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 "lp_perf.h"
  35 #include "lp_setup_context.h"
  36 #include "lp_rast.h"
  37 #include "lp_state_fs.h"
  38
  39 #define NUM_CHANNELS 4
  40
  41
  42 /**
  43  * Compute a0 for a constant-valued coefficient (GL_FLAT shading).
  44  */
  45 static void constant_coef( struct lp_setup_context *setup,
  46                            struct lp_rast_triangle *tri,
  47                            unsigned slot,
  48                            const float value,
  49                            unsigned i )
  50 {
  51    tri->inputs.a0[slot][i] = value;
  52    tri->inputs.dadx[slot][i] = 0.0f;
  53    tri->inputs.dady[slot][i] = 0.0f;
  54 }
  55
  56
  57 /**
  58  * Compute a0, dadx and dady for a linearly interpolated coefficient,
  59  * for a triangle.
  60  */
  61 static void linear_coef( struct lp_setup_context *setup,
  62                          struct lp_rast_triangle *tri,
  63                          float oneoverarea,
  64                          unsigned slot,
  65                          const float (*v1)[4],
  66                          const float (*v2)[4],
  67                          const float (*v3)[4],
  68                          unsigned vert_attr,
  69                          unsigned i)
  70 {
  71    float a1 = v1[vert_attr][i];
  72    float a2 = v2[vert_attr][i];
  73    float a3 = v3[vert_attr][i];
  74
  75    float da12 = a1 - a2;
  76    float da31 = a3 - a1;
  77    float dadx = (da12 * tri->dy31 - tri->dy12 * da31) * oneoverarea;
  78    float dady = (da31 * tri->dx12 - tri->dx31 * da12) * oneoverarea;
  79
  80    tri->inputs.dadx[slot][i] = dadx;
  81    tri->inputs.dady[slot][i] = dady;
  82
  83    /* calculate a0 as the value which would be sampled for the
  84     * fragment at (0,0), taking into account that we want to sample at
  85     * pixel centers, in other words (0.5, 0.5).
  86     *
  87     * this is neat but unfortunately not a good way to do things for
  88     * triangles with very large values of dadx or dady as it will
  89     * result in the subtraction and re-addition from a0 of a very
  90     * large number, which means we'll end up loosing a lot of the
  91     * fractional bits and precision from a0.  the way to fix this is
  92     * to define a0 as the sample at a pixel center somewhere near vmin
  93     * instead - i'll switch to this later.
  94     */
  95    tri->inputs.a0[slot][i] = (a1 -
  96                               (dadx * (v1[0][0] - setup->pixel_offset) +
  97                                dady * (v1[0][1] - setup->pixel_offset)));
  98 }
  99
 100
 101 /**
 102  * Compute a0, dadx and dady for a perspective-corrected interpolant,
 103  * for a triangle.
 104  * We basically multiply the vertex value by 1/w before computing
 105  * the plane coefficients (a0, dadx, dady).
 106  * Later, when we compute the value at a particular fragment position we'll
 107  * divide the interpolated value by the interpolated W at that fragment.
 108  */
 109 static void perspective_coef( struct lp_setup_context *setup,
 110                               struct lp_rast_triangle *tri,
 111                               float oneoverarea,
 112                               unsigned slot,
 113                               const float (*v1)[4],
 114                               const float (*v2)[4],
 115                               const float (*v3)[4],
 116                               unsigned vert_attr,
 117                               unsigned i)
 118 {
 119    /* premultiply by 1/w  (v[0][3] is always 1/w):
 120     */
 121    float a1 = v1[vert_attr][i] * v1[0][3];
 122    float a2 = v2[vert_attr][i] * v2[0][3];
 123    float a3 = v3[vert_attr][i] * v3[0][3];
 124    float da12 = a1 - a2;
 125    float da31 = a3 - a1;
 126    float dadx = (da12 * tri->dy31 - tri->dy12 * da31) * oneoverarea;
 127    float dady = (da31 * tri->dx12 - tri->dx31 * da12) * oneoverarea;
 128
 129    tri->inputs.dadx[slot][i] = dadx;
 130    tri->inputs.dady[slot][i] = dady;
 131    tri->inputs.a0[slot][i] = (a1 -
 132                               (dadx * (v1[0][0] - setup->pixel_offset) +
 133                                dady * (v1[0][1] - setup->pixel_offset)));
 134 }
 135
 136
 137 /**
 138  * Special coefficient setup for gl_FragCoord.
