烘培代码在 rcBuildHeightfieldLayers
本质上是为每个tile生成高度上的不同layer
算法的关键是三层循环:
for z 轴循环
for x 轴循环
for 高度span 循环
判断span和相邻span的连通性(x/z平面相邻cell)
如果联通, 则标注为同一个layer, 也就是在x/z平面上标注layer, 形成像是互不相交的面包片叠放的样子, 也有有坡度的layer
然后做了一些layer合并处理, 相邻的layer且在x/z平面不重叠且合并后高度差较小的, 可以合并为一个layer
同时layer记录了当前layer的上下高度范围, 边界(坐标系), 边界(体素),
heights记录了layer内每个span相对于layer的体素下边界的高度差(体素单位)
areas记录了layer内每个span的areas
cons记录了layer和span的相邻关系
(注意代码里改了一些变量的命名, 过于简化的变量名不利于新手看懂代码)
(另外, 代码里把y改成了z, recast本身代码里体素遍历都是 x/y平面, 按Unity习惯, 改成了 x/z 平面遍历, y代表高度)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 | /// See the #rcConfig documentation for more information on the configuration parameters./// /// @see rcAllocHeightfieldLayerSet, rcCompactHeightfield, rcHeightfieldLayerSet, rcConfigbool rcBuildHeightfieldLayers(rcContext* ctx, rcCompactHeightfield& chf, const int borderSize, const int walkableHeight, rcHeightfieldLayerSet& lset){ rcAssert(ctx); rcScopedTimer timer(ctx, RC_TIMER_BUILD_LAYERS); const int w = chf.width; const int h = chf.height; rcScopedDelete if (!srcReg) { ctx->log(RC_LOG_ERROR, "rcBuildHeightfieldLayers: Out of memory 'srcReg' (%d).", chf.spanCount); return false; } memset(srcReg,0xff,sizeof(unsigned char)*chf.spanCount); const int nsweeps = chf.width; rcScopedDeletesizeof(rcLayerSweepSpan)*nsweeps, RC_ALLOC_TEMP)); if (!sweeps) { ctx->log(RC_LOG_ERROR, "rcBuildHeightfieldLayers: Out of memory 'sweeps' (%d).", nsweeps); return false; } // Partition walkable area into monotone regions. int prevCount[256]; unsigned char regId = 0; //注意这里是三层循环: // for z 平面 // for x 平面 // for y 平面 (高度) // 最内层是对每个y平面的处理, 在每个y层面上根据span在x/z的连接性做region分配和合并, 也就是layer的意义: 按高度分层. 像是切片面包. // 从3d视角看是, 遍历x/z平面的每个cell, 依次检查当前cell与相邻cell在高度上的切片span是否有联通的, 如果有联通就把x/z平面相邻的cell上region赋值为相同id. 让x/z平面形成region.高度上 for (int z = borderSize; z < h-borderSize; ++z) { // prevCount 记录的是当前x轴上的sweep和上一轮x循环(-z方向)的region相连的span数量. memset(prevCount,0,sizeof(int)*regId); //(按行扫描编号), 这个编号在y的循环体内, 也就是每扫描一行x则重置, 扫描完一行后后面会把sweepId变成regionId, 所以重置没问题. unsigned char nowSweepId = 0; for (int x = borderSize; x < w-borderSize; ++x) { const rcCompactCell& c = chf.cells[x+z*w]; for (int i = (int)c.index, ni = (int)(c.index+c.count); i < ni; ++i) { const rcCompactSpan& s = chf.spans[i]; if (chf.areas[i] == RC_NULL_AREA) continue; unsigned char sweepId = 0xff; //(-1, 0)方向如果有连接 // -x if (rcGetCon(s, 0) != RC_NOT_CONNECTED) { const int ax = x + rcGetDirOffsetX(0); const int ay = z + rcGetDirOffsetY(0); const int ai = (int)chf.cells[ax+ay*w].index + rcGetCon(s, 0); //如果连接的不是NULL_AREA且它的sweepId并不是未初始化状态(未设置, 默认值0xff) (sweepId存储在srcReg里) //那么把自己的sweepId也设置为相邻这个span的sweepId,因为是从左到右遍历, 所以-x是刚刚遍历过的,如果连接(x轴相邻的span)且有srcReg, 则设置为相同srcReg if (chf.areas[ai] != RC_NULL_AREA && srcReg[ai] != 0xff) sweepId = srcReg[ai]; } // 如果和左侧相邻span(-1, 0)没有连接, 或者连接的area是NULL, 或者sweepId无效, 则把自己的sweepId设置为新的id. (新分配一个扫描编号) if (sweepId == 0xff) { sweepId = nowSweepId++; sweeps[sweepId].nei = 0xff; sweeps[sweepId].ns = 0; } // 检查完-x方向. 