tools/quake3/common/polylib.c

   1 /*
   2 Copyright (C) 1999-2006 Id Software, Inc. and contributors.
   3 For a list of contributors, see the accompanying CONTRIBUTORS file.
   4
   5 This file is part of GtkRadiant.
   6
   7 GtkRadiant is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2 of the License, or
  10 (at your option) any later version.
  11
  12 GtkRadiant is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GtkRadiant; if not, write to the Free Software
  19 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  20 */
  21
  22
  23 #include "cmdlib.h"
  24 #include "mathlib.h"
  25 #include "inout.h"
  26 #include "polylib.h"
  27 #include "qfiles.h"
  28
  29
  30 extern int numthreads;
  31
  32 // counters are only bumped when running single threaded,
  33 // because they are an awefull coherence problem
  34 int     c_active_windings;
  35 int     c_peak_windings;
  36 int     c_winding_allocs;
  37 int     c_winding_points;
  38
  39 #define BOGUS_RANGE     WORLD_SIZE
  40
  41 void pw(winding_t *w)
  42 {
  43         int             i;
  44         for (i=0 ; i<w->numpoints ; i++)
  45                 Sys_Printf ("(%5.1f, %5.1f, %5.1f)\n",w->p[i][0], w->p[i][1],w->p[i][2]);
  46 }
  47
  48
  49 /*
  50 =============
  51 AllocWinding
  52 =============
  53 */
  54 winding_t       *AllocWinding (int points)
  55 {
  56         winding_t       *w;
  57         int                     s;
  58
  59   if (points >= MAX_POINTS_ON_WINDING)
  60     Error ("AllocWinding failed: MAX_POINTS_ON_WINDING exceeded");
  61
  62         if (numthreads == 1)
  63         {
  64                 c_winding_allocs++;
  65                 c_winding_points += points;
  66                 c_active_windings++;
  67                 if (c_active_windings > c_peak_windings)
  68                         c_peak_windings = c_active_windings;
  69         }
  70         s = sizeof(vec_t)*3*points + sizeof(int);
  71         w = safe_malloc (s);
  72         memset (w, 0, s);
  73         return w;
  74 }
  75
  76 void FreeWinding (winding_t *w)
  77 {
  78         if (*(unsigned *)w == 0xdeaddead)
  79                 Error ("FreeWinding: freed a freed winding");
  80         *(unsigned *)w = 0xdeaddead;
  81
  82         if (numthreads == 1)
  83                 c_active_windings--;
  84         free (w);
  85 }
  86
  87 /*
  88 ============
  89 RemoveColinearPoints
  90 ============
  91 */
  92 int     c_removed;
  93
  94 void    RemoveColinearPoints (winding_t *w)
  95 {
  96         int             i, j, k;
  97         vec3_t  v1, v2;
  98         int             nump;
  99         vec3_t  p[MAX_POINTS_ON_WINDING];
 100
 101         nump = 0;
 102         for (i=0 ; i<w->numpoints ; i++)
 103         {
 104                 j = (i+1)%w->numpoints;
 105                 k = (i+w->numpoints-1)%w->numpoints;
 106                 VectorSubtract (w->p[j], w->p[i], v1);
 107                 VectorSubtract (w->p[i], w->p[k], v2);
 108                 VectorNormalize(v1,v1);
 109                 VectorNormalize(v2,v2);
 110                 if (DotProduct(v1, v2) < 0.999)
 111                 {
 112                         VectorCopy (w->p[i], p[nump]);
 113                         nump++;
 114                 }
 115         }
 116
 117         if (nump == w->numpoints)
 118                 return;
 119
 120         if (numthreads == 1)
 121                 c_removed += w->numpoints - nump;
 122         w->numpoints = nump;
 123         memcpy (w->p, p, nump*sizeof(p[0]));
 124 }
 125
 126 /*
 127 ============
 128 WindingPlane
 129 ============
 130 */
 131 void WindingPlane (winding_t *w, vec3_t normal, vec_t *dist)
 132 {
 133         vec3_t  v1, v2;
 134
 135         VectorSubtract (w->p[1], w->p[0], v1);
 136         VectorSubtract (w->p[2], w->p[0], v2);
 137         CrossProduct (v2, v1, normal);
