texmap/ntmap.c

   1 /*
   2 THE COMPUTER CODE CONTAINED HEREIN IS THE SOLE PROPERTY OF PARALLAX
   3 SOFTWARE CORPORATION ("PARALLAX").  PARALLAX, IN DISTRIBUTING THE CODE TO
   4 END-USERS, AND SUBJECT TO ALL OF THE TERMS AND CONDITIONS HEREIN, GRANTS A
   5 ROYALTY-FREE, PERPETUAL LICENSE TO SUCH END-USERS FOR USE BY SUCH END-USERS
   6 IN USING, DISPLAYING,  AND CREATING DERIVATIVE WORKS THEREOF, SO LONG AS
   7 SUCH USE, DISPLAY OR CREATION IS FOR NON-COMMERCIAL, ROYALTY OR REVENUE
   8 FREE PURPOSES.  IN NO EVENT SHALL THE END-USER USE THE COMPUTER CODE
   9 CONTAINED HEREIN FOR REVENUE-BEARING PURPOSES.  THE END-USER UNDERSTANDS
  10 AND AGREES TO THE TERMS HEREIN AND ACCEPTS THE SAME BY USE OF THIS FILE.
  11 COPYRIGHT 1993-1998 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
  12 */
  13 /*
  14  * $Source: /cvs/cvsroot/d2x/texmap/ntmap.c,v $
  15  * $Revision: 1.3 $
  16  * $Author: bradleyb $
  17  * $Date: 2001-01-31 15:18:04 $
  18  *
  19  * Start of conversion to new texture mapper.
  20  *
  21  * $Log: not supported by cvs2svn $
  22  * Revision 1.2  2001/01/31 14:04:46  bradleyb
  23  * Fix compiler warnings
  24  *
  25  * Revision 1.1.1.1  2001/01/19 03:30:16  bradleyb
  26  * Import of d2x-0.0.8
  27  *
  28  * Revision 1.4  1999/10/18 00:31:55  donut
  29  * allow FP_TMAP to be used without NO_ASM
  30  *
  31  * Revision 1.3  1999/08/05 22:53:41  sekmu
  32  *
  33  * D3D patch(es) from ADB
  34  *
  35  * Revision 1.2  1999/07/07 21:31:09  donut
  36  * removed unused vars from ntmap_scanline_lighted and slightly optomized it
  37  *
  38  * Revision 1.1.1.1  1999/06/14 22:14:06  donut
  39  * Import of d1x 1.37 source.
  40  *
  41  * Revision 1.52  1995/03/14  15:13:06  john
  42  * Increased MAX_Y_Pointers to 480.
  43  *
  44  * Revision 1.51  1995/02/23  14:25:09  john
  45  * Added editor tmap.
  46  *
  47  * Revision 1.50  1995/02/20  18:22:58  john
  48  * Put all the externs in the assembly modules into tmap_inc.asm.
  49  * Also, moved all the C versions of the inner loops into a new module,
  50  * scanline.c.
  51  *
  52  * Revision 1.49  1995/02/20  17:09:11  john
  53  * Added code so that you can build the tmapper with no assembly!
  54  *
  55  * Revision 1.48  1995/01/06  11:11:30  mike
  56  * even when not in editor, have 400 lines in texture map scanline table.
  57  *
  58  * Revision 1.47  1994/12/15  16:43:25  matt
  59  * Took out code only needed by editor
  60  *
  61  * Revision 1.46  1994/12/09  22:35:37  mike
  62  * fix bug in before call to asm_tmap_scanline_per causing write of pixel onto past right border onto left.
  63  *
  64  * Revision 1.45  1994/12/06  16:31:06  mike
  65  * fix bug in asm_tmap_scanline_matt interface.
  66  *
  67  * Revision 1.44  1994/12/04  20:37:18  mike
  68  * *** empty log message ***
  69  *
  70  * Revision 1.43  1994/12/02  23:30:04  mike
  71  * optimizations.
  72  *
  73  * Revision 1.42  1994/11/30  00:57:43  mike
  74  * optimizations.
  75  *
  76  * Revision 1.41  1994/11/28  13:34:27  mike
  77  * optimizations.
  78  *
  79  * Revision 1.40  1994/11/28  01:30:01  mike
  80  * kill warning.
  81  *
  82  * Revision 1.39  1994/11/28  01:28:59  mike
  83  * optimizations.
  84  *
  85  * Revision 1.38  1994/11/21  14:08:07  john
  86  * Took out all multiple instead of divide code.
  87  *
  88  * Revision 1.37  1994/11/19  15:21:52  mike
  89  * rip out unused code.
  90  *
  91  * Revision 1.36  1994/11/14  11:42:51  mike
  92  * optimization.
  93  *
  94  * Revision 1.35  1994/11/12  16:41:36  mike
  95  * *** empty log message ***
  96  *
  97  * Revision 1.34  1994/11/10  21:28:41  mike
  98  * remove call to init_interface_vars_to_assembler.
  99  *
 100  * Revision 1.33  1994/11/10  11:08:59  mike
 101  * detail level stuff.
 102  *
 103  * Revision 1.32  1994/11/09  22:55:52  matt
 104  * Added variable Current_seg_depth for detail level optimization
 105  *
 106  * Revision 1.31  1994/11/09  19:57:31  john
 107  * Added texture rle caching.
 108  *
 109  * Revision 1.30  1994/11/09  19:54:48  mike
 110  * Call flat shader if Tmap_flat_flag set.
 111  *
 112  * Revision 1.29  1994/11/02  21:33:31  john
 113  * Added Burger Bill's optimization, ie.. 2 muls per 8 pixels.
 114  *
 115  * Revision 1.28  1994/11/02  11:32:16  john
 116  * Added code for c callable inner loop and code to
 117  * test dividing out z0.
 118  *
 119  * Revision 1.27  1994/10/28  20:54:32  matt
 120  * Added error checking
 121  *
 122  * Revision 1.26  1994/10/25  11:20:20  mike
 123  * fix bug in lighting overflow checking for one scanline tall linear texture maps.
 124  *
 125  * Revision 1.25  1994/08/03  15:40:33  mike
 126  * Prevent divide overflows, decrease occurrence of precision-caused glitches.
 127  *
 128  * Revision 1.24  1994/07/27  09:31:16  mike
 129  * Fix concave texture map problem, decrease occurrence of unimportant int 3.
 130  *
 131  * Revision 1.23  1994/06/17  12:23:31  mike
 132  * Support non-lighted texture maps.
 133  *
 134  * Revision 1.22  1994/06/11  08:10:24  mike
 135  * Fix mysterious hang bug, lighting value was out of range.
 136  *
 137  * Revision 1.21  1994/06/09  16:10:16  mike
 138  * Change SC2000 from constant to variable.
