source/blender/bmesh/tools/bmesh_decimate_collapse.c

   1 /*
   2  * ***** BEGIN GPL LICENSE BLOCK *****
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version 2
   7  * of the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software Foundation,
  16  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  17  *
  18  * Contributor(s): Campbell Barton
  19  *
  20  * ***** END GPL LICENSE BLOCK *****
  21  */
  22
  23 /** \file blender/bmesh/tools/bmesh_decimate_collapse.c
  24  *  \ingroup bmesh
  25  *
  26  * BMesh decimator that uses an edge collapse method.
  27  */
  28
  29 #include <stddef.h>
  30
  31 #include "MEM_guardedalloc.h"
  32
  33 #include "DNA_scene_types.h"
  34
  35 #include "BLI_math.h"
  36 #include "BLI_quadric.h"
  37 #include "BLI_heap.h"
  38
  39 #include "BKE_customdata.h"
  40
  41 #include "bmesh.h"
  42 #include "bmesh_decimate.h"  /* own include */
  43
  44 #include "../intern/bmesh_structure.h"
  45
  46 /* defines for testing */
  47 #define USE_CUSTOMDATA
  48 #define USE_TRIANGULATE
  49 #define USE_VERT_NORMAL_INTERP  /* has the advantage that flipped faces don't mess up vertex normals */
  50
  51 /* these checks are for rare cases that we can't avoid since they are valid meshes still */
  52 #define USE_SAFETY_CHECKS
  53
  54 #define BOUNDARY_PRESERVE_WEIGHT 100.0f
  55 #define OPTIMIZE_EPS 0.01f  /* FLT_EPSILON is too small, see [#33106] */
  56 #define COST_INVALID FLT_MAX
  57
  58 typedef enum CD_UseFlag {
  59         CD_DO_VERT = (1 << 0),
  60         CD_DO_EDGE = (1 << 1),
  61         CD_DO_LOOP = (1 << 2)
  62 } CD_UseFlag;
  63
  64
  65 /* BMesh Helper Functions
  66  * ********************** */
  67
  68 /**
  69  * \param vquadrics must be calloc'd
  70  */
  71 static void bm_decim_build_quadrics(BMesh *bm, Quadric *vquadrics)
  72 {
  73         BMIter iter;
  74         BMFace *f;
  75         BMEdge *e;
  76
  77         BM_ITER_MESH (f, &iter, bm, BM_FACES_OF_MESH) {
  78                 BMLoop *l_first;
  79                 BMLoop *l_iter;
  80
  81                 const float *co = BM_FACE_FIRST_LOOP(f)->v->co;
  82                 const float *no = f->no;
  83                 const float offset = -dot_v3v3(no, co);
  84                 Quadric q;
  85
  86                 BLI_quadric_from_v3_dist(&q, no, offset);
  87
  88                 l_iter = l_first = BM_FACE_FIRST_LOOP(f);
  89                 do {
  90                         BLI_quadric_add_qu_qu(&vquadrics[BM_elem_index_get(l_iter->v)], &q);
  91                 } while ((l_iter = l_iter->next) != l_first);
  92         }
  93
  94         /* boundary edges */
  95         BM_ITER_MESH (e, &iter, bm, BM_EDGES_OF_MESH) {
  96                 if (UNLIKELY(BM_edge_is_boundary(e))) {
  97                         float edge_vector[3];
  98                         float edge_cross[3];
  99                         sub_v3_v3v3(edge_vector, e->v2->co, e->v1->co);
 100                         f = e->l->f;
 101                         cross_v3_v3v3(edge_cross, edge_vector, f->no);
 102
 103                         if (normalize_v3(edge_cross) > FLT_EPSILON) {
 104                                 Quadric q;
 105                                 BLI_quadric_from_v3_dist(&q, edge_cross, -dot_v3v3(edge_cross, e->v1->co));
 106                                 BLI_quadric_mul(&q, BOUNDARY_PRESERVE_WEIGHT);
 107
 108                                 BLI_quadric_add_qu_qu(&vquadrics[BM_elem_index_get(e->v1)], &q);
 109                                 BLI_quadric_add_qu_qu(&vquadrics[BM_elem_index_get(e->v2)], &q);
 110                         }
 111                 }
 112         }
 113 }
 114
 115
 116 static void bm_decim_calc_target_co(BMEdge *e, float optimize_co[3],
 117                                     const Quadric *vquadrics)
 118 {
 119         /* compute an edge contraction target for edge 'e'
 120          * this is computed by summing it's vertices quadrics and
 121          * optimizing the result. */
 122         Quadric q;
 123
 124         BLI_quadric_add_qu_ququ(&q,
 125                                 &vquadrics[BM_elem_index_get(e->v1)],
 126                                 &vquadrics[BM_elem_index_get(e->v2)]);
 127
 128
 129         if (BLI_quadric_optimize(&q, optimize_co, OPTIMIZE_EPS)) {
 130                 return;  /* all is good */
 131         }
 132         else {
 133                 mid_v3_v3v3(optimize_co, e->v1->co, e->v2->co);
 134         }
 135 }
 136
 137 static bool bm_edge_collapse_is_degenerate_flip(BMEdge *e, const float optimize_co[3])
 138 {
 139         BMIter liter;
 140         BMLoop *l;
 141         unsigned int i;
 142
 143         for (i = 0; i < 2; i++) {
 144                 /* loop over both verts */
 145                 BMVert *v = *((&e->v1) + i);
 146
 147                 BM_ITER_ELEM (l, &liter, v, BM_LOOPS_OF_VERT) {
 148                         if (l->e != e && l->prev->e != e) {
 149                                 float *co_prev = l->prev->v->co;
 150                                 float *co_next = l->next->v->co;
 151                                 float cross_exist[3];
 152                                 float cross_optim[3];
 153
 154 #if 1
 155                                 float vec_other[3];  /* line between the two outer verts, re-use for both cross products */
 156                                 float vec_exist[3];  /* before collapse */
 157                                 float vec_optim[3];  /* after collapse */
 158
 159                                 sub_v3_v3v3(vec_other, co_prev, co_next);
