pointy vertex whose angle is smaller than the threshold; miter it. 1904 Line bisector(innerPoint, outerPoint); 1905 Line tangent(v->fPoint, v->fPoint + SkPoint::Make(bisector.fA, bisector.fB)); 1906 if (tangent.fA == 0 && tangent.fB == 0) { 1907 continue; 1908 } 1909 tangent.normalize(); 1910 Line innerTangent(tangent); 1911 Line outerTangent(tangent); 1912 innerTangent.fC -= 0.5; 1913 outerTangent.fC += 0.5; 1914 SkPoint innerPoint1, innerPoint2, outerPoint1, outerPoint2; 1915 if (prevNormal.cross(normal) > 0) { 1916 // Miter inner points 1917 if (!innerTangent.intersect(prevInner, &innerPoint1) || 1918 !innerTangent.intersect(inner, &innerPoint2) || 1919 !outerTangent.intersect(bisector, &outerPoint)) { 1920 continue; 1921 } 1922 Line prevTangent(prevV->fPoint, 1923 prevV->fPoint + SkVector::Make(prevOuter.fA, prevOuter.fB)); 1924 Line nextTangent(nextV->fPoint, 1925 nextV->fPoint + SkVector::Make(outer.fA, outer.fB)); 1926 if (prevTangent.dist(outerPoint) > 0) { 1927 bisector.intersect(prevTangent, &outerPoint); 1928 } 1929 if (nextTangent.dist(outerPoint) < 0) { 1930 bisector.intersect(nextTangent, &outerPoint); 1931 } 1932 outerPoint1 = outerPoint2 = outerPoint; 1933 } else { 1934 // Miter outer points 1935 if (!outerTangent.intersect(prevOuter, &outerPoint1) || 1936 !outerTangent.intersect(outer, &outerPoint2)) { 1937 continue; 1938 } 1939 Line prevTangent(prevV->fPoint, 1940 prevV->fPoint + SkVector::Make(prevInner.fA, prevInner.fB)); 1941 Line nextTangent(nextV->fPoint, 1942 nextV->fPoint + SkVector::Make(inner.fA, inner.fB)); 1943 if (prevTangent.dist(innerPoint) > 0) { 1944 bisector.intersect(prevTangent, &innerPoint); 1945 } 1946 if (nextTangent.dist(innerPoint) < 0) { 1947 bisector.intersect(nextTangent, &innerPoint); 1948 } 1949 innerPoint1 = innerPoint2 = innerPoint; 1950 } 1951 if (!innerPoint1.isFinite() || !innerPoint2.isFinite() || 1952 !outerPoint1.isFinite() || !outerPoint2.isFinite()) { 1953 continue; 1954 } 1955 LOG("inner (%g, %g), (%g, %g), ", 1956 innerPoint1.fX, innerPoint1.fY, innerPoint2.fX, innerPoint2.fY); 1957 LOG("outer (%g, %g), (%g, %g)\n", 1958 outerPoint1.fX, outerPoint1.fY, outerPoint2.fX, outerPoint2.fY); 1959 Vertex* innerVertex1 = alloc.make<Vertex>(innerPoint1, 255); 1960 Vertex* innerVertex2 = alloc.make<Vertex>(innerPoint2, 255); 1961 Vertex* outerVertex1 = alloc.make<Vertex>(outerPoint1, 0); 1962 Vertex* outerVertex2 = alloc.make<Vertex>(outerPoint2, 0); 1963 innerVertex1->fPartner = outerVertex1; 1964 innerVertex2->fPartner = outerVertex2; 1965 outerVertex1->fPartner = innerVertex1; 1966 outerVertex2->fPartner = innerVertex2; 1967 if (!inversion(innerVertices.fTail, innerVertex1, prevEdge, c)) { 1968 innerInversion = false; 1969 } 1970 if (!inversion(outerVertices.fTail, outerVertex1, prevEdge, c)) { 1971 outerInversion = false; 1972 } 1973 innerVertices.append(innerVertex1); 1974 innerVertices.append(innerVertex2); 1975 outerVertices.append(outerVertex1); 1976 outerVertices.append(outerVertex2); 1977 } else { 1978 LOG("inner (%g, %g), ", innerPoint.fX, innerPoint.fY); 