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 struct tri_info {
  42
  43    float pixel_offset;
  44
  45    /* fixed point vertex coordinates */
  46    int x[3];
  47    int y[3];
  48
  49    /* float x,y deltas - all from the original coordinates
  50     */
  51    float dy01, dy20;
  52    float dx01, dx20;
  53    float oneoverarea;
  54
  55    const float (*v0)[4];
  56    const float (*v1)[4];
  57    const float (*v2)[4];
  58
  59    boolean frontfacing;
  60 };
  61
  62
  63
  64 static const int step_scissor_minx[16] = {
  65    0, 1, 0, 1,
  66    2, 3, 2, 3,
  67    0, 1, 0, 1,
  68    2, 3, 2, 3
  69 };
  70
  71 static const int step_scissor_maxx[16] = {
  72     0, -1,  0, -1,
  73    -2, -3, -2, -3,
  74     0, -1,  0, -1,
  75    -2, -3, -2, -3
  76 };
  77
  78 static const int step_scissor_miny[16] = {
  79    0, 0, 1, 1,
  80    0, 0, 1, 1,
  81    2, 2, 3, 3,
  82    2, 2, 3, 3
  83 };
  84
  85 static const int step_scissor_maxy[16] = {
  86     0,  0, -1, -1,
  87     0,  0, -1, -1,
  88    -2, -2, -3, -3,
  89    -2, -2, -3, -3
  90 };
  91
  92
  93
  94
  95 static INLINE int
  96 subpixel_snap(float a)
  97 {
  98    return util_iround(FIXED_ONE * a);
  99 }
 100
 101 static INLINE float
 102 fixed_to_float(int a)
 103 {
 104    return a * (1.0 / FIXED_ONE);
 105 }
 106
 107
 108
 109 /**
 110  * Compute a0 for a constant-valued coefficient (GL_FLAT shading).
 111  */
 112 static void constant_coef( struct lp_rast_triangle *tri,
 113                            unsigned slot,
 114                            const float value,
 115                            unsigned i )
 116 {
 117    tri->inputs.a0[slot][i] = value;
 118    tri->inputs.dadx[slot][i] = 0.0f;
 119    tri->inputs.dady[slot][i] = 0.0f;
 120 }
 121
 122
 123
 124 static void linear_coef( struct lp_rast_triangle *tri,
 125                          const struct tri_info *info,
 126                          unsigned slot,
 127                          unsigned vert_attr,
 128                          unsigned i)
 129 {
 130    float a0 = info->v0[vert_attr][i];
 131    float a1 = info->v1[vert_attr][i];
 132    float a2 = info->v2[vert_attr][i];
 133
 134    float da01 = a0 - a1;
 135    float da20 = a2 - a0;
 136    float dadx = (da01 * info->dy20 - info->dy01 * da20) * info->oneoverarea;
 137    float dady = (da20 * info->dx01 - info->dx20 * da01) * info->oneoverarea;
 138
 139    tri->inputs.dadx[slot][i] = dadx;
 140    tri->inputs.dady[slot][i] = dady;
 141
 142    /* calculate a0 as the value which would be sampled for the
 143     * fragment at (0,0), taking into account that we want to sample at
 144     * pixel centers, in other words (0.5, 0.5).
 145     *
 146     * this is neat but unfortunately not a good way to do things for
 147     * triangles with very large values of dadx or dady as it will
 148     * result in the subtraction and re-addition from a0 of a very
 149     * large number, which means we'll end up loosing a lot of the
 150     * fractional bits and precision from a0.  the way to fix this is
 151     * to define a0 as the sample at a pixel center somewhere near vmin
 152     * instead - i'll switch to this later.
 153     */
 154    tri->inputs.a0[slot][i] = (a0 -
 155                               (dadx * (info->v0[0][0] - info->pixel_offset) +
 156                                dady * (info->v0[0][1] - info->pixel_offset)));
 157 }
 158
 159
 160 /**
 161  * Compute a0, dadx and dady for a perspective-corrected interpolant,
 162  * for a triangle.