 139  *
 140  */
 141
 142 #ifdef HAVE_CONFIG_H
 143 #include <conf.h>
 144 #endif
 145
 146 #ifdef RCS
 147 static char rcsid[] = "$Id: ntmap.c,v 1.3 2001-01-31 15:18:04 bradleyb Exp $";
 148 #endif
 149
 150 #define VESA 0
 151 #define NUM_TMAPS 16
 152
 153 #define HEADLIGHT_LIGHTING 0
 154
 155 #define WIREFRAME 0
 156 #define PERSPECTIVE 1
 157
 158 #include "pstypes.h"
 159 #include "fix.h"
 160 #include "vecmat.h"
 161 #include "gr.h"
 162 #include "3d.h"
 163 #include "error.h"
 164 #include "rle.h"
 165
 166 #include "texmap.h"
 167 #include "texmapl.h"
 168 #ifdef NO_ASM
 169 #include "scanline.h"
 170 #endif
 171
 172 //#include "../main/textures.h"
 173
 174 #ifdef EDITOR
 175 #define EDITOR_TMAP 1       //if in, include extra stuff
 176 #endif
 177
 178 #define F15_5 (F1_0*15 + F0_5)
 179
 180 // Temporary texture map, interface from Matt's 3d system to Mike's texture mapper.
 181 g3ds_tmap Tmap1;
 182
 183 grs_bitmap Texmap_ptrs[NUM_TMAPS];
 184 grs_bitmap Texmap4_ptrs[NUM_TMAPS];
 185
 186 fix Range_max=0; // debug, kill me
 187
 188 int     Interpolation_method=0; // 0 = choose best method
 189 int     Lighting_on=1;                  // initialize to no lighting
 190 int     Tmap_flat_flag = 0;             //      1 = render texture maps as flat shaded polygons.
 191 int     Current_seg_depth;              // HACK INTERFACE: how far away the current segment (& thus texture) is
 192 int     Max_perspective_depth;
 193 int     Max_linear_depth;
 194 int     Max_flat_depth;
 195
 196 extern int Window_clip_left, Window_clip_bot, Window_clip_right, Window_clip_top;
 197
 198 // These variables are the interface to assembler.  They get set for each texture map, which is a real waste of time.
 199 //      They should be set only when they change, which is generally when the window bounds change.  And, even still, it's
 200 //      a pretty bad interface.
 201 int     bytes_per_row=-1;
 202 unsigned char *write_buffer;
 203 int     window_left;
 204 int     window_right;
 205 int     window_top;
 206 int     window_bottom;
 207 int     window_width;
 208 int     window_height;
 209
 210 #ifdef EDITOR_TMAP
 211 #define MAX_Y_POINTERS  600
 212 #else
 213 #define MAX_Y_POINTERS  600
 214 #endif
 215 int     y_pointers[MAX_Y_POINTERS];
 216
 217 fix fix_recip[FIX_RECIP_TABLE_SIZE];
 218
 219 int     Lighting_enabled;
 220 int     Fix_recip_table_computed=0;
 221
 222 fix fx_l, fx_u, fx_v, fx_z, fx_du_dx, fx_dv_dx, fx_dz_dx, fx_dl_dx;
 223 int fx_xleft, fx_xright, fx_y;
 224 unsigned char * pixptr;
 225 int per2_flag = 0;
 226 int Transparency_on = 0;
 227 int dither_intensity_lighting = 0;
 228
 229 ubyte * tmap_flat_cthru_table;
 230 ubyte tmap_flat_color;
 231 ubyte tmap_flat_shade_value;
 232
 233
 234
 235 // -------------------------------------------------------------------------------------
 236 void init_fix_recip_table(void)
 237 {
 238         int     i;
 239
 240         fix_recip[0] = F1_0;
 241
 242         for (i=1; i<FIX_RECIP_TABLE_SIZE; i++)
 243                 fix_recip[i] = F1_0/i;
 244
 245         Fix_recip_table_computed = 1;
 246 }
 247
 248 // -------------------------------------------------------------------------------------
 249 //      Initialize interface variables to assembler.
 250 //      These things used to be constants.  This routine is now (10/6/93) getting called for
 251 //      every texture map.  It should get called whenever the window changes, or, preferably,
 252 //      not at all.  I'm pretty sure these variables are only being used for range checking.
 253 void init_interface_vars_to_assembler(void)
 254 {
 255         grs_bitmap      *bp;
 256
 257         bp = &grd_curcanv->cv_bitmap;
 258
 259         Assert(bp!=NULL);
 260         Assert(bp->bm_data!=NULL);
 261         Assert(bp->bm_h <= MAX_Y_POINTERS);
 262
 263         //      If bytes_per_row has changed, create new table of pointers.
 264         if (bytes_per_row != (int) bp->bm_rowsize) {
 265                 int     y_val, i;
 266
 267                 bytes_per_row = (int) bp->bm_rowsize;
 268
 269                 y_val = 0;
 270                 for (i=0; i<MAX_Y_POINTERS; i++) {
 271                         y_pointers[i] = y_val;
 272                         y_val += bytes_per_row;
 273                 }
 274         }
 275
 276         write_buffer = (unsigned char *) bp->bm_data;
 277
 278         window_left = 0;
 279         window_right = (int) bp->bm_w-1;
 280         window_top = 0;
 281         window_bottom = (int) bp->bm_h-1;
 282
 283         Window_clip_left = window_left;
 284         Window_clip_right = window_right;
 285         Window_clip_top = window_top;
 286         Window_clip_bot = window_bottom;
 287
 288         window_width = bp->bm_w;
 289         window_height = bp->bm_h;
 290
 291         if (!Fix_recip_table_computed)
 292                 init_fix_recip_table();
 293 }
 294
 295 // -------------------------------------------------------------------------------------
 296 //                             VARIABLES
 297 extern g3ds_tmap Tmap1;
 298
 299 // -------------------------------------------------------------------------------------
 300 //      Returns number preceding val modulo modulus.
 301 //      prevmod(3,4) = 2
 302 //      prevmod(0,4) = 3
 303 int prevmod(int val,int modulus)
 304 {
 305         if (val > 0)
 306                 return val-1;
 307         else
 308                 return modulus-1;
 309 //      return (val + modulus - 1) % modulus;
 310 }
 311
 312
 313 //      Returns number succeeding val modulo modulus.
 314 //      succmod(3,4) = 0
 315 //      succmod(0,4) = 1
 316 int succmod(int val,int modulus)
 317 {
 318         if (val < modulus-1)
 319                 return val+1;
 320         else
 321                 return 0;
 322
 323 //      return (val + 1) % modulus;
 324 }
 325
 326 // -------------------------------------------------------------------------------------
 327 //      Select topmost vertex (minimum y coordinate) and bottommost (maximum y coordinate) in
 328 //      texture map.  If either is part of a horizontal edge, then select leftmost vertex for
 329 //      top, rightmost vertex for bottom.
