GrTessellator.cpp revision b56dedf70bdbf1a5e1e04dfbc83a374bffe6b00f
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 13#include "SkArenaAlloc.h" 14#include "SkGeometry.h" 15#include "SkPath.h" 16 17#include <stdio.h> 18 19/* 20 * There are six stages to the basic algorithm: 21 * 22 * 1) Linearize the path contours into piecewise linear segments (path_to_contours()). 23 * 2) Build a mesh of edges connecting the vertices (build_edges()). 24 * 3) Sort the vertices in Y (and secondarily in X) (merge_sort()). 25 * 4) Simplify the mesh by inserting new vertices at intersecting edges (simplify()). 26 * 5) Tessellate the simplified mesh into monotone polygons (tessellate()). 27 * 6) Triangulate the monotone polygons directly into a vertex buffer (polys_to_triangles()). 28 * 29 * For screenspace antialiasing, the algorithm is modified as follows: 30 * 31 * Run steps 1-5 above to produce polygons. 32 * 5b) Apply fill rules to extract boundary contours from the polygons (extract_boundaries()). 33 * 5c) Simplify boundaries to remove "pointy" vertices which cause inversions (simplify_boundary()). 34 * 5d) Displace edges by half a pixel inward and outward along their normals. Intersect to find 35 * new vertices, and set zero alpha on the exterior and one alpha on the interior. Build a new 36 * antialiased mesh from those vertices (boundary_to_aa_mesh()). 37 * Run steps 3-6 above on the new mesh, and produce antialiased triangles. 38 * 39 * The vertex sorting in step (3) is a merge sort, since it plays well with the linked list 40 * of vertices (and the necessity of inserting new vertices on intersection). 41 * 42 * Stages (4) and (5) use an active edge list, which a list of all edges for which the 43 * sweep line has crossed the top vertex, but not the bottom vertex. It's sorted 44 * left-to-right based on the point where both edges are active (when both top vertices 45 * have been seen, so the "lower" top vertex of the two). If the top vertices are equal 46 * (shared), it's sorted based on the last point where both edges are active, so the 47 * "upper" bottom vertex. 48 * 49 * The most complex step is the simplification (4). It's based on the Bentley-Ottman 50 * line-sweep algorithm, but due to floating point inaccuracy, the intersection points are 51 * not exact and may violate the mesh topology or active edge list ordering. We 52 * accommodate this by adjusting the topology of the mesh and AEL to match the intersection 53 * points. This occurs in three ways: 54 * 55 * A) Intersections may cause a shortened edge to no longer be ordered with respect to its 56 * neighbouring edges at the top or bottom vertex. This is handled by merging the 57 * edges (merge_collinear_edges()). 58 * B) Intersections may cause an edge to violate the left-to-right ordering of the 59 * active edge list. This is handled by splitting the neighbour edge on the 60 * intersected vertex (cleanup_active_edges()). 61 * C) Shortening an edge may cause an active edge to become inactive or an inactive edge 62 * to become active. This is handled by removing or inserting the edge in the active 63 * edge list (fix_active_state()). 64 * 65 * The tessellation steps (5) and (6) are based on "Triangulating Simple Polygons and 66 * Equivalent Problems" (Fournier and Montuno); also a line-sweep algorithm. Note that it 67 * currently uses a linked list for the active edge list, rather than a 2-3 tree as the 68 * paper describes. The 2-3 tree gives O(lg N) lookups, but insertion and removal also 69 * become O(lg N). In all the test cases, it was found that the cost of frequent O(lg N) 70 * insertions and removals was greater than the cost of infrequent O(N) lookups with the 71 * linked list implementation. With the latter, all removals are O(1), and most insertions 72 * are O(1), since we know the adjacent edge in the active edge list based on the topology. 73 * Only type 2 vertices (see paper) require the O(N) lookups, and these are much less 74 * frequent. There may be other data structures worth investigating, however. 75 * 76 * Note that the orientation of the line sweep algorithms is determined by the aspect ratio of the 77 * path bounds. When the path is taller than it is wide, we sort vertices based on increasing Y 78 * coordinate, and secondarily by increasing X coordinate. When the path is wider than it is tall, 79 * we sort by increasing X coordinate, but secondarily by *decreasing* Y coordinate. This is so 80 * that the "left" and "right" orientation in the code remains correct (edges to the left are 81 * increasing in Y; edges to the right are decreasing in Y). That is, the setting rotates 90 82 * degrees counterclockwise, rather that transposing. 83 */ 84 85#define LOGGING_ENABLED 0 86 87#if LOGGING_ENABLED 88#define LOG printf 89#else 90#define LOG(...) 91#endif 92 93namespace { 94 95const int kArenaChunkSize = 16 * 1024; 96 97struct Vertex; 98struct Edge; 99struct Poly; 100 101template <class T, T* T::*Prev, T* T::*Next> 102void list_insert(T* t, T* prev, T* next, T** head, T** tail) { 103 t->*Prev = prev; 104 t->*Next = next; 105 if (prev) { 106 prev->*Next = t; 107 } else if (head) { 108 *head = t; 109 } 110 if (next) { 111 next->*Prev = t; 112 } else if (tail) { 113 *tail = t; 114 } 115} 116 117template <class T, T* T::*Prev, T* T::*Next> 118void list_remove(T* t, T** head, T** tail) { 119 if (t->*Prev) { 120 t->*Prev->*Next = t->*Next; 121 } else if (head) { 122 *head = t->*Next; 123 } 124 if (t->*Next) { 125 t->*Next->*Prev = t->*Prev; 126 } else if (tail) { 127 *tail = t->*Prev; 128 } 129 t->*Prev = t->*Next = nullptr; 130} 131 132/** 133 * Vertices are used in three ways: first, the path contours are converted into a 134 * circularly-linked list of Vertices for each contour. After edge construction, the same Vertices 135 * are re-ordered by the merge sort according to the sweep_lt comparator (usually, increasing 136 * in Y) using the same fPrev/fNext pointers that were used for the contours, to avoid 137 * reallocation. Finally, MonotonePolys are built containing a circularly-linked list of 138 * Vertices. (Currently, those Vertices are newly-allocated for the MonotonePolys, since 139 * an individual Vertex from the path mesh may belong to multiple 140 * MonotonePolys, so the original Vertices cannot be re-used. 141 */ 142 143struct Vertex { 144 Vertex(const SkPoint& point, uint8_t alpha) 145 : fPoint(point), fPrev(nullptr), fNext(nullptr) 146 , fFirstEdgeAbove(nullptr), fLastEdgeAbove(nullptr) 147 , fFirstEdgeBelow(nullptr), fLastEdgeBelow(nullptr) 148 , fProcessed(false) 149 , fAlpha(alpha) 150#if LOGGING_ENABLED 151 , fID (-1.0f) 152#endif 153 {} 154 SkPoint fPoint; // Vertex position 155 Vertex* fPrev; // Linked list of contours, then Y-sorted vertices. 156 Vertex* fNext; // " 157 Edge* fFirstEdgeAbove; // Linked list of edges above this vertex. 158 Edge* fLastEdgeAbove; // " 159 Edge* fFirstEdgeBelow; // Linked list of edges below this vertex. 160 Edge* fLastEdgeBelow; // " 161 bool fProcessed; // Has this vertex been seen in simplify()? 162 uint8_t fAlpha; 163#if LOGGING_ENABLED 164 float fID; // Identifier used for logging. 