 160                                 sub_v3_v3v3(vec_exist, co_prev, v->co);
 161                                 sub_v3_v3v3(vec_optim, co_prev, optimize_co);
 162
 163                                 cross_v3_v3v3(cross_exist, vec_other, vec_exist);
 164                                 cross_v3_v3v3(cross_optim, vec_other, vec_optim);
 165
 166                                 /* normalize isn't really needed, but ensures the value at a unit we can compare against */
 167                                 normalize_v3(cross_exist);
 168                                 normalize_v3(cross_optim);
 169 #else
 170                                 normal_tri_v3(cross_exist, v->co,       co_prev, co_next);
 171                                 normal_tri_v3(cross_optim, optimize_co, co_prev, co_next);
 172 #endif
 173
 174                                 /* use a small value rather then zero so we don't flip a face in multiple steps
 175                                  * (first making it zero area, then flipping again) */
 176                                 if (dot_v3v3(cross_exist, cross_optim) <= FLT_EPSILON) {
 177                                         //printf("no flip\n");
 178                                         return true;
 179                                 }
 180                         }
 181                 }
 182         }
 183
 184         return false;
 185 }
 186
 187 static void bm_decim_build_edge_cost_single(BMEdge *e,
 188                                             const Quadric *vquadrics, const float *vweights,
 189                                             Heap *eheap, HeapNode **eheap_table)
 190 {
 191         const Quadric *q1, *q2;
 192         float optimize_co[3];
 193         float cost;
 194
 195         if (eheap_table[BM_elem_index_get(e)]) {
 196                 BLI_heap_remove(eheap, eheap_table[BM_elem_index_get(e)]);
 197         }
 198
 199         /* check we can collapse, some edges we better not touch */
 200         if (BM_edge_is_boundary(e)) {
 201                 if (e->l->f->len == 3) {
 202                         /* pass */
 203                 }
 204                 else {
 205                         /* only collapse tri's */
 206                         eheap_table[BM_elem_index_get(e)] = NULL;
 207                         return;
 208                 }
 209         }
 210         else if (BM_edge_is_manifold(e)) {
 211                 if ((e->l->f->len == 3) && (e->l->radial_next->f->len == 3)) {
 212                         /* pass */
 213                 }
 214                 else {
 215                         /* only collapse tri's */
 216                         eheap_table[BM_elem_index_get(e)] = NULL;
 217                         return;
 218                 }
 219         }
 220         else {
 221                 eheap_table[BM_elem_index_get(e)] = NULL;
 222                 return;
 223         }
 224
 225         if (vweights) {
 226                 if ((vweights[BM_elem_index_get(e->v1)] >= BM_MESH_DECIM_WEIGHT_MAX) &&
 227                     (vweights[BM_elem_index_get(e->v2)] >= BM_MESH_DECIM_WEIGHT_MAX))
 228                 {
 229                         /* skip collapsing this edge */
 230                         eheap_table[BM_elem_index_get(e)] = NULL;
 231                         return;
 232                 }
 233         }
 234         /* end sanity check */
 235
 236
 237         bm_decim_calc_target_co(e, optimize_co, vquadrics);
 238
 239         q1 = &vquadrics[BM_elem_index_get(e->v1)];
 240         q2 = &vquadrics[BM_elem_index_get(e->v2)];
 241
 242         if (vweights == NULL) {
 243                 cost = (BLI_quadric_evaluate(q1, optimize_co) +
 244                         BLI_quadric_evaluate(q2, optimize_co));
 245         }
 246         else {
 247                 /* add 1.0 so planar edges are still weighted against */
 248                 cost = (((BLI_quadric_evaluate(q1, optimize_co) + 1.0f) * vweights[BM_elem_index_get(e->v1)]) +
 249                         ((BLI_quadric_evaluate(q2, optimize_co) + 1.0f) * vweights[BM_elem_index_get(e->v2)]));
 250         }
 251         // print("COST %.12f\n");
 252
 253         eheap_table[BM_elem_index_get(e)] = BLI_heap_insert(eheap, cost, e);
 254 }
 255
 256
 257 /* use this for degenerate cases - add back to the heap with an invalid cost,
 258  * this way it may be calculated again if surrounding geometry changes */
 259 static void bm_decim_invalid_edge_cost_single(BMEdge *e,
 260                                               Heap *eheap, HeapNode **eheap_table)
 261 {
 262         BLI_assert(eheap_table[BM_elem_index_get(e)] == NULL);
 263         eheap_table[BM_elem_index_get(e)] = BLI_heap_insert(eheap, COST_INVALID, e);
 264 }
 265
 266 static void bm_decim_build_edge_cost(BMesh *bm,
 267                                      const Quadric *vquadrics, const float *vweights,
 268                                      Heap *eheap, HeapNode **eheap_table)
 269 {
 270         BMIter iter;
 271         BMEdge *e;
 272         unsigned int i;
 273
 274         BM_ITER_MESH_INDEX (e, &iter, bm, BM_EDGES_OF_MESH, i) {
 275                 eheap_table[i] = NULL;  /* keep sanity check happy */
 276                 bm_decim_build_edge_cost_single(e, vquadrics, vweights, eheap, eheap_table);
 277         }
 278 }
 279
 280 #ifdef USE_TRIANGULATE
 281 /* Temp Triangulation
 282  * ****************** */
 283
 284 /**
 285  * To keep things simple we can only collapse edges on triangulated data
 286  * (limitation with edge collapse and error calculation functions).
