caryclark | 624637c | 2015-05-11 07:21:27 -0700 | [diff] [blame] | 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 | // given a prospective edge, compute its initial winding by projecting a ray |
| 9 | // if the ray hits another edge |
| 10 | // if the edge doesn't have a winding yet, hop up to that edge and start over |
| 11 | // concern : check for hops forming a loop |
| 12 | // if the edge is unsortable, or |
| 13 | // the intersection is nearly at the ends, or |
| 14 | // the tangent at the intersection is nearly coincident to the ray, |
| 15 | // choose a different ray and try again |
| 16 | // concern : if it is unable to succeed after N tries, try another edge? direction? |
| 17 | // if no edge is hit, compute the winding directly |
| 18 | |
| 19 | // given the top span, project the most perpendicular ray and look for intersections |
| 20 | // let's try up and then down. What the hey |
| 21 | |
| 22 | // bestXY is initialized by caller with basePt |
| 23 | |
| 24 | #include "SkOpContour.h" |
| 25 | #include "SkOpSegment.h" |
| 26 | #include "SkPathOpsCurve.h" |
| 27 | |
| 28 | enum class SkOpRayDir { |
| 29 | kLeft, |
| 30 | kTop, |
| 31 | kRight, |
| 32 | kBottom, |
| 33 | }; |
| 34 | |
| 35 | #if DEBUG_WINDING |
| 36 | const char* gDebugRayDirName[] = { |
| 37 | "kLeft", |
| 38 | "kTop", |
| 39 | "kRight", |
| 40 | "kBottom" |
| 41 | }; |
| 42 | #endif |
| 43 | |
| 44 | static int xy_index(SkOpRayDir dir) { |
| 45 | return static_cast<int>(dir) & 1; |
| 46 | } |
| 47 | |
| 48 | static SkScalar pt_xy(const SkPoint& pt, SkOpRayDir dir) { |
| 49 | return (&pt.fX)[xy_index(dir)]; |
| 50 | } |
| 51 | |
| 52 | static SkScalar pt_yx(const SkPoint& pt, SkOpRayDir dir) { |
| 53 | return (&pt.fX)[!xy_index(dir)]; |
| 54 | } |
| 55 | |
| 56 | static double pt_dxdy(const SkDVector& v, SkOpRayDir dir) { |
| 57 | return (&v.fX)[xy_index(dir)]; |
| 58 | } |
| 59 | |
| 60 | static double pt_dydx(const SkDVector& v, SkOpRayDir dir) { |
| 61 | return (&v.fX)[!xy_index(dir)]; |
| 62 | } |
| 63 | |
| 64 | static SkScalar rect_side(const SkRect& r, SkOpRayDir dir) { |
| 65 | return (&r.fLeft)[static_cast<int>(dir)]; |
| 66 | } |
| 67 | |
| 68 | static bool sideways_overlap(const SkRect& rect, const SkPoint& pt, SkOpRayDir dir) { |
| 69 | int i = !xy_index(dir); |
| 70 | return approximately_between((&rect.fLeft)[i], (&pt.fX)[i], (&rect.fRight)[i]); |
| 71 | } |
| 72 | |
| 73 | static bool less_than(SkOpRayDir dir) { |
| 74 | return static_cast<bool>((static_cast<int>(dir) & 2) == 0); |
| 75 | } |
| 76 | |
| 77 | static bool ccw_dxdy(const SkDVector& v, SkOpRayDir dir) { |
| 78 | bool vPartPos = pt_dydx(v, dir) > 0; |
| 79 | bool leftBottom = ((static_cast<int>(dir) + 1) & 2) != 0; |
| 80 | return vPartPos == leftBottom; |
| 81 | } |
| 82 | |
| 83 | struct SkOpRayHit { |
| 84 | SkOpRayDir makeTestBase(SkOpSpan* span, double t) { |
halcanary | 96fcdcc | 2015-08-27 07:41:13 -0700 | [diff] [blame] | 85 | fNext = nullptr; |
caryclark | 624637c | 2015-05-11 07:21:27 -0700 | [diff] [blame] | 86 | fSpan = span; |
| 87 | fT = span->t() * (1 - t) + span->next()->t() * t; |
| 88 | SkOpSegment* segment = span->segment(); |
| 89 | fSlope = segment->dSlopeAtT(fT); |
| 90 | fPt = segment->ptAtT(fT); |
