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_rast.h"
  38 #include "lp_state_fs.h"
  39 #include "lp_state_setup.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 num_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 num_inputs,
  74                         unsigned nr_planes,
  75                         unsigned *tri_size)
  76 {
  77    unsigned input_array_sz = NUM_CHANNELS * (num_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    const struct lp_setup_variant_key *key = &setup->setup.variant->key;
 105    int i, j;
 106
 107    debug_printf("   wpos (%s[0]) xyzw %f %f %f %f\n",
 108                 name,
 109                 v[0][0], v[0][1], v[0][2], v[0][3]);
 110
 111    for (i = 0; i < key->num_inputs; i++) {
 112       const float *in = v[key->inputs[i].src_index];
 113
 114       debug_printf("  in[%d] (%s[%d]) %s%s%s%s ",
 115                    i,
 116                    name, key->inputs[i].src_index,
 117                    (key->inputs[i].usage_mask & 0x1) ? "x" : " ",
 118                    (key->inputs[i].usage_mask & 0x2) ? "y" : " ",
 119                    (key->inputs[i].usage_mask & 0x4) ? "z" : " ",
 120                    (key->inputs[i].usage_mask & 0x8) ? "w" : " ");
 121
 122       for (j = 0; j < 4; j++)
 123          if (key->inputs[i].usage_mask & (1<<j))
 124             debug_printf("%.5f ", in[j]);
 125
 126       debug_printf("\n");
 127    }
 128 }
 129
 130
 131 /**
 132  * Print triangle vertex attribs (for debug).
 133  */
 134 void
 135 lp_setup_print_triangle(struct lp_setup_context *setup,
 136                         const float (*v0)[4],
 137                         const float (*v1)[4],
 138                         const float (*v2)[4])
 139 {
 140    debug_printf("triangle\n");
 141
 142    {
 143       const float ex = v0[0][0] - v2[0][0];
 144       const float ey = v0[0][1] - v2[0][1];
 145       const float fx = v1[0][0] - v2[0][0];
 146       const float fy = v1[0][1] - v2[0][1];
 147
 148       /* det = cross(e,f).z */
 149       const float det = ex * fy - ey * fx;
 150       if (det < 0.0f)
 151          debug_printf("   - ccw\n");
 152       else if (det > 0.0f)
 153          debug_printf("   - cw\n");
 154       else
 155          debug_printf("   - zero area\n");
 156    }
 157
 158    lp_setup_print_vertex(setup, "v0", v0);
 159    lp_setup_print_vertex(setup, "v1", v1);
 160    lp_setup_print_vertex(setup, "v2", v2);
 161 }
 162
 163
 164 static unsigned
 165 lp_rast_tri_tab[9] = {
 166    0,               /* should be impossible */
 167    LP_RAST_OP_TRIANGLE_1,
 168    LP_RAST_OP_TRIANGLE_2,
 169    LP_RAST_OP_TRIANGLE_3,
 170    LP_RAST_OP_TRIANGLE_4,
 171    LP_RAST_OP_TRIANGLE_5,
 172    LP_RAST_OP_TRIANGLE_6,
 173    LP_RAST_OP_TRIANGLE_7,
 174    LP_RAST_OP_TRIANGLE_8
 175 };
 176
 177
 178
 179 /**
 180  * The primitive covers the whole tile- shade whole tile.
 181  *
 182  * \param tx, ty  the tile position in tiles, not pixels
 183  */
 184 static boolean
 185 lp_setup_whole_tile(struct lp_setup_context *setup,
 186                     const struct lp_rast_shader_inputs *inputs,
 187                     int tx, int ty)
 188 {
 189    struct lp_scene *scene = setup->scene;
 190
 191    LP_COUNT(nr_fully_covered_64);
 192
 193    /* if variant is opaque and scissor doesn't effect the tile */
 194    if (inputs->opaque) {
 195       if (!scene->fb.zsbuf) {
 196          /*
 197           * All previous rendering will be overwritten so reset the bin.