 287  *
 288  * But to avoid annoying users by only giving triangle results, we can
 289  * triangulate, keeping a reference between the faces, then join after
 290  * if the edges don't collapse, this will also allow more choices when
 291  * collapsing edges so even has some advantage over decimating quads
 292  * directly.
 293  *
 294  * \return true if any faces were triangulated.
 295  */
 296
 297 static bool bm_decim_triangulate_begin(BMesh *bm)
 298 {
 299         BMIter iter;
 300         BMFace *f;
 301         // bool has_quad;  // could optimize this a little
 302         bool has_cut = false;
 303
 304         BLI_assert((bm->elem_index_dirty & BM_VERT) == 0);
 305
 306         /* first clear loop index values */
 307         BM_ITER_MESH (f, &iter, bm, BM_FACES_OF_MESH) {
 308                 BMLoop *l_iter;
 309                 BMLoop *l_first;
 310
 311                 l_iter = l_first = BM_FACE_FIRST_LOOP(f);
 312                 do {
 313                         BM_elem_index_set(l_iter, -1);
 314                 } while ((l_iter = l_iter->next) != l_first);
 315
 316                 // has_quad |= (f->len == 4)
 317         }
 318
 319         /* adding new faces as we loop over faces
 320          * is normally best avoided, however in this case its not so bad because any face touched twice
 321          * will already be triangulated*/
 322         BM_ITER_MESH (f, &iter, bm, BM_FACES_OF_MESH) {
 323                 if (f->len == 4) {
 324                         BMLoop *f_l[4];
 325                         BMLoop *l_a, *l_b;
 326
 327                         {
 328                                 BMLoop *l_iter = BM_FACE_FIRST_LOOP(f);
 329
 330                                 f_l[0] = l_iter; l_iter = l_iter->next;
 331                                 f_l[1] = l_iter; l_iter = l_iter->next;
 332                                 f_l[2] = l_iter; l_iter = l_iter->next;
 333                                 f_l[3] = l_iter;
 334                         }
 335
 336                         if (len_squared_v3v3(f_l[0]->v->co, f_l[2]->v->co) <
 337                             len_squared_v3v3(f_l[1]->v->co, f_l[3]->v->co))
 338                         {
 339                                 l_a = f_l[0];
 340                                 l_b = f_l[2];
 341                         }
 342                         else {
 343                                 l_a = f_l[1];
 344                                 l_b = f_l[3];
 345                         }
 346
 347 #ifdef USE_SAFETY_CHECKS
 348                         if (BM_edge_exists(l_a->v, l_b->v) == false)
 349 #endif
 350                         {
 351                                 BMFace *f_new;
 352                                 BMLoop *l_new;
 353
 354                                 /* warning, NO_DOUBLE option here isn't handled as nice as it could be
 355                                  * - if there is a quad that has a free standing edge joining it along
 356                                  * where we want to split the face, there isnt a good way we can handle this.
 357                                  * currently that edge will get removed when joining the tris back into a quad. */
 358                                 f_new = BM_face_split(bm, f, l_a->v, l_b->v, &l_new, NULL, false);
 359
 360                                 if (f_new) {
 361                                         /* the value of this doesn't matter, only that the 2 loops match and have unique values */
 362                                         const int f_index = BM_elem_index_get(f);
 363
 364                                         /* since we just split theres only ever 2 loops */
 365                                         BLI_assert(BM_edge_is_manifold(l_new->e));
 366
 367                                         BM_elem_index_set(l_new, f_index);
 368                                         BM_elem_index_set(l_new->radial_next, f_index);
 369
 370                                         BM_face_normal_update(f);
 371                                         BM_face_normal_update(f_new);
 372
 373                                         has_cut = true;
 374                                 }
 375                         }
 376                 }
 377         }
 378
 379         BLI_assert((bm->elem_index_dirty & BM_VERT) == 0);
 380
 381         if (has_cut) {
 382                 /* now triangulation is done we need to correct index values */
 383                 BM_mesh_elem_index_ensure(bm, BM_EDGE | BM_FACE);
 384         }
 385
 386         return has_cut;
 387 }
 388
 389 static void bm_decim_triangulate_end(BMesh *bm)
 390 {
 391         /* decimation finished, now re-join */
 392         BMIter iter;
 393         BMEdge *e;
 394
 395         /* boundary edges */
 396         BM_ITER_MESH (e, &iter, bm, BM_EDGES_OF_MESH) {
 397                 BMLoop *l_a, *l_b;
 398                 if (BM_edge_loop_pair(e, &l_a, &l_b)) {
 399                         const int l_a_index = BM_elem_index_get(l_a);
 400                         if (l_a_index != -1) {
 401                                 const int l_b_index = BM_elem_index_get(l_b);
 402                                 if (l_a_index == l_b_index) {
 403                                         if (LIKELY(l_a->f->len == 3 && l_b->f->len == 3)) {
 404                                                 if (l_a->v != l_b->v) {  /* if this is the case, faces have become flipped */
 405                                                         /* check we are not making a degenerate quad */
 406                                                         BMVert *vquad[4] = {
 407                                                                 e->v1,
 408                                                                 BM_vert_in_edge(e, l_a->next->v) ? l_a->prev->v : l_a->next->v,
 409                                                                 e->v2,
 410                                                                 BM_vert_in_edge(e, l_b->next->v) ? l_b->prev->v : l_b->next->v,
 411                                                         };
 412
 413                                                         BLI_assert(ELEM3(vquad[0], vquad[1], vquad[2], vquad[3]) == false);
 414                                                         BLI_assert(ELEM3(vquad[1], vquad[0], vquad[2], vquad[3]) == false);
 415                                                         BLI_assert(ELEM3(vquad[2], vquad[1], vquad[0], vquad[3]) == false);
 416                                                         BLI_assert(ELEM3(vquad[3], vquad[1], vquad[2], vquad[0]) == false);
 417
 418                                                         if (is_quad_convex_v3(vquad[0]->co, vquad[1]->co, vquad[2]->co, vquad[3]->co)) {
 419                                                                 /* highly unlikely to fail, but prevents possible double-ups */
 420                                                                 BMFace *f[2] = {l_a->f, l_b->f};
 421                                                                 BM_faces_join(bm, f, 2, true);
 422                                                         }
 423                                                 }
 424                                         }
 425                                 }
 426                         }
 427                 }
 428         }
 429 }
 430
 431 #endif  /* USE_TRIANGULATE */
 432
 433 /* Edge Collapse Functions
 434  * *********************** */
 435
 436 #ifdef USE_CUSTOMDATA
 437
 438 /**
 439  * \param v is the target to merge into.