 138         VectorNormalize (normal, normal);
 139         *dist = DotProduct (w->p[0], normal);
 140
 141 }
 142
 143 /*
 144 =============
 145 WindingArea
 146 =============
 147 */
 148 vec_t   WindingArea (winding_t *w)
 149 {
 150         int             i;
 151         vec3_t  d1, d2, cross;
 152         vec_t   total;
 153
 154         total = 0;
 155         for (i=2 ; i<w->numpoints ; i++)
 156         {
 157                 VectorSubtract (w->p[i-1], w->p[0], d1);
 158                 VectorSubtract (w->p[i], w->p[0], d2);
 159                 CrossProduct (d1, d2, cross);
 160                 total += 0.5 * VectorLength ( cross );
 161         }
 162         return total;
 163 }
 164
 165 void    WindingBounds (winding_t *w, vec3_t mins, vec3_t maxs)
 166 {
 167         vec_t   v;
 168         int             i,j;
 169
 170         mins[0] = mins[1] = mins[2] = 99999;
 171         maxs[0] = maxs[1] = maxs[2] = -99999;
 172
 173         for (i=0 ; i<w->numpoints ; i++)
 174         {
 175                 for (j=0 ; j<3 ; j++)
 176                 {
 177                         v = w->p[i][j];
 178                         if (v < mins[j])
 179                                 mins[j] = v;
 180                         if (v > maxs[j])
 181                                 maxs[j] = v;
 182                 }
 183         }
 184 }
 185
 186 /*
 187 =============
 188 WindingCenter
 189 =============
 190 */
 191 void    WindingCenter (winding_t *w, vec3_t center)
 192 {
 193         int             i;
 194         float   scale;
 195
 196         VectorCopy (vec3_origin, center);
 197         for (i=0 ; i<w->numpoints ; i++)
 198                 VectorAdd (w->p[i], center, center);
 199
 200         scale = 1.0/w->numpoints;
 201         VectorScale (center, scale, center);
 202 }
 203
 204 /*
 205 =================
 206 BaseWindingForPlane
 207 =================
 208 */
 209 winding_t *BaseWindingForPlane (vec3_t normal, vec_t dist)
 210 {
 211         // The goal in this function is to replicate the exact behavior that was in the original
 212         // BaseWindingForPlane() function (see below).  The only thing we're going to change is the
 213         // accuracy of the operation.  The original code gave a preference for the vup vector to start
 214         // out as (0, 0, 1), unless the normal had a dominant Z value, in which case vup started out
 215         // as (1, 0, 0).  After that, vup was "bent" [along the plane defined by normal and vup] to
 216         // become perpendicular to normal.  After that the vright vector was computed as the cross
 217         // product of vup and normal.
 218
 219         // Once these vectors are calculated, I'm constructing the winding points in exactly the same
 220         // way as was done in the original function.  Orientation is the same.
 221
 222         // Note that the 4 points in the returned winding_t may actually not be necessary (3 might
 223         // be enough).  However, I want to minimize the chance of ANY bugs popping up due to any
 224         // change in behavior of this function.  Therefore, behavior stays exactly the same, except
 225         // for precision of math.  Performance might be better in the new function as well.
 226
 227         int             x, i;
 228         vec_t           max, v;
 229         vec3_t          vright, vup, org;
 230         winding_t       *w;
 231
 232         max = -BOGUS_RANGE;
 233         x = -1;
 234         for (i = 0; i < 3; i++) {
 235                 v = fabs(normal[i]);
 236                 if (v > max) {
 237                         x = i;
 238                         max = v;
 239                 }
 240         }
 241         if (x == -1) Error("BaseWindingForPlane: no axis found");
 242
 243         switch (x) {
 244                 case 0: // Fall through to next case.