1979 LOG("outer (%g, %g)\n", outerPoint.fX, outerPoint.fY); 1980 Vertex* innerVertex = alloc.make<Vertex>(innerPoint, 255); 1981 Vertex* outerVertex = alloc.make<Vertex>(outerPoint, 0); 1982 innerVertex->fPartner = outerVertex; 1983 outerVertex->fPartner = innerVertex; 1984 if (!inversion(innerVertices.fTail, innerVertex, prevEdge, c)) { 1985 innerInversion = false; 1986 } 1987 if (!inversion(outerVertices.fTail, outerVertex, prevEdge, c)) { 1988 outerInversion = false; 1989 } 1990 innerVertices.append(innerVertex); 1991 outerVertices.append(outerVertex); 1992 } 1993 } 1994 prevInner = inner; 1995 prevOuter = outer; 1996 prevV = v; 1997 prevEdge = e; 1998 prevNormal = normal; 1999 } 2000 if (!inversion(innerVertices.fTail, innerVertices.fHead, prevEdge, c)) { 2001 innerInversion = false; 2002 } 2003 if (!inversion(outerVertices.fTail, outerVertices.fHead, prevEdge, c)) { 2004 outerInversion = false; 2005 } 2006 // Outer edges get 1 winding, and inner edges get -2 winding. This ensures that the interior 2007 // is always filled (1 + -2 = -1 for normal cases, 1 + 2 = 3 for thin features where the 2008 // interior inverts). 2009 // For total inversion cases, the shape has now reversed handedness, so invert the winding 2010 // so it will be detected during collapse_overlap_regions(). 2011 int innerWinding = innerInversion ? 2 : -2; 2012 int outerWinding = outerInversion ? -1 : 1; 2013 for (Vertex* v = innerVertices.fHead; v && v->fNext; v = v->fNext) { 2014 connect(v, v->fNext, Edge::Type::kInner, c, alloc, innerWinding); 2015 } 2016 connect(innerVertices.fTail, innerVertices.fHead, Edge::Type::kInner, c, alloc, innerWinding); 2017 for (Vertex* v = outerVertices.fHead; v && v->fNext; v = v->fNext) { 2018 connect(v, v->fNext, Edge::Type::kOuter, c, alloc, outerWinding); 2019 } 2020 connect(outerVertices.fTail, outerVertices.fHead, Edge::Type::kOuter, c, alloc, outerWinding); 2021 innerMesh->append(innerVertices); 2022 outerMesh->append(outerVertices); 2023 } 2024 2025 void extract_boundary(EdgeList* boundary, Edge* e, SkPath::FillType fillType, SkArenaAlloc& alloc) { 2026 LOG("\nextracting boundary\n"); 2027 bool down = apply_fill_type(fillType, e->fWinding); 2028 while (e) { 2029 e->fWinding = down ? 1 : -1; 2030 Edge* next; 2031 e->fLine.normalize(); 2032 e->fLine = e->fLine * e->fWinding; 2033 boundary->append(e); 2034 if (down) { 2035 // Find outgoing edge, in clockwise order. 2036 if ((next = e->fNextEdgeAbove)) { 2037 down = false; 2038 } else if ((next = e->fBottom->fLastEdgeBelow)) { 2039 down = true; 2040 } else if ((next = e->fPrevEdgeAbove)) { 2041 down = false; 2042 } 2043 } else { 2044 // Find outgoing edge, in counter-clockwise order. 