再检查之前扫描过的z方向的邻居 (上一轮扫描过的) // 如果相连且sweepId不是0xff, 则判断是不是刚刚x方向新加的sweepId(还没邻居), 如果是则把z方向的这个邻居设置成自己的邻居 // 如果当前邻居是z方向的这个span, 则把ns++, 把邻居sweepId记录的数量也加1(prevCount[nrSweepId]++) // 如果当前邻居不是z方向这个span, 说明和-z这一行有两个邻居, 则把邻居置为无效值 // (0, -1) x/z平面的下面 -> -z, 注意源码是 x/y 平面, 这里原本注释写的 -y if (rcGetCon(s,3) != RC_NOT_CONNECTED) { const int ax = x + rcGetDirOffsetX(3); const int ay = z + rcGetDirOffsetY(3); const int ai = (int)chf.cells[ax+ay*w].index + rcGetCon(s, 3); const unsigned char nrRegId = srcReg[ai]; if (nrRegId != 0xff) { // Set neighbour when first valid neighbour is encoutered. if (sweeps[sweepId].ns == 0) sweeps[sweepId].nei = nrRegId; if (sweeps[sweepId].nei == nrRegId) { // Update existing neighbour sweeps[sweepId].ns++; prevCount[nrRegId]++; } else { // This is hit if there is nore than one neighbour. // Invalidate the neighbour. sweeps[sweepId].nei = 0xff; } } } srcReg[i] = sweepId; } } // Create unique ID. for (int i = 0; i < nowSweepId; ++i) { /// 如果邻居设置了, 而且邻居连接我的数量和我数量相同则说明我们是完全相临的, 可以合并, 否则意味着我的邻居可能还有其他sweepId和他相连. /// 类似下面, A先扫描完, 形成了一个完整连续的region=1, 再遍历B时, prevCount[1] = 4, (A行3个1和1个2), 但是sweeps[1] = 3, (B行3个1) /// 所以此时B行里的1和A行里的1不能合并了. 要给B行的1分配新的regionId /// /// <--- -x方向(左) /// | /// B: [1] [1] [1] [2] | -> 此处的1, 2都还是sweepId, 代表从左到右的扫描分割序号. /// A: [1] [1] [1] [1] [1] | -> 此时的1已经是regionId了. /// -z方向(下) /// /// /// B: [1] [1] | /// A: [1] [1] [1] | -> 这种情况可以合并, prevCount[A1].nei = 2, sweeps[B1].ns = 2 /// /// B: [1] [1] [1] [1] | /// A: [1] [1] [1] | -> 这种情况也可以合并, prevCount[A1].nei = 3, sweeps[B1].ns = 3, (B第四个[1]因为和下面无连接, 所以两边都不计数) /// /// If the neighbour is set and there is only one continuous connection to it, /// the sweep will be merged with the previous one, else new region is created. if (sweeps[i].nei != 0xff && prevCount[sweeps[i].nei] == (int)sweeps[i].ns) { sweeps[i].id = sweeps[i].nei; } else { if (regId == 255) { ctx->log(RC_LOG_ERROR, "rcBuildHeightfieldLayers: Region ID overflow."); return false; } sweeps[i].id = regId++; } } // 之前srcReg里记录的是sweepId, 现在改回regionId // Remap local sweep ids to region ids. for (int x = borderSize; x < w-borderSize; ++x) { const rcCompactCell& c = chf.cells[x+z*w]; for (int i = (int)c.index, ni = (int)(c.index+c.count); i < ni; ++i) { if (srcReg[i] != 0xff) srcReg[i] = sweeps[srcReg[i]].id; } } } // Allocate and init layer regions. const int nregs = (int)regId; rcScopedDeletesizeof(rcLayerRegion)*nregs, RC_ALLOC_TEMP)); if (!regs) { ctx->log(RC_LOG_ERROR, "rcBuildHeightfieldLayers: Out of memory 