 330 //      Important: Vertex is selected with integer precision.  So, if there are vertices at
 331 //      (0.0,0.7) and (0.5,0.3), the first vertex is selected, because they y coordinates are
 332 //      considered the same, so the smaller x is favored.
 333 //      Parameters:
 334 //              nv              number of vertices
 335 //              v3d     pointer to 3d vertices containing u,v,x2d,y2d coordinates
 336 //      Results in:
 337 //              *min_y_ind
 338 //              *max_y_ind
 339 // -------------------------------------------------------------------------------------
 340 void compute_y_bounds(g3ds_tmap *t, int *vlt, int *vlb, int *vrt, int *vrb,int *bottom_y_ind)
 341 {
 342         int     i;
 343         int     min_y,max_y;
 344         int     min_y_ind;
 345         int     original_vrt;
 346         fix     min_x;
 347
 348         // Scan all vertices, set min_y_ind to vertex with smallest y coordinate.
 349         min_y = f2i(t->verts[0].y2d);
 350         max_y = min_y;
 351         min_y_ind = 0;
 352         min_x = f2i(t->verts[0].x2d);
 353         *bottom_y_ind = 0;
 354
 355         for (i=1; i<t->nv; i++) {
 356                 if (f2i(t->verts[i].y2d) < min_y) {
 357                         min_y = f2i(t->verts[i].y2d);
 358                         min_y_ind = i;
 359                         min_x = f2i(t->verts[i].x2d);
 360                 } else if (f2i(t->verts[i].y2d) == min_y) {
 361                         if (f2i(t->verts[i].x2d) < min_x) {
 362                                 min_y_ind = i;
 363                                 min_x = f2i(t->verts[i].x2d);
 364                         }
 365                 }
 366                 if (f2i(t->verts[i].y2d) > max_y) {
 367                         max_y = f2i(t->verts[i].y2d);
 368                         *bottom_y_ind = i;
 369                 }
 370         }
 371
 372 //--removed mk, 11/27/94--      //      Check for a non-upright-hourglass polygon and fix, if necessary, by bashing a y coordinate.
 373 //--removed mk, 11/27/94--      //      min_y_ind = index of minimum y coordinate, *bottom_y_ind = index of maximum y coordinate
 374 //--removed mk, 11/27/94--{
 375 //--removed mk, 11/27/94--      int     max_temp, min_temp;
 376 //--removed mk, 11/27/94--
 377 //--removed mk, 11/27/94--      max_temp = *bottom_y_ind;
 378 //--removed mk, 11/27/94--      if (*bottom_y_ind < min_y_ind)
 379 //--removed mk, 11/27/94--              max_temp += t->nv;
 380 //--removed mk, 11/27/94--
 381 //--removed mk, 11/27/94--      for (i=min_y_ind; i<max_temp; i++) {
 382 //--removed mk, 11/27/94--              if (f2i(t->verts[i%t->nv].y2d) > f2i(t->verts[(i+1)%t->nv].y2d)) {
 383 //--removed mk, 11/27/94--                      Int3();
 384 //--removed mk, 11/27/94--                      t->verts[(i+1)%t->nv].y2d = t->verts[i%t->nv].y2d;
 385 //--removed mk, 11/27/94--              }
 386 //--removed mk, 11/27/94--      }
 387 //--removed mk, 11/27/94--
 388 //--removed mk, 11/27/94--      min_temp = min_y_ind;
 389 //--removed mk, 11/27/94--      if (min_y_ind < *bottom_y_ind)
 390 //--removed mk, 11/27/94--              min_temp += t->nv;
 391 //--removed mk, 11/27/94--
 392 //--removed mk, 11/27/94--      for (i=*bottom_y_ind; i<min_temp; i++) {
 393 //--removed mk, 11/27/94--              if (f2i(t->verts[i%t->nv].y2d) < f2i(t->verts[(i+1)%t->nv].y2d)) {
 394 //--removed mk, 11/27/94--                      Int3();
 395 //--removed mk, 11/27/94--                      t->verts[(i+1)%t->nv].y2d = t->verts[i%t->nv].y2d;
 396 //--removed mk, 11/27/94--              }
 397 //--removed mk, 11/27/94--      }
 398 //--removed mk, 11/27/94--}
 399
 400         // Set "vertex left top", etc. based on vertex with topmost y coordinate
 401         *vlt = min_y_ind;
 402         *vrt = *vlt;
 403         *vlb = prevmod(*vlt,t->nv);
 404         *vrb = succmod(*vrt,t->nv);
 405
 406         // If right edge is horizontal, then advance along polygon bound until it no longer is or until all
 407         // vertices have been examined.
 408         // (Left edge cannot be horizontal, because *vlt is set to leftmost point with highest y coordinate.)
 409
 410         original_vrt = *vrt;
 411
 412         while (f2i(t->verts[*vrt].y2d) == f2i(t->verts[*vrb].y2d)) {
 413                 if (succmod(*vrt,t->nv) == original_vrt) {
 414                         break;
 415                 }
 416                 *vrt = succmod(*vrt,t->nv);
 417                 *vrb = succmod(*vrt,t->nv);
 418         }
 419 }
 420
 421 // -------------------------------------------------------------------------------------
 422 //      Returns dx/dy given two vertices.