 198           */
 199          lp_scene_bin_reset( scene, tx, ty );
 200       }
 201
 202       LP_COUNT(nr_shade_opaque_64);
 203       return lp_scene_bin_command( scene, tx, ty,
 204                                    LP_RAST_OP_SHADE_TILE_OPAQUE,
 205                                    lp_rast_arg_inputs(inputs) );
 206    } else {
 207       LP_COUNT(nr_shade_64);
 208       return lp_scene_bin_command( scene, tx, ty,
 209                                    LP_RAST_OP_SHADE_TILE,
 210                                    lp_rast_arg_inputs(inputs) );
 211    }
 212 }
 213
 214
 215 /**
 216  * Do basic setup for triangle rasterization and determine which
 217  * framebuffer tiles are touched.  Put the triangle in the scene's
 218  * bins for the tiles which we overlap.
 219  */
 220 static boolean
 221 do_triangle_ccw(struct lp_setup_context *setup,
 222                 const float (*v0)[4],
 223                 const float (*v1)[4],
 224                 const float (*v2)[4],
 225                 boolean frontfacing )
 226 {
 227    struct lp_scene *scene = setup->scene;
 228    const struct lp_setup_variant_key *key = &setup->setup.variant->key;
 229    struct lp_rast_triangle *tri;
 230    int x[3];
 231    int y[3];
 232    int area;
 233    struct u_rect bbox;
 234    unsigned tri_bytes;
 235    int i;
 236    int nr_planes = 3;
 237
 238    if (0)
 239       lp_setup_print_triangle(setup, v0, v1, v2);
 240
 241    if (setup->scissor_test) {
 242       nr_planes = 7;
 243    }
 244    else {
 245       nr_planes = 3;
 246    }
 247
 248    /* x/y positions in fixed point */
 249    x[0] = subpixel_snap(v0[0][0] - setup->pixel_offset);
 250    x[1] = subpixel_snap(v1[0][0] - setup->pixel_offset);
 251    x[2] = subpixel_snap(v2[0][0] - setup->pixel_offset);
 252    y[0] = subpixel_snap(v0[0][1] - setup->pixel_offset);
 253    y[1] = subpixel_snap(v1[0][1] - setup->pixel_offset);
 254    y[2] = subpixel_snap(v2[0][1] - setup->pixel_offset);
 255
 256
 257    /* Bounding rectangle (in pixels) */
 258    {
 259       /* Yes this is necessary to accurately calculate bounding boxes
 260        * with the two fill-conventions we support.  GL (normally) ends
 261        * up needing a bottom-left fill convention, which requires
 262        * slightly different rounding.
 263        */
 264       int adj = (setup->pixel_offset != 0) ? 1 : 0;
 265
 266       bbox.x0 = (MIN3(x[0], x[1], x[2]) + (FIXED_ONE-1)) >> FIXED_ORDER;
 267       bbox.x1 = (MAX3(x[0], x[1], x[2]) + (FIXED_ONE-1)) >> FIXED_ORDER;
 268       bbox.y0 = (MIN3(y[0], y[1], y[2]) + (FIXED_ONE-1) + adj) >> FIXED_ORDER;
 269       bbox.y1 = (MAX3(y[0], y[1], y[2]) + (FIXED_ONE-1) + adj) >> FIXED_ORDER;
 270
 271       /* Inclusive coordinates:
 272        */
 273       bbox.x1--;
 274       bbox.y1--;
 275    }
 276
 277    if (bbox.x1 < bbox.x0 ||
 278        bbox.y1 < bbox.y0) {
 279       if (0) debug_printf("empty bounding box\n");
 280       LP_COUNT(nr_culled_tris);
 281       return TRUE;
 282    }
 283
 284    if (!u_rect_test_intersection(&setup->draw_region, &bbox)) {
 285       if (0) debug_printf("offscreen\n");
 286       LP_COUNT(nr_culled_tris);
 287       return TRUE;
 288    }
 289
 290    u_rect_find_intersection(&setup->draw_region, &bbox);
 291
 292    tri = lp_setup_alloc_triangle(scene,
 293                                  key->num_inputs,
 294                                  nr_planes,
 295                                  &tri_bytes);
 296    if (!tri)
 297       return FALSE;
 298
 299 #ifdef DEBUG
 300    tri->v[0][0] = v0[0][0];
 301    tri->v[1][0] = v1[0][0];
 302    tri->v[2][0] = v2[0][0];
 303    tri->v[0][1] = v0[0][1];
 304    tri->v[1][1] = v1[0][1];
 305    tri->v[2][1] = v2[0][1];
 306 #endif
 307
 308    tri->plane[0].dcdy = x[0] - x[1];
 309    tri->plane[1].dcdy = x[1] - x[2];
 310    tri->plane[2].dcdy = x[2] - x[0];
 311
 312    tri->plane[0].dcdx = y[0] - y[1];
 313    tri->plane[1].dcdx = y[1] - y[2];
 314    tri->plane[2].dcdx = y[2] - y[0];
 315
 316    area = (tri->plane[0].dcdy * tri->plane[2].dcdx -
 317            tri->plane[2].dcdy * tri->plane[0].dcdx);
 318
 319    LP_COUNT(nr_tris);
 320
 321    /* Cull non-ccw and zero-sized triangles.
