src/gallium/drivers/llvmpipe/lp_setup_tri.c

   1 /**************************************************************************
   2  *
   3  * Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
   4  * All Rights Reserved.
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a
   7  * copy of this software and associated documentation files (the
   8  * "Software"), to deal in the Software without restriction, including
   9  * without limitation the rights to use, copy, modify, merge, publish,
  10  * distribute, sub license, and/or sell copies of the Software, and to
  11  * permit persons to whom the Software is furnished to do so, subject to
  12  * the following conditions:
  13  *
  14  * The above copyright notice and this permission notice (including the
  15  * next paragraph) shall be included in all copies or substantial portions
  16  * of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  19  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  20  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
  21  * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
  22  * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  23  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  24  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  25  *
  26  **************************************************************************/
  27
  28 /*
  29  * Binning code for triangles
  30  */
  31
  32 #include "util/u_math.h"
  33 #include "util/u_memory.h"
  34 #include "util/u_rect.h"
  35 #include "lp_perf.h"
  36 #include "lp_setup_context.h"
  37 #include "lp_setup_coef.h"
  38 #include "lp_rast.h"
  39 #include "lp_state_fs.h"
  40
  41 #define NUM_CHANNELS 4
  42
  43
  44
  45 static INLINE int
  46 subpixel_snap(float a)
  47 {
  48    return util_iround(FIXED_ONE * a);
  49 }
  50
  51 static INLINE float
  52 fixed_to_float(int a)
  53 {
  54    return a * (1.0 / FIXED_ONE);
  55 }
  56
  57
  58
  59
  60
  61
  62
  63 /**
  64  * Alloc space for a new triangle plus the input.a0/dadx/dady arrays
  65  * immediately after it.
  66  * The memory is allocated from the per-scene pool, not per-tile.
  67  * \param tri_size  returns number of bytes allocated
  68  * \param nr_inputs  number of fragment shader inputs
  69  * \return pointer to triangle space
  70  */
  71 struct lp_rast_triangle *
  72 lp_setup_alloc_triangle(struct lp_scene *scene,
  73                         unsigned nr_inputs,
  74                         unsigned nr_planes,
  75                         unsigned *tri_size)
  76 {
  77    unsigned input_array_sz = NUM_CHANNELS * (nr_inputs + 1) * sizeof(float);
  78    struct lp_rast_triangle *tri;
  79    unsigned tri_bytes, bytes;
  80    char *inputs;
  81
  82    tri_bytes = align(Offset(struct lp_rast_triangle, plane[nr_planes]), 16);
  83    bytes = tri_bytes + (3 * input_array_sz);
  84
  85    tri = lp_scene_alloc_aligned( scene, bytes, 16 );
  86
  87    if (tri) {
  88       inputs = ((char *)tri) + tri_bytes;
  89       tri->inputs.a0   = (float (*)[4]) inputs;
  90       tri->inputs.dadx = (float (*)[4]) (inputs + input_array_sz);
  91       tri->inputs.dady = (float (*)[4]) (inputs + 2 * input_array_sz);
  92
  93       *tri_size = bytes;
  94    }
  95
  96    return tri;
  97 }
  98
  99 void
 100 lp_setup_print_vertex(struct lp_setup_context *setup,
 101                       const char *name,
 102                       const float (*v)[4])
 103 {
 104    int i, j;
 105
 106    debug_printf("   wpos (%s[0]) xyzw %f %f %f %f\n",
 107                 name,
 108                 v[0][0], v[0][1], v[0][2], v[0][3]);
 109
 110    for (i = 0; i < setup->fs.nr_inputs; i++) {
 111       const float *in = v[setup->fs.input[i].src_index];
 112
 113       debug_printf("  in[%d] (%s[%d]) %s%s%s%s ",
 114                    i,
 115                    name, setup->fs.input[i].src_index,
 116                    (setup->fs.input[i].usage_mask & 0x1) ? "x" : " ",
 117                    (setup->fs.input[i].usage_mask & 0x2) ? "y" : " ",
 118                    (setup->fs.input[i].usage_mask & 0x4) ? "z" : " ",
 119                    (setup->fs.input[i].usage_mask & 0x8) ? "w" : " ");
 120
 121       for (j = 0; j < 4; j++)
 122          if (setup->fs.input[i].usage_mask & (1<<j))
 123             debug_printf("%.5f ", in[j]);
 124
 125       debug_printf("\n");
 126    }
 127 }
 128
 129
 130 /**
 131  * Print triangle vertex attribs (for debug).