 423 //      If dy == 0, returns 0.0
 424 // -------------------------------------------------------------------------------------
 425 //--fix compute_dx_dy_lin(g3ds_tmap *t, int top_vertex,int bottom_vertex)
 426 //--{
 427 //--    int     dy;
 428 //--
 429 //--    // compute delta x with respect to y for any edge
 430 //--    dy = f2i(t->verts[bottom_vertex].y2d - t->verts[top_vertex].y2d) + 1;
 431 //--    if (dy)
 432 //--            return (t->verts[bottom_vertex].x2d - t->verts[top_vertex].x2d) / dy;
 433 //--    else
 434 //--            return 0;
 435 //--
 436 //--}
 437
 438 fix compute_du_dy_lin(g3ds_tmap *t, int top_vertex,int bottom_vertex, fix recip_dy)
 439 {
 440         return fixmul(t->verts[bottom_vertex].u - t->verts[top_vertex].u, recip_dy);
 441 }
 442
 443
 444 fix compute_dv_dy_lin(g3ds_tmap *t, int top_vertex,int bottom_vertex, fix recip_dy)
 445 {
 446         return fixmul(t->verts[bottom_vertex].v - t->verts[top_vertex].v, recip_dy);
 447 }
 448
 449 fix compute_dl_dy_lin(g3ds_tmap *t, int top_vertex,int bottom_vertex, fix recip_dy)
 450 {
 451         return fixmul(t->verts[bottom_vertex].l - t->verts[top_vertex].l, recip_dy);
 452
 453 }
 454
 455 fix compute_dx_dy(g3ds_tmap *t, int top_vertex,int bottom_vertex, fix recip_dy)
 456 {
 457         return fixmul(t->verts[bottom_vertex].x2d - t->verts[top_vertex].x2d, recip_dy);
 458 }
 459
 460 fix compute_du_dy(g3ds_tmap *t, int top_vertex,int bottom_vertex, fix recip_dy)
 461 {
 462         return fixmul(fixmul(t->verts[bottom_vertex].u,t->verts[bottom_vertex].z) - fixmul(t->verts[top_vertex].u,t->verts[top_vertex].z), recip_dy);
 463 }
 464
 465
 466 fix compute_dv_dy(g3ds_tmap *t, int top_vertex,int bottom_vertex, fix recip_dy)
 467 {
 468         return fixmul(fixmul(t->verts[bottom_vertex].v,t->verts[bottom_vertex].z) - fixmul(t->verts[top_vertex].v,t->verts[top_vertex].z), recip_dy);
 469
 470 }
 471
 472 fix compute_dz_dy(g3ds_tmap *t, int top_vertex,int bottom_vertex, fix recip_dy)
 473 {
 474         return fixmul(t->verts[bottom_vertex].z - t->verts[top_vertex].z, recip_dy);
 475
 476 }
 477 int Skip_short_flag=0;
 478
 479 // -------------------------------------------------------------------------------------
 480 //      Texture map current scanline in perspective.
 481 // -------------------------------------------------------------------------------------
 482 void ntmap_scanline_lighted(grs_bitmap *srcb, int y, fix xleft, fix xright, fix uleft, fix uright, fix vleft, fix vright, fix zleft, fix zright, fix lleft, fix lright)
 483 {
 484         fix     dx,recip_dx;
 485
 486         fx_xright = f2i(xright);
 487         //edited 06/27/99 Matt Mueller - moved these tests up from within the switch so as not to do a bunch of needless calculations when we are just gonna return anyway.  Slight fps boost?
 488         if (fx_xright < Window_clip_left)
 489                 return;
 490         fx_xleft = f2i(xleft);
 491         if (fx_xleft > Window_clip_right)
 492                 return;
 493         //end edit -MM
 494
 495         dx = fx_xright - fx_xleft;
 496         if ((dx < 0) || (xright < 0) || (xleft > xright))               // the (xleft > xright) term is not redundant with (dx < 0) because dx is computed using integers
 497                 return;
 498
 499         // setup to call assembler scanline renderer
 500         if (dx < FIX_RECIP_TABLE_SIZE)
 501                 recip_dx = fix_recip[dx];
 502         else
 503                 recip_dx = F1_0/dx;
 504
 505         fx_u = uleft;
 506         fx_v = vleft;
 507         fx_z = zleft;
 508
 509         fx_du_dx = fixmul(uright - uleft,recip_dx);
 510         fx_dv_dx = fixmul(vright - vleft,recip_dx);
 511         fx_dz_dx = fixmul(zright - zleft,recip_dx);
 512         fx_y = y;
 513         pixptr = srcb->bm_data;
 514
 515         switch (Lighting_enabled) {
 516                 case 0:
 517                         //added 05/17/99 Matt Mueller - prevent writing before the buffer
 518             if ((fx_y == 0) && (fx_xleft < 0))
 519                                 fx_xleft = 0;
 520                         //end addition -MM
 521                         if (fx_xright > Window_clip_right)
 522                                 fx_xright = Window_clip_right;
 523
 524                         #if (defined(NO_ASM) && !defined(ASM_PER)) || defined(FP_TMAP)
 525                                 c_tmap_scanline_per_nolight();
 526                         #else
 527                                 asm_tmap_scanline_per();
 528                         #endif
 529                         break;
 530                 case 1: {
 531                         fix     mul_thing;
 532
 533                         if (lleft < 0) lleft = 0;
 534                         if (lright < 0) lright = 0;
 535                         if (lleft > (NUM_LIGHTING_LEVELS*F1_0-F1_0/2)) lleft = (NUM_LIGHTING_LEVELS*F1_0-F1_0/2);
 536                         if (lright > (NUM_LIGHTING_LEVELS*F1_0-F1_0/2)) lright = (NUM_LIGHTING_LEVELS*F1_0-F1_0/2);
 537
 538                         fx_l = lleft;
 539                         fx_dl_dx = fixmul(lright - lleft,recip_dx);
 540
 541                         //      This is a pretty ugly hack to prevent lighting overflows.
 542                         mul_thing = dx * fx_dl_dx;
 543                         if (lleft + mul_thing < 0)
 544                                 fx_dl_dx += 12;
 545                         else if (lleft + mul_thing > (NUM_LIGHTING_LEVELS*F1_0-F1_0/2))
 546                                 fx_dl_dx -= 12;
 547
 548                         //added 05/17/99 Matt Mueller - prevent writing before the buffer
 549             if ((fx_y == 0) && (fx_xleft < 0))
 550                                 fx_xleft = 0;
 551                         //end addition -MM
 552                         if (fx_xright > Window_clip_right)
 553                                 fx_xright = Window_clip_right;
 554
 555                         #if (defined(NO_ASM) && !defined(ASM_PER)) || defined(FP_TMAP)
 556                                 c_tmap_scanline_per();
 557                         #else
 558                                 asm_tmap_scanline_per();
 559                         #endif
 560                         break;
 561                 }
 562                 case 2:
 563 #ifdef EDITOR_TMAP
 564                         fx_xright = f2i(xright);
 565                         fx_xleft = f2i(xleft);
 566
 567 #if defined(FL1_WITH_FLAT) || defined(NO_ASM)
 568                         tmap_flat_color = 1;
 569                         #ifdef NO_ASM
 570                         c_tmap_scanline_flat();
 571                         #else
 572                         asm_tmap_scanline_flat();
 573                         #endif
 574 #else
 575                         asm_tmap_scanline_matt();
 576 #endif
 577 #else
 578                         Int3(); //      Illegal, called an editor only routine!
 579 #endif
 580                         break;
 581         }
 582
 583 }
 584
 585 int Do_vertical_scan=0;
 586
 587 int     Break_on_flat=0;
 588
 589 // -------------------------------------------------------------------------------------
 590 //      Render a texture map with lighting using perspective interpolation in inner and outer loops.