 163  * We basically multiply the vertex value by 1/w before computing
 164  * the plane coefficients (a0, dadx, dady).
 165  * Later, when we compute the value at a particular fragment position we'll
 166  * divide the interpolated value by the interpolated W at that fragment.
 167  */
 168 static void perspective_coef( struct lp_rast_triangle *tri,
 169                               const struct tri_info *info,
 170                               unsigned slot,
 171                               unsigned vert_attr,
 172                               unsigned i)
 173 {
 174    /* premultiply by 1/w  (v[0][3] is always 1/w):
 175     */
 176    float a0 = info->v0[vert_attr][i] * info->v0[0][3];
 177    float a1 = info->v1[vert_attr][i] * info->v1[0][3];
 178    float a2 = info->v2[vert_attr][i] * info->v2[0][3];
 179    float da01 = a0 - a1;
 180    float da20 = a2 - a0;
 181    float dadx = (da01 * info->dy20 - info->dy01 * da20) * info->oneoverarea;
 182    float dady = (da20 * info->dx01 - info->dx20 * da01) * info->oneoverarea;
 183
 184    tri->inputs.dadx[slot][i] = dadx;
 185    tri->inputs.dady[slot][i] = dady;
 186    tri->inputs.a0[slot][i] = (a0 -
 187                               (dadx * (info->v0[0][0] - info->pixel_offset) +
 188                                dady * (info->v0[0][1] - info->pixel_offset)));
 189 }
 190
 191
 192 /**
 193  * Special coefficient setup for gl_FragCoord.
 194  * X and Y are trivial
 195  * Z and W are copied from position_coef which should have already been computed.
 196  * We could do a bit less work if we'd examine gl_FragCoord's swizzle mask.
 197  */
 198 static void
 199 setup_fragcoord_coef(struct lp_rast_triangle *tri,
 200                      const struct tri_info *info,
 201                      unsigned slot,
 202                      unsigned usage_mask)
 203 {
 204    /*X*/
 205    if (usage_mask & TGSI_WRITEMASK_X) {
 206       tri->inputs.a0[slot][0] = 0.0;
 207       tri->inputs.dadx[slot][0] = 1.0;
 208       tri->inputs.dady[slot][0] = 0.0;
 209    }
 210
 211    /*Y*/
 212    if (usage_mask & TGSI_WRITEMASK_Y) {
 213       tri->inputs.a0[slot][1] = 0.0;
 214       tri->inputs.dadx[slot][1] = 0.0;
 215       tri->inputs.dady[slot][1] = 1.0;
 216    }
 217
 218    /*Z*/
 219    if (usage_mask & TGSI_WRITEMASK_Z) {
 220       linear_coef(tri, info, slot, 0, 2);
 221    }
 222
 223    /*W*/
 224    if (usage_mask & TGSI_WRITEMASK_W) {
 225       linear_coef(tri, info, slot, 0, 3);
 226    }
 227 }
 228
 229
 230 /**
 231  * Setup the fragment input attribute with the front-facing value.
 232  * \param frontface  is the triangle front facing?
 233  */
 234 static void setup_facing_coef( struct lp_rast_triangle *tri,
 235                                unsigned slot,
 236                                boolean frontface,
 237                                unsigned usage_mask)
 238 {
 239    /* convert TRUE to 1.0 and FALSE to -1.0 */
 240    if (usage_mask & TGSI_WRITEMASK_X)
 241       constant_coef( tri, slot, 2.0f * frontface - 1.0f, 0 );
 242
 243    if (usage_mask & TGSI_WRITEMASK_Y)
 244       constant_coef( tri, slot, 0.0f, 1 ); /* wasted */
 245
 246    if (usage_mask & TGSI_WRITEMASK_Z)
 247       constant_coef( tri, slot, 0.0f, 2 ); /* wasted */
 248
 249    if (usage_mask & TGSI_WRITEMASK_W)
 250       constant_coef( tri, slot, 0.0f, 3 ); /* wasted */
 251 }
 252
 253
 254 /**
 255  * Compute the tri->coef[] array dadx, dady, a0 values.