2045 if ((next = e->fPrevEdgeBelow)) { 2046 down = true; 2047 } else if ((next = e->fTop->fFirstEdgeAbove)) { 2048 down = false; 2049 } else if ((next = e->fNextEdgeBelow)) { 2050 down = true; 2051 } 2052 } 2053 disconnect(e); 2054 e = next; 2055 } 2056 } 2057 2058 // Stage 5b: Extract boundaries from mesh, simplify and stroke them into a new mesh. 2059 2060 void extract_boundaries(const VertexList& inMesh, VertexList* innerVertices, 2061 VertexList* outerVertices, SkPath::FillType fillType, 2062 Comparator& c, SkArenaAlloc& alloc) { 2063 remove_non_boundary_edges(inMesh, fillType, alloc); 2064 for (Vertex* v = inMesh.fHead; v; v = v->fNext) { 2065 while (v->fFirstEdgeBelow) { 2066 EdgeList boundary; 2067 extract_boundary(&boundary, v->fFirstEdgeBelow, fillType, alloc); 2068 simplify_boundary(&boundary, c, alloc); 2069 stroke_boundary(&boundary, innerVertices, outerVertices, c, alloc); 2070 } 2071 } 2072 } 2073 2074 // This is a driver function that calls stages 2-5 in turn. 2075 2076 void contours_to_mesh(VertexList* contours, int contourCnt, bool antialias, 2077 VertexList* mesh, Comparator& c, SkArenaAlloc& alloc) { 2078 #if LOGGING_ENABLED 2079 for (int i = 0; i < contourCnt; ++i) { 2080 Vertex* v = contours[i].fHead; 2081 SkASSERT(v); 2082 LOG("path.moveTo(%20.20g, %20.20g);\n", v->fPoint.fX, v->fPoint.fY); 2083 for (v = v->fNext; v; v = v->fNext) { 2084 LOG("path.lineTo(%20.20g, %20.20g);\n", v->fPoint.fX, v->fPoint.fY); 2085 } 2086 } 2087 #endif 2088 sanitize_contours(contours, contourCnt, antialias); 2089 build_edges(contours, contourCnt, mesh, c, alloc); 2090 } 2091 2092 void sort_mesh(VertexList* vertices, Comparator& c, SkArenaAlloc& alloc) { 2093 if (!vertices || !vertices->fHead) { 2094 return; 2095 } 2096 2097 // Sort vertices in Y (secondarily in X). 2098 if (c.fDirection == Comparator::Direction::kHorizontal) { 2099 merge_sort<sweep_lt_horiz>(vertices); 2100 } else { 2101 merge_sort<sweep_lt_vert>(vertices); 2102 } 2103 #if LOGGING_ENABLED 2104 for (Vertex* v = vertices->fHead; v != nullptr; v = v->fNext) { 2105 static float gID = 0.0f; 2106 v->fID = gID++; 2107 } 2108 #endif 2109 } 2110 2111 Poly* contours_to_polys(VertexList* contours, int contourCnt, SkPath::FillType fillType, 2112 const SkRect& pathBounds, bool antialias, VertexList* outerMesh, 2113 SkArenaAlloc& alloc) { 2114 Comparator c(pathBounds.width() > pathBounds.height() ? Comparator::Direction::kHorizontal 2115 : Comparator::Direction::kVertical); 2116 VertexList mesh; 2117 contours_to_mesh(contours, contourCnt, antialias, &mesh, c, alloc); 2118 sort_mesh(&mesh, c, alloc); 2119 merge_coincident_vertices(&mesh, c, alloc); 2120 simplify(&mesh, c, alloc); 2121 if (antialias) { 2122 VertexList innerMesh; 2123 extract_boundaries(mesh, &innerMesh, outerMesh, fillType, c, alloc); 2124 sort_mesh(&innerMesh, c, alloc); 2125 sort_mesh(outerMesh, c, alloc); 2126 merge_coincident_vertices(&innerMesh, c, alloc); 2127 bool was_complex = merge_coincident_vertices(outerMesh, c, alloc); 2128 was_complex = simplify(&innerMesh, c, alloc) || was_complex; 2129 was_complex = simplify(outerMesh, c, alloc) || was_complex; 2130 LOG("\ninner mesh before:\n"); 2131 dump_mesh(innerMesh); 2132 LOG("\nouter mesh before:\n"); 2133 dump_mesh(*outerMesh); 2134 was_complex = collapse_overlap_regions(&innerMesh, c, alloc) || was_complex; 2135 was_complex = collapse_overlap_regions(outerMesh, c, alloc) || was_complex; 