| 91 | fValid = true; |
| 92 | return fabs(fSlope.fX) < fabs(fSlope.fY) ? SkOpRayDir::kLeft : SkOpRayDir::kTop; |
| 93 | } |
| 94 | |
| 95 | SkOpRayHit* fNext; |
| 96 | SkOpSpan* fSpan; |
| 97 | SkPoint fPt; |
| 98 | double fT; |
| 99 | SkDVector fSlope; |
| 100 | bool fValid; |
| 101 | }; |
| 102 | |
| 103 | void SkOpContour::rayCheck(const SkOpRayHit& base, SkOpRayDir dir, SkOpRayHit** hits, |
| 104 | SkChunkAlloc* allocator) { |
| 105 | // if the bounds extreme is outside the best, we're done |
| 106 | SkScalar baseXY = pt_xy(base.fPt, dir); |
| 107 | SkScalar boundsXY = rect_side(fBounds, dir); |
| 108 | bool checkLessThan = less_than(dir); |
| 109 | if (!approximately_equal(baseXY, boundsXY) && (baseXY < boundsXY) == checkLessThan) { |
| 110 | return; |
| 111 | } |
| 112 | SkOpSegment* testSegment = &fHead; |
| 113 | do { |
| 114 | testSegment->rayCheck(base, dir, hits, allocator); |
| 115 | } while ((testSegment = testSegment->next())); |
| 116 | } |
| 117 | |
| 118 | void SkOpSegment::rayCheck(const SkOpRayHit& base, SkOpRayDir dir, SkOpRayHit** hits, |
| 119 | SkChunkAlloc* allocator) { |
| 120 | if (!sideways_overlap(fBounds, base.fPt, dir)) { |
| 121 | return; |
| 122 | } |
| 123 | SkScalar baseXY = pt_xy(base.fPt, dir); |
| 124 | SkScalar boundsXY = rect_side(fBounds, dir); |
| 125 | bool checkLessThan = less_than(dir); |
| 126 | if (!approximately_equal(baseXY, boundsXY) && (baseXY < boundsXY) == checkLessThan) { |
| 127 | return; |
| 128 | } |
| 129 | double tVals[3]; |
| 130 | SkScalar baseYX = pt_yx(base.fPt, dir); |
| 131 | int roots = (*CurveIntercept[fVerb * 2 + xy_index(dir)])(fPts, fWeight, baseYX, tVals); |
| 132 | for (int index = 0; index < roots; ++index) { |
| 133 | double t = tVals[index]; |
| 134 | if (base.fSpan->segment() == this && approximately_equal(base.fT, t)) { |
| 135 | continue; |
| 136 | } |
| 137 | SkDVector slope; |
| 138 | SkPoint pt; |
| 139 | SkDEBUGCODE(sk_bzero(&slope, sizeof(slope))); |
| 140 | bool valid = false; |
| 141 | if (approximately_zero(t)) { |
| 142 | pt = fPts[0]; |
| 143 | } else if (approximately_equal(t, 1)) { |
| 144 | pt = fPts[SkPathOpsVerbToPoints(fVerb)]; |
| 145 | } else { |
| 146 | SkASSERT(between(0, t, 1)); |
| 147 | pt = this->ptAtT(t); |
| 148 | if (SkDPoint::ApproximatelyEqual(pt, base.fPt)) { |
| 149 | if (base.fSpan->segment() == this) { |
| 150 | continue; |
| 151 | } |
| 152 | } else { |
| 153 | SkScalar ptXY = pt_xy(pt, dir); |
| 154 | if (!approximately_equal(baseXY, ptXY) && (baseXY < ptXY) == checkLessThan) { |
| 155 | continue; |
| 156 | } |
| 157 | slope = this->dSlopeAtT(t); |
| 158 | if (fVerb == SkPath::kCubic_Verb && base.fSpan->segment() == this |
| 159 | && roughly_equal(base.fT, t) |
| 160 | && SkDPoint::RoughlyEqual(pt, base.fPt)) { |
| 161 | #if DEBUG_WINDING |
| 162 | SkDebugf("%s (rarely expect this)\n", __FUNCTION__); |
| 163 | #endif |
| 164 | continue; |
| 165 | } |
| 166 | if (fabs(pt_dydx(slope, dir) * 10000) > fabs(pt_dxdy(slope, dir))) { |
| 167 | valid = true; |
| 168 | } |
| 169 | } |
| 170 | } |
| 171 | SkOpSpan* span = this->windingSpanAtT(t); |
| 172 | if (!span) { |
| 173 | valid = false; |
| 174 | } else if (!span->windValue() && !span->oppValue()) { |