 256  */
 257 static void setup_tri_coefficients( struct lp_setup_context *setup,
 258                                     struct lp_rast_triangle *tri,
 259                                     const struct tri_info *info)
 260 {
 261    unsigned fragcoord_usage_mask = TGSI_WRITEMASK_XYZ;
 262    unsigned slot;
 263
 264    /* setup interpolation for all the remaining attributes:
 265     */
 266    for (slot = 0; slot < setup->fs.nr_inputs; slot++) {
 267       unsigned vert_attr = setup->fs.input[slot].src_index;
 268       unsigned usage_mask = setup->fs.input[slot].usage_mask;
 269       unsigned i;
 270
 271       switch (setup->fs.input[slot].interp) {
 272       case LP_INTERP_CONSTANT:
 273          if (setup->flatshade_first) {
 274             for (i = 0; i < NUM_CHANNELS; i++)
 275                if (usage_mask & (1 << i))
 276                   constant_coef(tri, slot+1, info->v0[vert_attr][i], i);
 277          }
 278          else {
 279             for (i = 0; i < NUM_CHANNELS; i++)
 280                if (usage_mask & (1 << i))
 281                   constant_coef(tri, slot+1, info->v2[vert_attr][i], i);
 282          }
 283          break;
 284
 285       case LP_INTERP_LINEAR:
 286          for (i = 0; i < NUM_CHANNELS; i++)
 287             if (usage_mask & (1 << i))
 288                linear_coef(tri, info, slot+1, vert_attr, i);
 289          break;
 290
 291       case LP_INTERP_PERSPECTIVE:
 292          for (i = 0; i < NUM_CHANNELS; i++)
 293             if (usage_mask & (1 << i))
 294                perspective_coef(tri, info, slot+1, vert_attr, i);
 295          fragcoord_usage_mask |= TGSI_WRITEMASK_W;
 296          break;
 297
 298       case LP_INTERP_POSITION:
 299          /*
 300           * The generated pixel interpolators will pick up the coeffs from
 301           * slot 0, so all need to ensure that the usage mask is covers all
 302           * usages.
 303           */
 304          fragcoord_usage_mask |= usage_mask;
 305          break;
 306
 307       case LP_INTERP_FACING:
 308          setup_facing_coef(tri, slot+1, info->frontfacing, usage_mask);
 309          break;
 310
 311       default:
 312          assert(0);
 313       }
 314    }
 315
 316    /* The internal position input is in slot zero:
 317     */
 318    setup_fragcoord_coef(tri, info, 0, fragcoord_usage_mask);
 319 }
 320
 321
 322
 323
 324
 325
 326 /**
 327  * Alloc space for a new triangle plus the input.a0/dadx/dady arrays
 328  * immediately after it.
 329  * The memory is allocated from the per-scene pool, not per-tile.
 330  * \param tri_size  returns number of bytes allocated
 331  * \param nr_inputs  number of fragment shader inputs
 332  * \return pointer to triangle space
 333  */
 334 static INLINE struct lp_rast_triangle *
 335 alloc_triangle(struct lp_scene *scene,
 336                unsigned nr_inputs,
 337                unsigned nr_planes,
 338                unsigned *tri_size)
 339 {
 340    unsigned input_array_sz = NUM_CHANNELS * (nr_inputs + 1) * sizeof(float);
 341    struct lp_rast_triangle *tri;
 342    unsigned tri_bytes, bytes;
 343    char *inputs;
 344
 345    assert(sizeof(*tri) % 16 == 0);
 346
 347    tri_bytes = align(Offset(struct lp_rast_triangle, plane[nr_planes]), 16);
 348    bytes = tri_bytes + (3 * input_array_sz);
 349
 350    tri = lp_scene_alloc_aligned( scene, bytes, 16 );
 351
 352    if (tri) {
 353       inputs = ((char *)tri) + tri_bytes;
 354       tri->inputs.a0   = (float (*)[4]) inputs;
 355       tri->inputs.dadx = (float (*)[4]) (inputs + input_array_sz);
 356       tri->inputs.dady = (float (*)[4]) (inputs + 2 * input_array_sz);
 357
 358       *tri_size = bytes;
 359    }
 360
 361    return tri;
 362 }
 363
 364
 365 /**
 366  * Print triangle vertex attribs (for debug).