2136 if (was_complex) { 2137 LOG("found complex mesh; taking slow path\n"); 2138 VertexList aaMesh; 2139 LOG("\ninner mesh after:\n"); 2140 dump_mesh(innerMesh); 2141 LOG("\nouter mesh after:\n"); 2142 dump_mesh(*outerMesh); 2143 connect_partners(outerMesh, c, alloc); 2144 connect_partners(&innerMesh, c, alloc); 2145 sorted_merge(&innerMesh, outerMesh, &aaMesh, c); 2146 merge_coincident_vertices(&aaMesh, c, alloc); 2147 simplify(&aaMesh, c, alloc); 2148 dump_mesh(aaMesh); 2149 outerMesh->fHead = outerMesh->fTail = nullptr; 2150 return tessellate(aaMesh, alloc); 2151 } else { 2152 LOG("no complex polygons; taking fast path\n"); 2153 return tessellate(innerMesh, alloc); 2154 } 2155 } else { 2156 return tessellate(mesh, alloc); 2157 } 2158 } 2159 2160 // Stage 6: Triangulate the monotone polygons into a vertex buffer. 2161 void* polys_to_triangles(Poly* polys, SkPath::FillType fillType, bool emitCoverage, void* data) { 2162 for (Poly* poly = polys; poly; poly = poly->fNext) { 2163 if (apply_fill_type(fillType, poly)) { 2164 data = poly->emit(emitCoverage, data); 2165 } 2166 } 2167 return data; 2168 } 2169 2170 Poly* path_to_polys(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 2171 int contourCnt, SkArenaAlloc& alloc, bool antialias, bool* isLinear, 2172 VertexList* outerMesh) { 2173 SkPath::FillType fillType = path.getFillType(); 2174 if (SkPath::IsInverseFillType(fillType)) { 2175 contourCnt++; 2176 } 2177 std::unique_ptr<VertexList[]> contours(new VertexList[contourCnt]); 2178 2179 path_to_contours(path, tolerance, clipBounds, contours.get(), alloc, isLinear); 2180 return contours_to_polys(contours.get(), contourCnt, path.getFillType(), path.getBounds(), 2181 antialias, outerMesh, alloc); 2182 } 2183 2184 int get_contour_count(const SkPath& path, SkScalar tolerance) { 2185 int contourCnt; 2186 int maxPts = GrPathUtils::worstCasePointCount(path, &contourCnt, tolerance); 2187 if (maxPts <= 0) { 2188 return 0; 2189 } 2190 return contourCnt; 2191 } 2192 2193 int64_t count_points(Poly* polys, SkPath::FillType fillType) { 2194 int64_t count = 0; 2195 for (Poly* poly = polys; poly; poly = poly->fNext) { 2196 if (apply_fill_type(fillType, poly) && poly->fCount >= 3) { 2197 count += (poly->fCount - 2) * (TESSELLATOR_WIREFRAME ? 6 : 3); 2198 } 2199 } 2200 return count; 2201 } 2202 2203 int64_t count_outer_mesh_points(const VertexList& outerMesh) { 2204 int64_t count = 0; 2205 for (Vertex* v = outerMesh.fHead; v; v = v->fNext) { 2206 for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { 2207 count += TESSELLATOR_WIREFRAME ? 12 : 6; 2208 } 2209 } 2210 return count; 2211 } 2212 2213 void* outer_mesh_to_triangles(const VertexList& outerMesh, bool emitCoverage, void* data) { 2214 for (Vertex* v = outerMesh.fHead; v; v = v->fNext) { 2215 for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { 2216 Vertex* v0 = e->fTop; 2217 Vertex* v1 = e->fBottom; 2218 Vertex* v2 = e->fBottom->fPartner; 2219 Vertex* v3 = e->fTop->fPartner; 2220 data = emit_triangle(v0, v1, v2, emitCoverage, data); 2221 data = emit_triangle(v0, v2, v3, emitCoverage, data); 2222 } 2223 } 2224 return data; 2225 } 2226 2227 } // namespace 2228 2229 namespace GrTessellator { 2230 2231 // Stage 6: Triangulate the monotone polygons into a vertex buffer. 