 132  */
 133 void
 134 lp_setup_print_triangle(struct lp_setup_context *setup,
 135                         const float (*v0)[4],
 136                         const float (*v1)[4],
 137                         const float (*v2)[4])
 138 {
 139    debug_printf("triangle\n");
 140
 141    {
 142       const float ex = v0[0][0] - v2[0][0];
 143       const float ey = v0[0][1] - v2[0][1];
 144       const float fx = v1[0][0] - v2[0][0];
 145       const float fy = v1[0][1] - v2[0][1];
 146
 147       /* det = cross(e,f).z */
 148       const float det = ex * fy - ey * fx;
 149       if (det < 0.0f)
 150          debug_printf("   - ccw\n");
 151       else if (det > 0.0f)
 152          debug_printf("   - cw\n");
 153       else
 154          debug_printf("   - zero area\n");
 155    }
 156
 157    lp_setup_print_vertex(setup, "v0", v0);
 158    lp_setup_print_vertex(setup, "v1", v1);
 159    lp_setup_print_vertex(setup, "v2", v2);
 160 }
 161
 162
 163 lp_rast_cmd lp_rast_tri_tab[9] = {
 164    NULL,               /* should be impossible */
 165    lp_rast_triangle_1,
 166    lp_rast_triangle_2,
 167    lp_rast_triangle_3,
 168    lp_rast_triangle_4,
 169    lp_rast_triangle_5,
 170    lp_rast_triangle_6,
 171    lp_rast_triangle_7,
 172    lp_rast_triangle_8
 173 };
 174
 175
 176
 177 /**
 178  * The primitive covers the whole tile- shade whole tile.
 179  *
 180  * \param tx, ty  the tile position in tiles, not pixels
 181  */
 182 static boolean
 183 lp_setup_whole_tile(struct lp_setup_context *setup,
 184                     const struct lp_rast_shader_inputs *inputs,
 185                     int tx, int ty)
 186 {
 187    struct lp_scene *scene = setup->scene;
 188
 189    LP_COUNT(nr_fully_covered_64);
 190
 191    /* if variant is opaque and scissor doesn't effect the tile */
 192    if (inputs->opaque) {
 193       if (!scene->fb.zsbuf) {
 194          /*
 195           * All previous rendering will be overwritten so reset the bin.
 196           */
 197          lp_scene_bin_reset( scene, tx, ty );
 198       }
 199
 200       LP_COUNT(nr_shade_opaque_64);
 201       return lp_scene_bin_command( scene, tx, ty,
 202                                   lp_rast_shade_tile_opaque,
 203                                   lp_rast_arg_inputs(inputs) );
 204    } else {
 205       LP_COUNT(nr_shade_64);
 206       return lp_scene_bin_command( scene, tx, ty,
 207                                    lp_rast_shade_tile,
 208                                    lp_rast_arg_inputs(inputs) );
 209    }
 210 }
 211
 212
 213 /**
 214  * Do basic setup for triangle rasterization and determine which
 215  * framebuffer tiles are touched.  Put the triangle in the scene's
 216  * bins for the tiles which we overlap.
 217  */
 218 static boolean
 219 do_triangle_ccw(struct lp_setup_context *setup,
 220                 const float (*v0)[4],
 221                 const float (*v1)[4],
 222                 const float (*v2)[4],
 223                 boolean frontfacing )
 224 {
 225    struct lp_scene *scene = lp_setup_get_current_scene(setup);
 226    struct lp_fragment_shader_variant *variant = setup->fs.current.variant;
 227    struct lp_rast_triangle *tri;
 228    int x[3];
 229    int y[3];
 230    float dy01, dy20;
 231    float dx01, dx20;
 232    float oneoverarea;
 233    struct lp_tri_info info;
 234    int area;
 235    struct u_rect bbox;
 236    unsigned tri_bytes;
 237    int i;
 238    int nr_planes = 3;
 239
 240    if (0)
 241       lp_setup_print_triangle(setup, v0, v1, v2);
 242
 243    if (setup->scissor_test) {
 244       nr_planes = 7;
 245    }
 246    else {
 247       nr_planes = 3;
 248    }
 249
 250    /* x/y positions in fixed point */
 251    x[0] = subpixel_snap(v0[0][0] - setup->pixel_offset);
 252    x[1] = subpixel_snap(v1[0][0] - setup->pixel_offset);
 253    x[2] = subpixel_snap(v2[0][0] - setup->pixel_offset);
 254    y[0] = subpixel_snap(v0[0][1] - setup->pixel_offset);
 255    y[1] = subpixel_snap(v1[0][1] - setup->pixel_offset);
 256    y[2] = subpixel_snap(v2[0][1] - setup->pixel_offset);
 257
 258
 259    /* Bounding rectangle (in pixels) */
 260    {
 261       /* Yes this is necessary to accurately calculate bounding boxes
 262        * with the two fill-conventions we support.  GL (normally) ends
 263        * up needing a bottom-left fill convention, which requires
 264        * slightly different rounding.