 367  */
 368 static void
 369 print_triangle(struct lp_setup_context *setup,
 370                const float (*v1)[4],
 371                const float (*v2)[4],
 372                const float (*v3)[4])
 373 {
 374    uint i;
 375
 376    debug_printf("llvmpipe triangle\n");
 377    for (i = 0; i < 1 + setup->fs.nr_inputs; i++) {
 378       debug_printf("  v1[%d]:  %f %f %f %f\n", i,
 379                    v1[i][0], v1[i][1], v1[i][2], v1[i][3]);
 380    }
 381    for (i = 0; i < 1 + setup->fs.nr_inputs; i++) {
 382       debug_printf("  v2[%d]:  %f %f %f %f\n", i,
 383                    v2[i][0], v2[i][1], v2[i][2], v2[i][3]);
 384    }
 385    for (i = 0; i < 1 + setup->fs.nr_inputs; i++) {
 386       debug_printf("  v3[%d]:  %f %f %f %f\n", i,
 387                    v3[i][0], v3[i][1], v3[i][2], v3[i][3]);
 388    }
 389 }
 390
 391
 392 lp_rast_cmd lp_rast_tri_tab[8] = {
 393    NULL,               /* should be impossible */
 394    lp_rast_triangle_1,
 395    lp_rast_triangle_2,
 396    lp_rast_triangle_3,
 397    lp_rast_triangle_4,
 398    lp_rast_triangle_5,
 399    lp_rast_triangle_6,
 400    lp_rast_triangle_7
 401 };
 402
 403 /**
 404  * Do basic setup for triangle rasterization and determine which
 405  * framebuffer tiles are touched.  Put the triangle in the scene's
 406  * bins for the tiles which we overlap.
 407  */
 408 static void
 409 do_triangle_ccw(struct lp_setup_context *setup,
 410                 const float (*v1)[4],
 411                 const float (*v2)[4],
 412                 const float (*v3)[4],
 413                 boolean frontfacing )
 414 {
 415
 416    struct lp_scene *scene = lp_setup_get_current_scene(setup);
 417    struct lp_fragment_shader_variant *variant = setup->fs.current.variant;
 418    struct lp_rast_triangle *tri;
 419    struct tri_info info;
 420    int area;
 421    int minx, maxx, miny, maxy;
 422    int ix0, ix1, iy0, iy1;
 423    unsigned tri_bytes;
 424    int i;
 425    int nr_planes = 3;
 426
 427    if (0)
 428       print_triangle(setup, v1, v2, v3);
 429
 430    if (setup->scissor_test) {
 431       nr_planes = 7;
 432    }
 433    else {
 434       nr_planes = 3;
 435    }
 436
 437
 438    tri = alloc_triangle(scene,
 439                         setup->fs.nr_inputs,
 440                         nr_planes,
 441                         &tri_bytes);
 442    if (!tri)
 443       return;
 444
 445 #ifdef DEBUG
 446    tri->v[0][0] = v1[0][0];
 447    tri->v[1][0] = v2[0][0];
 448    tri->v[2][0] = v3[0][0];
 449    tri->v[0][1] = v1[0][1];
 450    tri->v[1][1] = v2[0][1];
 451    tri->v[2][1] = v3[0][1];
 452 #endif
 453
 454    /* x/y positions in fixed point */
 455    info.x[0] = subpixel_snap(v1[0][0] - setup->pixel_offset);
 456    info.x[1] = subpixel_snap(v2[0][0] - setup->pixel_offset);
 457    info.x[2] = subpixel_snap(v3[0][0] - setup->pixel_offset);
 458    info.y[0] = subpixel_snap(v1[0][1] - setup->pixel_offset);
 459    info.y[1] = subpixel_snap(v2[0][1] - setup->pixel_offset);
 460    info.y[2] = subpixel_snap(v3[0][1] - setup->pixel_offset);
 461
 462    tri->plane[0].dcdy = info.x[0] - info.x[1];
 463    tri->plane[1].dcdy = info.x[1] - info.x[2];
 464    tri->plane[2].dcdy = info.x[2] - info.x[0];
 465
 466    tri->plane[0].dcdx = info.y[0] - info.y[1];
 467    tri->plane[1].dcdx = info.y[1] - info.y[2];
 468    tri->plane[2].dcdx = info.y[2] - info.y[0];
 469
 470    area = (tri->plane[0].dcdy * tri->plane[2].dcdx -
 471            tri->plane[2].dcdy * tri->plane[0].dcdx);
 472
 473    LP_COUNT(nr_tris);
 474
 475    /* Cull non-ccw and zero-sized triangles.