 591 // -------------------------------------------------------------------------------------
 592 void ntexture_map_lighted(grs_bitmap *srcb, g3ds_tmap *t)
 593 {
 594         int     vlt,vrt,vlb,vrb;        // vertex left top, vertex right top, vertex left bottom, vertex right bottom
 595         int     topy,boty,y, dy;
 596         fix     dx_dy_left,dx_dy_right;
 597         fix     du_dy_left,du_dy_right;
 598         fix     dv_dy_left,dv_dy_right;
 599         fix     dz_dy_left,dz_dy_right;
 600         fix     dl_dy_left,dl_dy_right;
 601         fix     recip_dyl, recip_dyr;
 602         int     max_y_vertex;
 603         fix     xleft,xright,uleft,vleft,uright,vright,zleft,zright,lleft,lright;
 604         int     next_break_left, next_break_right;
 605
 606         g3ds_vertex *v3d;
 607
 608         //remove stupid warnings in compile
 609         dl_dy_left = F1_0;
 610         dl_dy_right = F1_0;
 611         lleft = F1_0;
 612         lright = F1_0;
 613
 614         v3d = t->verts;
 615
 616         // Determine top and bottom y coords.
 617         compute_y_bounds(t,&vlt,&vlb,&vrt,&vrb,&max_y_vertex);
 618
 619         // Set top and bottom (of entire texture map) y coordinates.
 620         topy = f2i(v3d[vlt].y2d);
 621         boty = f2i(v3d[max_y_vertex].y2d);
 622         if (topy > Window_clip_bot)
 623                 return;
 624         if (boty > Window_clip_bot)
 625                 boty = Window_clip_bot;
 626
 627         // Set amount to change x coordinate for each advance to next scanline.
 628         dy = f2i(t->verts[vlb].y2d) - f2i(t->verts[vlt].y2d);
 629         if (dy < FIX_RECIP_TABLE_SIZE)
 630                 recip_dyl = fix_recip[dy];
 631         else
 632                 recip_dyl = F1_0/dy;
 633
 634         dx_dy_left = compute_dx_dy(t,vlt,vlb, recip_dyl);
 635         du_dy_left = compute_du_dy(t,vlt,vlb, recip_dyl);
 636         dv_dy_left = compute_dv_dy(t,vlt,vlb, recip_dyl);
 637         dz_dy_left = compute_dz_dy(t,vlt,vlb, recip_dyl);
 638
 639         dy = f2i(t->verts[vrb].y2d) - f2i(t->verts[vrt].y2d);
 640         if (dy < FIX_RECIP_TABLE_SIZE)
 641                 recip_dyr = fix_recip[dy];
 642         else
 643                 recip_dyr = F1_0/dy;
 644
 645         du_dy_right = compute_du_dy(t,vrt,vrb, recip_dyr);
 646         dx_dy_right = compute_dx_dy(t,vrt,vrb, recip_dyr);
 647         dv_dy_right = compute_dv_dy(t,vrt,vrb, recip_dyr);
 648         dz_dy_right = compute_dz_dy(t,vrt,vrb, recip_dyr);
 649
 650         if (Lighting_enabled) {
 651                 dl_dy_left = compute_dl_dy_lin(t,vlt,vlb, recip_dyl);
 652                 dl_dy_right = compute_dl_dy_lin(t,vrt,vrb, recip_dyr);
 653
 654                 lleft = v3d[vlt].l;
 655                 lright = v3d[vrt].l;
 656         }
 657
 658         // Set initial values for x, u, v
 659         xleft = v3d[vlt].x2d;
 660         xright = v3d[vrt].x2d;
 661
 662         zleft = v3d[vlt].z;
 663         zright = v3d[vrt].z;
 664
 665         uleft = fixmul(v3d[vlt].u,zleft);
 666         uright = fixmul(v3d[vrt].u,zright);
 667         vleft = fixmul(v3d[vlt].v,zleft);
 668         vright = fixmul(v3d[vrt].v,zright);
 669
 670         // scan all rows in texture map from top through first break.
 671         next_break_left = f2i(v3d[vlb].y2d);
 672         next_break_right = f2i(v3d[vrb].y2d);
 673
 674         for (y = topy; y < boty; y++) {
 675
 676                 // See if we have reached the end of the current left edge, and if so, set
 677                 // new values for dx_dy and x,u,v
 678                 if (y == next_break_left) {
 679                         fix     recip_dy;
 680
 681                         // Handle problem of double points.  Search until y coord is different.  Cannot get
 682                         // hung in an infinite loop because we know there is a vertex with a lower y coordinate
 683                         // because in the for loop, we don't scan all spanlines.
 684                         while (y == f2i(v3d[vlb].y2d)) {
 685                                 vlt = vlb;
 686                                 vlb = prevmod(vlb,t->nv);
 687                         }
 688                         next_break_left = f2i(v3d[vlb].y2d);
 689
 690                         dy = f2i(t->verts[vlb].y2d) - f2i(t->verts[vlt].y2d);
 691                         if (dy < FIX_RECIP_TABLE_SIZE)
 692                                 recip_dy = fix_recip[dy];
 693                         else
 694                                 recip_dy = F1_0/dy;
 695
 696                         dx_dy_left = compute_dx_dy(t,vlt,vlb, recip_dy);
 697
 698                         xleft = v3d[vlt].x2d;
 699                         zleft = v3d[vlt].z;
 700                         uleft = fixmul(v3d[vlt].u,zleft);
 701                         vleft = fixmul(v3d[vlt].v,zleft);
 702                         lleft = v3d[vlt].l;
 703
 704                         du_dy_left = compute_du_dy(t,vlt,vlb, recip_dy);
 705                         dv_dy_left = compute_dv_dy(t,vlt,vlb, recip_dy);
 706                         dz_dy_left = compute_dz_dy(t,vlt,vlb, recip_dy);
 707
 708                         if (Lighting_enabled) {
 709                                 dl_dy_left = compute_dl_dy_lin(t,vlt,vlb, recip_dy);
 710                                 lleft = v3d[vlt].l;
 711                         }
 712                 }
 713
 714                 // See if we have reached the end of the current left edge, and if so, set
 715                 // new values for dx_dy and x.  Not necessary to set new values for u,v.
