Main Page Namespace List Class Hierarchy Compound List File List Compound Members File Members
Main Page Namespace List Class Hierarchy Compound List File List Compound Members File Members #include "texture.h"#include "vector.h"#include "vertex.h"Go to the source code of this file.
Compounds | |
| class | POLYGON |
Functions | |
| int | SplitPolygon (POLYGON polygonToSplit, POLYGON planePolygon, POLYGON *polygons) |
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Definition at line 337 of file polygon.cpp. References Back, ClassifyPoint(), CrossVector(), Front, GetEdgeIntersection(), POLYGON::numVertices, OneFrontOneBack, OneFrontTwoBack, POLYGON::SetNormal(), TwoFrontOneBack, VERTEX::u, VERTEX::v, POLYGON::Vertex, VERTEX::x, VECTOR::x, VERTEX::y, VECTOR::y, VERTEX::z, and VECTOR::z. Referenced by BuildBSP(), and SelectPartitionfromList().
00338 {
00339 VECTOR planeNormal, polysNormal, pointOnPlane, edge1, edge2, temp;
00340 VERTEX ptA, ptB, outpts[4], inpts[4], intersection;
00341 int count = 0, out_c = 0, in_c = 0, sideA, sideB, outputFlag;
00342 VERTEX texvert1, texvert2; // texture calculation variables
00343 VECTOR t1, t2;
00344 float scale;
00345
00346 // get a point on the plane
00347 pointOnPlane.x = planeTriangle.Vertex[0].x;
00348 pointOnPlane.y = planeTriangle.Vertex[0].y;
00349 pointOnPlane.z = planeTriangle.Vertex[0].z;
00350
00351 // get the splitting planes normal
00352 edge1.x = planeTriangle.Vertex[1].x - planeTriangle.Vertex[0].x;
00353 edge1.y = planeTriangle.Vertex[1].y - planeTriangle.Vertex[0].y;
00354 edge1.z = planeTriangle.Vertex[1].z - planeTriangle.Vertex[0].z;
00355 edge2.x = planeTriangle.Vertex[2].x - planeTriangle.Vertex[0].x;
00356 edge2.y = planeTriangle.Vertex[2].y - planeTriangle.Vertex[0].y;
00357 edge2.z = planeTriangle.Vertex[2].z - planeTriangle.Vertex[0].z;
00358 planeNormal = CrossVector(edge1, edge2);
00359
00360 // get the normal of the triangle to split
00361 edge1.x = triangleToSplit.Vertex[1].x - triangleToSplit.Vertex[0].x;
00362 edge1.y = triangleToSplit.Vertex[1].y - triangleToSplit.Vertex[0].y;
00363 edge1.z = triangleToSplit.Vertex[1].z - triangleToSplit.Vertex[0].z;
00364 edge2.x = triangleToSplit.Vertex[2].x - triangleToSplit.Vertex[0].x;
00365 edge2.y = triangleToSplit.Vertex[2].y - triangleToSplit.Vertex[0].y;
00366 edge2.z = triangleToSplit.Vertex[2].z - triangleToSplit.Vertex[0].z;
00367 polysNormal = CrossVector(edge1, edge2);
00368
00369 // check if the triangle lies on the plane
00370 for (int loop = 0; loop < 3; loop++)
00371 {
00372 temp.x = triangleToSplit.Vertex[loop].x;
00373 temp.y = triangleToSplit.Vertex[loop].y;
00374 temp.z = triangleToSplit.Vertex[loop].z;
00375 if (ClassifyPoint(temp, pointOnPlane, planeNormal) == 0)
00376 count++;
00377 else
00378 break;
00379 }
00380 if (count == 3)
00381 {
00382 if (ClassifyPoint(polysNormal, pointOnPlane, planeNormal) == 1)
00383 return Front;
00384 if (ClassifyPoint(polysNormal, pointOnPlane, planeNormal) == -1)
00385 return Back;
00386 }
00387
00388 // find if all of the points are infront of or behind the plane
00389 int frontcount = 0, backcount = 0;