165#endif 166}; 167 168/***************************************************************************************/ 169 170struct AAParams { 171 bool fTweakAlpha; 172 GrColor fColor; 173}; 174 175typedef bool (*CompareFunc)(const SkPoint& a, const SkPoint& b); 176 177bool sweep_lt_horiz(const SkPoint& a, const SkPoint& b) { 178 return a.fX < b.fX || (a.fX == b.fX && a.fY > b.fY); 179} 180 181bool sweep_lt_vert(const SkPoint& a, const SkPoint& b) { 182 return a.fY < b.fY || (a.fY == b.fY && a.fX < b.fX); 183} 184 185struct Comparator { 186 enum class Direction { kVertical, kHorizontal }; 187 Comparator(Direction direction) : fDirection(direction) {} 188 bool sweep_lt(const SkPoint& a, const SkPoint& b) const { 189 return fDirection == Direction::kHorizontal ? sweep_lt_horiz(a, b) : sweep_lt_vert(a, b); 190 } 191 Direction fDirection; 192}; 193 194inline void* emit_vertex(Vertex* v, const AAParams* aaParams, void* data) { 195 if (!aaParams) { 196 SkPoint* d = static_cast<SkPoint*>(data); 197 *d++ = v->fPoint; 198 return d; 199 } 200 if (aaParams->fTweakAlpha) { 201 auto d = static_cast<GrDefaultGeoProcFactory::PositionColorAttr*>(data); 202 d->fPosition = v->fPoint; 203 d->fColor = SkAlphaMulQ(aaParams->fColor, SkAlpha255To256(v->fAlpha)); 204 d++; 205 return d; 206 } 207 auto d = static_cast<GrDefaultGeoProcFactory::PositionColorCoverageAttr*>(data); 208 d->fPosition = v->fPoint; 209 d->fColor = aaParams->fColor; 210 d->fCoverage = GrNormalizeByteToFloat(v->fAlpha); 211 d++; 212 return d; 213} 214 215void* emit_triangle(Vertex* v0, Vertex* v1, Vertex* v2, const AAParams* aaParams, void* data) { 216 LOG("emit_triangle (%g, %g) %d\n", v0->fPoint.fX, v0->fPoint.fY, v0->fAlpha); 217 LOG(" (%g, %g) %d\n", v1->fPoint.fX, v1->fPoint.fY, v1->fAlpha); 218 LOG(" (%g, %g) %d\n", v2->fPoint.fX, v2->fPoint.fY, v2->fAlpha); 219#if TESSELLATOR_WIREFRAME 220 data = emit_vertex(v0, aaParams, data); 221 data = emit_vertex(v1, aaParams, data); 222 data = emit_vertex(v1, aaParams, data); 223 data = emit_vertex(v2, aaParams, data); 224 data = emit_vertex(v2, aaParams, data); 225 data = emit_vertex(v0, aaParams, data); 226#else 227 data = emit_vertex(v0, aaParams, data); 228 data = emit_vertex(v1, aaParams, data); 229 data = emit_vertex(v2, aaParams, data); 230#endif 231 return data; 232} 233 234struct VertexList { 235 VertexList() : fHead(nullptr), fTail(nullptr) {} 236 VertexList(Vertex* head, Vertex* tail) : fHead(head), fTail(tail) {} 237 Vertex* fHead; 238 Vertex* fTail; 239 void insert(Vertex* v, Vertex* prev, Vertex* next) { 240 list_insert<Vertex, &Vertex::fPrev, &Vertex::fNext>(v, prev, next, &fHead, &fTail); 241 } 242 void append(Vertex* v) { 243 insert(v, fTail, nullptr); 244 } 245 void prepend(Vertex* v) { 246 insert(v, nullptr, fHead); 247 } 248 void remove(Vertex* v) { 249 list_remove<Vertex, &Vertex::fPrev, &Vertex::fNext>(v, &fHead, &fTail); 250 } 251 void close() { 252 if (fHead && fTail) { 253 fTail->fNext = fHead; 254 fHead->fPrev = fTail; 255 } 256 } 257}; 258 259// Round to nearest quarter-pixel. This is used for screenspace tessellation. 260 261inline void round(SkPoint* p) { 262 p->fX = SkScalarRoundToScalar(p->fX * SkFloatToScalar(4.0f)) * SkFloatToScalar(0.25f); 263 p->fY = SkScalarRoundToScalar(p->fY * SkFloatToScalar(4.0f)) * SkFloatToScalar(0.25f); 264} 265 266// A line equation in implicit form. fA * x + fB * y + fC = 0, for all points (x, y) on the line. 267struct Line { 268 Line(Vertex* p, Vertex* q) : Line(p->fPoint, q->fPoint) {} 269 Line(const SkPoint& p, const SkPoint& q) 270 : fA(static_cast<double>(q.fY) - p.fY) // a = dY 271 , fB(static_cast<double>(p.fX) - q.fX) // b = -dX 272 , fC(static_cast<double>(p.fY) * q.fX - // c = cross(q, p) 273 static_cast<double>(p.fX) * q.fY) {} 274 double dist(const SkPoint& p) const { 275 return fA * p.fX + fB * p.fY + fC; 276 } 277 double magSq() const { 278 return fA * fA + fB * fB; 279 } 280 281 // Compute the intersection of two (infinite) Lines. 282 bool intersect(const Line& other, SkPoint* point) { 283 double denom = fA * other.fB - fB * other.fA; 284 if (denom == 0.0) { 285 return false; 286 } 287 double scale = 1.0f / denom; 288 point->fX = SkDoubleToScalar((fB * other.fC - other.fB * fC) * scale); 289 point->fY = SkDoubleToScalar((other.fA * fC - fA * other.fC) * scale); 290 round(point); 291 return true; 292 } 293 double fA, fB, fC; 294}; 295 296/** 297 * An Edge joins a top Vertex to a bottom Vertex. Edge ordering for the list of "edges above" and 298 * "edge below" a vertex as well as for the active edge list is handled by isLeftOf()/isRightOf(). 299 * Note that an Edge will give occasionally dist() != 0 for its own endpoints (because floating 300 * point). For speed, that case is only tested by the callers which require it (e.g., 301 * cleanup_active_edges()). Edges also handle checking for intersection with other edges. 302 * Currently, this converts the edges to the parametric form, in order to avoid doing a division 303 * until an intersection has been confirmed. This is slightly slower in the "found" case, but 304 * a lot faster in the "not found" case. 305 * 306 * The coefficients of the line equation stored in double precision to avoid catastrphic 307 * cancellation in the isLeftOf() and isRightOf() checks. Using doubles ensures that the result is 308 * correct in float, since it's a polynomial of degree 2. The intersect() function, being 309 * degree 5, is still subject to catastrophic cancellation. We deal with that by assuming its 310 * output may be incorrect, and adjusting the mesh topology to match (see comment at the top of 311 * this file). 312 */ 313 314struct Edge { 315 enum class Type { kInner, kOuter, kConnector }; 316 Edge(Vertex* top, Vertex* bottom, int winding, Type type) 317 : fWinding(winding) 318 , fTop(top) 319 , fBottom(bottom) 320 , fType(type) 321 , fLeft(nullptr) 322 , fRight(nullptr) 323 , fPrevEdgeAbove(nullptr) 324 , fNextEdgeAbove(nullptr) 325 , fPrevEdgeBelow(nullptr) 326 , fNextEdgeBelow(nullptr) 327 , fLeftPoly(nullptr) 328 , fRightPoly(nullptr) 329 , fLeftPolyPrev(nullptr) 330 , fLeftPolyNext(nullptr) 331 , fRightPolyPrev(nullptr) 332 , fRightPolyNext(nullptr) 333 , fUsedInLeftPoly(false) 334 , fUsedInRightPoly(false) 335 , fLine(top, bottom) { 336 } 337 int fWinding; // 1 == edge goes downward; -1 = edge goes upward. 338 Vertex* fTop; // The top vertex in vertex-sort-order (sweep_lt). 339 Vertex* fBottom; // The bottom vertex in vertex-sort-order. 340 Type fType; 341 Edge* fLeft; // The linked list of edges in the active edge list. 342 Edge* fRight; // " 343 Edge* fPrevEdgeAbove; // The linked list of edges in the bottom Vertex's "edges above". 344 Edge* fNextEdgeAbove; // " 345 Edge* fPrevEdgeBelow; // The linked list of edges in the top Vertex's "edges below". 346 Edge* fNextEdgeBelow; // " 347 Poly* fLeftPoly; // The Poly to the left of this edge, if any. 348 Poly* fRightPoly; // The Poly to the right of this edge, if any. 349 Edge* fLeftPolyPrev; 350 Edge* fLeftPolyNext; 351 Edge* fRightPolyPrev; 352 Edge* fRightPolyNext; 353 bool fUsedInLeftPoly; 354 bool fUsedInRightPoly; 355 Line fLine; 356 double dist(const SkPoint& p) const { 357 return fLine.dist(p); 358 } 359 bool isRightOf(Vertex* v) const { 360 return fLine.dist(v->fPoint) < 0.0; 361 } 362 bool isLeftOf(Vertex* v) const { 363 return fLine.dist(v->fPoint) > 0.0; 364 } 365 void recompute() { 366 fLine = Line(fTop, fBottom); 367 } 368 bool intersect(const Edge& other, SkPoint* p, uint8_t* alpha = nullptr) { 369 LOG("intersecting %g -> %g with %g -> %g\n", 370 fTop->fID, fBottom->fID, 371 other.fTop->fID, other.fBottom->fID); 372 if (fTop == other.fTop || fBottom == other.fBottom) { 373 return false; 374 } 375 double denom = fLine.fA * other.fLine.fB - fLine.fB * other.fLine.fA; 376 if (denom == 0.0) { 377 return false; 378 } 379 double dx = static_cast<double>(other.fTop->fPoint.fX) - fTop->fPoint.fX; 380 double dy = static_cast<double>(other.fTop->fPoint.fY) - fTop->fPoint.fY; 381 double sNumer = dy * other.fLine.fB + dx * other.fLine.fA; 382 double tNumer = dy * fLine.fB + dx * fLine.fA; 383 // If (sNumer / denom) or (tNumer / denom) is not in [0..1], exit early. 384 // This saves us doing the divide below unless absolutely necessary. 