 440  */
 441 static void bm_edge_collapse_loop_customdata(BMesh *bm, BMLoop *l, BMVert *v_clear, BMVert *v_other,
 442                                              const float customdata_fac)
 443 {
 444         /* disable seam check - the seam check would have to be done per layer, its not really that important */
 445 //#define USE_SEAM
 446         /* these don't need to be updated, since they will get removed when the edge collapses */
 447         BMLoop *l_clear, *l_other;
 448         const bool is_manifold = BM_edge_is_manifold(l->e);
 449         int side;
 450
 451         /* l defines the vert to collapse into  */
 452
 453         /* first find the loop of 'v_other' thats attached to the face of 'l' */
 454         if (l->v == v_clear) {
 455                 l_clear = l;
 456                 l_other = l->next;
 457         }
 458         else {
 459                 l_clear = l->next;
 460                 l_other = l;
 461         }
 462
 463         BLI_assert(l_clear->v == v_clear);
 464         BLI_assert(l_other->v == v_other);
 465         (void)v_other;  /* quiet warnings for release */
 466
 467         /* now we have both corners of the face 'l->f' */
 468         for (side = 0; side < 2; side++) {
 469 #ifdef USE_SEAM
 470                 bool is_seam = false;
 471 #endif
 472                 void *src[2];
 473                 BMFace *f_exit = is_manifold ? l->radial_next->f : NULL;
 474                 BMEdge *e_prev = l->e;
 475                 BMLoop *l_first;
 476                 BMLoop *l_iter;
 477                 float w[2];
 478
 479                 if (side == 0) {
 480                         l_iter = l_first = l_clear;
 481                         src[0] = l_clear->head.data;
 482                         src[1] = l_other->head.data;
 483
 484                         w[0] = customdata_fac;
 485                         w[1] = 1.0f - customdata_fac;
 486                 }
 487                 else {
 488                         l_iter = l_first = l_other;
 489                         src[0] = l_other->head.data;
 490                         src[1] = l_clear->head.data;
 491
 492                         w[0] = 1.0f - customdata_fac;
 493                         w[1] = customdata_fac;
 494                 }
 495
 496                 // print_v2("weights", w);
 497
 498                 /* WATCH IT! - should NOT reference (_clear or _other) vars for this while loop */
 499
 500                 /* walk around the fan using 'e_prev' */
 501                 while (((l_iter = BM_vert_step_fan_loop(l_iter, &e_prev)) != l_first) && (l_iter != NULL)) {
 502                         int i;
 503                         /* quit once we hit the opposite face, if we have one */
 504                         if (f_exit && UNLIKELY(f_exit == l_iter->f)) {
 505                                 break;
 506                         }
 507
 508 #ifdef USE_SEAM
 509                         /* break out unless we find a match */
 510                         is_seam = true;
 511 #endif
 512
 513                         /* ok. we have a loop. now be smart with it! */
 514                         for (i = 0; i < bm->ldata.totlayer; i++) {
 515                                 if (CustomData_layer_has_math(&bm->ldata, i)) {
 516                                         const int offset = bm->ldata.layers[i].offset;
 517                                         const int type = bm->ldata.layers[i].type;
 518                                         void *cd_src[2] = {(char *)src[0] + offset,
 519                                                            (char *)src[1] + offset};
 520                                         void *cd_iter = (char *)l_iter->head.data + offset;
 521
 522                                         /* detect seams */
 523                                         if (CustomData_data_equals(type, cd_src[0], cd_iter)) {
 524                                                 CustomData_bmesh_interp_n(&bm->ldata, cd_src, w, NULL, 2, l_iter->head.data, i);
 525 #ifdef USE_SEAM
 526                                                 is_seam = false;
 527 #endif
 528                                         }
 529                                 }
 530                         }
 531
 532 #ifdef USE_SEAM
 533                         if (is_seam) {
 534                                 break;
 535                         }
 536 #endif
 537                 }
 538         }
 539
 540 //#undef USE_SEAM
 541
 542 }
 543 #endif  /* USE_CUSTOMDATA */
 544
 545 /**
 546  * Check if the collapse will result in a degenerate mesh,
 547  * that is - duplicate edges or faces.
 548  *
 549  * This situation could be checked for when calculating collapse cost
 550  * however its quite slow and a degenerate collapse could eventuate
 551  * after the cost is calculated, so instead, check just before collapsing.