 476     *
 477     * XXX: subject to overflow??
 478     */
 479    if (area <= 0) {
 480       lp_scene_putback_data( scene, tri_bytes );
 481       LP_COUNT(nr_culled_tris);
 482       return;
 483    }
 484
 485    /* Bounding rectangle (in pixels) */
 486    {
 487       /* Yes this is necessary to accurately calculate bounding boxes
 488        * with the two fill-conventions we support.  GL (normally) ends
 489        * up needing a bottom-left fill convention, which requires
 490        * slightly different rounding.
 491        */
 492       int adj = (setup->pixel_offset != 0) ? 1 : 0;
 493
 494       minx = (MIN3(info.x[0], info.x[1], info.x[2]) + (FIXED_ONE-1)) >> FIXED_ORDER;
 495       maxx = (MAX3(info.x[0], info.x[1], info.x[2]) + (FIXED_ONE-1)) >> FIXED_ORDER;
 496       miny = (MIN3(info.y[0], info.y[1], info.y[2]) + (FIXED_ONE-1) + adj) >> FIXED_ORDER;
 497       maxy = (MAX3(info.y[0], info.y[1], info.y[2]) + (FIXED_ONE-1) + adj) >> FIXED_ORDER;
 498    }
 499
 500    if (setup->scissor_test) {
 501       minx = MAX2(minx, setup->scissor.current.minx);
 502       maxx = MIN2(maxx, setup->scissor.current.maxx);
 503       miny = MAX2(miny, setup->scissor.current.miny);
 504       maxy = MIN2(maxy, setup->scissor.current.maxy);
 505    }
 506    else {
 507       minx = MAX2(minx, 0);
 508       miny = MAX2(miny, 0);
 509       maxx = MIN2(maxx, scene->fb.width);
 510       maxy = MIN2(maxy, scene->fb.height);
 511    }
 512
 513
 514    if (miny >= maxy || minx >= maxx) {
 515       lp_scene_putback_data( scene, tri_bytes );
 516       LP_COUNT(nr_culled_tris);
 517       return;
 518    }
 519
 520    /*
 521     */
 522    info.pixel_offset = setup->pixel_offset;
 523    info.v0 = v1;
 524    info.v1 = v2;
 525    info.v2 = v3;
 526    info.dx01 = info.v0[0][0] - info.v1[0][0];
 527    info.dx20 = info.v2[0][0] - info.v0[0][0];
 528    info.dy01 = info.v0[0][1] - info.v1[0][1];
 529    info.dy20 = info.v2[0][1] - info.v0[0][1];
 530    info.oneoverarea = 1.0 / (info.dx01 * info.dy20 - info.dx20 * info.dy01);
 531    info.frontfacing = frontfacing;
 532
 533    /* Setup parameter interpolants:
 534     */
 535    setup_tri_coefficients( setup, tri, &info );
 536
 537    tri->inputs.facing = frontfacing ? 1.0F : -1.0F;
 538    tri->inputs.state = setup->fs.stored;
 539
 540
 541
 542    for (i = 0; i < 3; i++) {
 543       struct lp_rast_plane *plane = &tri->plane[i];
 544
 545       /* half-edge constants, will be interated over the whole render
 546        * target.