| 175 | continue; |
| 176 | } |
| 177 | SkOpRayHit* newHit = SkOpTAllocator<SkOpRayHit>::Allocate(allocator); |
| 178 | newHit->fNext = *hits; |
| 179 | newHit->fPt = pt; |
| 180 | newHit->fSlope = slope; |
| 181 | newHit->fSpan = span; |
| 182 | newHit->fT = t; |
| 183 | newHit->fValid = valid; |
| 184 | *hits = newHit; |
| 185 | } |
| 186 | } |
| 187 | |
| 188 | SkOpSpan* SkOpSegment::windingSpanAtT(double tHit) { |
| 189 | SkOpSpan* span = &fHead; |
| 190 | SkOpSpanBase* next; |
| 191 | do { |
| 192 | next = span->next(); |
| 193 | if (approximately_equal(tHit, next->t())) { |
halcanary | 96fcdcc | 2015-08-27 07:41:13 -0700 | [diff] [blame] | 194 | return nullptr; |
caryclark | 624637c | 2015-05-11 07:21:27 -0700 | [diff] [blame] | 195 | } |
| 196 | if (tHit < next->t()) { |
| 197 | return span; |
| 198 | } |
| 199 | } while (!next->final() && (span = next->upCast())); |
halcanary | 96fcdcc | 2015-08-27 07:41:13 -0700 | [diff] [blame] | 200 | return nullptr; |
caryclark | 624637c | 2015-05-11 07:21:27 -0700 | [diff] [blame] | 201 | } |
| 202 | |
| 203 | static bool hit_compare_x(const SkOpRayHit* a, const SkOpRayHit* b) { |
| 204 | return a->fPt.fX < b->fPt.fX; |
| 205 | } |
| 206 | |
| 207 | static bool reverse_hit_compare_x(const SkOpRayHit* a, const SkOpRayHit* b) { |
| 208 | return b->fPt.fX < a->fPt.fX; |
| 209 | } |
| 210 | |
| 211 | static bool hit_compare_y(const SkOpRayHit* a, const SkOpRayHit* b) { |
| 212 | return a->fPt.fY < b->fPt.fY; |
| 213 | } |
| 214 | |
| 215 | static bool reverse_hit_compare_y(const SkOpRayHit* a, const SkOpRayHit* b) { |
| 216 | return b->fPt.fY < a->fPt.fY; |
| 217 | } |
| 218 | |
| 219 | static double get_t_guess(int tTry, int* dirOffset) { |
| 220 | double t = 0.5; |
| 221 | *dirOffset = tTry & 1; |
| 222 | int tBase = tTry >> 1; |
| 223 | int tBits = 0; |
| 224 | while (tTry >>= 1) { |
| 225 | t /= 2; |
| 226 | ++tBits; |
| 227 | } |
| 228 | if (tBits) { |
| 229 | int tIndex = (tBase - 1) & ((1 << tBits) - 1); |
| 230 | t += t * 2 * tIndex; |
| 231 | } |
| 232 | return t; |
| 233 | } |
| 234 | |
| 235 | bool SkOpSpan::sortableTop(SkOpContour* contourHead) { |
| 236 | SkChunkAlloc allocator(1024); |
| 237 | int dirOffset; |
| 238 | double t = get_t_guess(fTopTTry++, &dirOffset); |
| 239 | SkOpRayHit hitBase; |
| 240 | SkOpRayDir dir = hitBase.makeTestBase(this, t); |
| 241 | if (hitBase.fSlope.fX == 0 && hitBase.fSlope.fY == 0) { |
| 242 | return false; |
| 243 | } |
| 244 | SkOpRayHit* hitHead = &hitBase; |
| 245 | dir = static_cast<SkOpRayDir>(static_cast<int>(dir) + dirOffset); |
| 246 | SkOpContour* contour = contourHead; |
| 247 | do { |
| 248 | contour->rayCheck(hitBase, dir, &hitHead, &allocator); |
| 249 | } while ((contour = contour->next())); |
| 250 | // sort hits |
| 251 | SkSTArray<1, SkOpRayHit*> sorted; |
| 252 | SkOpRayHit* hit = hitHead; |
| 253 | while (hit) { |
| 254 | sorted.push_back(hit); |
| 255 | hit = hit->fNext; |
| 256 | } |
| 257 | int count = sorted.count(); |
| 258 | SkTQSort(sorted.begin(), sorted.end() - 1, xy_index(dir) |
| 259 | ? less_than(dir) ? hit_compare_y : reverse_hit_compare_y |
| 260 | : less_than(dir) ? hit_compare_x : reverse_hit_compare_x); |
| 261 | // verify windings |