 139  * X and Y are trivial
 140  * Z and W are copied from position_coef which should have already been computed.
 141  * We could do a bit less work if we'd examine gl_FragCoord's swizzle mask.
 142  */
 143 static void
 144 setup_fragcoord_coef(struct lp_setup_context *setup,
 145                      struct lp_rast_triangle *tri,
 146                      float oneoverarea,
 147                      unsigned slot,
 148                      const float (*v1)[4],
 149                      const float (*v2)[4],
 150                      const float (*v3)[4],
 151                      unsigned usage_mask)
 152 {
 153    /*X*/
 154    if (usage_mask & TGSI_WRITEMASK_X) {
 155       tri->inputs.a0[slot][0] = 0.0;
 156       tri->inputs.dadx[slot][0] = 1.0;
 157       tri->inputs.dady[slot][0] = 0.0;
 158    }
 159
 160    /*Y*/
 161    if (usage_mask & TGSI_WRITEMASK_Y) {
 162       tri->inputs.a0[slot][1] = 0.0;
 163       tri->inputs.dadx[slot][1] = 0.0;
 164       tri->inputs.dady[slot][1] = 1.0;
 165    }
 166
 167    /*Z*/
 168    if (usage_mask & TGSI_WRITEMASK_Z) {
 169       linear_coef(setup, tri, oneoverarea, slot, v1, v2, v3, 0, 2);
 170    }
 171
 172    /*W*/
 173    if (usage_mask & TGSI_WRITEMASK_W) {
 174       linear_coef(setup, tri, oneoverarea, slot, v1, v2, v3, 0, 3);
 175    }
 176 }
 177
 178
 179 /**
 180  * Setup the fragment input attribute with the front-facing value.
 181  * \param frontface  is the triangle front facing?
 182  */
 183 static void setup_facing_coef( struct lp_setup_context *setup,
 184                                struct lp_rast_triangle *tri,
 185                                unsigned slot,
 186                                boolean frontface,
 187                                unsigned usage_mask)
 188 {
 189    /* convert TRUE to 1.0 and FALSE to -1.0 */
 190    if (usage_mask & TGSI_WRITEMASK_X)
 191       constant_coef( setup, tri, slot, 2.0f * frontface - 1.0f, 0 );
 192
 193    if (usage_mask & TGSI_WRITEMASK_Y)
 194       constant_coef( setup, tri, slot, 0.0f, 1 ); /* wasted */
 195
 196    if (usage_mask & TGSI_WRITEMASK_Z)
 197       constant_coef( setup, tri, slot, 0.0f, 2 ); /* wasted */
 198
 199    if (usage_mask & TGSI_WRITEMASK_W)
 200       constant_coef( setup, tri, slot, 0.0f, 3 ); /* wasted */
 201 }
 202
 203
 204 /**
 205  * Compute the tri->coef[] array dadx, dady, a0 values.