385 if (denom > 0.0 ? (sNumer < 0.0 || sNumer > denom || tNumer < 0.0 || tNumer > denom) 386 : (sNumer > 0.0 || sNumer < denom || tNumer > 0.0 || tNumer < denom)) { 387 return false; 388 } 389 double s = sNumer / denom; 390 SkASSERT(s >= 0.0 && s <= 1.0); 391 p->fX = SkDoubleToScalar(fTop->fPoint.fX - s * fLine.fB); 392 p->fY = SkDoubleToScalar(fTop->fPoint.fY + s * fLine.fA); 393 if (alpha) { 394 if (fType == Type::kConnector) { 395 *alpha = (1.0 - s) * fTop->fAlpha + s * fBottom->fAlpha; 396 } else if (other.fType == Type::kConnector) { 397 double t = tNumer / denom; 398 *alpha = (1.0 - t) * other.fTop->fAlpha + t * other.fBottom->fAlpha; 399 } else if (fType == Type::kOuter && other.fType == Type::kOuter) { 400 *alpha = 0; 401 } else { 402 *alpha = 255; 403 } 404 } 405 return true; 406 } 407}; 408 409struct EdgeList { 410 EdgeList() : fHead(nullptr), fTail(nullptr) {} 411 Edge* fHead; 412 Edge* fTail; 413 void insert(Edge* edge, Edge* prev, Edge* next) { 414 list_insert<Edge, &Edge::fLeft, &Edge::fRight>(edge, prev, next, &fHead, &fTail); 415 } 416 void append(Edge* e) { 417 insert(e, fTail, nullptr); 418 } 419 void remove(Edge* edge) { 420 list_remove<Edge, &Edge::fLeft, &Edge::fRight>(edge, &fHead, &fTail); 421 } 422 void close() { 423 if (fHead && fTail) { 424 fTail->fRight = fHead; 425 fHead->fLeft = fTail; 426 } 427 } 428 bool contains(Edge* edge) const { 429 return edge->fLeft || edge->fRight || fHead == edge; 430 } 431}; 432 433/***************************************************************************************/ 434 435struct Poly { 436 Poly(Vertex* v, int winding) 437 : fFirstVertex(v) 438 , fWinding(winding) 439 , fHead(nullptr) 440 , fTail(nullptr) 441 , fNext(nullptr) 442 , fPartner(nullptr) 443 , fCount(0) 444 { 445#if LOGGING_ENABLED 446 static int gID = 0; 447 fID = gID++; 448 LOG("*** created Poly %d\n", fID); 449#endif 450 } 451 typedef enum { kLeft_Side, kRight_Side } Side; 452 struct MonotonePoly { 453 MonotonePoly(Edge* edge, Side side) 454 : fSide(side) 455 , fFirstEdge(nullptr) 456 , fLastEdge(nullptr) 457 , fPrev(nullptr) 458 , fNext(nullptr) { 459 this->addEdge(edge); 460 } 461 Side fSide; 462 Edge* fFirstEdge; 463 Edge* fLastEdge; 464 MonotonePoly* fPrev; 465 MonotonePoly* fNext; 466 void addEdge(Edge* edge) { 467 if (fSide == kRight_Side) { 468 SkASSERT(!edge->fUsedInRightPoly); 469 list_insert<Edge, &Edge::fRightPolyPrev, &Edge::fRightPolyNext>( 470 edge, fLastEdge, nullptr, &fFirstEdge, &fLastEdge); 471 edge->fUsedInRightPoly = true; 472 } else { 473 SkASSERT(!edge->fUsedInLeftPoly); 474 list_insert<Edge, &Edge::fLeftPolyPrev, &Edge::fLeftPolyNext>( 475 edge, fLastEdge, nullptr, &fFirstEdge, &fLastEdge); 476 edge->fUsedInLeftPoly = true; 477 } 478 } 479 480 void* emit(const AAParams* aaParams, void* data) { 481 Edge* e = fFirstEdge; 482 VertexList vertices; 483 vertices.append(e->fTop); 484 while (e != nullptr) { 485 if (kRight_Side == fSide) { 486 vertices.append(e->fBottom); 487 e = e->fRightPolyNext; 488 } else { 489 vertices.prepend(e->fBottom); 490 e = e->fLeftPolyNext; 491 } 492 } 493 Vertex* first = vertices.fHead; 494 Vertex* v = first->fNext; 495 while (v != vertices.fTail) { 496 SkASSERT(v && v->fPrev && v->fNext); 497 Vertex* prev = v->fPrev; 498 Vertex* curr = v; 499 Vertex* next = v->fNext; 500 double ax = static_cast<double>(curr->fPoint.fX) - prev->fPoint.fX; 501 double ay = static_cast<double>(curr->fPoint.fY) - prev->fPoint.fY; 502 double bx = static_cast<double>(next->fPoint.fX) - curr->fPoint.fX; 503 double by = static_cast<double>(next->fPoint.fY) - curr->fPoint.fY; 504 if (ax * by - ay * bx >= 0.0) { 505 data = emit_triangle(prev, curr, next, aaParams, data); 506 v->fPrev->fNext = v->fNext; 507 v->fNext->fPrev = v->fPrev; 508 if (v->fPrev == first) { 509 v = v->fNext; 510 } else { 511 v = v->fPrev; 512 } 513 } else { 514 v = v->fNext; 515 } 516 } 517 return data; 518 } 519 }; 520 Poly* addEdge(Edge* e, Side side, SkArenaAlloc& alloc) { 521 LOG("addEdge (%g -> %g) to poly %d, %s side\n", 522 e->fTop->fID, e->fBottom->fID, fID, side == kLeft_Side ? "left" : "right"); 523 Poly* partner = fPartner; 524 Poly* poly = this; 525 if (side == kRight_Side) { 526 if (e->fUsedInRightPoly) { 527 return this; 528 } 529 } else { 530 if (e->fUsedInLeftPoly) { 531 return this; 532 } 533 } 534 if (partner) { 535 fPartner = partner->fPartner = nullptr; 536 } 537 if (!fTail) { 538 fHead = fTail = alloc.make<MonotonePoly>(e, side); 539 fCount += 2; 540 } else if (e->fBottom == fTail->fLastEdge->fBottom) { 541 return poly; 542 } else if (side == fTail->fSide) { 543 fTail->addEdge(e); 544 fCount++; 545 } else { 546 e = alloc.make<Edge>(fTail->fLastEdge->fBottom, e->fBottom, 1, Edge::Type::kInner); 547 fTail->addEdge(e); 548 fCount++; 549 if (partner) { 550 partner->addEdge(e, side, alloc); 551 poly = partner; 552 } else { 553 MonotonePoly* m = alloc.make<MonotonePoly>(e, side); 554 m->fPrev = fTail; 555 fTail->fNext = m; 556 fTail = m; 557 } 558 } 559 return poly; 560 } 561 void* emit(const AAParams* aaParams, void *data) { 562 if (fCount < 3) { 563 return data; 564 } 565 LOG("emit() %d, size %d\n", fID, fCount); 566 for (MonotonePoly* m = fHead; m != nullptr; m = m->fNext) { 567 data = m->emit(aaParams, data); 568 } 569 return data; 570 } 571 Vertex* lastVertex() const { return fTail ? fTail->fLastEdge->fBottom : fFirstVertex; } 572 Vertex* fFirstVertex; 573 int fWinding; 574 MonotonePoly* fHead; 575 MonotonePoly* fTail; 576 Poly* fNext; 577 Poly* fPartner; 578 int fCount; 579#if LOGGING_ENABLED 580 int fID; 581#endif 582}; 583 584/***************************************************************************************/ 585 586bool coincident(const SkPoint& a, const SkPoint& b) { 587 return a == b; 588} 589 590Poly* new_poly(Poly** head, Vertex* v, int winding, SkArenaAlloc& alloc) { 591 Poly* poly = alloc.make<Poly>(v, winding); 592 poly->fNext = *head; 593 *head = poly; 594 return poly; 595} 596 597Vertex* append_point_to_contour(const SkPoint& p, Vertex* prev, Vertex** head, 598 SkArenaAlloc& alloc) { 599 Vertex* v = alloc.make<Vertex>(p, 255); 600#if LOGGING_ENABLED 601 static float gID = 0.0f; 602 v->fID = gID++; 603#endif 604 if (prev) { 605 prev->fNext = v; 606 v->fPrev = prev; 607 } else { 608 *head = v; 609 } 610 return v; 611} 612 613Vertex* generate_quadratic_points(const SkPoint& p0, 614 const SkPoint& p1, 615 const SkPoint& p2, 616 SkScalar tolSqd, 617 Vertex* prev, 618 Vertex** head, 619 int pointsLeft, 620 SkArenaAlloc& alloc) { 621 SkScalar d = p1.distanceToLineSegmentBetweenSqd(p0, p2); 622 if (pointsLeft < 2 || d < tolSqd || !SkScalarIsFinite(d)) { 623 return append_point_to_contour(p2, prev, head, alloc); 624 } 625 626 const SkPoint q[] = { 627 { SkScalarAve(p0.fX, p1.fX), SkScalarAve(p0.fY, p1.fY) }, 628 { SkScalarAve(p1.fX, p2.fX), SkScalarAve(p1.fY, p2.fY) }, 629 }; 630 const SkPoint r = { SkScalarAve(q[0].fX, q[1].fX), SkScalarAve(q[0].fY, q[1].fY) }; 631 632 pointsLeft >>= 1; 633 prev = generate_quadratic_points(p0, q[0], r, tolSqd, prev, head, pointsLeft, alloc); 634 prev = generate_quadratic_points(r, q[1], p2, tolSqd, prev, head, pointsLeft, alloc); 635 return prev; 636} 637 638Vertex* generate_cubic_points(const SkPoint& p0, 639 const SkPoint& p1, 640 const SkPoint& p2, 641 const SkPoint& p3, 642 SkScalar tolSqd, 643 Vertex* prev, 644 Vertex** head, 645 int pointsLeft, 646 SkArenaAlloc& alloc) { 647 SkScalar d1 = p1.distanceToLineSegmentBetweenSqd(p0, p3); 648 SkScalar d2 = p2.distanceToLineSegmentBetweenSqd(p0, p3); 649 if (pointsLeft < 2 || (d1 < tolSqd && d2 < tolSqd) || 650 !SkScalarIsFinite(d1) || !SkScalarIsFinite(d2)) { 651 return append_point_to_contour(p3, prev, head, alloc); 652 } 653 const SkPoint q[] = { 654 { SkScalarAve(p0.fX, p1.fX), SkScalarAve(p0.fY, p1.fY) }, 655 { SkScalarAve(p1.fX, p2.fX), SkScalarAve(p1.fY, p2.fY) }, 656 { SkScalarAve(p2.fX, p3.fX), SkScalarAve(p2.fY, p3.fY) } 657 }; 658 const SkPoint r[] = { 659 { SkScalarAve(q[0].fX, q[1].fX), SkScalarAve(q[0].fY, q[1].fY) }, 660 { SkScalarAve(q[1].fX, q[2].fX), SkScalarAve(q[1].fY, q[2].fY) } 661 }; 662 const SkPoint s = { SkScalarAve(r[0].fX, r[1].fX), SkScalarAve(r[0].fY, r[1].fY) }; 663 pointsLeft >>= 1; 664 prev = generate_cubic_points(p0, q[0], r[0], s, tolSqd, prev, head, pointsLeft, alloc); 665 prev = generate_cubic_points(s, r[1], q[2], p3, tolSqd, prev, head, pointsLeft, alloc); 666 return prev; 667} 668 669// Stage 1: convert the input path to a set of linear contours (linked list of Vertices). 