'regs' (%d).", nregs); return false; } memset(regs, 0, sizeof(rcLayerRegion)*nregs); for (int i = 0; i < nregs; ++i) { regs[i].layerId = 0xff; regs[i].ymin = 0xffff; regs[i].ymax = 0; } // Find region neighbours and overlapping regions. for (int z = 0; z < h; ++z) //遍历 z { for (int x = 0; x < w; ++x) //遍历 x/z 平面 { const rcCompactCell& c = chf.cells[x+z*w]; //记录y方向的区域id和数量 unsigned char lregs[RC_MAX_LAYERS]; int nlregs = 0; for (int i = (int)c.index, ni = (int)(c.index+c.count); i < ni; ++i) //遍历 y 方向 span { const rcCompactSpan& s = chf.spans[i]; const unsigned char regionId = srcReg[i]; if (regionId == 0xff) continue; //跳过没有区域的span regs[regionId].ymin = rcMin(regs[regionId].ymin, s.y); regs[regionId].ymax = rcMax(regs[regionId].ymax, s.y); // Collect all region layers. if (nlregs < RC_MAX_LAYERS) lregs[nlregs++] = regionId; // Update neighbours // 遍历4个方向, 记录邻居区域信息 (和自己不同区域) for (int dir = 0; dir < 4; ++dir) { if (rcGetCon(s, dir) != RC_NOT_CONNECTED) { const int ax = x + rcGetDirOffsetX(dir); const int ay = z + rcGetDirOffsetY(dir); const int ai = (int)chf.cells[ax+ay*w].index + rcGetCon(s, dir); const unsigned char nrReg = srcReg[ai]; if (nrReg != 0xff && nrReg != regionId) //邻居的region 和 自己不一样 { // Don't check return value -- if we cannot add the neighbor // it will just cause a few more regions to be created, which // is fine. addUnique(regs[regionId].neis, regs[regionId].nneis, RC_MAX_NEIS, nrReg); } } } } // 两层遍历高度(y)方向的区域 (两两检查), // Update overlapping regions. for (int i = 0; i < nlregs-1; ++i) { for (int j = i+1; j < nlregs; ++j) { if (lregs[i] != lregs[j]) { rcLayerRegion& ri = regs[lregs[i]]; rcLayerRegion& rj = regs[lregs[j]]; //在两个region的layers里记录该region在x/z平面上重叠的其他高度的regionId. 用于索引高度上的不同层. if (!addUnique(ri.layers, ri.nlayers, RC_MAX_LAYERS, lregs[j]) || !addUnique(rj.layers, rj.nlayers, RC_MAX_LAYERS, lregs[i])) { ctx->log(RC_LOG_ERROR, "rcBuildHeightfieldLayers: layer overflow (too many overlapping walkable platforms). Try increasing RC_MAX_LAYERS."); return false; } } } } } } // Create 2D layers from regions. unsigned char layerId = 0; static const int MAX_STACK = 64; unsigned char stack[MAX_STACK]; int nstack = 0; for (int i = 0; i < nregs; ++i) { rcLayerRegion& root = regs[i]; // Skip already visited. if (root.layerId != 0xff) continue; // Start search. // 分配 layerId root.layerId = layerId; root.base = 1; nstack = 0; stack[nstack++] = (unsigned char)i; //region序号入栈 while (nstack) { // Pop front rcLayerRegion& reg = regs[stack[0]]; nstack--; for (int j = 0; j < nstack; ++j) //移除stack第一个元素. stack[j] = stack[j+1]; const int nneis = (int)reg.nneis; for (int j = 0; j < nneis; ++j) { const unsigned char nei = reg.neis[j]; rcLayerRegion& nrReg = regs[nei]; // Skip already visited. if (nrReg.layerId != 0xff) continue; // Skip if the neighbour is overlapping root region. // 跳过 邻居是x/z重叠的不同高度的region if (contains(root.layers, root.nlayers, nei)) continue; // Skip if the height range would become too large. // 如果两个区域加起来的高度落差太大 跳过 (因为高度差不大的情况下会合并layer, 但是合并太多后会导致layer上下表面的高差越来越大, 这时候就要打断合并了) const int ymin = rcMin(root.ymin, nrReg.ymin); const int ymax = rcMax(root.ymax, nrReg.ymax); if ((ymax - ymin) >= 255) continue; if (nstack < MAX_STACK) { // Deepen 邻居入栈 stack[nstack++] = (unsigned char)nei; // Mark layer id // 将邻居的layerId设置为自己的layerId. 合并成一个layer nrReg.layerId = layerId; // Merge current layers to root. // 将邻居的高度layers也合并到自己的layers, (合并成一个layer了, 高度重叠区域信息也要合并). for (int k = 0; k < nrReg.nlayers; ++k) { if (!addUnique(root.layers, root.nlayers, RC_MAX_LAYERS, nrReg.layers[k])) { ctx->log(RC_LOG_ERROR, "rcBuildHeightfieldLayers: layer overflow (too many overlapping walkable platforms). Try increasing RC_MAX_LAYERS."); return false; } } root.ymin = rcMin(root.ymin, nrReg.ymin); // 更新合并后的layer上下表面. root.ymax = rcMax(root.ymax, nrReg.ymax); } } } layerId++; } // Merge non-overlapping regions that are close in height. // 合并高度上差异不大, 而且没有重叠的区域, 楼梯, 坡等 const unsigned short mergeHeight = (unsigned short)walkableHeight * 4; for (int i = 0; i < nregs; ++i) { rcLayerRegion& ri = regs[i]; if (!ri.base) continue; //只需要查询layer的 base region unsigned char newId = ri.layerId; for (;;) { unsigned char oldId = 0xff; for (int j = 0; j < nregs; ++j) //双层遍历 region 两两计算 { if (i == j) continue; rcLayerRegion& rj = regs[j]; if (!rj.base) continue; // Skip if the regions are not close to each other. // 两个区域的上下表面+合并高差 不重叠, 则无法合并 if (!overlapRange(ri.ymin,ri.ymax+mergeHeight, rj.ymin,rj.ymax+mergeHeight)) continue; // Skip if the height range would become too large. const int ymin = rcMin(ri.ymin, rj.ymin); const int ymax = rcMax(ri.ymax, rj.ymax); if ((ymax - ymin) >= 255) //合并后高差太大 跳过 continue; // Make sure that there is no overlap when merging 'ri' and 'rj'. bool overlap = false; // Iterate over all regions which have the same layerId as 'rj' for (int k = 0; k < nregs; ++k) { if (regs[k].layerId != rj.layerId) continue; // Check if region 'k' is overlapping region 'ri' // Index to 'regs' is the same as region id. // 和j相同layerId的区域, 判断是否和ri有重叠, 如果有重叠说明合并regionI 和 regionJ 后会导致用一个region在x/z平面出现重叠. 所以此时要break. 