 206  */
 207 static void setup_tri_coefficients( struct lp_setup_context *setup,
 208                                     struct lp_rast_triangle *tri,
 209                                     float oneoverarea,
 210                                     const float (*v1)[4],
 211                                     const float (*v2)[4],
 212                                     const float (*v3)[4],
 213                                     boolean frontface)
 214 {
 215    unsigned fragcoord_usage_mask = TGSI_WRITEMASK_XYZ;
 216    unsigned slot;
 217
 218    /* setup interpolation for all the remaining attributes:
 219     */
 220    for (slot = 0; slot < setup->fs.nr_inputs; slot++) {
 221       unsigned vert_attr = setup->fs.input[slot].src_index;
 222       unsigned usage_mask = setup->fs.input[slot].usage_mask;
 223       unsigned i;
 224
 225       switch (setup->fs.input[slot].interp) {
 226       case LP_INTERP_CONSTANT:
 227          if (setup->flatshade_first) {
 228             for (i = 0; i < NUM_CHANNELS; i++)
 229                if (usage_mask & (1 << i))
 230                   constant_coef(setup, tri, slot+1, v1[vert_attr][i], i);
 231          }
 232          else {
 233             for (i = 0; i < NUM_CHANNELS; i++)
 234                if (usage_mask & (1 << i))
 235                   constant_coef(setup, tri, slot+1, v3[vert_attr][i], i);
 236          }
 237          break;
 238
 239       case LP_INTERP_LINEAR:
 240          for (i = 0; i < NUM_CHANNELS; i++)
 241             if (usage_mask & (1 << i))
 242                linear_coef(setup, tri, oneoverarea, slot+1, v1, v2, v3, vert_attr, i);
 243          break;
 244
 245       case LP_INTERP_PERSPECTIVE:
 246          for (i = 0; i < NUM_CHANNELS; i++)
 247             if (usage_mask & (1 << i))
 248                perspective_coef(setup, tri, oneoverarea, slot+1, v1, v2, v3, vert_attr, i);
 249          fragcoord_usage_mask |= TGSI_WRITEMASK_W;
 250          break;
 251
 252       case LP_INTERP_POSITION:
 253          /*
 254           * The generated pixel interpolators will pick up the coeffs from
 255           * slot 0, so all need to ensure that the usage mask is covers all
 256           * usages.
 257           */
 258          fragcoord_usage_mask |= usage_mask;
 259          break;
 260
 261       case LP_INTERP_FACING:
 262          setup_facing_coef(setup, tri, slot+1, frontface, usage_mask);
 263          break;
 264
 265       default:
 266          assert(0);
 267       }
 268    }
 269
 270    /* The internal position input is in slot zero:
 271     */
 272    setup_fragcoord_coef(setup, tri, oneoverarea, 0, v1, v2, v3,
 273                         fragcoord_usage_mask);
 274 }
 275
 276
 277
 278 static INLINE int subpixel_snap( float a )
 279 {
 280    return util_iround(FIXED_ONE * a - (FIXED_ONE / 2));
 281 }
 282
 283
 284
 285 /**
 286  * Alloc space for a new triangle plus the input.a0/dadx/dady arrays
 287  * immediately after it.
 288  * The memory is allocated from the per-scene pool, not per-tile.
 289  * \param tri_size  returns number of bytes allocated
 290  * \param nr_inputs  number of fragment shader inputs
 291  * \return pointer to triangle space
 292  */
 293 static INLINE struct lp_rast_triangle *
 294 alloc_triangle(struct lp_scene *scene, unsigned nr_inputs, unsigned *tri_size)
 295 {
 296    unsigned input_array_sz = NUM_CHANNELS * (nr_inputs + 1) * sizeof(float);
 297    struct lp_rast_triangle *tri;
 298    unsigned bytes;
 299    char *inputs;
 300
 301    assert(sizeof(*tri) % 16 == 0);
 302
 303    bytes = sizeof(*tri) + (3 * input_array_sz);
 304
 305    tri = lp_scene_alloc_aligned( scene, bytes, 16 );
 306
 307    if (tri) {
 308       inputs = (char *) (tri + 1);
 309       tri->inputs.a0   = (float (*)[4]) inputs;
 310       tri->inputs.dadx = (float (*)[4]) (inputs + input_array_sz);
 311       tri->inputs.dady = (float (*)[4]) (inputs + 2 * input_array_sz);
 312
 313       *tri_size = bytes;
 314    }
 315
 316    return tri;
 317 }
 318
 319
 320 /**
 321  * Print triangle vertex attribs (for debug).