00390 for (int loop = 0; loop < 3; loop++)
00391 {
00392 temp.x = triangleToSplit.Vertex[loop].x;
00393 temp.y = triangleToSplit.Vertex[loop].y;
00394 temp.z = triangleToSplit.Vertex[loop].z;
00395 if (ClassifyPoint(temp, pointOnPlane, planeNormal) == 0)
00396 {
00397 frontcount++;
00398 backcount++;
00399 }
00400 else if (ClassifyPoint(temp, pointOnPlane, planeNormal) == 1)
00401 frontcount++;
00402 else if (ClassifyPoint(temp, pointOnPlane, planeNormal) == -1)
00403 backcount++;
00404 }
00405 if (frontcount == 3)
00406 return Front;
00407 if (backcount == 3)
00408 return Back;
00409
00410 // try to split the triangle
00411 ptA = triangleToSplit.Vertex[2];
00412 temp.x = ptA.x;
00413 temp.y = ptA.y;
00414 temp.z = ptA.z;
00415 sideA = ClassifyPoint(temp, pointOnPlane, planeNormal);
00416 for (int i = -1; ++i < 3;)
00417 {
00418 ptB = triangleToSplit.Vertex[i];
00419 temp.x = ptB.x;
00420 temp.y = ptB.y;
00421 temp.z = ptB.z;
00422 sideB = ClassifyPoint(temp, pointOnPlane, planeNormal);
00423 if (sideB > 0)
00424 {
00425 if (sideA < 0)
00426 {
00427 // find intersection
00428 edge1.x = ptA.x;
00429 edge1.y = ptA.y;
00430 edge1.z = ptA.z;
00431 edge2.x = ptB.x;
00432 edge2.y = ptB.y;
00433 edge2.z = ptB.z;
00434
00435 temp = GetEdgeIntersection(edge1, edge2, planeTriangle);
00436 intersection.x = temp.x;
00437 intersection.y = temp.y;
00438 intersection.z = temp.z;
00439
00440 // find the new texture coordinates
00441 texvert1.x = ptB.x - ptA.x;
00442 texvert1.y = ptB.y - ptA.y;
00443 texvert1.z = ptB.z - ptA.z;
00444 texvert2.x = intersection.x - ptA.x;
00445 texvert2.y = intersection.y - ptA.y;
00446 texvert2.z = intersection.z - ptA.z;
00447 texvert1.u = ptA.u;
00448 texvert2.u = ptB.u;
00449 texvert1.v = ptA.v;
00450 texvert2.v = ptB.v;
00451 t1.x = texvert1.x;
00452 t1.y = texvert1.y;
00453 t1.z = texvert1.z;
00454 t2.x = texvert2.x;
00455 t2.y = texvert2.y;
00456 t2.z = texvert2.z;
00457 scale = sqrt(t2.x*t2.x+t2.y*t2.y+t2.z*t2.z)/sqrt(t1.x*t1.x+t1.y*t1.y+t1.z*t1.z);
00458 intersection.u = texvert1.u + (texvert2.u - texvert1.u) * scale;
00459 intersection.v = texvert1.v + (texvert2.v - texvert1.v) * scale;
00460
00461 outpts[out_c++] = inpts[in_c++] = intersection;
00462 }
00463 inpts[in_c++] = ptB;
00464 }
00465 else if (sideB < 0)
00466 {
00467 if (sideA > 0)
00468 {
00469 // find intersection
00470 edge1.x = ptA.x;
00471 edge1.y = ptA.y;
00472 edge1.z = ptA.z;
00473 edge2.x = ptB.x;
00474 edge2.y = ptB.y;
00475 edge2.z = ptB.z;
00476
00477 temp = GetEdgeIntersection(edge1, edge2, planeTriangle);
00478 intersection.x = temp.x;
00479 intersection.y = temp.y;
00480 intersection.z = temp.z;
00481
00482 // find the new texture coordinates
00483 texvert1.x = ptB.x - ptA.x;
00484 texvert1.y = ptB.y - ptA.y;
00485 texvert1.z = ptB.z - ptA.z;
00486 texvert2.x = intersection.x - ptA.x;
00487 texvert2.y = intersection.y - ptA.y;
00488 texvert2.z = intersection.z - ptA.z;
00489 texvert1.u = ptA.u;
00490 texvert2.u = ptB.u;
00491 texvert1.v = ptA.v;
00492 texvert2.v = ptB.v;
00493 t1.x = texvert1.x;
00494 t1.y = texvert1.y;
00495 t1.z = texvert1.z;
00496 t2.x = texvert2.x;