 552  */
 553
 554 static void bm_edge_tag_enable(BMEdge *e)
 555 {
 556         BM_elem_flag_enable(e->v1, BM_ELEM_TAG);
 557         BM_elem_flag_enable(e->v2, BM_ELEM_TAG);
 558         if (e->l) {
 559                 BM_elem_flag_enable(e->l->f, BM_ELEM_TAG);
 560                 if (e->l != e->l->radial_next) {
 561                         BM_elem_flag_enable(e->l->radial_next->f, BM_ELEM_TAG);
 562                 }
 563         }
 564 }
 565
 566 static void bm_edge_tag_disable(BMEdge *e)
 567 {
 568         BM_elem_flag_disable(e->v1, BM_ELEM_TAG);
 569         BM_elem_flag_disable(e->v2, BM_ELEM_TAG);
 570         if (e->l) {
 571                 BM_elem_flag_disable(e->l->f, BM_ELEM_TAG);
 572                 if (e->l != e->l->radial_next) {
 573                         BM_elem_flag_disable(e->l->radial_next->f, BM_ELEM_TAG);
 574                 }
 575         }
 576 }
 577
 578 static int bm_edge_tag_test(BMEdge *e)
 579 {
 580         /* is the edge or one of its faces tagged? */
 581         return (BM_elem_flag_test(e->v1, BM_ELEM_TAG) ||
 582                 BM_elem_flag_test(e->v2, BM_ELEM_TAG) ||
 583                 (e->l && (BM_elem_flag_test(e->l->f, BM_ELEM_TAG) ||
 584                           (e->l != e->l->radial_next &&
 585                           BM_elem_flag_test(e->l->radial_next->f, BM_ELEM_TAG))))
 586                 );
 587 }
 588
 589 /* takes the edges loop */
 590 BLI_INLINE int bm_edge_is_manifold_or_boundary(BMLoop *l)
 591 {
 592 #if 0
 593         /* less optimized version of check below */
 594         return (BM_edge_is_manifold(l->e) || BM_edge_is_boundary(l->e);
 595 #else
 596         /* if the edge is a boundary it points to its self, else this must be a manifold */
 597         return LIKELY(l) && LIKELY(l->radial_next->radial_next == l);
 598 #endif
 599 }
 600
 601 static bool bm_edge_collapse_is_degenerate_topology(BMEdge *e_first)
 602 {
 603         /* simply check that there is no overlap between faces and edges of each vert,
 604          * (excluding the 2 faces attached to 'e' and 'e' its self) */
 605
 606         BMEdge *e_iter;
 607
 608         /* clear flags on both disks */
 609         e_iter = e_first;
 610         do {
 611                 if (!bm_edge_is_manifold_or_boundary(e_iter->l)) {
 612                         return true;
 613                 }
 614                 bm_edge_tag_disable(e_iter);
 615         } while ((e_iter = bmesh_disk_edge_next(e_iter, e_first->v1)) != e_first);
 616
 617         e_iter = e_first;
 618         do {
 619                 if (!bm_edge_is_manifold_or_boundary(e_iter->l)) {
 620                         return true;
 621                 }
 622                 bm_edge_tag_disable(e_iter);
 623         } while ((e_iter = bmesh_disk_edge_next(e_iter, e_first->v2)) != e_first);
 624
 625         /* now enable one side... */
 626         e_iter = e_first;
 627         do {
 628                 bm_edge_tag_enable(e_iter);
 629         } while ((e_iter = bmesh_disk_edge_next(e_iter, e_first->v1)) != e_first);
 630
 631         /* ... except for the edge we will collapse, we know thats shared,
 632          * disable this to avoid false positive. We could be smart and never enable these
 633          * face/edge tags in the first place but easier to do this */
 634         // bm_edge_tag_disable(e_first);
 635         /* do inline... */
 636         {
 637 #if 0
 638                 BMIter iter;
 639                 BMIter liter;
 640                 BMLoop *l;
 641                 BMVert *v;
 642                 BM_ITER_ELEM (l, &liter, e_first, BM_LOOPS_OF_EDGE) {
 643                         BM_elem_flag_disable(l->f, BM_ELEM_TAG);
 644                         BM_ITER_ELEM (v, &iter, l->f, BM_VERTS_OF_FACE) {
 645                                 BM_elem_flag_disable(v, BM_ELEM_TAG);
 646                         }
 647                 }
 648 #else
 649                 /* we know each face is a triangle, no looping/iterators needed here */
 650
 651                 BMLoop *l_radial;
 652                 BMLoop *l_face;
 653
 654                 l_radial = e_first->l;
 655                 l_face = l_radial;
 656                 BLI_assert(l_face->f->len == 3);
 657                 BM_elem_flag_disable(l_face->f, BM_ELEM_TAG);
 658                 BM_elem_flag_disable((l_face = l_radial)->v,     BM_ELEM_TAG);
 659                 BM_elem_flag_disable((l_face = l_face->next)->v, BM_ELEM_TAG);
 660                 BM_elem_flag_disable((         l_face->next)->v, BM_ELEM_TAG);
 661                 l_face = l_radial->radial_next;
 662                 if (l_radial != l_face) {
 663                         BLI_assert(l_face->f->len == 3);
 664                         BM_elem_flag_disable(l_face->f, BM_ELEM_TAG);
 665                         BM_elem_flag_disable((l_face = l_radial->radial_next)->v, BM_ELEM_TAG);
 666                         BM_elem_flag_disable((l_face = l_face->next)->v,          BM_ELEM_TAG);
 667                         BM_elem_flag_disable((         l_face->next)->v,          BM_ELEM_TAG);
 668                 }
 669 #endif
 670         }
 671
 672         /* and check for overlap */
 673         e_iter = e_first;
 674         do {
 675                 if (bm_edge_tag_test(e_iter)) {
 676                         return true;
 677                 }
 678         } while ((e_iter = bmesh_disk_edge_next(e_iter, e_first->v2)) != e_first);
 679
 680         return false;
 681 }
 682
 683 /**
 684  * special, highly limited edge collapse function
 685  * intended for speed over flexibility.
