Merge commit 'origin/gallium-0.1' into gallium-0.2
[mesa.git] / src / glu / sgi / libtess / mesh.c
1 /*
2 * SGI FREE SOFTWARE LICENSE B (Version 2.0, Sept. 18, 2008)
3 * Copyright (C) 1991-2000 Silicon Graphics, Inc. All Rights Reserved.
4 *
5 * Permission is hereby granted, free of charge, to any person obtaining a
6 * copy of this software and associated documentation files (the "Software"),
7 * to deal in the Software without restriction, including without limitation
8 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
9 * and/or sell copies of the Software, and to permit persons to whom the
10 * Software is furnished to do so, subject to the following conditions:
11 *
12 * The above copyright notice including the dates of first publication and
13 * either this permission notice or a reference to
14 * http://oss.sgi.com/projects/FreeB/
15 * shall be included in all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
18 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20 * SILICON GRAPHICS, INC. BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
21 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
22 * OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
23 * SOFTWARE.
24 *
25 * Except as contained in this notice, the name of Silicon Graphics, Inc.
26 * shall not be used in advertising or otherwise to promote the sale, use or
27 * other dealings in this Software without prior written authorization from
28 * Silicon Graphics, Inc.
29 */
30 /*
31 ** Author: Eric Veach, July 1994.
32 **
33 */
34
35 #include "gluos.h"
36 #include <stddef.h>
37 #include <assert.h>
38 #include "mesh.h"
39 #include "memalloc.h"
40
41 #define TRUE 1
42 #define FALSE 0
43
44 static GLUvertex *allocVertex()
45 {
46 return (GLUvertex *)memAlloc( sizeof( GLUvertex ));
47 }
48
49 static GLUface *allocFace()
50 {
51 return (GLUface *)memAlloc( sizeof( GLUface ));
52 }
53
54 /************************ Utility Routines ************************/
55
56 /* Allocate and free half-edges in pairs for efficiency.
57 * The *only* place that should use this fact is allocation/free.
58 */
59 typedef struct { GLUhalfEdge e, eSym; } EdgePair;
60
61 /* MakeEdge creates a new pair of half-edges which form their own loop.
62 * No vertex or face structures are allocated, but these must be assigned
63 * before the current edge operation is completed.
64 */
65 static GLUhalfEdge *MakeEdge( GLUhalfEdge *eNext )
66 {
67 GLUhalfEdge *e;
68 GLUhalfEdge *eSym;
69 GLUhalfEdge *ePrev;
70 EdgePair *pair = (EdgePair *)memAlloc( sizeof( EdgePair ));
71 if (pair == NULL) return NULL;
72
73 e = &pair->e;
74 eSym = &pair->eSym;
75
76 /* Make sure eNext points to the first edge of the edge pair */
77 if( eNext->Sym < eNext ) { eNext = eNext->Sym; }
78
79 /* Insert in circular doubly-linked list before eNext.
80 * Note that the prev pointer is stored in Sym->next.
81 */
82 ePrev = eNext->Sym->next;
83 eSym->next = ePrev;
84 ePrev->Sym->next = e;
85 e->next = eNext;
86 eNext->Sym->next = eSym;
87
88 e->Sym = eSym;
89 e->Onext = e;
90 e->Lnext = eSym;
91 e->Org = NULL;
92 e->Lface = NULL;
93 e->winding = 0;
94 e->activeRegion = NULL;
95
96 eSym->Sym = e;
97 eSym->Onext = eSym;
98 eSym->Lnext = e;
99 eSym->Org = NULL;
100 eSym->Lface = NULL;
101 eSym->winding = 0;
102 eSym->activeRegion = NULL;
103
104 return e;
105 }
106
107 /* Splice( a, b ) is best described by the Guibas/Stolfi paper or the
108 * CS348a notes (see mesh.h). Basically it modifies the mesh so that
109 * a->Onext and b->Onext are exchanged. This can have various effects
110 * depending on whether a and b belong to different face or vertex rings.
111 * For more explanation see __gl_meshSplice() below.