 265        */
 266       int adj = (setup->pixel_offset != 0) ? 1 : 0;
 267
 268       bbox.x0 = (MIN3(x[0], x[1], x[2]) + (FIXED_ONE-1)) >> FIXED_ORDER;
 269       bbox.x1 = (MAX3(x[0], x[1], x[2]) + (FIXED_ONE-1)) >> FIXED_ORDER;
 270       bbox.y0 = (MIN3(y[0], y[1], y[2]) + (FIXED_ONE-1) + adj) >> FIXED_ORDER;
 271       bbox.y1 = (MAX3(y[0], y[1], y[2]) + (FIXED_ONE-1) + adj) >> FIXED_ORDER;
 272
 273       /* Inclusive coordinates:
 274        */
 275       bbox.x1--;
 276       bbox.y1--;
 277    }
 278
 279    if (bbox.x1 < bbox.x0 ||
 280        bbox.y1 < bbox.y0) {
 281       if (0) debug_printf("empty bounding box\n");
 282       LP_COUNT(nr_culled_tris);
 283       return FALSE;
 284    }
 285
 286    if (!u_rect_test_intersection(&setup->draw_region, &bbox)) {
 287       if (0) debug_printf("offscreen\n");
 288       LP_COUNT(nr_culled_tris);
 289       return FALSE;
 290    }
 291
 292    u_rect_find_intersection(&setup->draw_region, &bbox);
 293
 294    tri = lp_setup_alloc_triangle(scene,
 295                                  setup->fs.nr_inputs,
 296                                  nr_planes,
 297                                  &tri_bytes);
 298    if (!tri)
 299       return FALSE;
 300
 301 #ifdef DEBUG
 302    tri->v[0][0] = v0[0][0];
 303    tri->v[1][0] = v1[0][0];
 304    tri->v[2][0] = v2[0][0];
 305    tri->v[0][1] = v0[0][1];
 306    tri->v[1][1] = v1[0][1];
 307    tri->v[2][1] = v2[0][1];
 308 #endif
 309
 310    tri->plane[0].dcdy = x[0] - x[1];
 311    tri->plane[1].dcdy = x[1] - x[2];
 312    tri->plane[2].dcdy = x[2] - x[0];
 313
 314    tri->plane[0].dcdx = y[0] - y[1];
 315    tri->plane[1].dcdx = y[1] - y[2];
 316    tri->plane[2].dcdx = y[2] - y[0];
 317
 318    area = (tri->plane[0].dcdy * tri->plane[2].dcdx -
 319            tri->plane[2].dcdy * tri->plane[0].dcdx);
 320
 321    LP_COUNT(nr_tris);
 322
 323    /* Cull non-ccw and zero-sized triangles.
 324     *
 325     * XXX: subject to overflow??
 326     */
 327    if (area <= 0) {
 328       lp_scene_putback_data( scene, tri_bytes );
 329       LP_COUNT(nr_culled_tris);
 330       return TRUE;
 331    }
 332
 333
 334    /*
 335     */
 336    dx01 = v0[0][0] - v1[0][0];
 337    dy01 = v0[0][1] - v1[0][1];
 338    dx20 = v2[0][0] - v0[0][0];
 339    dy20 = v2[0][1] - v0[0][1];
 340    oneoverarea = 1.0f / (dx01 * dy20 - dx20 * dy01);
 341
 342    info.v0 = v0;
 343    info.v1 = v1;
 344    info.v2 = v2;
 345    info.frontfacing = frontfacing;
 346    info.x0_center = v0[0][0] - setup->pixel_offset;
 347    info.y0_center = v0[0][1] - setup->pixel_offset;
 348    info.dx01_ooa  = dx01 * oneoverarea;
 349    info.dx20_ooa  = dx20 * oneoverarea;
 350    info.dy01_ooa  = dy01 * oneoverarea;
 351    info.dy20_ooa  = dy20 * oneoverarea;
 352
 353    /* Setup parameter interpolants:
 354     */
 355    lp_setup_tri_coef( setup, &tri->inputs, &info );
 356
 357    tri->inputs.facing = frontfacing ? 1.0F : -1.0F;
 358    tri->inputs.opaque = variant->opaque;
 359    tri->inputs.disable = FALSE;
 360    tri->inputs.state = setup->fs.stored;
 361
 362
 363
 364    for (i = 0; i < 3; i++) {
 365       struct lp_rast_plane *plane = &tri->plane[i];
 366
 367       /* half-edge constants, will be interated over the whole render
 368        * target.