 547        */
 548       plane->c = plane->dcdx * info.x[i] - plane->dcdy * info.y[i];
 549
 550       /* correct for top-left vs. bottom-left fill convention.
 551        *
 552        * note that we're overloading gl_rasterization_rules to mean
 553        * both (0.5,0.5) pixel centers *and* bottom-left filling
 554        * convention.
 555        *
 556        * GL actually has a top-left filling convention, but GL's
 557        * notion of "top" differs from gallium's...
 558        *
 559        * Also, sometimes (in FBO cases) GL will render upside down
 560        * to its usual method, in which case it will probably want
 561        * to use the opposite, top-left convention.
 562        */
 563       if (plane->dcdx < 0) {
 564          /* both fill conventions want this - adjust for left edges */
 565          plane->c++;
 566       }
 567       else if (plane->dcdx == 0) {
 568          if (setup->pixel_offset == 0) {
 569             /* correct for top-left fill convention:
 570              */
 571             if (plane->dcdy > 0) plane->c++;
 572          }
 573          else {
 574             /* correct for bottom-left fill convention:
 575              */
 576             if (plane->dcdy < 0) plane->c++;
 577          }
 578       }
 579
 580       plane->dcdx *= FIXED_ONE;
 581       plane->dcdy *= FIXED_ONE;
 582
 583       /* find trivial reject offsets for each edge for a single-pixel
 584        * sized block.  These will be scaled up at each recursive level to
 585        * match the active blocksize.  Scaling in this way works best if
 586        * the blocks are square.
 587        */
 588       plane->eo = 0;
 589       if (plane->dcdx < 0) plane->eo -= plane->dcdx;
 590       if (plane->dcdy > 0) plane->eo += plane->dcdy;
 591
 592       /* Calculate trivial accept offsets from the above.
 593        */
 594       plane->ei = plane->dcdy - plane->dcdx - plane->eo;
 595
 596       plane->step = tri->step[i];
 597
 598       /* Fill in the inputs.step[][] arrays.
 599        * We've manually unrolled some loops here.
 600        */
 601 #define SETUP_STEP(j, x, y) \
 602       tri->step[i][j] = y * plane->dcdy - x * plane->dcdx
 603
 604       SETUP_STEP(0, 0, 0);
 605       SETUP_STEP(1, 1, 0);
 606       SETUP_STEP(2, 0, 1);
 607       SETUP_STEP(3, 1, 1);
 608
 609       SETUP_STEP(4, 2, 0);
 610       SETUP_STEP(5, 3, 0);
 611       SETUP_STEP(6, 2, 1);
 612       SETUP_STEP(7, 3, 1);
 613
 614       SETUP_STEP(8, 0, 2);
 615       SETUP_STEP(9, 1, 2);
 616       SETUP_STEP(10, 0, 3);
 617       SETUP_STEP(11, 1, 3);
 618
 619       SETUP_STEP(12, 2, 2);
 620       SETUP_STEP(13, 3, 2);
 621       SETUP_STEP(14, 2, 3);
 622       SETUP_STEP(15, 3, 3);
 623 #undef STEP
 624    }
 625
 626
 627    /*
 628     * When rasterizing scissored tris, use the intersection of the
 629     * triangle bounding box and the scissor rect to generate the
 630     * scissor planes.
 631     *
 632     * This permits us to cut off the triangle "tails" that are present
 633     * in the intermediate recursive levels caused when two of the
 634     * triangles edges don't diverge quickly enough to trivially reject
 635     * exterior blocks from the triangle.
 636     *
 637     * It's not really clear if it's worth worrying about these tails,
 638     * but since we generate the planes for each scissored tri, it's
 639     * free to trim them in this case.