112 */
113 static void Splice( GLUhalfEdge *a, GLUhalfEdge *b )
114 {
115 GLUhalfEdge *aOnext = a->Onext;
116 GLUhalfEdge *bOnext = b->Onext;
117
118 aOnext->Sym->Lnext = b;
119 bOnext->Sym->Lnext = a;
120 a->Onext = bOnext;
121 b->Onext = aOnext;
122 }
123
124 /* MakeVertex( newVertex, eOrig, vNext ) attaches a new vertex and makes it the
125 * origin of all edges in the vertex loop to which eOrig belongs. "vNext" gives
126 * a place to insert the new vertex in the global vertex list. We insert
127 * the new vertex *before* vNext so that algorithms which walk the vertex
128 * list will not see the newly created vertices.
129 */
130 static void MakeVertex( GLUvertex *newVertex,
131 GLUhalfEdge *eOrig, GLUvertex *vNext )
132 {
133 GLUhalfEdge *e;
134 GLUvertex *vPrev;
135 GLUvertex *vNew = newVertex;
136
137 assert(vNew != NULL);
138
139 /* insert in circular doubly-linked list before vNext */
140 vPrev = vNext->prev;
141 vNew->prev = vPrev;
142 vPrev->next = vNew;
143 vNew->next = vNext;
144 vNext->prev = vNew;
145
146 vNew->anEdge = eOrig;
147 vNew->data = NULL;
148 /* leave coords, s, t undefined */
149
150 /* fix other edges on this vertex loop */
151 e = eOrig;
152 do {
153 e->Org = vNew;
154 e = e->Onext;
155 } while( e != eOrig );
156 }
157
158 /* MakeFace( newFace, eOrig, fNext ) attaches a new face and makes it the left
159 * face of all edges in the face loop to which eOrig belongs. "fNext" gives
160 * a place to insert the new face in the global face list. We insert
161 * the new face *before* fNext so that algorithms which walk the face
162 * list will not see the newly created faces.
163 */
164 static void MakeFace( GLUface *newFace, GLUhalfEdge *eOrig, GLUface *fNext )
165 {
166 GLUhalfEdge *e;
167 GLUface *fPrev;
168 GLUface *fNew = newFace;
169
170 assert(fNew != NULL);
171
172 /* insert in circular doubly-linked list before fNext */
173 fPrev = fNext->prev;
174 fNew->prev = fPrev;
175 fPrev->next = fNew;
176 fNew->next = fNext;
177 fNext->prev = fNew;
178
179 fNew->anEdge = eOrig;
180 fNew->data = NULL;
181 fNew->trail = NULL;
182 fNew->marked = FALSE;
183
184 /* The new face is marked "inside" if the old one was. This is a
185 * convenience for the common case where a face has been split in two.
186 */
187 fNew->inside = fNext->inside;
188
189 /* fix other edges on this face loop */
190 e = eOrig;
191 do {
192 e->Lface = fNew;
193 e = e->Lnext;
194 } while( e != eOrig );
195 }
196
197 /* KillEdge( eDel ) destroys an edge (the half-edges eDel and eDel->Sym),
198 * and removes from the global edge list.
199 */
200 static void KillEdge( GLUhalfEdge *eDel )
201 {
202 GLUhalfEdge *ePrev, *eNext;
203
204 /* Half-edges are allocated in pairs, see EdgePair above */
205 if( eDel->Sym < eDel ) { eDel = eDel->Sym; }
206
207 /* delete from circular doubly-linked list */
208 eNext = eDel->next;
209 ePrev = eDel->Sym->next;
210 eNext->Sym->next = ePrev;
211 ePrev->Sym->next = eNext;
212
213 memFree( eDel );
214 }
215
216
217 /* KillVertex( vDel ) destroys a vertex and removes it from the global
218 * vertex list. It updates the vertex loop to point to a given new vertex.
219 */
220 static void KillVertex( GLUvertex *vDel, GLUvertex *newOrg )
221 {
222 GLUhalfEdge *e, *eStart = vDel->anEdge;
223 GLUvertex *vPrev, *vNext;
224
225 /* change the origin of all affected edges */
226 e = eStart;
227 do {
228 e->Org = newOrg;
229 e = e->Onext;
230 } while( e != eStart );
231
232 /* delete from circular doubly-linked list */
233 vPrev = vDel->prev;
234 vNext = vDel->next;
235 vNext->prev = vPrev;
236 vPrev->next = vNext;
237
238 memFree( vDel );
239 }
240
241 /* KillFace( fDel ) destroys a face and removes it from the global face
242 * list. It updates the face loop to point to a given new face.