 322     *
 323     * XXX: subject to overflow??
 324     */
 325    if (area <= 0) {
 326       lp_scene_putback_data( scene, tri_bytes );
 327       LP_COUNT(nr_culled_tris);
 328       return TRUE;
 329    }
 330
 331    /* Setup parameter interpolants:
 332     */
 333    setup->setup.variant->jit_function( v0,
 334                                        v1,
 335                                        v2,
 336                                        frontfacing,
 337                                        tri->inputs.a0,
 338                                        tri->inputs.dadx,
 339                                        tri->inputs.dady,
 340                                        &setup->setup.variant->key );
 341
 342    tri->inputs.facing = frontfacing ? 1.0F : -1.0F;
 343    tri->inputs.disable = FALSE;
 344    tri->inputs.opaque = setup->fs.current.variant->opaque;
 345    tri->inputs.state = setup->fs.stored;
 346
 347    if (0)
 348       lp_dump_setup_coef(&setup->setup.variant->key,
 349                          (const float (*)[4])tri->inputs.a0,
 350                          (const float (*)[4])tri->inputs.dadx,
 351                          (const float (*)[4])tri->inputs.dady);
 352
 353    for (i = 0; i < 3; i++) {
 354       struct lp_rast_plane *plane = &tri->plane[i];
 355
 356       /* half-edge constants, will be interated over the whole render
 357        * target.
 358        */
 359       plane->c = plane->dcdx * x[i] - plane->dcdy * y[i];
 360
 361       /* correct for top-left vs. bottom-left fill convention.
 362        *
 363        * note that we're overloading gl_rasterization_rules to mean
 364        * both (0.5,0.5) pixel centers *and* bottom-left filling
 365        * convention.
 366        *
 367        * GL actually has a top-left filling convention, but GL's
 368        * notion of "top" differs from gallium's...
 369        *
 370        * Also, sometimes (in FBO cases) GL will render upside down
 371        * to its usual method, in which case it will probably want
 372        * to use the opposite, top-left convention.
 373        */
 374       if (plane->dcdx < 0) {
 375          /* both fill conventions want this - adjust for left edges */
 376          plane->c++;
 377       }
 378       else if (plane->dcdx == 0) {
 379          if (setup->pixel_offset == 0) {
 380             /* correct for top-left fill convention:
 381              */
 382             if (plane->dcdy > 0) plane->c++;
 383          }
 384          else {
 385             /* correct for bottom-left fill convention:
 386              */
 387             if (plane->dcdy < 0) plane->c++;
 388          }
 389       }
 390
 391       plane->dcdx *= FIXED_ONE;
 392       plane->dcdy *= FIXED_ONE;
 393
 394       /* find trivial reject offsets for each edge for a single-pixel
 395        * sized block.  These will be scaled up at each recursive level to
 396        * match the active blocksize.  Scaling in this way works best if
 397        * the blocks are square.
 398        */
 399       plane->eo = 0;
 400       if (plane->dcdx < 0) plane->eo -= plane->dcdx;
 401       if (plane->dcdy > 0) plane->eo += plane->dcdy;
 402
 403       /* Calculate trivial accept offsets from the above.