670 671void path_to_contours(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 672 Vertex** contours, SkArenaAlloc& alloc, bool *isLinear) { 673 SkScalar toleranceSqd = tolerance * tolerance; 674 675 SkPoint pts[4]; 676 bool done = false; 677 *isLinear = true; 678 SkPath::Iter iter(path, false); 679 Vertex* prev = nullptr; 680 Vertex* head = nullptr; 681 if (path.isInverseFillType()) { 682 SkPoint quad[4]; 683 clipBounds.toQuad(quad); 684 for (int i = 3; i >= 0; i--) { 685 prev = append_point_to_contour(quad[i], prev, &head, alloc); 686 } 687 head->fPrev = prev; 688 prev->fNext = head; 689 *contours++ = head; 690 head = prev = nullptr; 691 } 692 SkAutoConicToQuads converter; 693 while (!done) { 694 SkPath::Verb verb = iter.next(pts); 695 switch (verb) { 696 case SkPath::kConic_Verb: { 697 SkScalar weight = iter.conicWeight(); 698 const SkPoint* quadPts = converter.computeQuads(pts, weight, toleranceSqd); 699 for (int i = 0; i < converter.countQuads(); ++i) { 700 int pointsLeft = GrPathUtils::quadraticPointCount(quadPts, tolerance); 701 prev = generate_quadratic_points(quadPts[0], quadPts[1], quadPts[2], 702 toleranceSqd, prev, &head, pointsLeft, alloc); 703 quadPts += 2; 704 } 705 *isLinear = false; 706 break; 707 } 708 case SkPath::kMove_Verb: 709 if (head) { 710 head->fPrev = prev; 711 prev->fNext = head; 712 *contours++ = head; 713 } 714 head = prev = nullptr; 715 prev = append_point_to_contour(pts[0], prev, &head, alloc); 716 break; 717 case SkPath::kLine_Verb: { 718 prev = append_point_to_contour(pts[1], prev, &head, alloc); 719 break; 720 } 721 case SkPath::kQuad_Verb: { 722 int pointsLeft = GrPathUtils::quadraticPointCount(pts, tolerance); 723 prev = generate_quadratic_points(pts[0], pts[1], pts[2], toleranceSqd, prev, 724 &head, pointsLeft, alloc); 725 *isLinear = false; 726 break; 727 } 728 case SkPath::kCubic_Verb: { 729 int pointsLeft = GrPathUtils::cubicPointCount(pts, tolerance); 730 prev = generate_cubic_points(pts[0], pts[1], pts[2], pts[3], 731 toleranceSqd, prev, &head, pointsLeft, alloc); 732 *isLinear = false; 733 break; 734 } 735 case SkPath::kClose_Verb: 736 if (head) { 737 head->fPrev = prev; 738 prev->fNext = head; 739 *contours++ = head; 740 } 741 head = prev = nullptr; 742 break; 743 case SkPath::kDone_Verb: 744 if (head) { 745 head->fPrev = prev; 746 prev->fNext = head; 747 *contours++ = head; 748 } 749 done = true; 750 break; 751 } 752 } 753} 754 755inline bool apply_fill_type(SkPath::FillType fillType, int winding) { 756 switch (fillType) { 757 case SkPath::kWinding_FillType: 758 return winding != 0; 759 case SkPath::kEvenOdd_FillType: 760 return (winding & 1) != 0; 761 case SkPath::kInverseWinding_FillType: 762 return winding == 1; 763 case SkPath::kInverseEvenOdd_FillType: 764 return (winding & 1) == 1; 765 default: 766 SkASSERT(false); 767 return false; 768 } 769} 770 771inline bool apply_fill_type(SkPath::FillType fillType, Poly* poly) { 772 return poly && apply_fill_type(fillType, poly->fWinding); 773} 774 775Edge* new_edge(Vertex* prev, Vertex* next, Edge::Type type, Comparator& c, SkArenaAlloc& alloc) { 776 int winding = c.sweep_lt(prev->fPoint, next->fPoint) ? 1 : -1; 777 Vertex* top = winding < 0 ? next : prev; 778 Vertex* bottom = winding < 0 ? prev : next; 779 return alloc.make<Edge>(top, bottom, winding, type); 780} 781 782void remove_edge(Edge* edge, EdgeList* edges) { 783 LOG("removing edge %g -> %g\n", edge->fTop->fID, edge->fBottom->fID); 784 SkASSERT(edges->contains(edge)); 785 edges->remove(edge); 786} 787 788void insert_edge(Edge* edge, Edge* prev, EdgeList* edges) { 789 LOG("inserting edge %g -> %g\n", edge->fTop->fID, edge->fBottom->fID); 790 SkASSERT(!edges->contains(edge)); 791 Edge* next = prev ? prev->fRight : edges->fHead; 792 edges->insert(edge, prev, next); 793} 794 795void find_enclosing_edges(Vertex* v, EdgeList* edges, Edge** left, Edge** right) { 796 if (v->fFirstEdgeAbove) { 797 *left = v->fFirstEdgeAbove->fLeft; 798 *right = v->fLastEdgeAbove->fRight; 799 return; 800 } 801 Edge* next = nullptr; 802 Edge* prev; 803 for (prev = edges->fTail; prev != nullptr; prev = prev->fLeft) { 804 if (prev->isLeftOf(v)) { 805 break; 806 } 807 next = prev; 808 } 809 *left = prev; 810 *right = next; 811} 812 813void find_enclosing_edges(Edge* edge, EdgeList* edges, Comparator& c, Edge** left, Edge** right) { 814 Edge* prev = nullptr; 815 Edge* next; 816 for (next = edges->fHead; next != nullptr; next = next->fRight) { 817 if ((c.sweep_lt(next->fTop->fPoint, edge->fTop->fPoint) && next->isRightOf(edge->fTop)) || 818 (c.sweep_lt(edge->fTop->fPoint, next->fTop->fPoint) && edge->isLeftOf(next->fTop)) || 819 (c.sweep_lt(edge->fBottom->fPoint, next->fBottom->fPoint) && 820 next->isRightOf(edge->fBottom)) || 821 (c.sweep_lt(next->fBottom->fPoint, edge->fBottom->fPoint) && 822 edge->isLeftOf(next->fBottom))) { 823 break; 824 } 825 prev = next; 826 } 827 *left = prev; 828 *right = next; 829} 830 831void fix_active_state(Edge* edge, EdgeList* activeEdges, Comparator& c) { 832 if (!activeEdges) { 833 return; 834 } 835 if (activeEdges->contains(edge)) { 836 if (edge->fBottom->fProcessed || !edge->fTop->fProcessed) { 837 remove_edge(edge, activeEdges); 838 } 839 } else if (edge->fTop->fProcessed && !edge->fBottom->fProcessed) { 840 Edge* left; 841 Edge* right; 842 find_enclosing_edges(edge, activeEdges, c, &left, &right); 843 insert_edge(edge, left, activeEdges); 844 } 845} 846 847void insert_edge_above(Edge* edge, Vertex* v, Comparator& c) { 848 if (edge->fTop->fPoint == edge->fBottom->fPoint || 849 c.sweep_lt(edge->fBottom->fPoint, edge->fTop->fPoint)) { 850 return; 851 } 852 LOG("insert edge (%g -> %g) above vertex %g\n", edge->fTop->fID, edge->fBottom->fID, v->fID); 853 Edge* prev = nullptr; 854 Edge* next; 855 for (next = v->fFirstEdgeAbove; next; next = next->fNextEdgeAbove) { 856 if (next->isRightOf(edge->fTop)) { 857 break; 858 } 859 prev = next; 860 } 861 list_insert<Edge, &Edge::fPrevEdgeAbove, &Edge::fNextEdgeAbove>( 862 edge, prev, next, &v->fFirstEdgeAbove, &v->fLastEdgeAbove); 863} 864 865void insert_edge_below(Edge* edge, Vertex* v, Comparator& c) { 866 if (edge->fTop->fPoint == edge->fBottom->fPoint || 867 c.sweep_lt(edge->fBottom->fPoint, edge->fTop->fPoint)) { 868 return; 869 } 870 LOG("insert edge (%g -> %g) below vertex %g\n", edge->fTop->fID, edge->fBottom->fID, v->fID); 871 Edge* prev = nullptr; 872 Edge* next; 873 for (next = v->fFirstEdgeBelow; next; next = next->fNextEdgeBelow) { 874 if (next->isRightOf(edge->fBottom)) { 875 break; 876 } 877 prev = next; 878 } 879 list_insert<Edge, &Edge::fPrevEdgeBelow, &Edge::fNextEdgeBelow>( 880 edge, prev, next, &v->fFirstEdgeBelow, &v->fLastEdgeBelow); 881} 882 883void remove_edge_above(Edge* edge) { 884 LOG("removing edge (%g -> %g) above vertex %g\n", edge->fTop->fID, edge->fBottom->fID, 885 edge->fBottom->fID); 886 list_remove<Edge, &Edge::fPrevEdgeAbove, &Edge::fNextEdgeAbove>( 887 edge, &edge->fBottom->fFirstEdgeAbove, &edge->fBottom->fLastEdgeAbove); 888} 889 890void remove_edge_below(Edge* edge) { 891 LOG("removing edge (%g -> %g) below vertex %g\n", edge->fTop->fID, edge->fBottom->fID, 892 edge->fTop->fID); 893 list_remove<Edge, &Edge::fPrevEdgeBelow, &Edge::fNextEdgeBelow>( 894 edge, &edge->fTop->fFirstEdgeBelow, &edge->fTop->fLastEdgeBelow); 895} 896 897void disconnect(Edge* edge) 898{ 899 remove_edge_above(edge); 900 remove_edge_below(edge); 901} 902 903void erase_edge(Edge* edge, EdgeList* edges) { 904 LOG("erasing edge (%g -> %g)\n", edge->fTop->fID, edge->fBottom->fID); 905 disconnect(edge); 906 if (edges && edges->contains(edge)) { 907 remove_edge(edge, edges); 908 } 909} 910 911void merge_collinear_edges(Edge* edge, EdgeList* activeEdges, Comparator& c); 912 913void set_top(Edge* edge, Vertex* v, EdgeList* activeEdges, Comparator& c) { 914 remove_edge_below(edge); 915 edge->fTop = v; 916 edge->recompute(); 917 insert_edge_below(edge, v, c); 918 fix_active_state(edge, activeEdges, c); 919 merge_collinear_edges(edge, activeEdges, c); 920} 921 922void set_bottom(Edge* edge, Vertex* v, EdgeList* activeEdges, Comparator& c) { 923 remove_edge_above(edge); 924 edge->fBottom = v; 925 edge->recompute(); 926 insert_edge_above(edge, v, c); 927 fix_active_state(edge, activeEdges, c); 928 merge_collinear_edges(edge, activeEdges, c); 