243 */
244 static void KillFace( GLUface *fDel, GLUface *newLface )
245 {
246 GLUhalfEdge *e, *eStart = fDel->anEdge;
247 GLUface *fPrev, *fNext;
248
249 /* change the left face of all affected edges */
250 e = eStart;
251 do {
252 e->Lface = newLface;
253 e = e->Lnext;
254 } while( e != eStart );
255
256 /* delete from circular doubly-linked list */
257 fPrev = fDel->prev;
258 fNext = fDel->next;
259 fNext->prev = fPrev;
260 fPrev->next = fNext;
261
262 memFree( fDel );
263 }
264
265
266 /****************** Basic Edge Operations **********************/
267
268 /* __gl_meshMakeEdge creates one edge, two vertices, and a loop (face).
269 * The loop consists of the two new half-edges.
270 */
271 GLUhalfEdge *__gl_meshMakeEdge( GLUmesh *mesh )
272 {
273 GLUvertex *newVertex1= allocVertex();
274 GLUvertex *newVertex2= allocVertex();
275 GLUface *newFace= allocFace();
276 GLUhalfEdge *e;
277
278 /* if any one is null then all get freed */
279 if (newVertex1 == NULL || newVertex2 == NULL || newFace == NULL) {
280 if (newVertex1 != NULL) memFree(newVertex1);
281 if (newVertex2 != NULL) memFree(newVertex2);
282 if (newFace != NULL) memFree(newFace);
283 return NULL;
284 }
285
286 e = MakeEdge( &mesh->eHead );
287 if (e == NULL) return NULL;
288
289 MakeVertex( newVertex1, e, &mesh->vHead );
290 MakeVertex( newVertex2, e->Sym, &mesh->vHead );
291 MakeFace( newFace, e, &mesh->fHead );
292 return e;
293 }
294
295
296 /* __gl_meshSplice( eOrg, eDst ) is the basic operation for changing the
297 * mesh connectivity and topology. It changes the mesh so that
298 * eOrg->Onext <- OLD( eDst->Onext )
299 * eDst->Onext <- OLD( eOrg->Onext )
300 * where OLD(...) means the value before the meshSplice operation.
301 *
302 * This can have two effects on the vertex structure:
303 * - if eOrg->Org != eDst->Org, the two vertices are merged together
304 * - if eOrg->Org == eDst->Org, the origin is split into two vertices
305 * In both cases, eDst->Org is changed and eOrg->Org is untouched.
306 *
307 * Similarly (and independently) for the face structure,
308 * - if eOrg->Lface == eDst->Lface, one loop is split into two
309 * - if eOrg->Lface != eDst->Lface, two distinct loops are joined into one
310 * In both cases, eDst->Lface is changed and eOrg->Lface is unaffected.
311 *
312 * Some special cases:
313 * If eDst == eOrg, the operation has no effect.
314 * If eDst == eOrg->Lnext, the new face will have a single edge.
315 * If eDst == eOrg->Lprev, the old face will have a single edge.
316 * If eDst == eOrg->Onext, the new vertex will have a single edge.
317 * If eDst == eOrg->Oprev, the old vertex will have a single edge.
318 */
319 int __gl_meshSplice( GLUhalfEdge *eOrg, GLUhalfEdge *eDst )
320 {
321 int joiningLoops = FALSE;
322 int joiningVertices = FALSE;
323
324 if( eOrg == eDst ) return 1;
325
326 if( eDst->Org != eOrg->Org ) {
327 /* We are merging two disjoint vertices -- destroy eDst->Org */
328 joiningVertices = TRUE;
329 KillVertex( eDst->Org, eOrg->Org );
330 }
331 if( eDst->Lface != eOrg->Lface ) {
332 /* We are connecting two disjoint loops -- destroy eDst->Lface */
333 joiningLoops = TRUE;
334 KillFace( eDst->Lface, eOrg->Lface );
335 }
336
337 /* Change the edge structure */
338 Splice( eDst, eOrg );
339
340 if( ! joiningVertices ) {
341 GLUvertex *newVertex= allocVertex();
342 if (newVertex == NULL) return 0;
343
344 /* We split one vertex into two -- the new vertex is eDst->Org.