 404        */
 405       plane->ei = plane->dcdy - plane->dcdx - plane->eo;
 406    }
 407
 408
 409    /*
 410     * When rasterizing scissored tris, use the intersection of the
 411     * triangle bounding box and the scissor rect to generate the
 412     * scissor planes.
 413     *
 414     * This permits us to cut off the triangle "tails" that are present
 415     * in the intermediate recursive levels caused when two of the
 416     * triangles edges don't diverge quickly enough to trivially reject
 417     * exterior blocks from the triangle.
 418     *
 419     * It's not really clear if it's worth worrying about these tails,
 420     * but since we generate the planes for each scissored tri, it's
 421     * free to trim them in this case.
 422     *
 423     * Note that otherwise, the scissor planes only vary in 'C' value,
 424     * and even then only on state-changes.  Could alternatively store
 425     * these planes elsewhere.
 426     */
 427    if (nr_planes == 7) {
 428       tri->plane[3].dcdx = -1;
 429       tri->plane[3].dcdy = 0;
 430       tri->plane[3].c = 1-bbox.x0;
 431       tri->plane[3].ei = 0;
 432       tri->plane[3].eo = 1;
 433
 434       tri->plane[4].dcdx = 1;
 435       tri->plane[4].dcdy = 0;
 436       tri->plane[4].c = bbox.x1+1;
 437       tri->plane[4].ei = -1;
 438       tri->plane[4].eo = 0;
 439
 440       tri->plane[5].dcdx = 0;
 441       tri->plane[5].dcdy = 1;
 442       tri->plane[5].c = 1-bbox.y0;
 443       tri->plane[5].ei = 0;
 444       tri->plane[5].eo = 1;
 445
 446       tri->plane[6].dcdx = 0;
 447       tri->plane[6].dcdy = -1;
 448       tri->plane[6].c = bbox.y1+1;
 449       tri->plane[6].ei = -1;
 450       tri->plane[6].eo = 0;
 451    }
 452
 453    return lp_setup_bin_triangle( setup, tri, &bbox, nr_planes );
 454 }
 455
 456 /*
 457  * Round to nearest less or equal power of two of the input.
 458  *
 459  * Undefined if no bit set exists, so code should check against 0 first.
 460  */
 461 static INLINE uint32_t
 462 floor_pot(uint32_t n)
 463 {
 464 #if defined(PIPE_CC_GCC) && defined(PIPE_ARCH_X86)
 465    if (n == 0)
 466       return 0;
 467
 468    __asm__("bsr %1,%0"
 469           : "=r" (n)
 470           : "rm" (n));
 471    return 1 << n;
 472 #else
 473    n |= (n >>  1);
 474    n |= (n >>  2);
 475    n |= (n >>  4);
 476    n |= (n >>  8);
 477    n |= (n >> 16);
 478    return n - (n >> 1);
 479 #endif
 480 }
 481
 482
 483 boolean
 484 lp_setup_bin_triangle( struct lp_setup_context *setup,
 485                        struct lp_rast_triangle *tri,
 486                        const struct u_rect *bbox,
 487                        int nr_planes )
 488 {
 489    struct lp_scene *scene = setup->scene;
 490    int i;
 491
 492    /* What is the largest power-of-two boundary this triangle crosses:
 493     */
 494    int dx = floor_pot((bbox->x0 ^ bbox->x1) |
 495                       (bbox->y0 ^ bbox->y1));
 496
 497    /* The largest dimension of the rasterized area of the triangle
 498     * (aligned to a 4x4 grid), rounded down to the nearest power of two:
 499     */
 500    int sz = floor_pot((bbox->x1 - (bbox->x0 & ~3)) |
 501                       (bbox->y1 - (bbox->y0 & ~3)));
 502
 503    if (nr_planes == 3) {
 504       if (sz < 4 && dx < 64)
 505       {
 506          /* Triangle is contained in a single 4x4 stamp:
 507           */
 508          int mask = (bbox->x0 & 63 & ~3) | ((bbox->y0 & 63 & ~3) << 8);
 509
 510          return lp_scene_bin_command( scene,
 511                                       bbox->x0/64, bbox->y0/64,
 512                                       LP_RAST_OP_TRIANGLE_3_4,
 513                                       lp_rast_arg_triangle(tri, mask) );
 514       }
 515
 516       if (sz < 16 && dx < 64)
 517       {
 518          int mask = (bbox->x0 & 63 & ~3) | ((bbox->y0 & 63 & ~3) << 8);
 519
 520          /* Triangle is contained in a single 16x16 block:
 521           */
 522          return lp_scene_bin_command( scene,
 523                                       bbox->x0/64, bbox->y0/64,
 524                                       LP_RAST_OP_TRIANGLE_3_16,