 716                 if (y == next_break_right) {
 717                         fix     recip_dy;
 718
 719                         while (y == f2i(v3d[vrb].y2d)) {
 720                                 vrt = vrb;
 721                                 vrb = succmod(vrb,t->nv);
 722                         }
 723
 724                         next_break_right = f2i(v3d[vrb].y2d);
 725
 726                         dy = f2i(t->verts[vrb].y2d) - f2i(t->verts[vrt].y2d);
 727                         if (dy < FIX_RECIP_TABLE_SIZE)
 728                                 recip_dy = fix_recip[dy];
 729                         else
 730                                 recip_dy = F1_0/dy;
 731
 732                         dx_dy_right = compute_dx_dy(t,vrt,vrb, recip_dy);
 733
 734                         xright = v3d[vrt].x2d;
 735                         zright = v3d[vrt].z;
 736                         uright = fixmul(v3d[vrt].u,zright);
 737                         vright = fixmul(v3d[vrt].v,zright);
 738
 739                         du_dy_right = compute_du_dy(t,vrt,vrb, recip_dy);
 740                         dv_dy_right = compute_dv_dy(t,vrt,vrb, recip_dy);
 741                         dz_dy_right = compute_dz_dy(t,vrt,vrb, recip_dy);
 742
 743                         if (Lighting_enabled) {
 744                                 dl_dy_right = compute_dl_dy_lin(t,vrt,vrb, recip_dy);
 745                                 lright = v3d[vrt].l;
 746                         }
 747                 }
 748
 749                 if (Lighting_enabled) {
 750                         if (y >= Window_clip_top)
 751                                 ntmap_scanline_lighted(srcb,y,xleft,xright,uleft,uright,vleft,vright,zleft,zright,lleft,lright);
 752                         lleft += dl_dy_left;
 753                         lright += dl_dy_right;
 754                 } else
 755                         if (y >= Window_clip_top)
 756                                 ntmap_scanline_lighted(srcb,y,xleft,xright,uleft,uright,vleft,vright,zleft,zright,lleft,lright);
 757
 758                 uleft += du_dy_left;
 759                 vleft += dv_dy_left;
 760
 761                 uright += du_dy_right;
 762                 vright += dv_dy_right;
 763
 764                 xleft += dx_dy_left;
 765                 xright += dx_dy_right;
 766
 767                 zleft += dz_dy_left;
 768                 zright += dz_dy_right;
 769
 770         }
 771
 772         // We can get lleft or lright out of bounds here because we compute dl_dy using fixed point values,
 773         //      but we plot an integer number of scanlines, therefore doing an integer number of additions of the delta.
 774
 775 //if (Break_on_flat)
 776 //      mprintf(0, "[%i %i %i] ", y, f2i(xleft), f2i(xright));
 777
 778         ntmap_scanline_lighted(srcb,y,xleft,xright,uleft,uright,vleft,vright,zleft,zright,lleft,lright);
 779 }
 780
 781
 782 // -------------------------------------------------------------------------------------
 783 //      Texture map current scanline using linear interpolation.
 784 // -------------------------------------------------------------------------------------
 785 void ntmap_scanline_lighted_linear(grs_bitmap *srcb, int y, fix xleft, fix xright, fix uleft, fix uright, fix vleft, fix vright, fix lleft, fix lright)
 786 {
 787         fix     u,v,l;
 788         fix     dx,recip_dx;
 789
 790         fix     du_dx,dv_dx,dl_dx;
 791
 792         u = uleft;
 793         v = vleft;
 794         l = lleft;
 795
 796         dx = f2i(xright) - f2i(xleft);
 797         if ((dx < 0) || (xright < 0) || (xleft > xright))               // the (xleft > xright) term is not redundant with (dx < 0) because dx is computed using integers
 798                 return;
 799
 800                 // setup to call assembler scanline renderer
 801                 if (dx < FIX_RECIP_TABLE_SIZE)
 802                         recip_dx = fix_recip[dx];
 803                 else
 804                         recip_dx = F1_0/dx;
 805
 806                 du_dx = fixmul(uright - uleft,recip_dx);
 807                 dv_dx = fixmul(vright - vleft,recip_dx);
 808
 809                 fx_u = uleft;
 810                 fx_v = vleft;
 811                 fx_du_dx = du_dx;
 812                 fx_dv_dx = dv_dx;
 813                 fx_y = y;
 814                 fx_xright = f2i(xright);
 815                 fx_xleft = f2i(xleft);
 816                 pixptr = srcb->bm_data;
 817
 818                 switch (Lighting_enabled) {
 819                         case 0:
 820                                 //added 07/11/99 adb - prevent writing before the buffer
 821                                 if (fx_xleft < 0)
 822                                         fx_xleft = 0;
 823                                 //end addition -adb
 824
 825                                 #ifdef NO_ASM
 826                                         c_tmap_scanline_lin_nolight();
 827                                 #else
 828                                         #ifdef NO_ASM_NOLIGHT
 829                                         asm_tmap_scanline_lin_lighted();
 830                                         #else
 831                                         asm_tmap_scanline_lin();
 832                                         #endif
 833                                 #endif
 834                                 break;
 835                         case 1:
 836                                 if (lleft < F1_0/2)
 837                                         lleft = F1_0/2;
 838                                 if (lright < F1_0/2)
 839                                         lright = F1_0/2;
 840
 841                                 if (lleft > MAX_LIGHTING_VALUE*NUM_LIGHTING_LEVELS)
 842                                         lleft = MAX_LIGHTING_VALUE*NUM_LIGHTING_LEVELS;
 843                                 if (lright > MAX_LIGHTING_VALUE*NUM_LIGHTING_LEVELS)
 844                                         lright = MAX_LIGHTING_VALUE*NUM_LIGHTING_LEVELS;
 845
 846                                 //added 07/11/99 adb - prevent writing before the buffer
 847                                 if (fx_xleft < 0)
 848                                         fx_xleft = 0;
 849                                 //end addition -adb
 850
 851 {
 852                         fix mul_thing;
 853
 854                         fx_l = lleft;
 855                         fx_dl_dx = fixmul(lright - lleft,recip_dx);
 856
 857                         //      This is a pretty ugly hack to prevent lighting overflows.
 858                         mul_thing = dx * fx_dl_dx;
 859                         if (lleft + mul_thing < 0)
 860                                 fx_dl_dx += 12;
 861                         else if (lleft + mul_thing > (NUM_LIGHTING_LEVELS*F1_0-F1_0/2))
 862                                 fx_dl_dx -= 12;
 863 }
 864
 865                                 fx_l = lleft;
 866                                 dl_dx = fixmul(lright - lleft,recip_dx);
 867                                 fx_dl_dx = dl_dx;
 868                                 #ifdef NO_ASM
 869                                         c_tmap_scanline_lin();
 870                                 #else
 871                                         asm_tmap_scanline_lin_lighted();
 872                                 #endif
 873                                 break;
 874                         case 2:
 875 #ifdef EDITOR_TMAP
 876                                 fx_xright = f2i(xright);
 877                                 fx_xleft = f2i(xleft);
 878 #if defined(FL1_WITH_FLAT) || defined(NO_ASM)
 879                                 tmap_flat_color = 1;
 880                                 #ifdef NO_ASM
 881                                 c_tmap_scanline_flat();
 882                                 #else
 883                                 asm_tmap_scanline_flat();
 884                                 #endif
 885 #else
 886                                 asm_tmap_scanline_matt();
 887 #endif
 888 #else
 889                                 Int3(); //      Illegal, called an editor only routine!
 890 #endif
 891                                 break;
 892                 }
 893 }
 894
 895 // -------------------------------------------------------------------------------------
 896 //      Render a texture map with lighting using perspective interpolation in inner and outer loops.