345 * Make sure the old vertex points to a valid half-edge.
346 */
347 MakeVertex( newVertex, eDst, eOrg->Org );
348 eOrg->Org->anEdge = eOrg;
349 }
350 if( ! joiningLoops ) {
351 GLUface *newFace= allocFace();
352 if (newFace == NULL) return 0;
353
354 /* We split one loop into two -- the new loop is eDst->Lface.
355 * Make sure the old face points to a valid half-edge.
356 */
357 MakeFace( newFace, eDst, eOrg->Lface );
358 eOrg->Lface->anEdge = eOrg;
359 }
360
361 return 1;
362 }
363
364
365 /* __gl_meshDelete( eDel ) removes the edge eDel. There are several cases:
366 * if (eDel->Lface != eDel->Rface), we join two loops into one; the loop
367 * eDel->Lface is deleted. Otherwise, we are splitting one loop into two;
368 * the newly created loop will contain eDel->Dst. If the deletion of eDel
369 * would create isolated vertices, those are deleted as well.
370 *
371 * This function could be implemented as two calls to __gl_meshSplice
372 * plus a few calls to memFree, but this would allocate and delete
373 * unnecessary vertices and faces.
374 */
375 int __gl_meshDelete( GLUhalfEdge *eDel )
376 {
377 GLUhalfEdge *eDelSym = eDel->Sym;
378 int joiningLoops = FALSE;
379
380 /* First step: disconnect the origin vertex eDel->Org. We make all
381 * changes to get a consistent mesh in this "intermediate" state.
382 */
383 if( eDel->Lface != eDel->Rface ) {
384 /* We are joining two loops into one -- remove the left face */
385 joiningLoops = TRUE;
386 KillFace( eDel->Lface, eDel->Rface );
387 }
388
389 if( eDel->Onext == eDel ) {
390 KillVertex( eDel->Org, NULL );
391 } else {
392 /* Make sure that eDel->Org and eDel->Rface point to valid half-edges */
393 eDel->Rface->anEdge = eDel->Oprev;
394 eDel->Org->anEdge = eDel->Onext;
395
396 Splice( eDel, eDel->Oprev );
397 if( ! joiningLoops ) {
398 GLUface *newFace= allocFace();
399 if (newFace == NULL) return 0;
400
401 /* We are splitting one loop into two -- create a new loop for eDel. */
402 MakeFace( newFace, eDel, eDel->Lface );
403 }
404 }
405
406 /* Claim: the mesh is now in a consistent state, except that eDel->Org
407 * may have been deleted. Now we disconnect eDel->Dst.
408 */
409 if( eDelSym->Onext == eDelSym ) {
410 KillVertex( eDelSym->Org, NULL );
411 KillFace( eDelSym->Lface, NULL );
412 } else {
413 /* Make sure that eDel->Dst and eDel->Lface point to valid half-edges */
414 eDel->Lface->anEdge = eDelSym->Oprev;
415 eDelSym->Org->anEdge = eDelSym->Onext;
416 Splice( eDelSym, eDelSym->Oprev );
417 }
418
419 /* Any isolated vertices or faces have already been freed. */
420 KillEdge( eDel );
421
422 return 1;
423 }
424
425
426 /******************** Other Edge Operations **********************/
427
428 /* All these routines can be implemented with the basic edge
429 * operations above. They are provided for convenience and efficiency.
430 */
431
432
433 /* __gl_meshAddEdgeVertex( eOrg ) creates a new edge eNew such that
434 * eNew == eOrg->Lnext, and eNew->Dst is a newly created vertex.
435 * eOrg and eNew will have the same left face.
436 */
437 GLUhalfEdge *__gl_meshAddEdgeVertex( GLUhalfEdge *eOrg )
438 {
439 GLUhalfEdge *eNewSym;
440 GLUhalfEdge *eNew = MakeEdge( eOrg );
441 if (eNew == NULL) return NULL;
442
443 eNewSym = eNew->Sym;
444
445 /* Connect the new edge appropriately */
446 Splice( eNew, eOrg->Lnext );
447
448 /* Set the vertex and face information */
449 eNew->Org = eOrg->Dst;
450 {
451 GLUvertex *newVertex= allocVertex();
452 if (newVertex == NULL) return NULL;
453
454 MakeVertex( newVertex, eNewSym, eNew->Org );
455 }
456 eNew->Lface = eNewSym->Lface = eOrg->Lface;
457
458 return eNew;
459 }
460
461
462 /* __gl_meshSplitEdge( eOrg ) splits eOrg into two edges eOrg and eNew,
463 * such that eNew == eOrg->Lnext. The new vertex is eOrg->Dst == eNew->Org.