00497 t2.y = texvert2.y;
00498 t2.z = texvert2.z;
00499 scale = sqrt(t2.x*t2.x+t2.y*t2.y+t2.z*t2.z)/sqrt(t1.x*t1.x+t1.y*t1.y+t1.z*t1.z);
00500 intersection.u = texvert1.u + (texvert2.u - texvert1.u) * scale;
00501 intersection.v = texvert1.v + (texvert2.v - texvert1.v) * scale;
00502
00503 outpts[out_c++] = inpts[in_c++] = intersection;
00504 }
00505 outpts[out_c++] = ptB;
00506 }
00507 else
00508 outpts[out_c++] = inpts[in_c++] = ptB;
00509 ptA = ptB;
00510 sideA = sideB;
00511 }
00512
00513 if (in_c == 4) // two triangles are infront, one behind
00514 {
00515 outputFlag = TwoFrontOneBack;
00516 if (triangles)
00517 {
00518 triangles[0].Vertex[0] = inpts[0];
00519 triangles[0].Vertex[1] = inpts[1];
00520 triangles[0].Vertex[2] = inpts[2];
00521 triangles[0].numVertices = 3;
00522 triangles[0].SetNormal();
00523 triangles[1].Vertex[0] = inpts[0];
00524 triangles[1].Vertex[1] = inpts[2];
00525 triangles[1].Vertex[2] = inpts[3];
00526 triangles[1].numVertices = 3;
00527 triangles[1].SetNormal();
00528 triangles[2].Vertex[0] = outpts[0];
00529 triangles[2].Vertex[1] = outpts[1];
00530 triangles[2].Vertex[2] = outpts[2];
00531 triangles[2].numVertices = 3;
00532 triangles[2].SetNormal();
00533 }
00534 }
00535 else if (out_c == 4) // one triangle is infront, two behind
00536 {
00537 outputFlag = OneFrontTwoBack;
00538 if (triangles)
00539 {
00540 triangles[0].Vertex[0] = inpts[0];
00541 triangles[0].Vertex[1] = inpts[1];
00542 triangles[0].Vertex[2] = inpts[2];
00543 triangles[0].numVertices = 3;
00544 triangles[0].SetNormal();
00545 triangles[1].Vertex[0] = outpts[0];
00546 triangles[1].Vertex[1] = outpts[1];
00547 triangles[1].Vertex[2] = outpts[2];
00548 triangles[1].numVertices = 3;
00549 triangles[1].SetNormal();
00550 triangles[2].Vertex[0] = outpts[0];
00551 triangles[2].Vertex[1] = outpts[2];
00552 triangles[2].Vertex[2] = outpts[3];
00553 triangles[2].numVertices = 3;
00554 triangles[2].SetNormal();
00555 }
00556 }
00557 else if (in_c == 3 && out_c == 3) // plane bisects the triangle
00558 {
00559 outputFlag = OneFrontOneBack;
00560 if (triangles)
00561 {
00562 triangles[0].Vertex[0] = inpts[0];
00563 triangles[0].Vertex[1] = inpts[1];
00564 triangles[0].Vertex[2] = inpts[2];
00565 triangles[0].numVertices = 3;
00566 triangles[0].SetNormal();
00567 triangles[1].Vertex[0] = outpts[0];
00568 triangles[1].Vertex[1] = outpts[1];
00569 triangles[1].Vertex[2] = outpts[2];
00570 triangles[1].numVertices = 3;
00571 triangles[1].SetNormal();
00572 }
00573 }
00574 else // then triangle must be totally infront of or behind the plane
00575 {
00576 int side;
00577
00578 for (int loop = 0; loop < 3; loop++)
00579 {
00580 temp.x = triangleToSplit.Vertex[loop].x;
00581 temp.y = triangleToSplit.Vertex[loop].y;
00582 temp.z = triangleToSplit.Vertex[loop].z;
00583 side = ClassifyPoint(temp, pointOnPlane, planeNormal);
00584 if (side == 1)
00585 {
00586 outputFlag = Front;
00587 break;
00588 }
00589 else if (side == -1)
00590 {
00591 outputFlag = Back;
00592 break;
00593 }
00594 }
00595 }
00596 return outputFlag;
00597 }
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