 525                                       lp_rast_arg_triangle(tri, mask) );
 526       }
 527    }
 528
 529
 530    /* Determine which tile(s) intersect the triangle's bounding box
 531     */
 532    if (dx < TILE_SIZE)
 533    {
 534       int ix0 = bbox->x0 / TILE_SIZE;
 535       int iy0 = bbox->y0 / TILE_SIZE;
 536
 537       assert(iy0 == bbox->y1 / TILE_SIZE &&
 538              ix0 == bbox->x1 / TILE_SIZE);
 539
 540       /* Triangle is contained in a single tile:
 541        */
 542       return lp_scene_bin_command( scene, ix0, iy0,
 543                                    lp_rast_tri_tab[nr_planes],
 544                                    lp_rast_arg_triangle(tri, (1<<nr_planes)-1) );
 545    }
 546    else
 547    {
 548       int c[7];
 549       int ei[7];
 550       int eo[7];
 551       int xstep[7];
 552       int ystep[7];
 553       int x, y;
 554
 555       int ix0 = bbox->x0 / TILE_SIZE;
 556       int iy0 = bbox->y0 / TILE_SIZE;
 557       int ix1 = bbox->x1 / TILE_SIZE;
 558       int iy1 = bbox->y1 / TILE_SIZE;
 559
 560       for (i = 0; i < nr_planes; i++) {
 561          c[i] = (tri->plane[i].c +
 562                  tri->plane[i].dcdy * iy0 * TILE_SIZE -
 563                  tri->plane[i].dcdx * ix0 * TILE_SIZE);
 564
 565          ei[i] = tri->plane[i].ei << TILE_ORDER;
 566          eo[i] = tri->plane[i].eo << TILE_ORDER;
 567          xstep[i] = -(tri->plane[i].dcdx << TILE_ORDER);
 568          ystep[i] = tri->plane[i].dcdy << TILE_ORDER;
 569       }
 570
 571
 572
 573       /* Test tile-sized blocks against the triangle.
 574        * Discard blocks fully outside the tri.  If the block is fully
 575        * contained inside the tri, bin an lp_rast_shade_tile command.
 576        * Else, bin a lp_rast_triangle command.
 577        */
 578       for (y = iy0; y <= iy1; y++)
 579       {
 580          boolean in = FALSE;  /* are we inside the triangle? */
 581          int cx[7];
 582
 583          for (i = 0; i < nr_planes; i++)
 584             cx[i] = c[i];
 585
 586          for (x = ix0; x <= ix1; x++)
 587          {
 588             int out = 0;
 589             int partial = 0;
 590
 591             for (i = 0; i < nr_planes; i++) {
 592                int planeout = cx[i] + eo[i];
 593                int planepartial = cx[i] + ei[i] - 1;
 594                out |= (planeout >> 31);
 595                partial |= (planepartial >> 31) & (1<<i);
 596             }
 597
 598             if (out) {
 599                /* do nothing */
 600                if (in)
 601                   break;  /* exiting triangle, all done with this row */
 602                LP_COUNT(nr_empty_64);
 603             }
 604             else if (partial) {
 605                /* Not trivially accepted by at least one plane -
 606                 * rasterize/shade partial tile
 607                 */
 608                int count = util_bitcount(partial);
 609                in = TRUE;
 610                if (!lp_scene_bin_command( scene, x, y,
 611                                           lp_rast_tri_tab[count],
 612                                           lp_rast_arg_triangle(tri, partial) ))
 613                   goto fail;
 614
 615                LP_COUNT(nr_partially_covered_64);
 616             }
 617             else {
 618                /* triangle covers the whole tile- shade whole tile */
 619                LP_COUNT(nr_fully_covered_64);
 620                in = TRUE;
 621                if (!lp_setup_whole_tile(setup, &tri->inputs, x, y))
 622                   goto fail;
 623             }
 624
 625             /* Iterate cx values across the region:
 626              */
 627             for (i = 0; i < nr_planes; i++)
 628                cx[i] += xstep[i];
 629          }
 630
 631          /* Iterate c values down the region:
 632           */
 633          for (i = 0; i < nr_planes; i++)
 634             c[i] += ystep[i];
 635       }
 636    }
 637
 638    return TRUE;
 639
 640 fail:
 641    /* Need to disable any partially binned triangle.  This is easier
 642     * than trying to locate all the triangle, shade-tile, etc,
 643     * commands which may have been binned.