464 * eOrg and eNew will have the same left face.
465 */
466 GLUhalfEdge *__gl_meshSplitEdge( GLUhalfEdge *eOrg )
467 {
468 GLUhalfEdge *eNew;
469 GLUhalfEdge *tempHalfEdge= __gl_meshAddEdgeVertex( eOrg );
470 if (tempHalfEdge == NULL) return NULL;
471
472 eNew = tempHalfEdge->Sym;
473
474 /* Disconnect eOrg from eOrg->Dst and connect it to eNew->Org */
475 Splice( eOrg->Sym, eOrg->Sym->Oprev );
476 Splice( eOrg->Sym, eNew );
477
478 /* Set the vertex and face information */
479 eOrg->Dst = eNew->Org;
480 eNew->Dst->anEdge = eNew->Sym; /* may have pointed to eOrg->Sym */
481 eNew->Rface = eOrg->Rface;
482 eNew->winding = eOrg->winding; /* copy old winding information */
483 eNew->Sym->winding = eOrg->Sym->winding;
484
485 return eNew;
486 }
487
488
489 /* __gl_meshConnect( eOrg, eDst ) creates a new edge from eOrg->Dst
490 * to eDst->Org, and returns the corresponding half-edge eNew.
491 * If eOrg->Lface == eDst->Lface, this splits one loop into two,
492 * and the newly created loop is eNew->Lface. Otherwise, two disjoint
493 * loops are merged into one, and the loop eDst->Lface is destroyed.
494 *
495 * If (eOrg == eDst), the new face will have only two edges.
496 * If (eOrg->Lnext == eDst), the old face is reduced to a single edge.
497 * If (eOrg->Lnext->Lnext == eDst), the old face is reduced to two edges.
498 */
499 GLUhalfEdge *__gl_meshConnect( GLUhalfEdge *eOrg, GLUhalfEdge *eDst )
500 {
501 GLUhalfEdge *eNewSym;
502 int joiningLoops = FALSE;
503 GLUhalfEdge *eNew = MakeEdge( eOrg );
504 if (eNew == NULL) return NULL;
505
506 eNewSym = eNew->Sym;
507
508 if( eDst->Lface != eOrg->Lface ) {
509 /* We are connecting two disjoint loops -- destroy eDst->Lface */
510 joiningLoops = TRUE;
511 KillFace( eDst->Lface, eOrg->Lface );
512 }
513
514 /* Connect the new edge appropriately */
515 Splice( eNew, eOrg->Lnext );
516 Splice( eNewSym, eDst );
517
518 /* Set the vertex and face information */
519 eNew->Org = eOrg->Dst;
520 eNewSym->Org = eDst->Org;
521 eNew->Lface = eNewSym->Lface = eOrg->Lface;
522
523 /* Make sure the old face points to a valid half-edge */
524 eOrg->Lface->anEdge = eNewSym;
525
526 if( ! joiningLoops ) {
527 GLUface *newFace= allocFace();
528 if (newFace == NULL) return NULL;
529
530 /* We split one loop into two -- the new loop is eNew->Lface */
531 MakeFace( newFace, eNew, eOrg->Lface );
532 }
533 return eNew;
534 }
535
536
537 /******************** Other Operations **********************/
538
539 /* __gl_meshZapFace( fZap ) destroys a face and removes it from the
540 * global face list. All edges of fZap will have a NULL pointer as their
541 * left face. Any edges which also have a NULL pointer as their right face
542 * are deleted entirely (along with any isolated vertices this produces).
543 * An entire mesh can be deleted by zapping its faces, one at a time,
544 * in any order. Zapped faces cannot be used in further mesh operations!