 245                 case 1:
 246                         vright[0] = -normal[1];
 247                         vright[1] = normal[0];
 248                         vright[2] = 0;
 249                         break;
 250                 case 2:
 251                         vright[0] = 0;
 252                         vright[1] = -normal[2];
 253                         vright[2] = normal[1];
 254                         break;
 255         }
 256         // NOTE: vright is NOT a unit vector at this point.
 257         VectorSetLength(vright, MAX_WORLD_COORD * 2, vright);
 258         CrossProduct(normal, vright, vup);
 259         VectorScale(normal, dist, org);
 260
 261         w = AllocWinding(4);
 262
 263         VectorSubtract(org, vright, w->p[0]);
 264         VectorAdd(w->p[0], vup, w->p[0]);
 265
 266         VectorAdd(org, vright, w->p[1]);
 267         VectorAdd(w->p[1], vup, w->p[1]);
 268
 269         VectorAdd(org, vright, w->p[2]);
 270         VectorSubtract(w->p[2], vup, w->p[2]);
 271
 272         VectorSubtract(org, vright, w->p[3]);
 273         VectorSubtract(w->p[3], vup, w->p[3]);
 274
 275         w->numpoints = 4;
 276
 277         return w;
 278 }
 279
 280 // Old function, not used but here for reference.  Please do not modify it.
 281 // (You may remove it at some point.)
 282 winding_t *_BaseWindingForPlane_orig_(vec3_t normal, vec_t dist)
 283 {
 284         int             i, x;
 285         vec_t   max, v;
 286         vec3_t  org, vright, vup;
 287         winding_t       *w;
 288
 289 // find the major axis
 290
 291         max = -BOGUS_RANGE;
 292         x = -1;
 293         for (i=0 ; i<3; i++)
 294         {
 295                 v = fabs(normal[i]);
 296                 if (v > max)
 297                 {
 298                         x = i;
 299                         max = v;
 300                 }
 301         }
 302         if (x==-1)
 303                 Error ("BaseWindingForPlane: no axis found");
 304
 305         VectorCopy (vec3_origin, vup);
 306         switch (x)
 307         {
 308         case 0:
 309         case 1:
 310                 vup[2] = 1;
 311                 break;
 312         case 2:
 313                 vup[0] = 1;
 314                 break;
 315         }
 316
 317         v = DotProduct (vup, normal);
 318         VectorMA (vup, -v, normal, vup);
 319         VectorNormalize (vup, vup);
 320
 321         VectorScale (normal, dist, org);
 322
 323         CrossProduct (vup, normal, vright);
 324
 325         // LordHavoc: this has to use *2 because otherwise some created points may
 326         // be inside the world (think of a diagonal case), and any brush with such
 327         // points should be removed, failure to detect such cases is disasterous
 328         VectorScale (vup, MAX_WORLD_COORD*2, vup);
 329         VectorScale (vright, MAX_WORLD_COORD*2, vright);
 330
 331   // project a really big       axis aligned box onto the plane
 332         w = AllocWinding (4);
 333
 334         VectorSubtract (org, vright, w->p[0]);
 335         VectorAdd (w->p[0], vup, w->p[0]);
 336
 337         VectorAdd (org, vright, w->p[1]);
 338         VectorAdd (w->p[1], vup, w->p[1]);
 339
 340         VectorAdd (org, vright, w->p[2]);
 341         VectorSubtract (w->p[2], vup, w->p[2]);
 342
 343         VectorSubtract (org, vright, w->p[3]);
 344         VectorSubtract (w->p[3], vup, w->p[3]);
 345
 346         w->numpoints = 4;
 347
 348         return w;
 349 }
 350
 351 /*
 352 ==================
 353 CopyWinding
 354 ==================
 355 */
 356 winding_t       *CopyWinding (winding_t *w)
 357 {
 358         size_t                  size;
 359         winding_t       *c;
 360
 361         c = AllocWinding (w->numpoints);
 362         size = (size_t)((winding_t *)NULL)->p[w->numpoints];
 363         memcpy (c, w, size);
 364         return c;
 365 }
 366
 367 /*
 368 ==================
 369 ReverseWinding
 370 ==================
 371 */
 372 winding_t       *ReverseWinding (winding_t *w)
 373 {
 374         int                     i;
