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 static unsigned
 164 lp_rast_tri_tab[9] = {
 165    0,               /* should be impossible */
 166    LP_RAST_OP_TRIANGLE_1,
 167    LP_RAST_OP_TRIANGLE_2,
 168    LP_RAST_OP_TRIANGLE_3,
 169    LP_RAST_OP_TRIANGLE_4,
 170    LP_RAST_OP_TRIANGLE_5,
 171    LP_RAST_OP_TRIANGLE_6,
 172    LP_RAST_OP_TRIANGLE_7,
 173    LP_RAST_OP_TRIANGLE_8
 174 };
 175
 176
 177
 178 /**
 179  * The primitive covers the whole tile- shade whole tile.
 180  *
 181  * \param tx, ty  the tile position in tiles, not pixels
 182  */
 183 static boolean
 184 lp_setup_whole_tile(struct lp_setup_context *setup,
 185                     const struct lp_rast_shader_inputs *inputs,
 186                     int tx, int ty)
 187 {
 188    struct lp_scene *scene = setup->scene;
 189
 190    LP_COUNT(nr_fully_covered_64);
 191
 192    /* if variant is opaque and scissor doesn't effect the tile */
 193    if (inputs->opaque) {
 194       if (!scene->fb.zsbuf) {
 195          /*
 196           * All previous rendering will be overwritten so reset the bin.
 197           */
 198          lp_scene_bin_reset( scene, tx, ty );
 199       }
 200
 201       LP_COUNT(nr_shade_opaque_64);
 202       return lp_scene_bin_command( scene, tx, ty,
 203                                    LP_RAST_OP_SHADE_TILE_OPAQUE,
 204                                    lp_rast_arg_inputs(inputs) );
 205    } else {
 206       LP_COUNT(nr_shade_64);
 207       return lp_scene_bin_command( scene, tx, ty,
 208                                    LP_RAST_OP_SHADE_TILE,
 209                                    lp_rast_arg_inputs(inputs) );
 210    }
 211 }
 212
 213
 214 /**
 215  * Do basic setup for triangle rasterization and determine which
 216  * framebuffer tiles are touched.  Put the triangle in the scene's
 217  * bins for the tiles which we overlap.
 218  */
 219 static boolean
 220 do_triangle_ccw(struct lp_setup_context *setup,
 221                 const float (*v0)[4],
 222                 const float (*v1)[4],
 223                 const float (*v2)[4],
 224                 boolean frontfacing )
 225 {
 226    struct lp_scene *scene = setup->scene;
 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 TRUE;
 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 TRUE;
 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.disable = FALSE;
 359    tri->inputs.opaque = setup->fs.current.variant->opaque;
 360    tri->inputs.state = setup->fs.stored;
 361
 362
 363    for (i = 0; i < 3; i++) {
 364       struct lp_rast_plane *plane = &tri->plane[i];
 365
 366       /* half-edge constants, will be interated over the whole render
 367        * target.
 368        */
 369       plane->c = plane->dcdx * x[i] - plane->dcdy * y[i];
 370
 371       /* correct for top-left vs. bottom-left fill convention.
 372        *
 373        * note that we're overloading gl_rasterization_rules to mean
 374        * both (0.5,0.5) pixel centers *and* bottom-left filling
 375        * convention.
 376        *
 377        * GL actually has a top-left filling convention, but GL's
 378        * notion of "top" differs from gallium's...
 379        *
 380        * Also, sometimes (in FBO cases) GL will render upside down
 381        * to its usual method, in which case it will probably want
 382        * to use the opposite, top-left convention.