 686  * can only collapse edges connected to (1, 2) tris.
 687  *
 688  * Important - dont add vert/edge/face data on collapsing!
 689  *
 690  * \param e_clear_other let caller know what edges we remove besides \a e_clear
 691  * \param customdata_flag merge factor, scales from 0 - 1 ('v_clear' -> 'v_other')
 692  */
 693 static bool bm_edge_collapse(BMesh *bm, BMEdge *e_clear, BMVert *v_clear, int r_e_clear_other[2],
 694 #ifdef USE_CUSTOMDATA
 695                              const CD_UseFlag customdata_flag,
 696                              const float customdata_fac
 697 #else
 698                              const CD_UseFlag UNUSED(customdata_flag),
 699                              const float UNUSED(customdata_fac)
 700 #endif
 701                             )
 702 {
 703         BMVert *v_other;
 704
 705         v_other = BM_edge_other_vert(e_clear, v_clear);
 706         BLI_assert(v_other != NULL);
 707
 708         if (BM_edge_is_manifold(e_clear)) {
 709                 BMLoop *l_a, *l_b;
 710                 BMEdge *e_a_other[2], *e_b_other[2];
 711                 bool ok;
 712
 713                 ok = BM_edge_loop_pair(e_clear, &l_a, &l_b);
 714
 715                 BLI_assert(ok == true);
 716                 BLI_assert(l_a->f->len == 3);
 717                 BLI_assert(l_b->f->len == 3);
 718
 719                 /* keep 'v_clear' 0th */
 720                 if (BM_vert_in_edge(l_a->prev->e, v_clear)) {
 721                         e_a_other[0] = l_a->prev->e;
 722                         e_a_other[1] = l_a->next->e;
 723                 }
 724                 else {
 725                         e_a_other[1] = l_a->prev->e;
 726                         e_a_other[0] = l_a->next->e;
 727                 }
 728
 729                 if (BM_vert_in_edge(l_b->prev->e, v_clear)) {
 730                         e_b_other[0] = l_b->prev->e;
 731                         e_b_other[1] = l_b->next->e;
 732                 }
 733                 else {
 734                         e_b_other[1] = l_b->prev->e;
 735                         e_b_other[0] = l_b->next->e;
 736                 }
 737
 738                 /* we could assert this case, but better just bail out */
 739 #if 0
 740                 BLI_assert(e_a_other[0] != e_b_other[0]);
 741                 BLI_assert(e_a_other[0] != e_b_other[1]);
 742                 BLI_assert(e_b_other[0] != e_a_other[0]);
 743                 BLI_assert(e_b_other[0] != e_a_other[1]);
 744 #endif
 745                 /* not totally common but we want to avoid */
 746                 if (ELEM(e_a_other[0], e_b_other[0], e_b_other[1]) ||
 747                     ELEM(e_a_other[1], e_b_other[0], e_b_other[1]))
 748                 {
 749                         return false;
 750                 }
 751
 752                 BLI_assert(BM_edge_share_vert(e_a_other[0], e_b_other[0]));
 753                 BLI_assert(BM_edge_share_vert(e_a_other[1], e_b_other[1]));
 754
 755                 r_e_clear_other[0] = BM_elem_index_get(e_a_other[0]);
 756                 r_e_clear_other[1] = BM_elem_index_get(e_b_other[0]);
 757
 758 #ifdef USE_CUSTOMDATA
 759                 /* before killing, do customdata */
 760                 if (customdata_flag & CD_DO_VERT) {
 761                         BM_data_interp_from_verts(bm, v_other, v_clear, v_other, customdata_fac);
 762                 }
 763                 if (customdata_flag & CD_DO_EDGE) {
 764                         BM_data_interp_from_edges(bm, e_a_other[1], e_a_other[0], e_a_other[1], customdata_fac);
 765                         BM_data_interp_from_edges(bm, e_b_other[1], e_b_other[0], e_b_other[1], customdata_fac);
 766                 }
 767                 if (customdata_flag & CD_DO_LOOP) {
 768                         bm_edge_collapse_loop_customdata(bm, e_clear->l,              v_clear, v_other, customdata_fac);
 769                         bm_edge_collapse_loop_customdata(bm, e_clear->l->radial_next, v_clear, v_other, customdata_fac);
 770                 }
 771 #endif
 772
 773                 BM_edge_kill(bm, e_clear);
 774
 775                 v_other->head.hflag |= v_clear->head.hflag;
 776                 BM_vert_splice(bm, v_clear, v_other);
 777
 778                 e_a_other[1]->head.hflag |= e_a_other[0]->head.hflag;
 779                 e_b_other[1]->head.hflag |= e_b_other[0]->head.hflag;
 780                 BM_edge_splice(bm, e_a_other[0], e_a_other[1]);
 781                 BM_edge_splice(bm, e_b_other[0], e_b_other[1]);
 782
 783                 // BM_mesh_validate(bm);
 784
 785                 return true;
 786         }
 787         else if (BM_edge_is_boundary(e_clear)) {
 788                 /* same as above but only one triangle */
 789                 BMLoop *l_a;
 790                 BMEdge *e_a_other[2];
 791
 792                 l_a = e_clear->l;
 793
 794                 BLI_assert(l_a->f->len == 3);
 795
 796                 /* keep 'v_clear' 0th */
 797                 if (BM_vert_in_edge(l_a->prev->e, v_clear)) {
 798                         e_a_other[0] = l_a->prev->e;
 799                         e_a_other[1] = l_a->next->e;
 800                 }
 801                 else {
 802                         e_a_other[1] = l_a->prev->e;
 803                         e_a_other[0] = l_a->next->e;
 804                 }
 805
 806                 r_e_clear_other[0] = BM_elem_index_get(e_a_other[0]);