 322  */
 323 static void
 324 print_triangle(struct lp_setup_context *setup,
 325                const float (*v1)[4],
 326                const float (*v2)[4],
 327                const float (*v3)[4])
 328 {
 329    uint i;
 330
 331    debug_printf("llvmpipe triangle\n");
 332    for (i = 0; i < setup->fs.nr_inputs; i++) {
 333       debug_printf("  v1[%d]:  %f %f %f %f\n", i,
 334                    v1[i][0], v1[i][1], v1[i][2], v1[i][3]);
 335    }
 336    for (i = 0; i < setup->fs.nr_inputs; i++) {
 337       debug_printf("  v2[%d]:  %f %f %f %f\n", i,
 338                    v2[i][0], v2[i][1], v2[i][2], v2[i][3]);
 339    }
 340    for (i = 0; i < setup->fs.nr_inputs; i++) {
 341       debug_printf("  v3[%d]:  %f %f %f %f\n", i,
 342                    v3[i][0], v3[i][1], v3[i][2], v3[i][3]);
 343    }
 344 }
 345
 346
 347 /**
 348  * Do basic setup for triangle rasterization and determine which
 349  * framebuffer tiles are touched.  Put the triangle in the scene's
 350  * bins for the tiles which we overlap.
 351  */
 352 static void
 353 do_triangle_ccw(struct lp_setup_context *setup,
 354                 const float (*v1)[4],
 355                 const float (*v2)[4],
 356                 const float (*v3)[4],
 357                 boolean frontfacing )
 358 {
 359    /* x/y positions in fixed point */
 360    const int x1 = subpixel_snap(v1[0][0] + 0.5 - setup->pixel_offset);
 361    const int x2 = subpixel_snap(v2[0][0] + 0.5 - setup->pixel_offset);
 362    const int x3 = subpixel_snap(v3[0][0] + 0.5 - setup->pixel_offset);
 363    const int y1 = subpixel_snap(v1[0][1] + 0.5 - setup->pixel_offset);
 364    const int y2 = subpixel_snap(v2[0][1] + 0.5 - setup->pixel_offset);
 365    const int y3 = subpixel_snap(v3[0][1] + 0.5 - setup->pixel_offset);
 366
 367    struct lp_scene *scene = lp_setup_get_current_scene(setup);
 368    struct lp_rast_triangle *tri;
 369    int area;
 370    float oneoverarea;
 371    int minx, maxx, miny, maxy;
 372    unsigned tri_bytes;
 373
 374    if (0)
 375       print_triangle(setup, v1, v2, v3);
 376
 377    tri = alloc_triangle(scene, setup->fs.nr_inputs, &tri_bytes);
 378    if (!tri)
 379       return;
 380
 381 #ifdef DEBUG
 382    tri->v[0][0] = v1[0][0];
 383    tri->v[1][0] = v2[0][0];
 384    tri->v[2][0] = v3[0][0];
 385    tri->v[0][1] = v1[0][1];
 386    tri->v[1][1] = v2[0][1];
 387    tri->v[2][1] = v3[0][1];
 388 #endif
 389
 390    tri->dx12 = x1 - x2;
 391    tri->dx23 = x2 - x3;
 392    tri->dx31 = x3 - x1;
 393
 394    tri->dy12 = y1 - y2;
 395    tri->dy23 = y2 - y3;
 396    tri->dy31 = y3 - y1;
 397
 398    area = (tri->dx12 * tri->dy31 - tri->dx31 * tri->dy12);
 399
 400    LP_COUNT(nr_tris);
 401
 402    /* Cull non-ccw and zero-sized triangles.
 403     *
 404     * XXX: subject to overflow??
 405     */
 406    if (area <= 0) {
 407       lp_scene_putback_data( scene, tri_bytes );
 408       LP_COUNT(nr_culled_tris);
 409       return;
 410    }
 411
 412    /* Bounding rectangle (in pixels) */
 413    minx = (MIN3(x1, x2, x3) + (FIXED_ONE-1)) >> FIXED_ORDER;
 414    maxx = (MAX3(x1, x2, x3) + (FIXED_ONE-1)) >> FIXED_ORDER;
 415    miny = (MIN3(y1, y2, y3) + (FIXED_ONE-1)) >> FIXED_ORDER;
 416    maxy = (MAX3(y1, y2, y3) + (FIXED_ONE-1)) >> FIXED_ORDER;
 417
 418    if (setup->scissor_test) {
 419       minx = MAX2(minx, setup->scissor.current.minx);
 420       maxx = MIN2(maxx, setup->scissor.current.maxx);
 421       miny = MAX2(miny, setup->scissor.current.miny);
 422       maxy = MIN2(maxy, setup->scissor.current.maxy);
 423    }
 424
 425    if (miny == maxy ||
 426        minx == maxx) {
 427       lp_scene_putback_data( scene, tri_bytes );
 428       LP_COUNT(nr_culled_tris);
 429       return;
 430    }
 431
 432    /*
 433     */
 434    oneoverarea = ((float)FIXED_ONE) / (float)area;
 435
 436    /* Setup parameter interpolants:
 437     */
 438    setup_tri_coefficients( setup, tri, oneoverarea, v1, v2, v3, frontfacing );
 439
 440    tri->inputs.facing = frontfacing ? 1.0F : -1.0F;
 441
 442    /* half-edge constants, will be interated over the whole render target.