 375         winding_t       *c;
 376
 377         c = AllocWinding (w->numpoints);
 378         for (i=0 ; i<w->numpoints ; i++)
 379         {
 380                 VectorCopy (w->p[w->numpoints-1-i], c->p[i]);
 381         }
 382         c->numpoints = w->numpoints;
 383         return c;
 384 }
 385
 386
 387 /*
 388 =============
 389 ClipWindingEpsilon
 390 =============
 391 */
 392 void    ClipWindingEpsilon (winding_t *in, vec3_t normal, vec_t dist,
 393                                 vec_t epsilon, winding_t **front, winding_t **back)
 394 {
 395         vec_t   dists[MAX_POINTS_ON_WINDING+4];
 396         int             sides[MAX_POINTS_ON_WINDING+4];
 397         int             counts[3];
 398         static  vec_t   dot;            // VC 4.2 optimizer bug if not static
 399         int             i, j;
 400         vec_t   *p1, *p2;
 401         vec3_t  mid;
 402         winding_t       *f, *b;
 403         int             maxpts;
 404
 405         counts[0] = counts[1] = counts[2] = 0;
 406
 407 // determine sides for each point
 408         for (i=0 ; i<in->numpoints ; i++)
 409   {
 410
 411                 dot = DotProduct (in->p[i], normal);
 412                 dot -= dist;
 413                 dists[i] = dot;
 414                 if (dot > epsilon)
 415                         sides[i] = SIDE_FRONT;
 416                 else if (dot < -epsilon)
 417                         sides[i] = SIDE_BACK;
 418                 else
 419                 {
 420                         sides[i] = SIDE_ON;
 421                 }
 422                 counts[sides[i]]++;
 423         }
 424         sides[i] = sides[0];
 425         dists[i] = dists[0];
 426
 427         *front = *back = NULL;
 428
 429         if (!counts[0])
 430         {
 431                 *back = CopyWinding (in);
 432                 return;
 433         }
 434         if (!counts[1])
 435         {
 436                 *front = CopyWinding (in);
 437                 return;
 438         }
 439
 440         maxpts = in->numpoints+4;       // cant use counts[0]+2 because
 441                                                                 // of fp grouping errors
 442
 443         *front = f = AllocWinding (maxpts);
 444         *back = b = AllocWinding (maxpts);
 445
 446         for (i=0 ; i<in->numpoints ; i++)
 447         {
 448                 p1 = in->p[i];
 449
 450                 if (sides[i] == SIDE_ON)
 451                 {
 452                         VectorCopy (p1, f->p[f->numpoints]);
 453                         f->numpoints++;
 454                         VectorCopy (p1, b->p[b->numpoints]);
 455                         b->numpoints++;
 456                         continue;
 457                 }
 458
 459                 if (sides[i] == SIDE_FRONT)
 460                 {
 461                         VectorCopy (p1, f->p[f->numpoints]);
 462                         f->numpoints++;
 463                 }
 464                 if (sides[i] == SIDE_BACK)
 465                 {
 466                         VectorCopy (p1, b->p[b->numpoints]);
 467                         b->numpoints++;
 468                 }
 469
 470                 if (sides[i+1] == SIDE_ON || sides[i+1] == sides[i])
 471                         continue;
 472
 473         // generate a split point
 474                 p2 = in->p[(i+1)%in->numpoints];
 475
 476                 dot = dists[i] / (dists[i]-dists[i+1]);
 477                 for (j=0 ; j<3 ; j++)
 478                 {       // avoid round off error when possible
 479                         if (normal[j] == 1)
 480                                 mid[j] = dist;
 481                         else if (normal[j] == -1)
 482                                 mid[j] = -dist;
 483                         else
 484                                 mid[j] = p1[j] + dot*(p2[j]-p1[j]);
 485                 }
 486
 487                 VectorCopy (mid, f->p[f->numpoints]);
 488                 f->numpoints++;
 489                 VectorCopy (mid, b->p[b->numpoints]);
 490                 b->numpoints++;