 807                 r_e_clear_other[1] = -1;
 808
 809 #ifdef USE_CUSTOMDATA
 810                 /* before killing, do customdata */
 811                 if (customdata_flag & CD_DO_VERT) {
 812                         BM_data_interp_from_verts(bm, v_other, v_clear, v_other, customdata_fac);
 813                 }
 814                 if (customdata_flag & CD_DO_EDGE) {
 815                         BM_data_interp_from_edges(bm, e_a_other[1], e_a_other[0], e_a_other[1], customdata_fac);
 816                 }
 817                 if (customdata_flag & CD_DO_LOOP) {
 818                         bm_edge_collapse_loop_customdata(bm, e_clear->l, v_clear, v_other, customdata_fac);
 819                 }
 820 #endif
 821
 822                 BM_edge_kill(bm, e_clear);
 823
 824                 v_other->head.hflag |= v_clear->head.hflag;
 825                 BM_vert_splice(bm, v_clear, v_other);
 826
 827                 e_a_other[1]->head.hflag |= e_a_other[0]->head.hflag;
 828                 BM_edge_splice(bm, e_a_other[0], e_a_other[1]);
 829
 830                 // BM_mesh_validate(bm);
 831
 832                 return true;
 833         }
 834         else {
 835                 return false;
 836         }
 837 }
 838
 839
 840 /* collapse e the edge, removing e->v2 */
 841 static void bm_decim_edge_collapse(BMesh *bm, BMEdge *e,
 842                                    Quadric *vquadrics, float *vweights,
 843                                    Heap *eheap, HeapNode **eheap_table,
 844                                    const CD_UseFlag customdata_flag)
 845 {
 846         int e_clear_other[2];
 847         BMVert *v_other = e->v1;
 848         int v_clear_index = BM_elem_index_get(e->v2);  /* the vert is removed so only store the index */
 849         float optimize_co[3];
 850         float customdata_fac;
 851
 852 #ifdef USE_VERT_NORMAL_INTERP
 853         float v_clear_no[3];
 854         copy_v3_v3(v_clear_no, e->v2->no);
 855 #endif
 856
 857         /* disallow collapsing which results in degenerate cases */
 858         if (UNLIKELY(bm_edge_collapse_is_degenerate_topology(e))) {
 859                 bm_decim_invalid_edge_cost_single(e, eheap, eheap_table);  /* add back with a high cost */
 860                 return;
 861         }
 862
 863         bm_decim_calc_target_co(e, optimize_co, vquadrics);
 864
 865         /* check if this would result in an overlapping face */
 866         if (UNLIKELY(bm_edge_collapse_is_degenerate_flip(e, optimize_co))) {
 867                 bm_decim_invalid_edge_cost_single(e, eheap, eheap_table);  /* add back with a high cost */
 868                 return;
 869         }
 870
 871         /* use for customdata merging */
 872         if (LIKELY(compare_v3v3(e->v1->co, e->v2->co, FLT_EPSILON) == false)) {
 873                 customdata_fac = line_point_factor_v3(optimize_co, e->v1->co, e->v2->co);
 874 #if 0
 875                 /* simple test for stupid collapse */
 876                 if (customdata_fac < 0.0 - FLT_EPSILON || customdata_fac > 1.0f + FLT_EPSILON) {
 877                         return;
 878                 }
 879 #endif
 880         }
 881         else {
 882                 /* avoid divide by zero */
 883                 customdata_fac = 0.5f;
 884         }
 885
 886         if (bm_edge_collapse(bm, e, e->v2, e_clear_other, customdata_flag, customdata_fac)) {
 887                 /* update collapse info */
 888                 int i;
 889
 890                 if (vweights) {
 891                         vweights[BM_elem_index_get(v_other)] += vweights[v_clear_index];
 892                 }
 893
 894                 e = NULL;  /* paranoid safety check */
 895
 896                 copy_v3_v3(v_other->co, optimize_co);
 897
 898                 /* remove eheap */
 899                 for (i = 0; i < 2; i++) {
 900                         /* highly unlikely 'eheap_table[ke_other[i]]' would be NULL, but do for sanity sake */
 901                         if ((e_clear_other[i] != -1) && (eheap_table[e_clear_other[i]] != NULL)) {
 902                                 BLI_heap_remove(eheap, eheap_table[e_clear_other[i]]);
 903                                 eheap_table[e_clear_other[i]] = NULL;
 904                         }
 905                 }
 906
 907                 /* update vertex quadric, add kept vertex from killed vertex */
 908                 BLI_quadric_add_qu_qu(&vquadrics[BM_elem_index_get(v_other)], &vquadrics[v_clear_index]);
 909
 910                 /* update connected normals */
 911
 912                 /* in fact face normals are not used for progressive updates, no need to update them */
 913                 // BM_vert_normal_update_all(v);
 914 #ifdef USE_VERT_NORMAL_INTERP
 915                 interp_v3_v3v3(v_other->no, v_other->no, v_clear_no, customdata_fac);
 916                 normalize_v3(v_other->no);
 917 #else
 918                 BM_vert_normal_update(v_other);
 919 #endif
 920
 921
 922                 /* update error costs and the eheap */
 923                 if (LIKELY(v_other->e)) {
 924                         BMEdge *e_iter;
 925                         BMEdge *e_first;
 926                         e_iter = e_first = v_other->e;
 927                         do {
 928                                 BLI_assert(BM_edge_find_double(e_iter) == NULL);