 443     */
 444    tri->c1 = tri->dy12 * x1 - tri->dx12 * y1;
 445    tri->c2 = tri->dy23 * x2 - tri->dx23 * y2;
 446    tri->c3 = tri->dy31 * x3 - tri->dx31 * y3;
 447
 448    /* correct for top-left fill convention:
 449     */
 450    if (tri->dy12 < 0 || (tri->dy12 == 0 && tri->dx12 > 0)) tri->c1++;
 451    if (tri->dy23 < 0 || (tri->dy23 == 0 && tri->dx23 > 0)) tri->c2++;
 452    if (tri->dy31 < 0 || (tri->dy31 == 0 && tri->dx31 > 0)) tri->c3++;
 453
 454    tri->dy12 *= FIXED_ONE;
 455    tri->dy23 *= FIXED_ONE;
 456    tri->dy31 *= FIXED_ONE;
 457
 458    tri->dx12 *= FIXED_ONE;
 459    tri->dx23 *= FIXED_ONE;
 460    tri->dx31 *= FIXED_ONE;
 461
 462    /* find trivial reject offsets for each edge for a single-pixel
 463     * sized block.  These will be scaled up at each recursive level to
 464     * match the active blocksize.  Scaling in this way works best if
 465     * the blocks are square.
 466     */
 467    tri->eo1 = 0;
 468    if (tri->dy12 < 0) tri->eo1 -= tri->dy12;
 469    if (tri->dx12 > 0) tri->eo1 += tri->dx12;
 470
 471    tri->eo2 = 0;
 472    if (tri->dy23 < 0) tri->eo2 -= tri->dy23;
 473    if (tri->dx23 > 0) tri->eo2 += tri->dx23;
 474
 475    tri->eo3 = 0;
 476    if (tri->dy31 < 0) tri->eo3 -= tri->dy31;
 477    if (tri->dx31 > 0) tri->eo3 += tri->dx31;
 478
 479    /* Calculate trivial accept offsets from the above.
 480     */
 481    tri->ei1 = tri->dx12 - tri->dy12 - tri->eo1;
 482    tri->ei2 = tri->dx23 - tri->dy23 - tri->eo2;
 483    tri->ei3 = tri->dx31 - tri->dy31 - tri->eo3;
 484
 485    /* Fill in the inputs.step[][] arrays.
 486     * We've manually unrolled some loops here.
 487     */
 488    {
 489       const int xstep1 = -tri->dy12;
 490       const int xstep2 = -tri->dy23;
 491       const int xstep3 = -tri->dy31;
 492       const int ystep1 = tri->dx12;
 493       const int ystep2 = tri->dx23;
 494       const int ystep3 = tri->dx31;
 495
 496 #define SETUP_STEP(i, x, y)                                \
 497       do {                                                 \
 498          tri->inputs.step[0][i] = x * xstep1 + y * ystep1; \
 499          tri->inputs.step[1][i] = x * xstep2 + y * ystep2; \
 500          tri->inputs.step[2][i] = x * xstep3 + y * ystep3; \
 501       } while (0)
 502
 503       SETUP_STEP(0, 0, 0);
 504       SETUP_STEP(1, 1, 0);
 505       SETUP_STEP(2, 0, 1);
 506       SETUP_STEP(3, 1, 1);
 507
 508       SETUP_STEP(4, 2, 0);
 509       SETUP_STEP(5, 3, 0);
 510       SETUP_STEP(6, 2, 1);
 511       SETUP_STEP(7, 3, 1);
 512
 513       SETUP_STEP(8, 0, 2);
 514       SETUP_STEP(9, 1, 2);
 515       SETUP_STEP(10, 0, 3);
 516       SETUP_STEP(11, 1, 3);
 517
 518       SETUP_STEP(12, 2, 2);
 519       SETUP_STEP(13, 3, 2);
 520       SETUP_STEP(14, 2, 3);
 521       SETUP_STEP(15, 3, 3);
 522 #undef STEP
 523    }
 524
 525    /*
 526     * All fields of 'tri' are now set.  The remaining code here is
 527     * concerned with binning.