| 262 | #if DEBUG_WINDING |
| 263 | SkDebugf("%s dir=%s seg=%d t=%1.9g pt=(%1.9g,%1.9g)\n", __FUNCTION__, |
| 264 | gDebugRayDirName[static_cast<int>(dir)], hitBase.fSpan->segment()->debugID(), |
| 265 | hitBase.fT, hitBase.fPt.fX, hitBase.fPt.fY); |
| 266 | for (int index = 0; index < count; ++index) { |
| 267 | hit = sorted[index]; |
| 268 | SkOpSpan* span = hit->fSpan; |
halcanary | 96fcdcc | 2015-08-27 07:41:13 -0700 | [diff] [blame] | 269 | SkOpSegment* hitSegment = span ? span->segment() : nullptr; |
caryclark | 624637c | 2015-05-11 07:21:27 -0700 | [diff] [blame] | 270 | bool operand = span ? hitSegment->operand() : false; |
| 271 | bool ccw = ccw_dxdy(hit->fSlope, dir); |
| 272 | SkDebugf("%s [%d] valid=%d operand=%d span=%d ccw=%d ", __FUNCTION__, index, |
| 273 | hit->fValid, operand, span ? span->debugID() : -1, ccw); |
| 274 | if (span) { |
| 275 | hitSegment->dumpPtsInner(); |
| 276 | } |
| 277 | SkDebugf(" t=%1.9g pt=(%1.9g,%1.9g) slope=(%1.9g,%1.9g)\n", hit->fT, |
| 278 | hit->fPt.fX, hit->fPt.fY, hit->fSlope.fX, hit->fSlope.fY); |
| 279 | } |
| 280 | #endif |
halcanary | 96fcdcc | 2015-08-27 07:41:13 -0700 | [diff] [blame] | 281 | const SkPoint* last = nullptr; |
caryclark | 624637c | 2015-05-11 07:21:27 -0700 | [diff] [blame] | 282 | int wind = 0; |
| 283 | int oppWind = 0; |
| 284 | for (int index = 0; index < count; ++index) { |
| 285 | hit = sorted[index]; |
| 286 | if (!hit->fValid) { |
| 287 | return false; |
| 288 | } |
| 289 | bool ccw = ccw_dxdy(hit->fSlope, dir); |
| 290 | SkASSERT(!approximately_zero(hit->fT) || !hit->fValid); |
| 291 | SkOpSpan* span = hit->fSpan; |
| 292 | SkOpSegment* hitSegment = span->segment(); |
| 293 | if (!span) { |
| 294 | return false; |
| 295 | } |
| 296 | if (span->windValue() == 0 && span->oppValue() == 0) { |
| 297 | continue; |
| 298 | } |
| 299 | if (last && SkDPoint::ApproximatelyEqual(*last, hit->fPt)) { |
| 300 | return false; |
| 301 | } |
| 302 | if (index < count - 1) { |
| 303 | const SkPoint& next = sorted[index + 1]->fPt; |
| 304 | if (SkDPoint::ApproximatelyEqual(next, hit->fPt)) { |
| 305 | return false; |
| 306 | } |
| 307 | } |
| 308 | bool operand = hitSegment->operand(); |
| 309 | if (operand) { |
| 310 | SkTSwap(wind, oppWind); |
| 311 | } |
| 312 | int lastWind = wind; |
| 313 | int lastOpp = oppWind; |
| 314 | int windValue = ccw ? -span->windValue() : span->windValue(); |
| 315 | int oppValue = ccw ? -span->oppValue() : span->oppValue(); |
| 316 | wind += windValue; |
| 317 | oppWind += oppValue; |
| 318 | bool sumSet = false; |
| 319 | int spanSum = span->windSum(); |
| 320 | int windSum = SkOpSegment::UseInnerWinding(lastWind, wind) ? wind : lastWind; |
| 321 | if (spanSum == SK_MinS32) { |
| 322 | span->setWindSum(windSum); |
| 323 | sumSet = true; |
| 324 | } else { |
| 325 | // the need for this condition suggests that UseInnerWinding is flawed |
| 326 | // happened when last = 1 wind = -1 |
| 327 | #if 0 |
| 328 | SkASSERT((hitSegment->isXor() ? (windSum & 1) == (spanSum & 1) : windSum == spanSum) |
| 329 | || (abs(wind) == abs(lastWind) |
| 330 | && (windSum ^ wind ^ lastWind) == spanSum)); |
| 331 | #endif |
| 332 | } |
| 333 | int oSpanSum = span->oppSum(); |