 929                                 bm_decim_build_edge_cost_single(e_iter, vquadrics, vweights, eheap, eheap_table);
 930                         } while ((e_iter = bmesh_disk_edge_next(e_iter, v_other)) != e_first);
 931                 }
 932
 933                 /* this block used to be disabled,
 934                  * but enable now since surrounding faces may have been
 935                  * set to COST_INVALID because of a face overlap that no longer occurs */
 936 #if 1
 937                 /* optional, update edges around the vertex face fan */
 938                 {
 939                         BMIter liter;
 940                         BMLoop *l;
 941                         BM_ITER_ELEM (l, &liter, v_other, BM_LOOPS_OF_VERT) {
 942                                 if (l->f->len == 3) {
 943                                         BMEdge *e_outer;
 944                                         if (BM_vert_in_edge(l->prev->e, l->v))
 945                                                 e_outer = l->next->e;
 946                                         else
 947                                                 e_outer = l->prev->e;
 948
 949                                         BLI_assert(BM_vert_in_edge(e_outer, l->v) == false);
 950
 951                                         bm_decim_build_edge_cost_single(e_outer, vquadrics, vweights, eheap, eheap_table);
 952                                 }
 953                         }
 954                 }
 955                 /* end optional update */
 956 #endif
 957         }
 958         else {
 959                 /* add back with a high cost */
 960                 bm_decim_invalid_edge_cost_single(e, eheap, eheap_table);
 961         }
 962 }
 963
 964
 965 /* Main Decimate Function
 966  * ********************** */
 967
 968 /**
 969  * \brief BM_mesh_decimate
 970  * \param bm The mesh
 971  * \param factor face count multiplier [0 - 1]
 972  * \param vweights Optional array of vertex  aligned weights [0 - 1],
 973  *        a vertex group is the usual source for this.
 974  */
 975 void BM_mesh_decimate_collapse(BMesh *bm, const float factor, float *vweights, const bool do_triangulate)
 976 {
 977         Heap *eheap;             /* edge heap */
 978         HeapNode **eheap_table;  /* edge index aligned table pointing to the eheap */
 979         Quadric *vquadrics;      /* vert index aligned quadrics */
 980         int tot_edge_orig;
 981         int face_tot_target;
 982         bool use_triangulate;
 983
 984         CD_UseFlag customdata_flag = 0;
 985
 986 #ifdef USE_TRIANGULATE
 987         /* temp convert quads to triangles */
 988         use_triangulate = bm_decim_triangulate_begin(bm);
 989 #endif
 990
 991
 992         /* alloc vars */
 993         vquadrics = MEM_callocN(sizeof(Quadric) * bm->totvert, __func__);
 994         /* since some edges may be degenerate, we might be over allocing a little here */
 995         eheap = BLI_heap_new_ex(bm->totedge);
 996         eheap_table = MEM_mallocN(sizeof(HeapNode *) * bm->totedge, __func__);
 997         tot_edge_orig = bm->totedge;
 998
 999
1000         /* build initial edge collapse cost data */
1001         bm_decim_build_quadrics(bm, vquadrics);
1002
1003         bm_decim_build_edge_cost(bm, vquadrics, vweights, eheap, eheap_table);
1004
1005         face_tot_target = bm->totface * factor;
1006         bm->elem_index_dirty |= BM_FACE | BM_EDGE | BM_VERT;
1007
1008
1009 #ifdef USE_CUSTOMDATA
1010         /* initialize customdata flag, we only need math for loops */
1011         if (CustomData_has_interp(&bm->vdata))  customdata_flag |= CD_DO_VERT;
1012         if (CustomData_has_interp(&bm->edata))  customdata_flag |= CD_DO_EDGE;
1013         if (CustomData_has_math(&bm->ldata))    customdata_flag |= CD_DO_LOOP;
1014 #endif
1015
1016         /* iterative edge collapse and maintain the eheap */
1017         while ((bm->totface > face_tot_target) &&
1018                (BLI_heap_is_empty(eheap) == false) &&
1019                (BLI_heap_node_value(BLI_heap_top(eheap)) != COST_INVALID))
1020         {
1021                 // const float value = BLI_heap_node_value(BLI_heap_top(eheap));
1022                 BMEdge *e = BLI_heap_popmin(eheap);
1023                 BLI_assert(BM_elem_index_get(e) < tot_edge_orig);  /* handy to detect corruptions elsewhere */
1024
1025                 // printf("COST %.10f\n", value);
1026
1027                 /* under normal conditions wont be accessed again,
1028                  * but NULL just incase so we don't use freed node */
1029                 eheap_table[BM_elem_index_get(e)] = NULL;
1030
1031                 bm_decim_edge_collapse(bm, e, vquadrics, vweights, eheap, eheap_table, customdata_flag);
1032         }
1033
1034
1035 #ifdef USE_TRIANGULATE
1036         if (do_triangulate == false) {
1037                 /* its possible we only had triangles, skip this step in that case */
1038                 if (LIKELY(use_triangulate)) {
1039                         /* temp convert quads to triangles */
1040                         bm_decim_triangulate_end(bm);
1041                 }
1042         }
1043 #endif
1044
1045         /* free vars */
1046         MEM_freeN(vquadrics);
1047         MEM_freeN(eheap_table);
1048         BLI_heap_free(eheap, NULL);
1049
1050         /* testing only */
1051         // BM_mesh_validate(bm);
1052
1053         (void)tot_edge_orig;  /* quiet release build warning */
1054 }