 383        */
 384       if (plane->dcdx < 0) {
 385          /* both fill conventions want this - adjust for left edges */
 386          plane->c++;
 387       }
 388       else if (plane->dcdx == 0) {
 389          if (setup->pixel_offset == 0) {
 390             /* correct for top-left fill convention:
 391              */
 392             if (plane->dcdy > 0) plane->c++;
 393          }
 394          else {
 395             /* correct for bottom-left fill convention:
 396              */
 397             if (plane->dcdy < 0) plane->c++;
 398          }
 399       }
 400
 401       plane->dcdx *= FIXED_ONE;
 402       plane->dcdy *= FIXED_ONE;
 403
 404       /* find trivial reject offsets for each edge for a single-pixel
 405        * sized block.  These will be scaled up at each recursive level to
 406        * match the active blocksize.  Scaling in this way works best if
 407        * the blocks are square.
 408        */
 409       plane->eo = 0;
 410       if (plane->dcdx < 0) plane->eo -= plane->dcdx;
 411       if (plane->dcdy > 0) plane->eo += plane->dcdy;
 412
 413       /* Calculate trivial accept offsets from the above.
 414        */
 415       plane->ei = plane->dcdy - plane->dcdx - plane->eo;
 416    }
 417
 418
 419    /*
 420     * When rasterizing scissored tris, use the intersection of the
 421     * triangle bounding box and the scissor rect to generate the
 422     * scissor planes.
 423     *
 424     * This permits us to cut off the triangle "tails" that are present
 425     * in the intermediate recursive levels caused when two of the
 426     * triangles edges don't diverge quickly enough to trivially reject
 427     * exterior blocks from the triangle.
 428     *
 429     * It's not really clear if it's worth worrying about these tails,
 430     * but since we generate the planes for each scissored tri, it's
 431     * free to trim them in this case.
 432     *
 433     * Note that otherwise, the scissor planes only vary in 'C' value,
 434     * and even then only on state-changes.  Could alternatively store
 435     * these planes elsewhere.
 436     */
 437    if (nr_planes == 7) {
 438       tri->plane[3].dcdx = -1;
 439       tri->plane[3].dcdy = 0;
 440       tri->plane[3].c = 1-bbox.x0;
 441       tri->plane[3].ei = 0;
 442       tri->plane[3].eo = 1;
 443
 444       tri->plane[4].dcdx = 1;
 445       tri->plane[4].dcdy = 0;
 446       tri->plane[4].c = bbox.x1+1;
 447       tri->plane[4].ei = -1;
 448       tri->plane[4].eo = 0;
 449
 450       tri->plane[5].dcdx = 0;
 451       tri->plane[5].dcdy = 1;
 452       tri->plane[5].c = 1-bbox.y0;
 453       tri->plane[5].ei = 0;
 454       tri->plane[5].eo = 1;
 455
 456       tri->plane[6].dcdx = 0;
 457       tri->plane[6].dcdy = -1;
 458       tri->plane[6].c = bbox.y1+1;
 459       tri->plane[6].ei = -1;
 460       tri->plane[6].eo = 0;
 461    }
 462
 463    return lp_setup_bin_triangle( setup, tri, &bbox, nr_planes );
 464 }
 465
 466
 467 boolean
 468 lp_setup_bin_triangle( struct lp_setup_context *setup,
 469                        struct lp_rast_triangle *tri,
 470                        const struct u_rect *bbox,
 471                        int nr_planes )
 472 {
 473    struct lp_scene *scene = setup->scene;
 474    int ix0, ix1, iy0, iy1;
 475    int i;
 476
 477    /*
 478     * All fields of 'tri' are now set.  The remaining code here is
 479     * concerned with binning.