 491         }
 492
 493         if (f->numpoints > maxpts || b->numpoints > maxpts)
 494                 Error ("ClipWinding: points exceeded estimate");
 495         if (f->numpoints > MAX_POINTS_ON_WINDING || b->numpoints > MAX_POINTS_ON_WINDING)
 496                 Error ("ClipWinding: MAX_POINTS_ON_WINDING");
 497 }
 498
 499
 500 /*
 501 =============
 502 ChopWindingInPlace
 503 =============
 504 */
 505 void ChopWindingInPlace (winding_t **inout, vec3_t normal, vec_t dist, vec_t epsilon)
 506 {
 507         winding_t       *in;
 508         vec_t   dists[MAX_POINTS_ON_WINDING+4];
 509         int             sides[MAX_POINTS_ON_WINDING+4];
 510         int             counts[3];
 511         static  vec_t   dot;            // VC 4.2 optimizer bug if not static
 512         int             i, j;
 513         vec_t   *p1, *p2;
 514         vec3_t  mid;
 515         winding_t       *f;
 516         int             maxpts;
 517
 518         in = *inout;
 519         counts[0] = counts[1] = counts[2] = 0;
 520
 521 // determine sides for each point
 522         for (i=0 ; i<in->numpoints ; i++)
 523         {
 524                 dot = DotProduct (in->p[i], normal);
 525                 dot -= dist;
 526                 dists[i] = dot;
 527                 if (dot > epsilon)
 528                         sides[i] = SIDE_FRONT;
 529                 else if (dot < -epsilon)
 530                         sides[i] = SIDE_BACK;
 531                 else
 532                 {
 533                         sides[i] = SIDE_ON;
 534                 }
 535                 counts[sides[i]]++;
 536         }
 537         sides[i] = sides[0];
 538         dists[i] = dists[0];
 539
 540         if (!counts[0])
 541         {
 542                 FreeWinding (in);
 543                 *inout = NULL;
 544                 return;
 545         }
 546         if (!counts[1])
 547                 return;         // inout stays the same
 548
 549         maxpts = in->numpoints+4;       // cant use counts[0]+2 because
 550                                                                 // of fp grouping errors
 551
 552         f = AllocWinding (maxpts);
 553
 554         for (i=0 ; i<in->numpoints ; i++)
 555         {
 556                 p1 = in->p[i];
 557
 558                 if (sides[i] == SIDE_ON)
 559                 {
 560                         VectorCopy (p1, f->p[f->numpoints]);
 561                         f->numpoints++;
 562                         continue;
 563                 }
 564
 565                 if (sides[i] == SIDE_FRONT)
 566                 {
 567                         VectorCopy (p1, f->p[f->numpoints]);
 568                         f->numpoints++;
 569                 }
 570
 571                 if (sides[i+1] == SIDE_ON || sides[i+1] == sides[i])
 572                         continue;
 573
 574         // generate a split point
 575                 p2 = in->p[(i+1)%in->numpoints];
 576
 577                 dot = dists[i] / (dists[i]-dists[i+1]);
 578                 for (j=0 ; j<3 ; j++)
 579                 {       // avoid round off error when possible
 580                         if (normal[j] == 1)
 581                                 mid[j] = dist;
 582                         else if (normal[j] == -1)
 583                                 mid[j] = -dist;
 584                         else
 585                                 mid[j] = p1[j] + dot*(p2[j]-p1[j]);
 586                 }
 587
 588                 VectorCopy (mid, f->p[f->numpoints]);
 589                 f->numpoints++;
 590         }
 591
 592         if (f->numpoints > maxpts)
 593                 Error ("ClipWinding: points exceeded estimate");
 594         if (f->numpoints > MAX_POINTS_ON_WINDING)
 595                 Error ("ClipWinding: MAX_POINTS_ON_WINDING");
 596
 597         FreeWinding (in);
 598         *inout = f;
 599 }
 600
 601
 602 /*
 603 =================
 604 ChopWinding
 605
 606 Returns the fragment of in that is on the front side
 607 of the cliping plane.  The original is freed.