不能合并 if (contains(ri.layers,ri.nlayers, (unsigned char)k)) { overlap = true; break; } } // Cannot merge of regions overlap. if (overlap) continue; // Can merge i and j. oldId = rj.layerId; break; } // Could not find anything to merge with, stop. if (oldId == 0xff) break; // Merge for (int j = 0; j < nregs; ++j) { rcLayerRegion& rj = regs[j]; if (rj.layerId == oldId) { rj.base = 0; // Remap layerIds. rj.layerId = newId; // Add overlaid layers from 'rj' to 'ri'. // 合并之后, 同样也需要 将邻居的高度layers也合并到自己的layers, (合并成一个layer了, 高度重叠区域信息也要合并). for (int k = 0; k < rj.nlayers; ++k) { if (!addUnique(ri.layers, ri.nlayers, RC_MAX_LAYERS, rj.layers[k])) { ctx->log(RC_LOG_ERROR, "rcBuildHeightfieldLayers: layer overflow (too many overlapping walkable platforms). Try increasing RC_MAX_LAYERS."); return false; } } // Update height bounds. ri.ymin = rcMin(ri.ymin, rj.ymin); // 更新合并后的layer上下表面. ri.ymax = rcMax(ri.ymax, rj.ymax); } } } } // 合并后layerId不连续了, 所以这里要重新remap下, 保持layerId连续 // Compact layerIds unsigned char remap[256]; memset(remap, 0, 256); // Find number of unique layers. layerId = 0; for (int i = 0; i < nregs; ++i) remap[regs[i].layerId] = 1; for (int oldLayerId = 0; oldLayerId < 256; ++oldLayerId) { if (remap[oldLayerId]) remap[oldLayerId] = layerId++; else remap[oldLayerId] = 0xff; } // Remap ids. for (int i = 0; i < nregs; ++i) regs[i].layerId = remap[regs[i].layerId]; //从remap里查询oldLayerId对应的新layerId, 并赋值 // No layers, return empty. if (layerId == 0) return true; // Create layers. rcAssert(lset.layers == 0); const int lw = w - borderSize*2; const int lh = h - borderSize*2; // Build contracted bbox for layers. float bmin[3], bmax[3]; rcVcopy(bmin, chf.bmin); rcVcopy(bmax, chf.bmax); bmin[0] += borderSize*chf.cs; bmin[2] += borderSize*chf.cs; bmax[0] -= borderSize*chf.cs; bmax[2] -= borderSize*chf.cs; lset.nlayers = (int)layerId; lset.layers = (rcHeightfieldLayer*)rcAlloc(sizeof(rcHeightfieldLayer)*lset.nlayers, RC_ALLOC_PERM); if (!lset.layers) { ctx->log(RC_LOG_ERROR, "rcBuildHeightfieldLayers: Out of memory 'layers' (%d).", lset.nlayers); return false; } memset(lset.layers, 0, sizeof(rcHeightfieldLayer)*lset.nlayers); // Store layers. for (int i = 0; i < lset.nlayers; ++i) { unsigned char curId = (unsigned char)i; rcHeightfieldLayer* layer = &lset.layers[curId]; const int gridSize = sizeof(unsigned char)*lw*lh; //体素x/z空间size, 二维数组长度 layer->heights = (unsigned char*)rcAlloc(gridSize, RC_ALLOC_PERM); if (!layer->heights) { ctx->log(RC_LOG_ERROR, "rcBuildHeightfieldLayers: Out of memory 'heights' (%d).", gridSize); return false; } memset(layer->heights, 0xff, gridSize); layer->areas = (unsigned char*)rcAlloc(gridSize, RC_ALLOC_PERM); if (!layer->areas) { ctx->log(RC_LOG_ERROR, "rcBuildHeightfieldLayers: Out of memory 'areas' (%d).", gridSize); return false; } memset(layer->areas, 0, gridSize); layer->cons = (unsigned char*)rcAlloc(gridSize, RC_ALLOC_PERM); if (!layer->cons) { ctx->log(RC_LOG_ERROR, "rcBuildHeightfieldLayers: Out of memory 'cons' (%d).", gridSize); return false; } memset(layer->cons, 0, gridSize); // Find layer height bounds. int hmin = 0, hmax = 0; //上下表面高度 (体素单位) for (int j = 0; j < nregs; ++j) { if (regs[j].base && regs[j].layerId == curId) { hmin = (int)regs[j].ymin; hmax = (int)regs[j].ymax; //此处应该可以break ? } } layer->width = lw; layer->height = lh; layer->cs = chf.cs; layer->ch = chf.ch; // Adjust the bbox to fit the heightfield. rcVcopy(layer->bmin, bmin); rcVcopy(layer->bmax, bmax); layer->bmin[1] = bmin[1] + hmin*chf.ch; //体素高度转坐标高度 layer->bmax[1] = bmin[1] + hmax*chf.ch; layer->hmin = hmin; layer->hmax = hmax; // Update usable data region. layer->minx = layer->width; layer->maxx = 0; layer->miny = layer->height; layer->maxy = 0; // Copy height and area from compact heightfield. for (int z = 0; z < lh; ++z) { for (int x = 0; x < lw; ++x) { const int cx = borderSize+x; const int cz = borderSize+z; const rcCompactCell& c = chf.cells[cx+cz*w]; for (int j = (int)c.index, nj = (int)(c.index+c.count); j < nj; ++j) { const rcCompactSpan& span = chf.spans[j]; // Skip unassigned regions. if (srcReg[j] == 0xff) continue; // Skip of does nto belong to current layer. unsigned char lid = regs[srcReg[j]].layerId; if (lid != curId) continue; // Update data bounds. layer->minx = rcMin(layer->minx, x); layer->maxx = rcMax(layer->maxx, x); layer->miny = rcMin(layer->miny, z); layer->maxy = rcMax(layer->maxy, z); // Store height and area type. const int idx = x+z*lw; layer->heights[idx] = (unsigned char)(span.y - hmin); layer->areas[idx] = chf.areas[j]; // Check connection. unsigned char portal = 0; unsigned char con = 0; for (int dir = 0; dir < 4; ++dir) { if (rcGetCon(span, dir) != RC_NOT_CONNECTED) { const int ax = cx + rcGetDirOffsetX(dir); const int ay = cz + rcGetDirOffsetY(dir); const int ai = (int)chf.cells[ax+ay*w].index + rcGetCon(span, dir); unsigned char alid = srcReg[ai] != 0xff ? regs[srcReg[ai]].layerId : 0xff; // Portal mask if (chf.areas[ai] != RC_NULL_AREA && lid != alid) { portal |= (unsigned char)(1< // Update height so that it matches on both sides of the portal. const rcCompactSpan& as = chf.spans[ai]; if (as.y > hmin) layer->heights[idx] = rcMax(layer->heights[idx], (unsigned char)(as.y - hmin)); } // Valid connection mask // 相邻的同layer的span连接信息记录在 cons的低4位. (上下左右) if (chf.areas[ai] != RC_NULL_AREA && lid == alid) { const int nx = ax - borderSize; const int ny = ay - borderSize; if (nx >= 0 && ny >= 0 && nx < lw && ny < lh) con |= (unsigned char)(1< } } } layer->cons[idx] = (portal << 4) | con; //相邻的不同layer的信息记录在cons的高4位. } } } if (layer->minx > layer->maxx) layer->minx = layer->maxx = 0; if (layer->miny > layer->maxy) layer->miny = layer->maxy = 0; } return true;} |
有两个文档也可以看一下, 看懂了上面的代码再去看文章就清楚多了. 如果不好理解代码. 可以结合文章图例一起看. 代码注释已经非常详细了, 只是没有图例
https://blog.csdn.net/zstu_zy/article/details/97247013
https ://www.jianshu.com/p/f6cd9b7696f6