 480     */
 481
 482    /* Convert to tile coordinates, and inclusive ranges:
 483     */
 484    if (nr_planes == 3) {
 485       int ix0 = bbox->x0 / 16;
 486       int iy0 = bbox->y0 / 16;
 487       int ix1 = bbox->x1 / 16;
 488       int iy1 = bbox->y1 / 16;
 489
 490       if (iy0 == iy1 && ix0 == ix1)
 491       {
 492
 493          /* Triangle is contained in a single 16x16 block:
 494           */
 495          int mask = (ix0 & 3) | ((iy0 & 3) << 4);
 496
 497          return lp_scene_bin_command( scene, ix0/4, iy0/4,
 498                                       LP_RAST_OP_TRIANGLE_3_16,
 499                                       lp_rast_arg_triangle(tri, mask) );
 500       }
 501    }
 502
 503    ix0 = bbox->x0 / TILE_SIZE;
 504    iy0 = bbox->y0 / TILE_SIZE;
 505    ix1 = bbox->x1 / TILE_SIZE;
 506    iy1 = bbox->y1 / TILE_SIZE;
 507
 508    /*
 509     * Clamp to framebuffer size
 510     */
 511    assert(ix0 == MAX2(ix0, 0));
 512    assert(iy0 == MAX2(iy0, 0));
 513    assert(ix1 == MIN2(ix1, scene->tiles_x - 1));
 514    assert(iy1 == MIN2(iy1, scene->tiles_y - 1));
 515
 516    /* Determine which tile(s) intersect the triangle's bounding box
 517     */
 518    if (iy0 == iy1 && ix0 == ix1)
 519    {
 520       /* Triangle is contained in a single tile:
 521        */
 522       return lp_scene_bin_command( scene, ix0, iy0,
 523                                    lp_rast_tri_tab[nr_planes],
 524                                    lp_rast_arg_triangle(tri, (1<<nr_planes)-1) );
 525    }
 526    else
 527    {
 528       int c[7];
 529       int ei[7];
 530       int eo[7];
 531       int xstep[7];
 532       int ystep[7];
 533       int x, y;
 534
 535       for (i = 0; i < nr_planes; i++) {
 536          c[i] = (tri->plane[i].c +
 537                  tri->plane[i].dcdy * iy0 * TILE_SIZE -
 538                  tri->plane[i].dcdx * ix0 * TILE_SIZE);
 539
 540          ei[i] = tri->plane[i].ei << TILE_ORDER;
 541          eo[i] = tri->plane[i].eo << TILE_ORDER;
 542          xstep[i] = -(tri->plane[i].dcdx << TILE_ORDER);
 543          ystep[i] = tri->plane[i].dcdy << TILE_ORDER;
 544       }
 545
 546
 547
 548       /* Test tile-sized blocks against the triangle.
 549        * Discard blocks fully outside the tri.  If the block is fully
 550        * contained inside the tri, bin an lp_rast_shade_tile command.
 551        * Else, bin a lp_rast_triangle command.
 552        */
 553       for (y = iy0; y <= iy1; y++)
 554       {
 555          boolean in = FALSE;  /* are we inside the triangle? */
 556          int cx[7];
 557
 558          for (i = 0; i < nr_planes; i++)
 559             cx[i] = c[i];
 560
 561          for (x = ix0; x <= ix1; x++)
 562          {
 563             int out = 0;
 564             int partial = 0;
 565
 566             for (i = 0; i < nr_planes; i++) {
 567                int planeout = cx[i] + eo[i];
 568                int planepartial = cx[i] + ei[i] - 1;
 569                out |= (planeout >> 31);
 570                partial |= (planepartial >> 31) & (1<<i);
 571             }
 572
 573             if (out) {
 574                /* do nothing */
 575                if (in)
 576                   break;  /* exiting triangle, all done with this row */
 577                LP_COUNT(nr_empty_64);
 578             }
 579             else if (partial) {
 580                /* Not trivially accepted by at least one plane -
 581                 * rasterize/shade partial tile
 582                 */
 583                int count = util_bitcount(partial);
 584                in = TRUE;
 585                if (!lp_scene_bin_command( scene, x, y,
 586                                           lp_rast_tri_tab[count],
 587                                           lp_rast_arg_triangle(tri, partial) ))
 588                   goto fail;
 589
 590                LP_COUNT(nr_partially_covered_64);
 591             }
 592             else {
 593                /* triangle covers the whole tile- shade whole tile */
 594                LP_COUNT(nr_fully_covered_64);
 595                in = TRUE;
 596                if (!lp_setup_whole_tile(setup, &tri->inputs, x, y))
 597                   goto fail;
 598             }
 599
 600             /* Iterate cx values across the region:
 601              */
 602             for (i = 0; i < nr_planes; i++)
 603                cx[i] += xstep[i];
 604          }
 605
 606          /* Iterate c values down the region:
 607           */
 608          for (i = 0; i < nr_planes; i++)
 609             c[i] += ystep[i];
 610       }
 611    }
 612
 613    return TRUE;
 614
 615 fail:
 616    /* Need to disable any partially binned triangle.  This is easier
 617     * than trying to locate all the triangle, shade-tile, etc,
 618     * commands which may have been binned.