 528     */
 529
 530    /* Convert to tile coordinates:
 531     */
 532    minx = minx / TILE_SIZE;
 533    miny = miny / TILE_SIZE;
 534    maxx = maxx / TILE_SIZE;
 535    maxy = maxy / TILE_SIZE;
 536
 537    /*
 538     * Clamp to framebuffer size
 539     */
 540    minx = MAX2(minx, 0);
 541    miny = MAX2(miny, 0);
 542    maxx = MIN2(maxx, scene->tiles_x - 1);
 543    maxy = MIN2(maxy, scene->tiles_y - 1);
 544
 545    /* Determine which tile(s) intersect the triangle's bounding box
 546     */
 547    if (miny == maxy && minx == maxx)
 548    {
 549       /* Triangle is contained in a single tile:
 550        */
 551       lp_scene_bin_command( scene, minx, miny, lp_rast_triangle,
 552                             lp_rast_arg_triangle(tri) );
 553    }
 554    else
 555    {
 556       int c1 = (tri->c1 +
 557                 tri->dx12 * miny * TILE_SIZE -
 558                 tri->dy12 * minx * TILE_SIZE);
 559       int c2 = (tri->c2 +
 560                 tri->dx23 * miny * TILE_SIZE -
 561                 tri->dy23 * minx * TILE_SIZE);
 562       int c3 = (tri->c3 +
 563                 tri->dx31 * miny * TILE_SIZE -
 564                 tri->dy31 * minx * TILE_SIZE);
 565
 566       int ei1 = tri->ei1 << TILE_ORDER;
 567       int ei2 = tri->ei2 << TILE_ORDER;
 568       int ei3 = tri->ei3 << TILE_ORDER;
 569
 570       int eo1 = tri->eo1 << TILE_ORDER;
 571       int eo2 = tri->eo2 << TILE_ORDER;
 572       int eo3 = tri->eo3 << TILE_ORDER;
 573
 574       int xstep1 = -(tri->dy12 << TILE_ORDER);
 575       int xstep2 = -(tri->dy23 << TILE_ORDER);
 576       int xstep3 = -(tri->dy31 << TILE_ORDER);
 577
 578       int ystep1 = tri->dx12 << TILE_ORDER;
 579       int ystep2 = tri->dx23 << TILE_ORDER;
 580       int ystep3 = tri->dx31 << TILE_ORDER;
 581       int x, y;
 582
 583
 584       /* Test tile-sized blocks against the triangle.
 585        * Discard blocks fully outside the tri.  If the block is fully
 586        * contained inside the tri, bin an lp_rast_shade_tile command.
 587        * Else, bin a lp_rast_triangle command.