 608 =================
 609 */
 610 winding_t       *ChopWinding (winding_t *in, vec3_t normal, vec_t dist)
 611 {
 612         winding_t       *f, *b;
 613
 614         ClipWindingEpsilon (in, normal, dist, ON_EPSILON, &f, &b);
 615         FreeWinding (in);
 616         if (b)
 617                 FreeWinding (b);
 618         return f;
 619 }
 620
 621
 622 /*
 623 =================
 624 CheckWinding
 625
 626 =================
 627 */
 628 void CheckWinding (winding_t *w)
 629 {
 630         int             i, j;
 631         vec_t   *p1, *p2;
 632         vec_t   d, edgedist;
 633         vec3_t  dir, edgenormal, facenormal;
 634         vec_t   area;
 635         vec_t   facedist;
 636
 637         if (w->numpoints < 3)
 638                 Error ("CheckWinding: %i points",w->numpoints);
 639
 640         area = WindingArea(w);
 641         if (area < 1)
 642                 Error ("CheckWinding: %f area", area);
 643
 644         WindingPlane (w, facenormal, &facedist);
 645
 646         for (i=0 ; i<w->numpoints ; i++)
 647         {
 648                 p1 = w->p[i];
 649
 650                 for (j=0 ; j<3 ; j++)
 651                         if (p1[j] > MAX_WORLD_COORD || p1[j] < MIN_WORLD_COORD)
 652                                 Error ("CheckFace: MAX_WORLD_COORD exceeded: %f",p1[j]);
 653
 654                 j = i+1 == w->numpoints ? 0 : i+1;
 655
 656         // check the point is on the face plane
 657                 d = DotProduct (p1, facenormal) - facedist;
 658                 if (d < -ON_EPSILON || d > ON_EPSILON)
 659                         Error ("CheckWinding: point off plane");
 660
 661         // check the edge isnt degenerate
 662                 p2 = w->p[j];
 663                 VectorSubtract (p2, p1, dir);
 664
 665                 if (VectorLength (dir) < ON_EPSILON)
 666                         Error ("CheckWinding: degenerate edge");
 667
 668                 CrossProduct (facenormal, dir, edgenormal);
 669                 VectorNormalize (edgenormal, edgenormal);
 670                 edgedist = DotProduct (p1, edgenormal);
 671                 edgedist += ON_EPSILON;
 672
 673         // all other points must be on front side
 674                 for (j=0 ; j<w->numpoints ; j++)
 675                 {
 676                         if (j == i)
 677                                 continue;
 678                         d = DotProduct (w->p[j], edgenormal);
 679                         if (d > edgedist)
 680                                 Error ("CheckWinding: non-convex");
 681                 }
 682         }
 683 }
 684
 685
 686 /*
 687 ============
 688 WindingOnPlaneSide
 689 ============
 690 */
 691 int             WindingOnPlaneSide (winding_t *w, vec3_t normal, vec_t dist)
 692 {
 693         qboolean        front, back;
 694         int                     i;
 695         vec_t           d;
 696
 697         front = qfalse;
 698         back = qfalse;
 699         for (i=0 ; i<w->numpoints ; i++)
 700         {
 701                 d = DotProduct (w->p[i], normal) - dist;
 702                 if (d < -ON_EPSILON)
 703                 {
 704                         if (front)
 705                                 return SIDE_CROSS;
 706                         back = qtrue;
 707                         continue;
 708                 }
 709                 if (d > ON_EPSILON)
 710                 {
 711                         if (back)
 712                                 return SIDE_CROSS;
 713                         front = qtrue;
 714                         continue;
 715                 }
 716         }
 717
 718         if (back)
 719                 return SIDE_BACK;
 720         if (front)
 721                 return SIDE_FRONT;
 722         return SIDE_ON;
 723 }
 724
 725
 726 /*
 727 =================
 728 AddWindingToConvexHull