929} 930 931void merge_edges_above(Edge* edge, Edge* other, EdgeList* activeEdges, Comparator& c) { 932 if (coincident(edge->fTop->fPoint, other->fTop->fPoint)) { 933 LOG("merging coincident above edges (%g, %g) -> (%g, %g)\n", 934 edge->fTop->fPoint.fX, edge->fTop->fPoint.fY, 935 edge->fBottom->fPoint.fX, edge->fBottom->fPoint.fY); 936 other->fWinding += edge->fWinding; 937 erase_edge(edge, activeEdges); 938 } else if (c.sweep_lt(edge->fTop->fPoint, other->fTop->fPoint)) { 939 other->fWinding += edge->fWinding; 940 set_bottom(edge, other->fTop, activeEdges, c); 941 } else { 942 edge->fWinding += other->fWinding; 943 set_bottom(other, edge->fTop, activeEdges, c); 944 } 945} 946 947void merge_edges_below(Edge* edge, Edge* other, EdgeList* activeEdges, Comparator& c) { 948 if (coincident(edge->fBottom->fPoint, other->fBottom->fPoint)) { 949 LOG("merging coincident below edges (%g, %g) -> (%g, %g)\n", 950 edge->fTop->fPoint.fX, edge->fTop->fPoint.fY, 951 edge->fBottom->fPoint.fX, edge->fBottom->fPoint.fY); 952 other->fWinding += edge->fWinding; 953 erase_edge(edge, activeEdges); 954 } else if (c.sweep_lt(edge->fBottom->fPoint, other->fBottom->fPoint)) { 955 edge->fWinding += other->fWinding; 956 set_top(other, edge->fBottom, activeEdges, c); 957 } else { 958 other->fWinding += edge->fWinding; 959 set_top(edge, other->fBottom, activeEdges, c); 960 } 961} 962 963void merge_collinear_edges(Edge* edge, EdgeList* activeEdges, Comparator& c) { 964 if (edge->fPrevEdgeAbove && (edge->fTop == edge->fPrevEdgeAbove->fTop || 965 !edge->fPrevEdgeAbove->isLeftOf(edge->fTop))) { 966 merge_edges_above(edge, edge->fPrevEdgeAbove, activeEdges, c); 967 } else if (edge->fNextEdgeAbove && (edge->fTop == edge->fNextEdgeAbove->fTop || 968 !edge->isLeftOf(edge->fNextEdgeAbove->fTop))) { 969 merge_edges_above(edge, edge->fNextEdgeAbove, activeEdges, c); 970 } 971 if (edge->fPrevEdgeBelow && (edge->fBottom == edge->fPrevEdgeBelow->fBottom || 972 !edge->fPrevEdgeBelow->isLeftOf(edge->fBottom))) { 973 merge_edges_below(edge, edge->fPrevEdgeBelow, activeEdges, c); 974 } else if (edge->fNextEdgeBelow && (edge->fBottom == edge->fNextEdgeBelow->fBottom || 975 !edge->isLeftOf(edge->fNextEdgeBelow->fBottom))) { 976 merge_edges_below(edge, edge->fNextEdgeBelow, activeEdges, c); 977 } 978} 979 980void split_edge(Edge* edge, Vertex* v, EdgeList* activeEdges, Comparator& c, SkArenaAlloc& alloc); 981 982void cleanup_active_edges(Edge* edge, EdgeList* activeEdges, Comparator& c, SkArenaAlloc& alloc) { 983 Vertex* top = edge->fTop; 984 Vertex* bottom = edge->fBottom; 985 if (edge->fLeft) { 986 Vertex* leftTop = edge->fLeft->fTop; 987 Vertex* leftBottom = edge->fLeft->fBottom; 988 if (c.sweep_lt(leftTop->fPoint, top->fPoint) && !edge->fLeft->isLeftOf(top)) { 989 split_edge(edge->fLeft, edge->fTop, activeEdges, c, alloc); 990 } else if (c.sweep_lt(top->fPoint, leftTop->fPoint) && !edge->isRightOf(leftTop)) { 991 split_edge(edge, leftTop, activeEdges, c, alloc); 992 } else if (c.sweep_lt(bottom->fPoint, leftBottom->fPoint) && 993 !edge->fLeft->isLeftOf(bottom)) { 994 split_edge(edge->fLeft, bottom, activeEdges, c, alloc); 995 } else if (c.sweep_lt(leftBottom->fPoint, bottom->fPoint) && !edge->isRightOf(leftBottom)) { 996 split_edge(edge, leftBottom, activeEdges, c, alloc); 997 } 998 } 999 if (edge->fRight) { 1000 Vertex* rightTop = edge->fRight->fTop; 1001 Vertex* rightBottom = edge->fRight->fBottom; 1002 if (c.sweep_lt(rightTop->fPoint, top->fPoint) && !edge->fRight->isRightOf(top)) { 1003 split_edge(edge->fRight, top, activeEdges, c, alloc); 1004 } else if (c.sweep_lt(top->fPoint, rightTop->fPoint) && !edge->isLeftOf(rightTop)) { 1005 split_edge(edge, rightTop, activeEdges, c, alloc); 1006 } else if (c.sweep_lt(bottom->fPoint, rightBottom->fPoint) && 1007 !edge->fRight->isRightOf(bottom)) { 1008 split_edge(edge->fRight, bottom, activeEdges, c, alloc); 1009 } else if (c.sweep_lt(rightBottom->fPoint, bottom->fPoint) && 1010 !edge->isLeftOf(rightBottom)) { 1011 split_edge(edge, rightBottom, activeEdges, c, alloc); 1012 } 1013 } 1014} 1015 1016void split_edge(Edge* edge, Vertex* v, EdgeList* activeEdges, Comparator& c, SkArenaAlloc& alloc) { 1017 LOG("splitting edge (%g -> %g) at vertex %g (%g, %g)\n", 1018 edge->fTop->fID, edge->fBottom->fID, 1019 v->fID, v->fPoint.fX, v->fPoint.fY); 1020 if (c.sweep_lt(v->fPoint, edge->fTop->fPoint)) { 1021 set_top(edge, v, activeEdges, c); 1022 } else if (c.sweep_lt(edge->fBottom->fPoint, v->fPoint)) { 1023 set_bottom(edge, v, activeEdges, c); 1024 } else { 1025 Edge* newEdge = alloc.make<Edge>(v, edge->fBottom, edge->fWinding, edge->fType); 1026 insert_edge_below(newEdge, v, c); 1027 insert_edge_above(newEdge, edge->fBottom, c); 1028 set_bottom(edge, v, activeEdges, c); 1029 cleanup_active_edges(edge, activeEdges, c, alloc); 1030 fix_active_state(newEdge, activeEdges, c); 1031 merge_collinear_edges(newEdge, activeEdges, c); 1032 } 1033} 1034 1035Edge* connect(Vertex* prev, Vertex* next, Edge::Type type, Comparator& c, SkArenaAlloc& alloc, 1036 int winding_scale = 1) { 1037 Edge* edge = new_edge(prev, next, type, c, alloc); 1038 insert_edge_below(edge, edge->fTop, c); 1039 insert_edge_above(edge, edge->fBottom, c); 1040 edge->fWinding *= winding_scale; 1041 merge_collinear_edges(edge, nullptr, c); 1042 return edge; 1043} 1044 1045void merge_vertices(Vertex* src, Vertex* dst, VertexList* mesh, Comparator& c, 1046 SkArenaAlloc& alloc) { 1047 LOG("found coincident verts at %g, %g; merging %g into %g\n", src->fPoint.fX, src->fPoint.fY, 1048 src->fID, dst->fID); 1049 dst->fAlpha = SkTMax(src->fAlpha, dst->fAlpha); 1050 for (Edge* edge = src->fFirstEdgeAbove; edge;) { 1051 Edge* next = edge->fNextEdgeAbove; 1052 set_bottom(edge, dst, nullptr, c); 1053 edge = next; 1054 } 1055 for (Edge* edge = src->fFirstEdgeBelow; edge;) { 1056 Edge* next = edge->fNextEdgeBelow; 1057 set_top(edge, dst, nullptr, c); 1058 edge = next; 1059 } 1060 mesh->remove(src); 1061} 1062 1063uint8_t max_edge_alpha(Edge* a, Edge* b) { 1064 if (a->fType == Edge::Type::kInner || b->fType == Edge::Type::kInner) { 1065 return 255; 1066 } else if (a->fType == Edge::Type::kOuter && b->fType == Edge::Type::kOuter) { 1067 return 0; 1068 } else { 1069 return SkTMax(SkTMax(a->fTop->fAlpha, a->fBottom->fAlpha), 1070 SkTMax(b->fTop->fAlpha, b->fBottom->fAlpha)); 1071 } 1072} 1073 1074Vertex* check_for_intersection(Edge* edge, Edge* other, EdgeList* activeEdges, Comparator& c, 1075 SkArenaAlloc& alloc) { 1076 if (!edge || !other) { 1077 return nullptr; 1078 } 1079 SkPoint p; 1080 uint8_t alpha; 1081 if (edge->intersect(*other, &p, &alpha)) { 1082 Vertex* v; 1083 LOG("found intersection, pt is %g, %g\n", p.fX, p.fY); 1084 if (p == edge->fTop->fPoint || c.sweep_lt(p, edge->fTop->fPoint)) { 1085 split_edge(other, edge->fTop, activeEdges, c, alloc); 1086 v = edge->fTop; 1087 } else if (p == edge->fBottom->fPoint || c.sweep_lt(edge->fBottom->fPoint, p)) { 1088 split_edge(other, edge->fBottom, activeEdges, c, alloc); 1089 v = edge->fBottom; 1090 } else if (p == other->fTop->fPoint || c.sweep_lt(p, other->fTop->fPoint)) { 1091 split_edge(edge, other->fTop, activeEdges, c, alloc); 1092 v = other->fTop; 1093 } else if (p == other->fBottom->fPoint || c.sweep_lt(other->fBottom->fPoint, p)) { 1094 split_edge(edge, other->fBottom, activeEdges, c, alloc); 1095 v = other->fBottom; 1096 } else { 1097 Vertex* nextV = edge->fTop; 1098 while (c.sweep_lt(p, nextV->fPoint)) { 1099 nextV = nextV->fPrev; 1100 } 1101 while (c.sweep_lt(nextV->fPoint, p)) { 1102 nextV = nextV->fNext; 1103 } 1104 Vertex* prevV = nextV->fPrev; 1105 if (coincident(prevV->fPoint, p)) { 1106 v = prevV; 1107 } else if (coincident(nextV->fPoint, p)) { 1108 v = nextV; 1109 } else { 1110 v = alloc.make<Vertex>(p, alpha); 1111 LOG("inserting between %g (%g, %g) and %g (%g, %g)\n", 1112 prevV->fID, prevV->fPoint.fX, prevV->fPoint.fY, 1113 nextV->fID, nextV->fPoint.fX, nextV->fPoint.fY); 1114#if LOGGING_ENABLED 1115 v->fID = (nextV->fID + prevV->fID) * 0.5f; 1116#endif 1117 v->fPrev = prevV; 1118 v->fNext = nextV; 1119 prevV->fNext = v; 1120 nextV->fPrev = v; 1121 } 1122 split_edge(edge, v, activeEdges, c, alloc); 1123 split_edge(other, v, activeEdges, c, alloc); 1124 } 1125 v->fAlpha = SkTMax(v->fAlpha, alpha); 1126 return v; 1127 } 1128 return nullptr; 1129} 1130 1131void sanitize_contours(Vertex** contours, int contourCnt, bool approximate) { 1132 for (int i = 0; i < contourCnt; ++i) { 1133 SkASSERT(contours[i]); 1134 if (approximate) { 1135 round(&contours[i]->fPrev->fPoint); 1136 } 1137 for (Vertex* v = contours[i];;) { 1138 if (approximate) { 1139 round(&v->fPoint); 1140 } 1141 if (coincident(v->fPrev->fPoint, v->fPoint)) { 1142 LOG("vertex %g,%g coincident; removing\n", v->fPoint.fX, v->fPoint.fY); 1143 if (v->fPrev == v) { 1144 contours[i] = nullptr; 1145 break; 1146 } 1147 v->fPrev->fNext = v->fNext; 1148 v->fNext->fPrev = v->fPrev; 1149 if (contours[i] == v) { 1150 contours[i] = v->fPrev; 1151 } 1152 v = v->fPrev; 1153 } else { 1154 v = v->fNext; 1155 if (v == contours[i]) break; 1156 } 1157 } 1158 } 1159} 1160 1161void merge_coincident_vertices(VertexList* mesh, Comparator& c, SkArenaAlloc& alloc) { 1162 for (Vertex* v = mesh->fHead->fNext; v != nullptr; v = v->fNext) { 1163 if (c.sweep_lt(v->fPoint, v->fPrev->fPoint)) { 1164 v->fPoint = v->fPrev->fPoint; 1165 } 1166 if (coincident(v->fPrev->fPoint, v->fPoint)) { 1167 merge_vertices(v->fPrev, v, mesh, c, alloc); 1168 } 1169 } 1170} 1171 1172// Stage 2: convert the contours to a mesh of edges connecting the vertices. 1173 1174void build_edges(Vertex** contours, int contourCnt, VertexList* mesh, Comparator& c, 1175 SkArenaAlloc& alloc) { 1176 Vertex* prev = nullptr; 1177 for (int i = 0; i < contourCnt; ++i) { 1178 for (Vertex* v = contours[i]; v != nullptr;) { 1179 Vertex* vNext = v->fNext; 1180 connect(v->fPrev, v, Edge::Type::kInner, c, alloc); 1181 if (prev) { 1182 prev->fNext = v; 1183 v->fPrev = prev; 1184 } else { 1185 mesh->fHead = v; 1186 } 1187 prev = v; 1188 v = vNext; 1189 if (v == contours[i]) break; 1190 } 1191 } 1192 if (prev) { 1193 prev->fNext = mesh->fHead->fPrev = nullptr; 1194 } 1195 mesh->fTail = prev; 1196} 1197 1198// Stage 3: sort the vertices by increasing sweep direction. 1199 1200template <CompareFunc sweep_lt> 1201void merge_sort(VertexList* vertices) { 1202 Vertex* slow = vertices->fHead; 1203 if (!slow) { 1204 return; 1205 } 1206 Vertex* fast = slow->fNext; 1207 if (!fast) { 1208 return; 1209 } 1210 do { 1211 fast = fast->fNext; 1212 if (fast) { 1213 fast = fast->fNext; 1214 slow = slow->fNext; 1215 } 1216 } while (fast); 1217 VertexList front(vertices->fHead, slow); 1218 VertexList back(slow->fNext, vertices->fTail); 1219 front.fTail->fNext = back.fHead->fPrev = nullptr; 1220 1221 merge_sort<sweep_lt>(&front); 1222 merge_sort<sweep_lt>(&back); 1223 1224 vertices->fHead = vertices->fTail = nullptr; 1225 Vertex* a = front.fHead; 1226 Vertex* b = back.fHead; 1227 while (a && b) { 1228 if (sweep_lt(a->fPoint, b->fPoint)) { 1229 Vertex* next = a->fNext; 1230 vertices->append(a); 1231 a = next; 1232 } else { 1233 Vertex* next = b->fNext; 1234 vertices->append(b); 1235 b = next; 1236 } 1237 } 1238 if (a) { 1239 vertices->insert(a, vertices->fTail, a->fNext); 1240 } 1241 if (b) { 1242 vertices->insert(b, vertices->fTail, b->fNext); 1243 } 1244} 1245 1246// Stage 4: Simplify the mesh by inserting new vertices at intersecting edges. 1247 1248void simplify(const VertexList& vertices, Comparator& c, SkArenaAlloc& alloc) { 1249 LOG("simplifying complex polygons\n"); 1250 EdgeList activeEdges; 1251 for (Vertex* v = vertices.fHead; v != nullptr; v = v->fNext) { 1252 if (!v->fFirstEdgeAbove && !v->fFirstEdgeBelow) { 1253 continue; 1254 } 1255#if LOGGING_ENABLED 1256 LOG("\nvertex %g: (%g,%g), alpha %d\n", v->fID, v->fPoint.fX, v->fPoint.fY, v->fAlpha); 1257#endif 1258 Edge* leftEnclosingEdge; 1259 Edge* rightEnclosingEdge; 1260 bool restartChecks; 1261 do { 1262 restartChecks = false; 1263 find_enclosing_edges(v, &activeEdges, &leftEnclosingEdge, &rightEnclosingEdge); 1264 if (v->fFirstEdgeBelow) { 1265 for (Edge* edge = v->fFirstEdgeBelow; edge; edge = edge->fNextEdgeBelow) { 1266 if (check_for_intersection(edge, leftEnclosingEdge, &activeEdges, c, alloc)) { 1267 restartChecks = true; 1268 break; 1269 } 1270 if (check_for_intersection(edge, rightEnclosingEdge, &activeEdges, c, alloc)) { 1271 restartChecks = true; 1272 break; 1273 } 1274 } 1275 } else { 1276 if (Vertex* pv = check_for_intersection(leftEnclosingEdge, rightEnclosingEdge, 1277 &activeEdges, c, alloc)) { 1278 if (c.sweep_lt(pv->fPoint, v->fPoint)) { 1279 v = pv; 1280 } 1281 restartChecks = true; 1282 } 1283 1284 } 1285 } while (restartChecks); 1286 if (v->fAlpha == 0) { 1287 if ((leftEnclosingEdge && leftEnclosingEdge->fWinding < 0) && 1288 (rightEnclosingEdge && rightEnclosingEdge->fWinding > 0)) { 1289 v->fAlpha = max_edge_alpha(leftEnclosingEdge, rightEnclosingEdge); 1290 } 1291 } 1292 for (Edge* e = v->fFirstEdgeAbove; e; e = e->fNextEdgeAbove) { 1293 remove_edge(e, &activeEdges); 1294 } 1295 Edge* leftEdge = leftEnclosingEdge; 1296 for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { 1297 insert_edge(e, leftEdge, &activeEdges); 1298 leftEdge = e; 1299 } 1300 v->fProcessed = true; 1301 } 1302} 1303 1304// Stage 5: Tessellate the simplified mesh into monotone polygons. 1305 1306Poly* tessellate(const VertexList& vertices, SkArenaAlloc& alloc) { 1307 LOG("tessellating simple polygons\n"); 1308 EdgeList activeEdges; 1309 Poly* polys = nullptr; 1310 for (Vertex* v = vertices.fHead; v != nullptr; v = v->fNext) { 1311 if (!v->fFirstEdgeAbove && !v->fFirstEdgeBelow) { 1312 continue; 1313 } 1314#if LOGGING_ENABLED 1315 LOG("\nvertex %g: (%g,%g), alpha %d\n", v->fID, v->fPoint.fX, v->fPoint.fY, v->fAlpha); 1316#endif 1317 Edge* leftEnclosingEdge; 1318 Edge* rightEnclosingEdge; 1319 find_enclosing_edges(v, &activeEdges, &leftEnclosingEdge, &rightEnclosingEdge); 1320 Poly* leftPoly; 1321 Poly* rightPoly; 1322 if (v->fFirstEdgeAbove) { 1323 leftPoly = v->fFirstEdgeAbove->fLeftPoly; 1324 rightPoly = v->fLastEdgeAbove->fRightPoly; 1325 } else { 1326 leftPoly = leftEnclosingEdge ? leftEnclosingEdge->fRightPoly : nullptr; 1327 rightPoly = rightEnclosingEdge ? rightEnclosingEdge->fLeftPoly : nullptr; 1328 } 1329#if LOGGING_ENABLED 1330 LOG("edges above:\n"); 1331 for (Edge* e = v->fFirstEdgeAbove; e; e = e->fNextEdgeAbove) { 1332 LOG("%g -> %g, lpoly %d, rpoly %d\n", e->fTop->fID, e->fBottom->fID, 1333 e->fLeftPoly ? e->fLeftPoly->fID : -1, e->fRightPoly ? e->fRightPoly->fID : -1); 1334 } 1335 LOG("edges below:\n"); 1336 for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { 1337 LOG("%g -> %g, lpoly %d, rpoly %d\n", e->fTop->fID, e->fBottom->fID, 1338 e->fLeftPoly ? e->fLeftPoly->fID : -1, e->fRightPoly ? e->fRightPoly->fID : -1); 1339 } 1340#endif 1341 if (v->fFirstEdgeAbove) { 1342 if (leftPoly) { 1343 leftPoly = leftPoly->addEdge(v->fFirstEdgeAbove, Poly::kRight_Side, alloc); 1344 } 1345 if (rightPoly) { 1346 rightPoly = rightPoly->addEdge(v->fLastEdgeAbove, Poly::kLeft_Side, alloc); 1347 } 1348 for (Edge* e = v->fFirstEdgeAbove; e != v->fLastEdgeAbove; e = e->fNextEdgeAbove) { 1349 Edge* rightEdge = e->fNextEdgeAbove; 1350 SkASSERT(rightEdge->isRightOf(e->fTop)); 1351 remove_edge(e, &activeEdges); 1352 if (e->fRightPoly) { 1353 e->fRightPoly->addEdge(e, Poly::kLeft_Side, alloc); 1354 } 1355 if (rightEdge->fLeftPoly && rightEdge->fLeftPoly != e->fRightPoly) { 1356 rightEdge->fLeftPoly->addEdge(e, Poly::kRight_Side, alloc); 1357 } 1358 } 1359 remove_edge(v->fLastEdgeAbove, &activeEdges); 1360 if (!v->fFirstEdgeBelow) { 1361 if (leftPoly && rightPoly && leftPoly != rightPoly) { 1362 SkASSERT(leftPoly->fPartner == nullptr && rightPoly->fPartner == nullptr); 1363 rightPoly->fPartner = leftPoly; 1364 leftPoly->fPartner = rightPoly; 1365 } 1366 } 1367 } 1368 if (v->fFirstEdgeBelow) { 1369 if (!v->fFirstEdgeAbove) { 1370 if (leftPoly && rightPoly) { 1371 if (leftPoly == rightPoly) { 1372 if (leftPoly->fTail && leftPoly->fTail->fSide == Poly::kLeft_Side) { 1373 leftPoly = new_poly(&polys, leftPoly->lastVertex(), 1374 leftPoly->fWinding, alloc); 1375 leftEnclosingEdge->fRightPoly = leftPoly; 1376 } else { 1377 rightPoly = new_poly(&polys, rightPoly->lastVertex(), 1378 rightPoly->fWinding, alloc); 1379 rightEnclosingEdge->fLeftPoly = rightPoly; 1380 } 1381 } 1382 Edge* join = alloc.make<Edge>(leftPoly->lastVertex(), v, 1, Edge::Type::kInner); 1383 leftPoly = leftPoly->addEdge(join, Poly::kRight_Side, alloc); 1384 rightPoly = rightPoly->addEdge(join, Poly::kLeft_Side, alloc); 1385 } 1386 } 1387 Edge* leftEdge = v->fFirstEdgeBelow; 1388 leftEdge->fLeftPoly = leftPoly; 1389 insert_edge(leftEdge, leftEnclosingEdge, &activeEdges); 1390 for (Edge* rightEdge = leftEdge->fNextEdgeBelow; rightEdge; 1391 rightEdge = rightEdge->fNextEdgeBelow) { 1392 insert_edge(rightEdge, leftEdge, &activeEdges); 1393 int winding = leftEdge->fLeftPoly ? leftEdge->fLeftPoly->fWinding : 0; 1394 winding += leftEdge->fWinding; 1395 if (winding != 0) { 1396 Poly* poly = new_poly(&polys, v, winding, alloc); 1397 leftEdge->fRightPoly = rightEdge->fLeftPoly = poly; 1398 } 1399 leftEdge = rightEdge; 1400 } 1401 v->fLastEdgeBelow->fRightPoly = rightPoly; 1402 } 1403#if LOGGING_ENABLED 1404 LOG("\nactive edges:\n"); 1405 for (Edge* e = activeEdges.fHead; e != nullptr; e = e->fRight) { 1406 LOG("%g -> %g, lpoly %d, rpoly %d\n", e->fTop->fID, e->fBottom->fID, 1407 e->fLeftPoly ? e->fLeftPoly->fID : -1, e->fRightPoly ? e->fRightPoly->fID : -1); 1408 } 1409#endif 1410 } 1411 return polys; 1412} 1413 1414void remove_non_boundary_edges(const VertexList& mesh, SkPath::FillType fillType, 1415 SkArenaAlloc& alloc) { 1416 LOG("removing non-boundary edges\n"); 1417 EdgeList activeEdges; 1418 for (Vertex* v = mesh.fHead; v != nullptr; v = v->fNext) { 1419 if (!v->fFirstEdgeAbove && !v->fFirstEdgeBelow) { 1420 continue; 1421 } 1422 Edge* leftEnclosingEdge; 1423 Edge* rightEnclosingEdge; 1424 find_enclosing_edges(v, &activeEdges, &leftEnclosingEdge, &rightEnclosingEdge); 1425 bool prevFilled = leftEnclosingEdge && 1426 apply_fill_type(fillType, leftEnclosingEdge->fWinding); 1427 for (Edge* e = v->fFirstEdgeAbove; e;) { 1428 Edge* next = e->fNextEdgeAbove; 1429 remove_edge(e, &activeEdges); 1430 bool filled = apply_fill_type(fillType, e->fWinding); 1431 if (filled == prevFilled) { 1432 disconnect(e); 1433 } 1434 prevFilled = filled; 1435 e = next; 1436 } 1437 Edge* prev = leftEnclosingEdge; 1438 for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { 1439 if (prev) { 1440 e->fWinding += prev->fWinding; 1441 } 1442 insert_edge(e, prev, &activeEdges); 1443 prev = e; 1444 } 1445 } 1446} 1447 1448// Note: this is the normal to the edge, but not necessarily unit length. 1449void get_edge_normal(const Edge* e, SkVector* normal) { 1450 normal->set(SkDoubleToScalar(e->fLine.fA) * e->fWinding, 1451 SkDoubleToScalar(e->fLine.fB) * e->fWinding); 1452} 1453 1454// Stage 5c: detect and remove "pointy" vertices whose edge normals point in opposite directions 1455// and whose adjacent vertices are less than a quarter pixel from an edge. These are guaranteed to 1456// invert on stroking. 1457 1458void simplify_boundary(EdgeList* boundary, Comparator& c, SkArenaAlloc& alloc) { 1459 Edge* prevEdge = boundary->fTail; 1460 SkVector prevNormal; 1461 get_edge_normal(prevEdge, &prevNormal); 1462 for (Edge* e = boundary->fHead; e != nullptr;) { 1463 Vertex* prev = prevEdge->fWinding == 1 ? prevEdge->fTop : prevEdge->fBottom; 1464 Vertex* next = e->fWinding == 1 ? e->fBottom : e->fTop; 1465 double dist = e->dist(prev->fPoint); 1466 SkVector normal; 1467 get_edge_normal(e, &normal); 1468 double denom = 0.0625f * e->fLine.magSq(); 1469 if (prevNormal.dot(normal) < 0.0 && (dist * dist) <= denom) { 1470 Edge* join = new_edge(prev, next, Edge::Type::kInner, c, alloc); 1471 insert_edge(join, e, boundary); 1472 remove_edge(prevEdge, boundary); 1473 remove_edge(e, boundary); 1474 if (join->fLeft && join->fRight) { 1475 prevEdge = join->fLeft; 1476 e = join; 1477 } else { 1478 prevEdge = boundary->fTail; 1479 e = boundary->fHead; // join->fLeft ? join->fLeft : join; 1480 } 1481 get_edge_normal(prevEdge, &prevNormal); 1482 } else { 1483 prevEdge = e; 1484 prevNormal = normal; 1485 e = e->fRight; 1486 } 1487 } 1488} 1489 1490void fix_inversions(Vertex* prev, Vertex* next, Edge* prevBisector, Edge* nextBisector, 1491 Edge* prevEdge, Comparator& c) { 1492 if (!prev || !next) { 1493 return; 1494 } 1495 int winding = c.sweep_lt(prev->fPoint, next->fPoint) ? 1 : -1; 1496 SkPoint p; 1497 uint8_t alpha; 1498 if (winding != prevEdge->fWinding && prevBisector->intersect(*nextBisector, &p, &alpha)) { 1499 prev->fPoint = next->fPoint = p; 1500 prev->fAlpha = next->fAlpha = alpha; 1501 } 1502} 1503 1504// Stage 5d: Displace edges by half a pixel inward and outward along their normals. Intersect to 1505// find new vertices, and set zero alpha on the exterior and one alpha on the interior. Build a 1506// new antialiased mesh from those vertices. 1507 1508void boundary_to_aa_mesh(EdgeList* boundary, VertexList* mesh, Comparator& c, SkArenaAlloc& alloc) { 1509 // A boundary with fewer than 3 edges is degenerate. 1510 if (!boundary->fHead || !boundary->fHead->fRight || !boundary->fHead->fRight->fRight) { 1511 return; 1512 } 1513 Edge* prevEdge = boundary->fTail; 1514 float radius = 0.5f; 1515 double offset = radius * sqrt(prevEdge->fLine.magSq()) * prevEdge->fWinding; 1516 Line prevInner(prevEdge->fLine); 1517 prevInner.fC -= offset; 1518 Line prevOuter(prevEdge->fLine); 1519 prevOuter.fC += offset; 1520 VertexList innerVertices; 1521 VertexList outerVertices; 1522 Edge* prevBisector = nullptr; 1523 for (Edge* e = boundary->fHead; e != nullptr; e = e->fRight) { 1524 double offset = radius * sqrt(e->fLine.magSq()) * e->fWinding; 1525 Line inner(e->fLine); 1526 inner.fC -= offset; 1527 Line outer(e->fLine); 1528 outer.fC += offset; 1529 SkPoint innerPoint, outerPoint; 1530 if (prevInner.intersect(inner, &innerPoint) && 1531 prevOuter.intersect(outer, &outerPoint)) { 1532 Vertex* innerVertex = alloc.make<Vertex>(innerPoint, 255); 1533 Vertex* outerVertex = alloc.make<Vertex>(outerPoint, 0); 1534 Edge* bisector = new_edge(outerVertex, innerVertex, Edge::Type::kConnector, c, alloc); 1535 fix_inversions(innerVertices.fTail, innerVertex, prevBisector, bisector, prevEdge, c); 1536 fix_inversions(outerVertices.fTail, outerVertex, prevBisector, bisector, prevEdge, c); 1537 innerVertices.append(innerVertex); 1538 outerVertices.append(outerVertex); 1539 prevBisector = bisector; 1540 } 1541 prevInner = inner; 1542 prevOuter = outer; 1543 prevEdge = e; 1544 } 1545 innerVertices.close(); 1546 outerVertices.close(); 1547 1548 Vertex* innerVertex = innerVertices.fHead; 1549 Vertex* outerVertex = outerVertices.fHead; 1550 if (!innerVertex || !outerVertex) { 1551 return; 1552 } 1553 Edge* bisector = new_edge(outerVertices.fHead, innerVertices.fHead, Edge::Type::kConnector, c, 1554 alloc); 1555 fix_inversions(innerVertices.fTail, innerVertices.fHead, prevBisector, bisector, prevEdge, c); 1556 fix_inversions(outerVertices.fTail, outerVertices.fHead, prevBisector, bisector, prevEdge, c); 1557 do { 1558 // Connect vertices into a quad mesh. Outer edges get default (1) winding. 1559 // Inner edges get -2 winding. This ensures that the interior is always filled 1560 // (-1 winding number for normal cases, 3 for thin features where the interior inverts). 1561 // Connector edges get zero winding, since they're only structural (i.e., to ensure 1562 // no 0-0-0 alpha triangles are produced), and shouldn't affect the poly winding number. 1563 connect(outerVertex->fPrev, outerVertex, Edge::Type::kOuter, c, alloc); 1564 connect(innerVertex->fPrev, innerVertex, Edge::Type::kInner, c, alloc, -2); 1565 connect(outerVertex, innerVertex, Edge::Type::kConnector, c, alloc, 0); 1566 Vertex* innerNext = innerVertex->fNext; 1567 Vertex* outerNext = outerVertex->fNext; 1568 mesh->append(innerVertex); 1569 mesh->append(outerVertex); 1570 innerVertex = innerNext; 1571 outerVertex = outerNext; 1572 } while (innerVertex != innerVertices.fHead && outerVertex != outerVertices.fHead); 1573} 1574 1575void extract_boundary(EdgeList* boundary, Edge* e, SkPath::FillType fillType, SkArenaAlloc& alloc) { 1576 bool down = apply_fill_type(fillType, e->fWinding); 1577 while (e) { 1578 e->fWinding = down ? 