 640     *
 641     * Note that otherwise, the scissor planes only vary in 'C' value,
 642     * and even then only on state-changes.  Could alternatively store
 643     * these planes elsewhere.
 644     */
 645    if (nr_planes == 7) {
 646       tri->plane[3].step = step_scissor_minx;
 647       tri->plane[3].dcdx = -1;
 648       tri->plane[3].dcdy = 0;
 649       tri->plane[3].c = 1-minx;
 650       tri->plane[3].ei = 0;
 651       tri->plane[3].eo = 1;
 652
 653       tri->plane[4].step = step_scissor_maxx;
 654       tri->plane[4].dcdx = 1;
 655       tri->plane[4].dcdy = 0;
 656       tri->plane[4].c = maxx;
 657       tri->plane[4].ei = -1;
 658       tri->plane[4].eo = 0;
 659
 660       tri->plane[5].step = step_scissor_miny;
 661       tri->plane[5].dcdx = 0;
 662       tri->plane[5].dcdy = 1;
 663       tri->plane[5].c = 1-miny;
 664       tri->plane[5].ei = 0;
 665       tri->plane[5].eo = 1;
 666
 667       tri->plane[6].step = step_scissor_maxy;
 668       tri->plane[6].dcdx = 0;
 669       tri->plane[6].dcdy = -1;
 670       tri->plane[6].c = maxy;
 671       tri->plane[6].ei = -1;
 672       tri->plane[6].eo = 0;
 673    }
 674
 675
 676    /*
 677     * All fields of 'tri' are now set.  The remaining code here is
 678     * concerned with binning.
 679     */
 680
 681    /* Convert to tile coordinates, and inclusive ranges:
 682     */
 683    ix0 = minx / TILE_SIZE;
 684    iy0 = miny / TILE_SIZE;
 685    ix1 = (maxx-1) / TILE_SIZE;
 686    iy1 = (maxy-1) / TILE_SIZE;
 687
 688    /*
 689     * Clamp to framebuffer size
 690     */
 691    assert(ix0 == MAX2(ix0, 0));
 692    assert(iy0 == MAX2(iy0, 0));
 693    assert(ix1 == MIN2(ix1, scene->tiles_x - 1));
 694    assert(iy1 == MIN2(iy1, scene->tiles_y - 1));
 695
 696    /* Determine which tile(s) intersect the triangle's bounding box
 697     */
 698    if (iy0 == iy1 && ix0 == ix1)
 699    {
 700       /* Triangle is contained in a single tile:
 701        */
 702       lp_scene_bin_command( scene, ix0, iy0,
 703                             lp_rast_tri_tab[nr_planes],
 704                             lp_rast_arg_triangle(tri, (1<<nr_planes)-1) );
 705    }
 706    else
 707    {
 708       int c[7];
 709       int ei[7];
 710       int eo[7];
 711       int xstep[7];
 712       int ystep[7];
 713       int x, y;
 714
 715       for (i = 0; i < nr_planes; i++) {
 716          c[i] = (tri->plane[i].c +
 717                  tri->plane[i].dcdy * iy0 * TILE_SIZE -
 718                  tri->plane[i].dcdx * ix0 * TILE_SIZE);
 719
 720          ei[i] = tri->plane[i].ei << TILE_ORDER;
 721          eo[i] = tri->plane[i].eo << TILE_ORDER;
 722          xstep[i] = -(tri->plane[i].dcdx << TILE_ORDER);
 723          ystep[i] = tri->plane[i].dcdy << TILE_ORDER;
 724       }
 725
 726
 727
 728       /* Test tile-sized blocks against the triangle.
 729        * Discard blocks fully outside the tri.  If the block is fully
 730        * contained inside the tri, bin an lp_rast_shade_tile command.
 731        * Else, bin a lp_rast_triangle command.