 588        */
 589       for (y = miny; y <= maxy; y++)
 590       {
 591          int cx1 = c1;
 592          int cx2 = c2;
 593          int cx3 = c3;
 594          boolean in = FALSE;  /* are we inside the triangle? */
 595
 596          for (x = minx; x <= maxx; x++)
 597          {
 598             if (cx1 + eo1 < 0 ||
 599                 cx2 + eo2 < 0 ||
 600                 cx3 + eo3 < 0)
 601             {
 602                /* do nothing */
 603                LP_COUNT(nr_empty_64);
 604                if (in)
 605                   break;  /* exiting triangle, all done with this row */
 606             }
 607             else if (cx1 + ei1 > 0 &&
 608                      cx2 + ei2 > 0 &&
 609                      cx3 + ei3 > 0)
 610             {
 611                /* triangle covers the whole tile- shade whole tile */
 612                LP_COUNT(nr_fully_covered_64);
 613                in = TRUE;
 614                if (setup->fs.current.variant->opaque) {
 615                   lp_scene_bin_reset( scene, x, y );
 616                   lp_scene_bin_command( scene, x, y,
 617                                         lp_rast_set_state,
 618                                         lp_rast_arg_state(setup->fs.stored) );
 619                }
 620                lp_scene_bin_command( scene, x, y,
 621                                      lp_rast_shade_tile,
 622                                      lp_rast_arg_inputs(&tri->inputs) );
 623             }
 624             else
 625             {
 626                /* rasterizer/shade partial tile */
 627                LP_COUNT(nr_partially_covered_64);
 628                in = TRUE;
 629                lp_scene_bin_command( scene, x, y,
 630                                      lp_rast_triangle,
 631                                      lp_rast_arg_triangle(tri) );
 632             }
 633
 634             /* Iterate cx values across the region:
 635              */
 636             cx1 += xstep1;
 637             cx2 += xstep2;
 638             cx3 += xstep3;
 639          }
 640
 641          /* Iterate c values down the region:
 642           */
 643          c1 += ystep1;
 644          c2 += ystep2;
 645          c3 += ystep3;
 646       }
 647    }
 648 }
 649
 650
 651 /**
 652  * Draw triangle if it's CW, cull otherwise.
 653  */
 654 static void triangle_cw( struct lp_setup_context *setup,
 655                          const float (*v0)[4],
 656                          const float (*v1)[4],
 657                          const float (*v2)[4] )
 658 {
 659    do_triangle_ccw( setup, v1, v0, v2, !setup->ccw_is_frontface );
 660 }
 661
 662
 663 /**
 664  * Draw triangle if it's CCW, cull otherwise.
 665  */
 666 static void triangle_ccw( struct lp_setup_context *setup,
 667                          const float (*v0)[4],
 668                          const float (*v1)[4],
 669                          const float (*v2)[4] )
 670 {
 671    do_triangle_ccw( setup, v0, v1, v2, setup->ccw_is_frontface );
 672 }
 673
 674
 675
 676 /**
 677  * Draw triangle whether it's CW or CCW.
 678  */
 679 static void triangle_both( struct lp_setup_context *setup,
 680                            const float (*v0)[4],
 681                            const float (*v1)[4],
 682                            const float (*v2)[4] )
 683 {
 684    /* edge vectors e = v0 - v2, f = v1 - v2 */
 685    const float ex = v0[0][0] - v2[0][0];
 686    const float ey = v0[0][1] - v2[0][1];
 687    const float fx = v1[0][0] - v2[0][0];
 688    const float fy = v1[0][1] - v2[0][1];
 689
 690    /* det = cross(e,f).z */
 691    if (ex * fy - ey * fx < 0.0f)
 692       triangle_ccw( setup, v0, v1, v2 );
 693    else
 694       triangle_cw( setup, v0, v1, v2 );
 695 }
 696
 697
 698 static void triangle_nop( struct lp_setup_context *setup,
 699                           const float (*v0)[4],
 700                           const float (*v1)[4],
 701                           const float (*v2)[4] )
 702 {
 703 }
 704
 705
 706 void
 707 lp_setup_choose_triangle( struct lp_setup_context *setup )
 708 {
 709    switch (setup->cullmode) {
 710    case PIPE_FACE_NONE:
 711       setup->triangle = triangle_both;
 712       break;
 713    case PIPE_FACE_BACK:
 714       setup->triangle = setup->ccw_is_frontface ? triangle_ccw : triangle_cw;
 715       break;
 716    case PIPE_FACE_FRONT:
 717       setup->triangle = setup->ccw_is_frontface ? triangle_cw : triangle_ccw;
 718       break;
 719    default:
 720       setup->triangle = triangle_nop;
 721       break;
 722    }
 723 }