545 */
546 void __gl_meshZapFace( GLUface *fZap )
547 {
548 GLUhalfEdge *eStart = fZap->anEdge;
549 GLUhalfEdge *e, *eNext, *eSym;
550 GLUface *fPrev, *fNext;
551
552 /* walk around face, deleting edges whose right face is also NULL */
553 eNext = eStart->Lnext;
554 do {
555 e = eNext;
556 eNext = e->Lnext;
557
558 e->Lface = NULL;
559 if( e->Rface == NULL ) {
560 /* delete the edge -- see __gl_MeshDelete above */
561
562 if( e->Onext == e ) {
563 KillVertex( e->Org, NULL );
564 } else {
565 /* Make sure that e->Org points to a valid half-edge */
566 e->Org->anEdge = e->Onext;
567 Splice( e, e->Oprev );
568 }
569 eSym = e->Sym;
570 if( eSym->Onext == eSym ) {
571 KillVertex( eSym->Org, NULL );
572 } else {
573 /* Make sure that eSym->Org points to a valid half-edge */
574 eSym->Org->anEdge = eSym->Onext;
575 Splice( eSym, eSym->Oprev );
576 }
577 KillEdge( e );
578 }
579 } while( e != eStart );
580
581 /* delete from circular doubly-linked list */
582 fPrev = fZap->prev;
583 fNext = fZap->next;
584 fNext->prev = fPrev;
585 fPrev->next = fNext;
586
587 memFree( fZap );
588 }
589
590
591 /* __gl_meshNewMesh() creates a new mesh with no edges, no vertices,
592 * and no loops (what we usually call a "face").
593 */
594 GLUmesh *__gl_meshNewMesh( void )
595 {
596 GLUvertex *v;
597 GLUface *f;
598 GLUhalfEdge *e;
599 GLUhalfEdge *eSym;
600 GLUmesh *mesh = (GLUmesh *)memAlloc( sizeof( GLUmesh ));
601 if (mesh == NULL) {
602 return NULL;
603 }
604
605 v = &mesh->vHead;
606 f = &mesh->fHead;
607 e = &mesh->eHead;
608 eSym = &mesh->eHeadSym;
609
610 v->next = v->prev = v;
611 v->anEdge = NULL;
612 v->data = NULL;
613
614 f->next = f->prev = f;
615 f->anEdge = NULL;
616 f->data = NULL;
617 f->trail = NULL;
618 f->marked = FALSE;
619 f->inside = FALSE;
620
621 e->next = e;
622 e->Sym = eSym;
623 e->Onext = NULL;
624 e->Lnext = NULL;
625 e->Org = NULL;
626 e->Lface = NULL;
627 e->winding = 0;
628 e->activeRegion = NULL;
629
630 eSym->next = eSym;
631 eSym->Sym = e;
632 eSym->Onext = NULL;
633 eSym->Lnext = NULL;
634 eSym->Org = NULL;
635 eSym->Lface = NULL;
636 eSym->winding = 0;
637 eSym->activeRegion = NULL;
638
639 return mesh;
640 }
641
642
643 /* __gl_meshUnion( mesh1, mesh2 ) forms the union of all structures in
644 * both meshes, and returns the new mesh (the old meshes are destroyed).
645 */
646 GLUmesh *__gl_meshUnion( GLUmesh *mesh1, GLUmesh *mesh2 )
647 {
648 GLUface *f1 = &mesh1->fHead;
649 GLUvertex *v1 = &mesh1->vHead;
650 GLUhalfEdge *e1 = &mesh1->eHead;
651 GLUface *f2 = &mesh2->fHead;
652 GLUvertex *v2 = &mesh2->vHead;
653 GLUhalfEdge *e2 = &mesh2->eHead;
654
655 /* Add the faces, vertices, and edges of mesh2 to those of mesh1 */
656 if( f2->next != f2 ) {
657 f1->prev->next = f2->next;
658 f2->next->prev = f1->prev;
659 f2->prev->next = f1;
660 f1->prev = f2->prev;
661 }
662
663 if( v2->next != v2 ) {
664 v1->prev->next = v2->next;
665 v2->next->prev = v1->prev;
666 v2->prev->next = v1;
667 v1->prev = v2->prev;
668 }
669
670 if( e2->next != e2 ) {
671 e1->Sym->next->Sym->next = e2->next;
672 e2->next->Sym->next = e1->Sym->next;
673 e2->Sym->next->Sym->next = e1;
674 e1->Sym->next = e2->Sym->next;
675 }
676
677 memFree( mesh2 );
678 return mesh1;
679 }
680
681
682 #ifdef DELETE_BY_ZAPPING
683
684 /* __gl_meshDeleteMesh( mesh ) will free all storage for any valid mesh.