 897 // -------------------------------------------------------------------------------------
 898 void ntexture_map_lighted_linear(grs_bitmap *srcb, g3ds_tmap *t)
 899 {
 900         int     vlt,vrt,vlb,vrb;        // vertex left top, vertex right top, vertex left bottom, vertex right bottom
 901         int     topy,boty,y, dy;
 902         fix     dx_dy_left,dx_dy_right;
 903         fix     du_dy_left,du_dy_right;
 904         fix     dv_dy_left,dv_dy_right;
 905         fix     dl_dy_left,dl_dy_right;
 906         int     max_y_vertex;
 907         fix     xleft,xright,uleft,vleft,uright,vright,lleft,lright;
 908         int     next_break_left, next_break_right;
 909         fix     recip_dyl, recip_dyr;
 910
 911         g3ds_vertex *v3d;
 912
 913         //remove stupid warnings in compile
 914         dl_dy_left = F1_0;
 915         dl_dy_right = F1_0;
 916         lleft = F1_0;
 917         lright = F1_0;
 918
 919         v3d = t->verts;
 920
 921         // Determine top and bottom y coords.
 922         compute_y_bounds(t,&vlt,&vlb,&vrt,&vrb,&max_y_vertex);
 923
 924         // Set top and bottom (of entire texture map) y coordinates.
 925         topy = f2i(v3d[vlt].y2d);
 926         boty = f2i(v3d[max_y_vertex].y2d);
 927
 928         if (topy > Window_clip_bot)
 929                 return;
 930         if (boty > Window_clip_bot)
 931                 boty = Window_clip_bot;
 932
 933         dy = f2i(t->verts[vlb].y2d) - f2i(t->verts[vlt].y2d);
 934         if (dy < FIX_RECIP_TABLE_SIZE)
 935                 recip_dyl = fix_recip[dy];
 936         else
 937                 recip_dyl = F1_0/dy;
 938
 939         dy = f2i(t->verts[vrb].y2d) - f2i(t->verts[vrt].y2d);
 940         if (dy < FIX_RECIP_TABLE_SIZE)
 941                 recip_dyr = fix_recip[dy];
 942         else
 943                 recip_dyr = F1_0/dy;
 944
 945         // Set amount to change x coordinate for each advance to next scanline.
 946         dx_dy_left = compute_dx_dy(t,vlt,vlb, recip_dyl);
 947         dx_dy_right = compute_dx_dy(t,vrt,vrb, recip_dyr);
 948
 949         du_dy_left = compute_du_dy_lin(t,vlt,vlb, recip_dyl);
 950         du_dy_right = compute_du_dy_lin(t,vrt,vrb, recip_dyr);
 951
 952         dv_dy_left = compute_dv_dy_lin(t,vlt,vlb, recip_dyl);
 953         dv_dy_right = compute_dv_dy_lin(t,vrt,vrb, recip_dyr);
 954
 955         if (Lighting_enabled) {
 956                 dl_dy_left = compute_dl_dy_lin(t,vlt,vlb, recip_dyl);
 957                 dl_dy_right = compute_dl_dy_lin(t,vrt,vrb, recip_dyr);
 958
 959                 lleft = v3d[vlt].l;
 960                 lright = v3d[vrt].l;
 961         }
 962
 963         // Set initial values for x, u, v
 964         xleft = v3d[vlt].x2d;
 965         xright = v3d[vrt].x2d;
 966
 967         uleft = v3d[vlt].u;
 968         uright = v3d[vrt].u;
 969         vleft = v3d[vlt].v;
 970         vright = v3d[vrt].v;
 971
 972         // scan all rows in texture map from top through first break.
 973         next_break_left = f2i(v3d[vlb].y2d);
 974         next_break_right = f2i(v3d[vrb].y2d);
 975
 976         for (y = topy; y < boty; y++) {
 977
 978                 // See if we have reached the end of the current left edge, and if so, set
 979                 // new values for dx_dy and x,u,v
 980                 if (y == next_break_left) {
 981                         fix     recip_dy;
 982
 983                         // Handle problem of double points.  Search until y coord is different.  Cannot get
 984                         // hung in an infinite loop because we know there is a vertex with a lower y coordinate
 985                         // because in the for loop, we don't scan all spanlines.
 986                         while (y == f2i(v3d[vlb].y2d)) {
 987                                 vlt = vlb;
 988                                 vlb = prevmod(vlb,t->nv);
 989                         }
 990                         next_break_left = f2i(v3d[vlb].y2d);
 991
 992                         dy = f2i(t->verts[vlb].y2d) - f2i(t->verts[vlt].y2d);
 993                         if (dy < FIX_RECIP_TABLE_SIZE)
 994                                 recip_dy = fix_recip[dy];
 995                         else
 996                                 recip_dy = F1_0/dy;
 997
 998                         dx_dy_left = compute_dx_dy(t,vlt,vlb, recip_dy);
 999
1000                         xleft = v3d[vlt].x2d;
1001                         uleft = v3d[vlt].u;
1002                         vleft = v3d[vlt].v;
1003                         lleft = v3d[vlt].l;
1004
1005                         du_dy_left = compute_du_dy_lin(t,vlt,vlb, recip_dy);
1006                         dv_dy_left = compute_dv_dy_lin(t,vlt,vlb, recip_dy);
1007
1008                         if (Lighting_enabled) {
1009                                 dl_dy_left = compute_dl_dy_lin(t,vlt,vlb, recip_dy);
1010                                 lleft = v3d[vlt].l;
1011                         }
1012                 }
1013
1014                 // See if we have reached the end of the current left edge, and if so, set
1015                 // new values for dx_dy and x.  Not necessary to set new values for u,v.