2232 2233 int PathToTriangles(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 2234 VertexAllocator* vertexAllocator, bool antialias, bool* isLinear) { 2235 int contourCnt = get_contour_count(path, tolerance); 2236 if (contourCnt <= 0) { 2237 *isLinear = true; 2238 return 0; 2239 } 2240 SkArenaAlloc alloc(kArenaChunkSize); 2241 VertexList outerMesh; 2242 Poly* polys = path_to_polys(path, tolerance, clipBounds, contourCnt, alloc, antialias, 2243 isLinear, &outerMesh); 2244 SkPath::FillType fillType = antialias ? SkPath::kWinding_FillType : path.getFillType(); 2245 int64_t count64 = count_points(polys, fillType); 2246 if (antialias) { 2247 count64 += count_outer_mesh_points(outerMesh); 2248 } 2249 if (0 == count64 || count64 > SK_MaxS32) { 2250 return 0; 2251 } 2252 int count = count64; 2253 2254 void* verts = vertexAllocator->lock(count); 2255 if (!verts) { 2256 SkDebugf("Could not allocate vertices\n"); 2257 return 0; 2258 } 2259 2260 LOG("emitting %d verts\n", count); 2261 void* end = polys_to_triangles(polys, fillType, antialias, verts); 2262 end = outer_mesh_to_triangles(outerMesh, true, end); 2263 2264 int actualCount = static_cast<int>((static_cast<uint8_t*>(end) - static_cast<uint8_t*>(verts)) 2265 / vertexAllocator->stride()); 2266 SkASSERT(actualCount <= count); 2267 vertexAllocator->unlock(actualCount); 2268 return actualCount; 2269 } 2270 2271 int PathToVertices(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 2272 GrTessellator::WindingVertex** verts) { 2273 int contourCnt = get_contour_count(path, tolerance); 2274 if (contourCnt <= 0) { 2275 *verts = nullptr; 2276 return 0; 2277 } 2278 SkArenaAlloc alloc(kArenaChunkSize); 2279 bool isLinear; 2280 Poly* polys = path_to_polys(path, tolerance, clipBounds, contourCnt, alloc, false, &isLinear, 2281 nullptr); 2282 SkPath::FillType fillType = path.getFillType(); 2283 int64_t count64 = count_points(polys, fillType); 2284 if (0 == count64 || count64 > SK_MaxS32) { 2285 *verts = nullptr; 2286 return 0; 2287 } 2288 int count = count64; 2289 2290 *verts = new GrTessellator::WindingVertex[count]; 2291 GrTessellator::WindingVertex* vertsEnd = *verts; 2292 SkPoint* points = new SkPoint[count]; 2293 SkPoint* pointsEnd = points; 2294 for (Poly* poly = polys; poly; poly = poly->fNext) { 2295 if (apply_fill_type(fillType, poly)) { 2296 SkPoint* start = pointsEnd; 2297 pointsEnd = static_cast<SkPoint*>(poly->emit(false, pointsEnd)); 2298 while (start != pointsEnd) { 2299 vertsEnd->fPos = *start; 2300 vertsEnd->fWinding = poly->fWinding; 2301 ++start; 2302 ++vertsEnd; 2303 } 2304 } 2305 } 2306 int actualCount = static_cast<int>(vertsEnd - *verts); 2307 SkASSERT(actualCount <= count); 2308 SkASSERT(pointsEnd - points == actualCount); 2309 delete[] points; 2310 return actualCount; 2311 } 2312 2313 } // namespace 2314