 369        */
 370       plane->c = plane->dcdx * x[i] - plane->dcdy * y[i];
 371
 372       /* correct for top-left vs. bottom-left fill convention.
 373        *
 374        * note that we're overloading gl_rasterization_rules to mean
 375        * both (0.5,0.5) pixel centers *and* bottom-left filling
 376        * convention.
 377        *
 378        * GL actually has a top-left filling convention, but GL's
 379        * notion of "top" differs from gallium's...
 380        *
 381        * Also, sometimes (in FBO cases) GL will render upside down
 382        * to its usual method, in which case it will probably want
 383        * to use the opposite, top-left convention.
 384        */
 385       if (plane->dcdx < 0) {
 386          /* both fill conventions want this - adjust for left edges */
 387          plane->c++;
 388       }
 389       else if (plane->dcdx == 0) {
 390          if (setup->pixel_offset == 0) {
 391             /* correct for top-left fill convention:
 392              */
 393             if (plane->dcdy > 0) plane->c++;
 394          }
 395          else {
 396             /* correct for bottom-left fill convention:
 397              */
 398             if (plane->dcdy < 0) plane->c++;
 399          }
 400       }
 401
 402       plane->dcdx *= FIXED_ONE;
 403       plane->dcdy *= FIXED_ONE;
 404
 405       /* find trivial reject offsets for each edge for a single-pixel
 406        * sized block.  These will be scaled up at each recursive level to
 407        * match the active blocksize.  Scaling in this way works best if
 408        * the blocks are square.
 409        */
 410       plane->eo = 0;
 411       if (plane->dcdx < 0) plane->eo -= plane->dcdx;
 412       if (plane->dcdy > 0) plane->eo += plane->dcdy;
 413
 414       /* Calculate trivial accept offsets from the above.
 415        */
 416       plane->ei = plane->dcdy - plane->dcdx - plane->eo;
 417    }
 418
 419
 420    /*
 421     * When rasterizing scissored tris, use the intersection of the
 422     * triangle bounding box and the scissor rect to generate the
 423     * scissor planes.
 424     *
 425     * This permits us to cut off the triangle "tails" that are present
 426     * in the intermediate recursive levels caused when two of the
 427     * triangles edges don't diverge quickly enough to trivially reject
 428     * exterior blocks from the triangle.
 429     *
 430     * It's not really clear if it's worth worrying about these tails,
 431     * but since we generate the planes for each scissored tri, it's
 432     * free to trim them in this case.
 433     *
 434     * Note that otherwise, the scissor planes only vary in 'C' value,
 435     * and even then only on state-changes.  Could alternatively store
 436     * these planes elsewhere.
 437     */
 438    if (nr_planes == 7) {
 439       tri->plane[3].dcdx = -1;
 440       tri->plane[3].dcdy = 0;
 441       tri->plane[3].c = 1-bbox.x0;
 442       tri->plane[3].ei = 0;
 443       tri->plane[3].eo = 1;
 444
 445       tri->plane[4].dcdx = 1;
 446       tri->plane[4].dcdy = 0;
 447       tri->plane[4].c = bbox.x1+1;
 448       tri->plane[4].ei = -1;
 449       tri->plane[4].eo = 0;
 450
 451       tri->plane[5].dcdx = 0;
 452       tri->plane[5].dcdy = 1;
 453       tri->plane[5].c = 1-bbox.y0;
 454       tri->plane[5].ei = 0;
 455       tri->plane[5].eo = 1;
 456
 457       tri->plane[6].dcdx = 0;
 458       tri->plane[6].dcdy = -1;
 459       tri->plane[6].c = bbox.y1+1;
 460       tri->plane[6].ei = -1;
 461       tri->plane[6].eo = 0;
 462    }
 463
 464    return lp_setup_bin_triangle( setup, tri, &bbox, nr_planes );
 465 }
 466
 467
 468 boolean
 469 lp_setup_bin_triangle( struct lp_setup_context *setup,
 470                        struct lp_rast_triangle *tri,
 471                        const struct u_rect *bbox,
 472                        int nr_planes )
 473 {
 474    struct lp_scene *scene = setup->scene;
 475    int ix0, ix1, iy0, iy1;
 476    int i;
 477
 478    /*
 479     * All fields of 'tri' are now set.  The remaining code here is
 480     * concerned with binning.