| 334 | int oppSum = SkOpSegment::UseInnerWinding(lastOpp, oppWind) ? oppWind : lastOpp; |
| 335 | if (oSpanSum == SK_MinS32) { |
| 336 | span->setOppSum(oppSum); |
| 337 | } else { |
| 338 | #if 0 |
| 339 | SkASSERT(hitSegment->oppXor() ? (oppSum & 1) == (oSpanSum & 1) : oppSum == oSpanSum |
| 340 | || (abs(oppWind) == abs(lastOpp) |
| 341 | && (oppSum ^ oppWind ^ lastOpp) == oSpanSum)); |
| 342 | #endif |
| 343 | } |
| 344 | if (sumSet) { |
caryclark | 5b5ddd7 | 2015-05-18 05:12:56 -0700 | [diff] [blame] | 345 | if (this->globalState()->phase() == SkOpGlobalState::kFixWinding) { |
| 346 | hitSegment->contour()->setCcw(ccw); |
| 347 | } else { |
halcanary | 96fcdcc | 2015-08-27 07:41:13 -0700 | [diff] [blame] | 348 | (void) hitSegment->markAndChaseWinding(span, span->next(), windSum, oppSum, nullptr); |
| 349 | (void) hitSegment->markAndChaseWinding(span->next(), span, windSum, oppSum, nullptr); |
caryclark | 5b5ddd7 | 2015-05-18 05:12:56 -0700 | [diff] [blame] | 350 | } |
caryclark | 624637c | 2015-05-11 07:21:27 -0700 | [diff] [blame] | 351 | } |
| 352 | if (operand) { |
| 353 | SkTSwap(wind, oppWind); |
| 354 | } |
| 355 | last = &hit->fPt; |
caryclark | 4e1a4c9 | 2015-05-18 12:56:57 -0700 | [diff] [blame] | 356 | this->globalState()->bumpNested(); |
caryclark | 624637c | 2015-05-11 07:21:27 -0700 | [diff] [blame] | 357 | } |
| 358 | return true; |
| 359 | } |
| 360 | |
| 361 | SkOpSpan* SkOpSegment::findSortableTop(SkOpContour* contourHead) { |
| 362 | SkOpSpan* span = &fHead; |
| 363 | SkOpSpanBase* next; |
| 364 | do { |
| 365 | next = span->next(); |
| 366 | if (span->done()) { |
| 367 | continue; |
| 368 | } |
| 369 | if (span->windSum() != SK_MinS32) { |
| 370 | return span; |
| 371 | } |
| 372 | if (span->sortableTop(contourHead)) { |
| 373 | return span; |
| 374 | } |
| 375 | } while (!next->final() && (span = next->upCast())); |
halcanary | 96fcdcc | 2015-08-27 07:41:13 -0700 | [diff] [blame] | 376 | return nullptr; |
caryclark | 624637c | 2015-05-11 07:21:27 -0700 | [diff] [blame] | 377 | } |
| 378 | |
| 379 | SkOpSpan* SkOpContour::findSortableTop(SkOpContour* contourHead) { |
| 380 | SkOpSegment* testSegment = &fHead; |
| 381 | do { |
| 382 | if (testSegment->done()) { |
| 383 | continue; |
| 384 | } |
| 385 | SkOpSpan* result = testSegment->findSortableTop(contourHead); |
| 386 | if (result) { |
| 387 | return result; |
| 388 | } |
| 389 | } while ((testSegment = testSegment->next())); |
halcanary | 96fcdcc | 2015-08-27 07:41:13 -0700 | [diff] [blame] | 390 | return nullptr; |
caryclark | 624637c | 2015-05-11 07:21:27 -0700 | [diff] [blame] | 391 | } |
| 392 | |
| 393 | SkOpSpan* FindSortableTop(SkOpContourHead* contourHead) { |
| 394 | for (int index = 0; index < SkOpGlobalState::kMaxWindingTries; ++index) { |
| 395 | SkOpContour* contour = contourHead; |
| 396 | do { |
| 397 | if (contour->done()) { |
| 398 | continue; |
| 399 | } |
| 400 | SkOpSpan* result = contour->findSortableTop(contourHead); |
| 401 | if (result) { |
| 402 | return result; |
| 403 | } |
| 404 | } while ((contour = contour->next())); |
| 405 | } |
halcanary | 96fcdcc | 2015-08-27 07:41:13 -0700 | [diff] [blame] | 406 | return nullptr; |
caryclark | 624637c | 2015-05-11 07:21:27 -0700 | [diff] [blame] | 407 | } |