Split source poly into front and back. If either front or back is degenerate, don't do anything. If we have a front and a back, then add the verts to our vertex list and fill out the poly structures.
| 522 | // Split source poly into front and back. If either front or back is degenerate, don't do anything. |
| 523 | // If we have a front and a back, then add the verts to our vertex list and fill out the poly structures. |
| 524 | bool DepthSortList::splitPoly(const Poly & src, Point3F & normal, F32 k, Poly & frontPoly, Poly & backPoly) |
| 525 | { |
| 526 | frontVerts.clear(); |
| 527 | backVerts.clear(); |
| 528 | |
| 529 | // already degenerate... |
| 530 | AssertFatal(src.vertexCount>=3,"DepthSortList::splitPoly - Don't need to split a triangle!"); |
| 531 | |
| 532 | S32 startSize = mVertexList.size(); |
| 533 | |
| 534 | // Assume back and front are degenerate polygons until proven otherwise. |
| 535 | bool backDegen = true, frontDegen = true; |
| 536 | |
| 537 | U32 bIdx; |
| 538 | Point3F * a, * b; |
| 539 | F32 dota, dotb; |
| 540 | S32 signA, signB; |
| 541 | |
| 542 | F32 splitTolSq = SPLIT_TOL * SPLIT_TOL * mDot(normal,normal); |
| 543 | |
| 544 | bIdx = mIndexList[src.vertexStart+src.vertexCount-1]; |
| 545 | b = &mVertexList[bIdx].point; |
| 546 | dotb = mDot(normal,*b)-k; |
| 547 | |
| 548 | // Sign variable coded as follows: 1 for outside, 0 on the plane and -1 for inside. |
| 549 | if (dotb*dotb > splitTolSq) |
| 550 | signB = dotb > 0.0f ? 1 : -1; |
| 551 | else |
| 552 | signB = 0; |
| 553 | |
| 554 | S32 i; |
| 555 | for (i = 0; i<src.vertexCount; i++) |
| 556 | { |
| 557 | a = b; |
| 558 | bIdx = mIndexList[src.vertexStart+i]; |
| 559 | b = &mVertexList[bIdx].point; |
| 560 | dota = dotb; |
| 561 | dotb = mDot(normal,*b)-k; |
| 562 | signA = signB; |
| 563 | if (dotb*dotb > splitTolSq) |
| 564 | signB = dotb > 0.0f ? 1 : -1; |
| 565 | else |
| 566 | signB = 0; |
| 567 | |
| 568 | switch(signA*3 + signB + 4) // +4 is to make values go from 0 up...hopefully enticing compiler to make a jump-table |
| 569 | { |
| 570 | case 0: // A-, B- |
| 571 | case 3: // A., B- |
| 572 | backVerts.push_back(bIdx); |
| 573 | backDegen = false; |
| 574 | break; |
| 575 | case 8: // A+, B+ |
| 576 | case 5: // A., B+ |
| 577 | frontVerts.push_back(bIdx); |
| 578 | frontDegen = false; |
| 579 | break; |
| 580 | |
| 581 | case 1: // A-, B. |