 481     */
 482
 483    /* Convert to tile coordinates, and inclusive ranges:
 484     */
 485    if (nr_planes == 3) {
 486       int ix0 = bbox->x0 / 16;
 487       int iy0 = bbox->y0 / 16;
 488       int ix1 = bbox->x1 / 16;
 489       int iy1 = bbox->y1 / 16;
 490
 491       if (iy0 == iy1 && ix0 == ix1)
 492       {
 493
 494          /* Triangle is contained in a single 16x16 block:
 495           */
 496          int mask = (ix0 & 3) | ((iy0 & 3) << 4);
 497
 498          return lp_scene_bin_command( scene, ix0/4, iy0/4,
 499                                       lp_rast_triangle_3_16,
 500                                       lp_rast_arg_triangle(tri, mask) );
 501       }
 502    }
 503
 504    ix0 = bbox->x0 / TILE_SIZE;
 505    iy0 = bbox->y0 / TILE_SIZE;
 506    ix1 = bbox->x1 / TILE_SIZE;
 507    iy1 = bbox->y1 / TILE_SIZE;
 508
 509    /*
 510     * Clamp to framebuffer size
 511     */
 512    assert(ix0 == MAX2(ix0, 0));
 513    assert(iy0 == MAX2(iy0, 0));
 514    assert(ix1 == MIN2(ix1, scene->tiles_x - 1));
 515    assert(iy1 == MIN2(iy1, scene->tiles_y - 1));
 516
 517    /* Determine which tile(s) intersect the triangle's bounding box
 518     */
 519    if (iy0 == iy1 && ix0 == ix1)
 520    {
 521       /* Triangle is contained in a single tile:
 522        */
 523       return lp_scene_bin_command( scene, ix0, iy0,
 524                                    lp_rast_tri_tab[nr_planes],
 525                                    lp_rast_arg_triangle(tri, (1<<nr_planes)-1) );
 526    }
 527    else
 528    {
 529       int c[7];
 530       int ei[7];
 531       int eo[7];
 532       int xstep[7];
 533       int ystep[7];
 534       int x, y;
 535
 536       for (i = 0; i < nr_planes; i++) {
 537          c[i] = (tri->plane[i].c +
 538                  tri->plane[i].dcdy * iy0 * TILE_SIZE -
 539                  tri->plane[i].dcdx * ix0 * TILE_SIZE);
 540
 541          ei[i] = tri->plane[i].ei << TILE_ORDER;
 542          eo[i] = tri->plane[i].eo << TILE_ORDER;
 543          xstep[i] = -(tri->plane[i].dcdx << TILE_ORDER);
 544          ystep[i] = tri->plane[i].dcdy << TILE_ORDER;
 545       }
 546
 547
 548
 549       /* Test tile-sized blocks against the triangle.
 550        * Discard blocks fully outside the tri.  If the block is fully
 551        * contained inside the tri, bin an lp_rast_shade_tile command.
 552        * Else, bin a lp_rast_triangle command.