1 : -1; 1579 Edge* next; 1580 boundary->append(e); 1581 if (down) { 1582 // Find outgoing edge, in clockwise order. 1583 if ((next = e->fNextEdgeAbove)) { 1584 down = false; 1585 } else if ((next = e->fBottom->fLastEdgeBelow)) { 1586 down = true; 1587 } else if ((next = e->fPrevEdgeAbove)) { 1588 down = false; 1589 } 1590 } else { 1591 // Find outgoing edge, in counter-clockwise order. 1592 if ((next = e->fPrevEdgeBelow)) { 1593 down = true; 1594 } else if ((next = e->fTop->fFirstEdgeAbove)) { 1595 down = false; 1596 } else if ((next = e->fNextEdgeBelow)) { 1597 down = true; 1598 } 1599 } 1600 disconnect(e); 1601 e = next; 1602 } 1603} 1604 1605// Stage 5b: Extract boundaries from mesh, simplify and stroke them into a new mesh. 1606 1607void extract_boundaries(const VertexList& inMesh, VertexList* outMesh, SkPath::FillType fillType, 1608 Comparator& c, SkArenaAlloc& alloc) { 1609 remove_non_boundary_edges(inMesh, fillType, alloc); 1610 for (Vertex* v = inMesh.fHead; v; v = v->fNext) { 1611 while (v->fFirstEdgeBelow) { 1612 EdgeList boundary; 1613 extract_boundary(&boundary, v->fFirstEdgeBelow, fillType, alloc); 1614 simplify_boundary(&boundary, c, alloc); 1615 boundary_to_aa_mesh(&boundary, outMesh, c, alloc); 1616 } 1617 } 1618} 1619 1620// This is a driver function which calls stages 2-5 in turn. 1621 1622void contours_to_mesh(Vertex** contours, int contourCnt, bool antialias, 1623 VertexList* mesh, Comparator& c, SkArenaAlloc& alloc) { 1624#if LOGGING_ENABLED 1625 for (int i = 0; i < contourCnt; ++i) { 1626 Vertex* v = contours[i]; 1627 SkASSERT(v); 1628 LOG("path.moveTo(%20.20g, %20.20g);\n", v->fPoint.fX, v->fPoint.fY); 1629 for (v = v->fNext; v != contours[i]; v = v->fNext) { 1630 LOG("path.lineTo(%20.20g, %20.20g);\n", v->fPoint.fX, v->fPoint.fY); 1631 } 1632 } 1633#endif 1634 sanitize_contours(contours, contourCnt, antialias); 1635 build_edges(contours, contourCnt, mesh, c, alloc); 1636} 1637 1638void sort_and_simplify(VertexList* vertices, Comparator& c, SkArenaAlloc& alloc) { 1639 if (!vertices || !vertices->fHead) { 1640 return; 1641 } 1642 1643 // Sort vertices in Y (secondarily in X). 1644 if (c.fDirection == Comparator::Direction::kHorizontal) { 1645 merge_sort<sweep_lt_horiz>(vertices); 1646 } else { 1647 merge_sort<sweep_lt_vert>(vertices); 1648 } 1649 merge_coincident_vertices(vertices, c, alloc); 1650#if LOGGING_ENABLED 1651 for (Vertex* v = vertices->fHead; v != nullptr; v = v->fNext) { 1652 static float gID = 0.0f; 1653 v->fID = gID++; 1654 } 1655#endif 1656 simplify(*vertices, c, alloc); 1657} 1658 1659Poly* contours_to_polys(Vertex** contours, int contourCnt, SkPath::FillType fillType, 1660 const SkRect& pathBounds, bool antialias, 1661 SkArenaAlloc& alloc) { 1662 Comparator c(pathBounds.width() > pathBounds.height() ? Comparator::Direction::kHorizontal 1663 : Comparator::Direction::kVertical); 1664 VertexList mesh; 1665 contours_to_mesh(contours, contourCnt, antialias, &mesh, c, alloc); 1666 sort_and_simplify(&mesh, c, alloc); 1667 if (antialias) { 1668 VertexList aaMesh; 1669 extract_boundaries(mesh, &aaMesh, fillType, c, alloc); 1670 sort_and_simplify(&aaMesh, c, alloc); 1671 return tessellate(aaMesh, alloc); 1672 } else { 1673 return tessellate(mesh, alloc); 1674 } 1675} 1676 1677// Stage 6: Triangulate the monotone polygons into a vertex buffer. 1678void* polys_to_triangles(Poly* polys, SkPath::FillType fillType, const AAParams* aaParams, 1679 void* data) { 1680 for (Poly* poly = polys; poly; poly = poly->fNext) { 1681 if (apply_fill_type(fillType, poly)) { 1682 data = poly->emit(aaParams, data); 1683 } 1684 } 1685 return data; 1686} 1687 1688Poly* path_to_polys(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 1689 int contourCnt, SkArenaAlloc& alloc, bool antialias, bool* isLinear) { 1690 SkPath::FillType fillType = path.getFillType(); 1691 if (SkPath::IsInverseFillType(fillType)) { 1692 contourCnt++; 1693 } 1694 std::unique_ptr<Vertex*[]> contours(new Vertex* [contourCnt]); 1695 1696 path_to_contours(path, tolerance, clipBounds, contours.get(), alloc, isLinear); 1697 return contours_to_polys(contours.get(), contourCnt, path.getFillType(), path.getBounds(), 1698 antialias, alloc); 1699} 1700 1701int get_contour_count(const SkPath& path, SkScalar tolerance) { 1702 int contourCnt; 1703 int maxPts = GrPathUtils::worstCasePointCount(path, &contourCnt, tolerance); 1704 if (maxPts <= 0) { 1705 return 0; 1706 } 1707 if (maxPts > ((int)SK_MaxU16 + 1)) { 1708 SkDebugf("Path not rendered, too many verts (%d)\n", maxPts); 1709 return 0; 1710 } 1711 return contourCnt; 1712} 1713 1714int count_points(Poly* polys, SkPath::FillType fillType) { 1715 int count = 0; 1716 for (Poly* poly = polys; poly; poly = poly->fNext) { 1717 if (apply_fill_type(fillType, poly) && poly->fCount >= 3) { 1718 count += (poly->fCount - 2) * (TESSELLATOR_WIREFRAME ? 6 : 3); 1719 } 1720 } 1721 return count; 1722} 1723 1724} // namespace 1725 1726namespace GrTessellator { 1727 1728// Stage 6: Triangulate the monotone polygons into a vertex buffer. 1729 1730int PathToTriangles(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 1731 VertexAllocator* vertexAllocator, bool antialias, const GrColor& color, 1732 bool canTweakAlphaForCoverage, bool* isLinear) { 1733 int contourCnt = get_contour_count(path, tolerance); 1734 if (contourCnt <= 0) { 1735 *isLinear = true; 1736 return 0; 1737 } 1738 SkArenaAlloc alloc(kArenaChunkSize); 1739 Poly* polys = path_to_polys(path, tolerance, clipBounds, contourCnt, alloc, antialias, 1740 isLinear); 1741 SkPath::FillType fillType = antialias ? SkPath::kWinding_FillType : path.getFillType(); 1742 int count = count_points(polys, fillType); 1743 if (0 == count) { 1744 return 0; 1745 } 1746 1747 void* verts = vertexAllocator->lock(count); 1748 if (!verts) { 1749 SkDebugf("Could not allocate vertices\n"); 1750 return 0; 1751 } 1752 1753 LOG("emitting %d verts\n", count); 1754 AAParams aaParams; 1755 aaParams.fTweakAlpha = canTweakAlphaForCoverage; 1756 aaParams.fColor = color; 1757 1758 void* end = polys_to_triangles(polys, fillType, antialias ? &aaParams : nullptr, verts); 1759 int actualCount = static_cast<int>((static_cast<uint8_t*>(end) - static_cast<uint8_t*>(verts)) 1760 / vertexAllocator->stride()); 1761 SkASSERT(actualCount <= count); 1762 vertexAllocator->unlock(actualCount); 1763 return actualCount; 1764} 1765 1766int PathToVertices(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 1767 GrTessellator::WindingVertex** verts) { 1768 int contourCnt = get_contour_count(path, tolerance); 1769 if (contourCnt <= 0) { 1770 return 0; 1771 } 1772 SkArenaAlloc alloc(kArenaChunkSize); 1773 bool isLinear; 1774 Poly* polys = path_to_polys(path, tolerance, clipBounds, contourCnt, alloc, false, &isLinear); 1775 SkPath::FillType fillType = path.getFillType(); 1776 int count = count_points(polys, fillType); 1777 if (0 == count) { 1778 *verts = nullptr; 1779 return 0; 1780 } 1781 1782 *verts = new GrTessellator::WindingVertex[count]; 1783 GrTessellator::WindingVertex* vertsEnd = *verts; 1784 SkPoint* points = new SkPoint[count]; 1785 SkPoint* pointsEnd = points; 1786 for (Poly* poly = polys; poly; poly = poly->fNext) { 1787 if (apply_fill_type(fillType, poly)) { 1788 SkPoint* start = pointsEnd; 1789 pointsEnd = static_cast<SkPoint*>(poly->emit(nullptr, pointsEnd)); 1790 while (start != pointsEnd) { 1791 vertsEnd->fPos = *start; 1792 vertsEnd->fWinding = poly->fWinding; 1793 ++start; 1794 ++vertsEnd; 1795 } 1796 } 1797 } 1798 int actualCount = static_cast<int>(vertsEnd - *verts); 1799 SkASSERT(actualCount <= count); 1800 SkASSERT(pointsEnd - points == actualCount); 1801 delete[] points; 1802 return actualCount; 1803} 1804 1805} // namespace 1806