685 */
686 void __gl_meshDeleteMesh( GLUmesh *mesh )
687 {
688 GLUface *fHead = &mesh->fHead;
689
690 while( fHead->next != fHead ) {
691 __gl_meshZapFace( fHead->next );
692 }
693 assert( mesh->vHead.next == &mesh->vHead );
694
695 memFree( mesh );
696 }
697
698 #else
699
700 /* __gl_meshDeleteMesh( mesh ) will free all storage for any valid mesh.
701 */
702 void __gl_meshDeleteMesh( GLUmesh *mesh )
703 {
704 GLUface *f, *fNext;
705 GLUvertex *v, *vNext;
706 GLUhalfEdge *e, *eNext;
707
708 for( f = mesh->fHead.next; f != &mesh->fHead; f = fNext ) {
709 fNext = f->next;
710 memFree( f );
711 }
712
713 for( v = mesh->vHead.next; v != &mesh->vHead; v = vNext ) {
714 vNext = v->next;
715 memFree( v );
716 }
717
718 for( e = mesh->eHead.next; e != &mesh->eHead; e = eNext ) {
719 /* One call frees both e and e->Sym (see EdgePair above) */
720 eNext = e->next;
721 memFree( e );
722 }
723
724 memFree( mesh );
725 }
726
727 #endif
728
729 #ifndef NDEBUG
730
731 /* __gl_meshCheckMesh( mesh ) checks a mesh for self-consistency.
732 */
733 void __gl_meshCheckMesh( GLUmesh *mesh )
734 {
735 GLUface *fHead = &mesh->fHead;
736 GLUvertex *vHead = &mesh->vHead;
737 GLUhalfEdge *eHead = &mesh->eHead;
738 GLUface *f, *fPrev;
739 GLUvertex *v, *vPrev;
740 GLUhalfEdge *e, *ePrev;
741
742 fPrev = fHead;
743 for( fPrev = fHead ; (f = fPrev->next) != fHead; fPrev = f) {
744 assert( f->prev == fPrev );
745 e = f->anEdge;
746 do {
747 assert( e->Sym != e );
748 assert( e->Sym->Sym == e );
749 assert( e->Lnext->Onext->Sym == e );
750 assert( e->Onext->Sym->Lnext == e );
751 assert( e->Lface == f );
752 e = e->Lnext;
753 } while( e != f->anEdge );
754 }
755 assert( f->prev == fPrev && f->anEdge == NULL && f->data == NULL );
756
757 vPrev = vHead;
758 for( vPrev = vHead ; (v = vPrev->next) != vHead; vPrev = v) {
759 assert( v->prev == vPrev );
760 e = v->anEdge;
761 do {
762 assert( e->Sym != e );
763 assert( e->Sym->Sym == e );
764 assert( e->Lnext->Onext->Sym == e );
765 assert( e->Onext->Sym->Lnext == e );
766 assert( e->Org == v );
767 e = e->Onext;
768 } while( e != v->anEdge );
769 }
770 assert( v->prev == vPrev && v->anEdge == NULL && v->data == NULL );
771
772 ePrev = eHead;
773 for( ePrev = eHead ; (e = ePrev->next) != eHead; ePrev = e) {
774 assert( e->Sym->next == ePrev->Sym );
775 assert( e->Sym != e );
776 assert( e->Sym->Sym == e );
777 assert( e->Org != NULL );
778 assert( e->Dst != NULL );
779 assert( e->Lnext->Onext->Sym == e );
780 assert( e->Onext->Sym->Lnext == e );
781 }
782 assert( e->Sym->next == ePrev->Sym
783 && e->Sym == &mesh->eHeadSym
784 && e->Sym->Sym == e
785 && e->Org == NULL && e->Dst == NULL
786 && e->Lface == NULL && e->Rface == NULL );
787 }
788
789 #endif