 553        */
 554       for (y = iy0; y <= iy1; y++)
 555       {
 556          boolean in = FALSE;  /* are we inside the triangle? */
 557          int cx[7];
 558
 559          for (i = 0; i < nr_planes; i++)
 560             cx[i] = c[i];
 561
 562          for (x = ix0; x <= ix1; x++)
 563          {
 564             int out = 0;
 565             int partial = 0;
 566
 567             for (i = 0; i < nr_planes; i++) {
 568                int planeout = cx[i] + eo[i];
 569                int planepartial = cx[i] + ei[i] - 1;
 570                out |= (planeout >> 31);
 571                partial |= (planepartial >> 31) & (1<<i);
 572             }
 573
 574             if (out) {
 575                /* do nothing */
 576                if (in)
 577                   break;  /* exiting triangle, all done with this row */
 578                LP_COUNT(nr_empty_64);
 579             }
 580             else if (partial) {
 581                /* Not trivially accepted by at least one plane -
 582                 * rasterize/shade partial tile
 583                 */
 584                int count = util_bitcount(partial);
 585                in = TRUE;
 586                if (!lp_scene_bin_command( scene, x, y,
 587                                           lp_rast_tri_tab[count],
 588                                           lp_rast_arg_triangle(tri, partial) ))
 589                   goto fail;
 590
 591                LP_COUNT(nr_partially_covered_64);
 592             }
 593             else {
 594                /* triangle covers the whole tile- shade whole tile */
 595                LP_COUNT(nr_fully_covered_64);
 596                in = TRUE;
 597                if (!lp_setup_whole_tile(setup, &tri->inputs, x, y))
 598                   goto fail;
 599             }
 600
 601             /* Iterate cx values across the region:
 602              */
 603             for (i = 0; i < nr_planes; i++)
 604                cx[i] += xstep[i];
 605          }
 606
 607          /* Iterate c values down the region:
 608           */
 609          for (i = 0; i < nr_planes; i++)
 610             c[i] += ystep[i];
 611       }
 612    }
 613
 614    return TRUE;
 615
 616 fail:
 617    /* Need to disable any partially binned triangle.  This is easier
 618     * than trying to locate all the triangle, shade-tile, etc,
 619     * commands which may have been binned.
 620     */
 621    tri->inputs.disable = TRUE;
 622    return FALSE;
 623 }
 624
 625
 626 /**
 627  * Draw triangle if it's CW, cull otherwise.
 628  */
 629 static void triangle_cw( struct lp_setup_context *setup,
 630                          const float (*v0)[4],
 631                          const float (*v1)[4],
 632                          const float (*v2)[4] )
 633 {
 634    if (!do_triangle_ccw( setup, v1, v0, v2, !setup->ccw_is_frontface ))
 635    {
 636       lp_setup_flush_and_restart(setup);
 637
 638       if (!do_triangle_ccw( setup, v1, v0, v2, !setup->ccw_is_frontface ))
 639          assert(0);
 640    }
 641 }
 642
 643
 644 /**
 645  * Draw triangle if it's CCW, cull otherwise.
 646  */
 647 static void triangle_ccw( struct lp_setup_context *setup,
 648                          const float (*v0)[4],
 649                          const float (*v1)[4],
 650                          const float (*v2)[4] )
 651 {
 652    if (!do_triangle_ccw( setup, v0, v1, v2, setup->ccw_is_frontface ))
 653    {
 654       lp_setup_flush_and_restart(setup);
 655       if (!do_triangle_ccw( setup, v0, v1, v2, setup->ccw_is_frontface ))
 656          assert(0);
 657    }
 658 }
 659
 660
 661
 662 /**
 663  * Draw triangle whether it's CW or CCW.
 664  */
 665 static void triangle_both( struct lp_setup_context *setup,
 666                            const float (*v0)[4],
 667                            const float (*v1)[4],
 668                            const float (*v2)[4] )
 669 {
 670    /* edge vectors e = v0 - v2, f = v1 - v2 */
 671    const float ex = v0[0][0] - v2[0][0];
 672    const float ey = v0[0][1] - v2[0][1];
 673    const float fx = v1[0][0] - v2[0][0];
 674    const float fy = v1[0][1] - v2[0][1];
 675
 676    /* det = cross(e,f).z */
 677    const float det = ex * fy - ey * fx;
 678    if (det < 0.0f)
 679       triangle_ccw( setup, v0, v1, v2 );
 680    else if (det > 0.0f)
 681       triangle_cw( setup, v0, v1, v2 );
 682 }
 683
 684
 685 static void triangle_nop( struct lp_setup_context *setup,
 686                           const float (*v0)[4],
 687                           const float (*v1)[4],
 688                           const float (*v2)[4] )
 689 {
 690 }
 691
 692
 693 void
 694 lp_setup_choose_triangle( struct lp_setup_context *setup )
 695 {
 696    switch (setup->cullmode) {
 697    case PIPE_FACE_NONE:
 698       setup->triangle = triangle_both;
 699       break;
 700    case PIPE_FACE_BACK:
 701       setup->triangle = setup->ccw_is_frontface ? triangle_ccw : triangle_cw;
 702       break;
 703    case PIPE_FACE_FRONT:
 704       setup->triangle = setup->ccw_is_frontface ? triangle_cw : triangle_ccw;
 705       break;
 706    default:
 707       setup->triangle = triangle_nop;
 708       break;
 709    }
 710 }