1016                 if (y == next_break_right) {
1017                         fix     recip_dy;
1018
1019                         while (y == f2i(v3d[vrb].y2d)) {
1020                                 vrt = vrb;
1021                                 vrb = succmod(vrb,t->nv);
1022                         }
1023
1024                         dy = f2i(t->verts[vrb].y2d) - f2i(t->verts[vrt].y2d);
1025                         if (dy < FIX_RECIP_TABLE_SIZE)
1026                                 recip_dy = fix_recip[dy];
1027                         else
1028                                 recip_dy = F1_0/dy;
1029
1030                         next_break_right = f2i(v3d[vrb].y2d);
1031                         dx_dy_right = compute_dx_dy(t,vrt,vrb, recip_dy);
1032
1033                         xright = v3d[vrt].x2d;
1034                         uright = v3d[vrt].u;
1035                         vright = v3d[vrt].v;
1036
1037                         du_dy_right = compute_du_dy_lin(t,vrt,vrb, recip_dy);
1038                         dv_dy_right = compute_dv_dy_lin(t,vrt,vrb, recip_dy);
1039
1040                         if (Lighting_enabled) {
1041                                 dl_dy_right = compute_dl_dy_lin(t,vrt,vrb, recip_dy);
1042                                 lright = v3d[vrt].l;
1043                         }
1044                 }
1045
1046                 if (Lighting_enabled) {
1047                         ntmap_scanline_lighted_linear(srcb,y,xleft,xright,uleft,uright,vleft,vright,lleft,lright);
1048                         lleft += dl_dy_left;
1049                         lright += dl_dy_right;
1050                 } else
1051                         ntmap_scanline_lighted_linear(srcb,y,xleft,xright,uleft,uright,vleft,vright,lleft,lright);
1052
1053                 uleft += du_dy_left;
1054                 vleft += dv_dy_left;
1055
1056                 uright += du_dy_right;
1057                 vright += dv_dy_right;
1058
1059                 xleft += dx_dy_left;
1060                 xright += dx_dy_right;
1061
1062         }
1063
1064         // We can get lleft or lright out of bounds here because we compute dl_dy using fixed point values,
1065         //      but we plot an integer number of scanlines, therefore doing an integer number of additions of the delta.
1066
1067         ntmap_scanline_lighted_linear(srcb,y,xleft,xright,uleft,uright,vleft,vright,lleft,lright);
1068 }
1069
1070 // fix  DivNum = F1_0*12;
1071
1072 extern void draw_tmap_flat(grs_bitmap *bp,int nverts,g3s_point **vertbuf);
1073
1074 // -------------------------------------------------------------------------------------
1075 // Interface from Matt's data structures to Mike's texture mapper.
1076 // -------------------------------------------------------------------------------------
1077 void draw_tmap(grs_bitmap *bp,int nverts,g3s_point **vertbuf)
1078 {
1079         int     i;
1080
1081         //      These variables are used in system which renders texture maps which lie on one scanline as a line.
1082         // fix  div_numerator;
1083         int     lighting_on_save = Lighting_on;
1084
1085         Assert(nverts <= MAX_TMAP_VERTS);
1086
1087
1088 #ifdef USE_MULT_CODE
1089         if ( !divide_table_filled ) fill_divide_table();
1090 #endif
1091
1092         // -- now called from g3_start_frame -- init_interface_vars_to_assembler();
1093
1094         //      If no transparency and seg depth is large, render as flat shaded.
1095         if ((Current_seg_depth > Max_linear_depth) && ((bp->bm_flags & 3) == 0)) {
1096                 draw_tmap_flat(bp, nverts, vertbuf);
1097                 return;
1098         }
1099
1100         if ( bp->bm_flags & BM_FLAG_RLE )
1101                 bp = rle_expand_texture( bp );          // Expand if rle'd
1102
1103         Transparency_on = bp->bm_flags & BM_FLAG_TRANSPARENT;
1104         if (bp->bm_flags & BM_FLAG_NO_LIGHTING)
1105                 Lighting_on = 0;
1106
1107
1108         // Setup texture map in Tmap1
1109         Tmap1.nv = nverts;                                              // Initialize number of vertices
1110
1111 //      div_numerator = DivNum; //f1_0*3;
1112
1113         for (i=0; i<nverts; i++) {
1114                 g3ds_vertex     *tvp = &Tmap1.verts[i];
1115                 g3s_point       *vp = vertbuf[i];
1116
1117                 tvp->x2d = vp->p3_sx;
1118                 tvp->y2d = vp->p3_sy;
1119
1120                 //      Check for overflow on fixdiv.  Will overflow on vp->z <= something small.  Allow only as low as 256.
1121                 if (vp->p3_z < 256) {
1122                         vp->p3_z = 256;
1123                         // Int3();              // we would overflow if we divided!
1124                 }
1125
1126                 tvp->z = fixdiv(F1_0*12, vp->p3_z);
1127                 tvp->u = vp->p3_u << 6; //* bp->bm_w;
1128                 tvp->v = vp->p3_v << 6; //* bp->bm_h;
1129
1130                 Assert(Lighting_on < 3);
1131
1132                 if (Lighting_on)
1133                         tvp->l = vp->p3_l * NUM_LIGHTING_LEVELS;
1134         }
1135
1136
1137         Lighting_enabled = Lighting_on;
1138
1139         // Now, call my texture mapper.
1140         if (Lighting_on) {
1141                 switch (Interpolation_method) { // 0 = choose, 1 = linear, 2 = /8 perspective, 3 = full perspective
1142                         case 0:                                                         // choose best interpolation
1143                                 per2_flag = 1;
1144                                 if (Current_seg_depth > Max_perspective_depth)
1145                                         ntexture_map_lighted_linear(bp, &Tmap1);
1146                                 else
1147                                         ntexture_map_lighted(bp, &Tmap1);
1148                                 break;
1149                         case 1:                                                         // linear interpolation
1150                                 per2_flag = 1;
1151                                 ntexture_map_lighted_linear(bp, &Tmap1);
1152                                 break;
1153                         case 2:                                                         // perspective every 8th pixel interpolation
1154                                 per2_flag = 1;
1155                                 ntexture_map_lighted(bp, &Tmap1);
1156                                 break;
1157                         case 3:                                                         // perspective every pixel interpolation
1158                                 per2_flag = 0;                                  // this hack means do divide every pixel
1159                                 ntexture_map_lighted(bp, &Tmap1);
1160                                 break;
1161                         default:
1162                                 Assert(0);                              // Illegal value for Interpolation_method, must be 0,1,2,3
1163                 }
1164         } else {
1165                 switch (Interpolation_method) { // 0 = choose, 1 = linear, 2 = /8 perspective, 3 = full perspective
1166                         case 0:                                                         // choose best interpolation
1167                                 per2_flag = 1;
1168                                 if (Current_seg_depth > Max_perspective_depth)
1169                                         ntexture_map_lighted_linear(bp, &Tmap1);
1170                                 else
1171                                         ntexture_map_lighted(bp, &Tmap1);
1172                                 break;
1173                         case 1:                                                         // linear interpolation
1174                                 per2_flag = 1;
1175                                 ntexture_map_lighted_linear(bp, &Tmap1);
1176                                 break;
1177                         case 2:                                                         // perspective every 8th pixel interpolation
1178                                 per2_flag = 1;
1179                                 ntexture_map_lighted(bp, &Tmap1);
1180                                 break;
1181                         case 3:                                                         // perspective every pixel interpolation
1182                                 per2_flag = 0;                                  // this hack means do divide every pixel
1183                                 ntexture_map_lighted(bp, &Tmap1);
1184                                 break;
1185                         default:
1186                                 Assert(0);                              // Illegal value for Interpolation_method, must be 0,1,2,3
1187                 }
1188         }
1189
1190         Lighting_on = lighting_on_save;
1191
1192 }
1193