 644     */
 645    tri->inputs.disable = TRUE;
 646    return FALSE;
 647 }
 648
 649
 650 /**
 651  * Draw triangle if it's CW, cull otherwise.
 652  */
 653 static void triangle_cw( struct lp_setup_context *setup,
 654                          const float (*v0)[4],
 655                          const float (*v1)[4],
 656                          const float (*v2)[4] )
 657 {
 658    if (!do_triangle_ccw( setup, v1, v0, v2, !setup->ccw_is_frontface ))
 659    {
 660       lp_setup_flush_and_restart(setup);
 661
 662       if (!do_triangle_ccw( setup, v1, v0, v2, !setup->ccw_is_frontface ))
 663          assert(0);
 664    }
 665 }
 666
 667
 668 /**
 669  * Draw triangle if it's CCW, cull otherwise.
 670  */
 671 static void triangle_ccw( struct lp_setup_context *setup,
 672                          const float (*v0)[4],
 673                          const float (*v1)[4],
 674                          const float (*v2)[4] )
 675 {
 676    if (!do_triangle_ccw( setup, v0, v1, v2, setup->ccw_is_frontface ))
 677    {
 678       lp_setup_flush_and_restart(setup);
 679       if (!do_triangle_ccw( setup, v0, v1, v2, setup->ccw_is_frontface ))
 680          assert(0);
 681    }
 682 }
 683
 684
 685
 686 /**
 687  * Draw triangle whether it's CW or CCW.
 688  */
 689 static void triangle_both( struct lp_setup_context *setup,
 690                            const float (*v0)[4],
 691                            const float (*v1)[4],
 692                            const float (*v2)[4] )
 693 {
 694    /* edge vectors e = v0 - v2, f = v1 - v2 */
 695    const float ex = v0[0][0] - v2[0][0];
 696    const float ey = v0[0][1] - v2[0][1];
 697    const float fx = v1[0][0] - v2[0][0];
 698    const float fy = v1[0][1] - v2[0][1];
 699
 700    /* det = cross(e,f).z */
 701    const float det = ex * fy - ey * fx;
 702    if (det < 0.0f)
 703       triangle_ccw( setup, v0, v1, v2 );
 704    else if (det > 0.0f)
 705       triangle_cw( setup, v0, v1, v2 );
 706 }
 707
 708
 709 static void triangle_nop( struct lp_setup_context *setup,
 710                           const float (*v0)[4],
 711                           const float (*v1)[4],
 712                           const float (*v2)[4] )
 713 {
 714 }
 715
 716
 717 void
 718 lp_setup_choose_triangle( struct lp_setup_context *setup )
 719 {
 720    switch (setup->cullmode) {
 721    case PIPE_FACE_NONE:
 722       setup->triangle = triangle_both;
 723       break;
 724    case PIPE_FACE_BACK:
 725       setup->triangle = setup->ccw_is_frontface ? triangle_ccw : triangle_cw;
 726       break;
 727    case PIPE_FACE_FRONT:
 728       setup->triangle = setup->ccw_is_frontface ? triangle_cw : triangle_ccw;
 729       break;
 730    default:
 731       setup->triangle = triangle_nop;
 732       break;
 733    }
 734 }