 729
 730 Both w and *hull are on the same plane
 731 =================
 732 */
 733 #define MAX_HULL_POINTS         128
 734 void    AddWindingToConvexHull( winding_t *w, winding_t **hull, vec3_t normal ) {
 735         int                     i, j, k;
 736         float           *p, *copy;
 737         vec3_t          dir;
 738         float           d;
 739         int                     numHullPoints, numNew;
 740         vec3_t          hullPoints[MAX_HULL_POINTS];
 741         vec3_t          newHullPoints[MAX_HULL_POINTS];
 742         vec3_t          hullDirs[MAX_HULL_POINTS];
 743         qboolean        hullSide[MAX_HULL_POINTS];
 744         qboolean        outside;
 745
 746         if ( !*hull ) {
 747                 *hull = CopyWinding( w );
 748                 return;
 749         }
 750
 751         numHullPoints = (*hull)->numpoints;
 752         memcpy( hullPoints, (*hull)->p, numHullPoints * sizeof(vec3_t) );
 753
 754         for ( i = 0 ; i < w->numpoints ; i++ ) {
 755                 p = w->p[i];
 756
 757                 // calculate hull side vectors
 758                 for ( j = 0 ; j < numHullPoints ; j++ ) {
 759                         k = ( j + 1 ) % numHullPoints;
 760
 761                         VectorSubtract( hullPoints[k], hullPoints[j], dir );
 762                         VectorNormalize( dir, dir );
 763                         CrossProduct( normal, dir, hullDirs[j] );
 764                 }
 765
 766                 outside = qfalse;
 767                 for ( j = 0 ; j < numHullPoints ; j++ ) {
 768                         VectorSubtract( p, hullPoints[j], dir );
 769                         d = DotProduct( dir, hullDirs[j] );
 770                         if ( d >= ON_EPSILON ) {
 771                                 outside = qtrue;
 772                         }
 773                         if ( d >= -ON_EPSILON ) {
 774                                 hullSide[j] = qtrue;
 775                         } else {
 776                                 hullSide[j] = qfalse;
 777                         }
 778                 }
 779
 780                 // if the point is effectively inside, do nothing
 781                 if ( !outside ) {
 782                         continue;
 783                 }
 784
 785                 // find the back side to front side transition
 786                 for ( j = 0 ; j < numHullPoints ; j++ ) {
 787                         if ( !hullSide[ j % numHullPoints ] && hullSide[ (j + 1) % numHullPoints ] ) {
 788                                 break;
 789                         }
 790                 }
 791                 if ( j == numHullPoints ) {
 792                         continue;
 793                 }
 794
 795                 // insert the point here
 796                 VectorCopy( p, newHullPoints[0] );
 797                 numNew = 1;
 798
 799                 // copy over all points that aren't double fronts
 800                 j = (j+1)%numHullPoints;
 801                 for ( k = 0 ; k < numHullPoints ; k++ ) {
 802                         if ( hullSide[ (j+k) % numHullPoints ] && hullSide[ (j+k+1) % numHullPoints ] ) {
 803                                 continue;
 804                         }
 805                         copy = hullPoints[ (j+k+1) % numHullPoints ];
 806                         VectorCopy( copy, newHullPoints[numNew] );
 807                         numNew++;
 808                 }
 809
 810                 numHullPoints = numNew;
 811                 memcpy( hullPoints, newHullPoints, numHullPoints * sizeof(vec3_t) );
 812         }
 813
 814         FreeWinding( *hull );
 815         w = AllocWinding( numHullPoints );
 816         w->numpoints = numHullPoints;
 817         *hull = w;
 818         memcpy( w->p, hullPoints, numHullPoints * sizeof(vec3_t) );
 819 }
 820
 821