 619     */
 620    tri->inputs.disable = TRUE;
 621    return FALSE;
 622 }
 623
 624
 625 /**
 626  * Draw triangle if it's CW, cull otherwise.
 627  */
 628 static void triangle_cw( struct lp_setup_context *setup,
 629                          const float (*v0)[4],
 630                          const float (*v1)[4],
 631                          const float (*v2)[4] )
 632 {
 633    if (!do_triangle_ccw( setup, v1, v0, v2, !setup->ccw_is_frontface ))
 634    {
 635       lp_setup_flush_and_restart(setup);
 636
 637       if (!do_triangle_ccw( setup, v1, v0, v2, !setup->ccw_is_frontface ))
 638          assert(0);
 639    }
 640 }
 641
 642
 643 /**
 644  * Draw triangle if it's CCW, cull otherwise.
 645  */
 646 static void triangle_ccw( struct lp_setup_context *setup,
 647                          const float (*v0)[4],
 648                          const float (*v1)[4],
 649                          const float (*v2)[4] )
 650 {
 651    if (!do_triangle_ccw( setup, v0, v1, v2, setup->ccw_is_frontface ))
 652    {
 653       lp_setup_flush_and_restart(setup);
 654       if (!do_triangle_ccw( setup, v0, v1, v2, setup->ccw_is_frontface ))
 655          assert(0);
 656    }
 657 }
 658
 659
 660
 661 /**
 662  * Draw triangle whether it's CW or CCW.
 663  */
 664 static void triangle_both( struct lp_setup_context *setup,
 665                            const float (*v0)[4],
 666                            const float (*v1)[4],
 667                            const float (*v2)[4] )
 668 {
 669    /* edge vectors e = v0 - v2, f = v1 - v2 */
 670    const float ex = v0[0][0] - v2[0][0];
 671    const float ey = v0[0][1] - v2[0][1];
 672    const float fx = v1[0][0] - v2[0][0];
 673    const float fy = v1[0][1] - v2[0][1];
 674
 675    /* det = cross(e,f).z */
 676    const float det = ex * fy - ey * fx;
 677    if (det < 0.0f)
 678       triangle_ccw( setup, v0, v1, v2 );
 679    else if (det > 0.0f)
 680       triangle_cw( setup, v0, v1, v2 );
 681 }
 682
 683
 684 static void triangle_nop( struct lp_setup_context *setup,
 685                           const float (*v0)[4],
 686                           const float (*v1)[4],
 687                           const float (*v2)[4] )
 688 {
 689 }
 690
 691
 692 void
 693 lp_setup_choose_triangle( struct lp_setup_context *setup )
 694 {
 695    switch (setup->cullmode) {
 696    case PIPE_FACE_NONE:
 697       setup->triangle = triangle_both;
 698       break;
 699    case PIPE_FACE_BACK:
 700       setup->triangle = setup->ccw_is_frontface ? triangle_ccw : triangle_cw;
 701       break;
 702    case PIPE_FACE_FRONT:
 703       setup->triangle = setup->ccw_is_frontface ? triangle_cw : triangle_ccw;
 704       break;
 705    default:
 706       setup->triangle = triangle_nop;
 707       break;
 708    }
 709 }