 732        */
 733       for (y = iy0; y <= iy1; y++)
 734       {
 735          boolean in = FALSE;  /* are we inside the triangle? */
 736          int cx[7];
 737
 738          for (i = 0; i < nr_planes; i++)
 739             cx[i] = c[i];
 740
 741          for (x = ix0; x <= ix1; x++)
 742          {
 743             int out = 0;
 744             int partial = 0;
 745
 746             for (i = 0; i < nr_planes; i++) {
 747                int planeout = cx[i] + eo[i];
 748                int planepartial = cx[i] + ei[i] - 1;
 749                out |= (planeout >> 31);
 750                partial |= (planepartial >> 31) & (1<<i);
 751             }
 752
 753             if (out) {
 754                /* do nothing */
 755                if (in)
 756                   break;  /* exiting triangle, all done with this row */
 757                LP_COUNT(nr_empty_64);
 758             }
 759             else if (partial) {
 760                /* Not trivially accepted by at least one plane -
 761                 * rasterize/shade partial tile
 762                 */
 763                int count = util_bitcount(partial);
 764                in = TRUE;
 765                lp_scene_bin_command( scene, x, y,
 766                                      lp_rast_tri_tab[count],
 767                                      lp_rast_arg_triangle(tri, partial) );
 768
 769                LP_COUNT(nr_partially_covered_64);
 770             }
 771             else {
 772                /* triangle covers the whole tile- shade whole tile */
 773                LP_COUNT(nr_fully_covered_64);
 774                in = TRUE;
 775                if (variant->opaque &&
 776                    !setup->fb.zsbuf) {
 777                   lp_scene_bin_reset( scene, x, y );
 778                }
 779                lp_scene_bin_command( scene, x, y,
 780                                      lp_rast_shade_tile,
 781                                      lp_rast_arg_inputs(&tri->inputs) );
 782             }
 783
 784             /* Iterate cx values across the region:
 785              */
 786             for (i = 0; i < nr_planes; i++)
 787                cx[i] += xstep[i];
 788          }
 789
 790          /* Iterate c values down the region:
 791           */
 792          for (i = 0; i < nr_planes; i++)
 793             c[i] += ystep[i];
 794       }
 795    }
 796 }
 797
 798
 799 /**
 800  * Draw triangle if it's CW, cull otherwise.
 801  */
 802 static void triangle_cw( struct lp_setup_context *setup,
 803                          const float (*v0)[4],
 804                          const float (*v1)[4],
 805                          const float (*v2)[4] )
 806 {
 807    do_triangle_ccw( setup, v1, v0, v2, !setup->ccw_is_frontface );
 808 }
 809
 810
 811 /**
 812  * Draw triangle if it's CCW, cull otherwise.
 813  */
 814 static void triangle_ccw( struct lp_setup_context *setup,
 815                          const float (*v0)[4],
 816                          const float (*v1)[4],
 817                          const float (*v2)[4] )
 818 {
 819    do_triangle_ccw( setup, v0, v1, v2, setup->ccw_is_frontface );
 820 }
 821
 822
 823
 824 /**
 825  * Draw triangle whether it's CW or CCW.
 826  */
 827 static void triangle_both( struct lp_setup_context *setup,
 828                            const float (*v0)[4],
 829                            const float (*v1)[4],
 830                            const float (*v2)[4] )
 831 {
 832    /* edge vectors e = v0 - v2, f = v1 - v2 */
 833    const float ex = v0[0][0] - v2[0][0];
 834    const float ey = v0[0][1] - v2[0][1];
 835    const float fx = v1[0][0] - v2[0][0];
 836    const float fy = v1[0][1] - v2[0][1];
 837
 838    /* det = cross(e,f).z */
 839    if (ex * fy - ey * fx < 0.0f)
 840       triangle_ccw( setup, v0, v1, v2 );
 841    else
 842       triangle_cw( setup, v0, v1, v2 );
 843 }
 844
 845
 846 static void triangle_nop( struct lp_setup_context *setup,
 847                           const float (*v0)[4],
 848                           const float (*v1)[4],
 849                           const float (*v2)[4] )
 850 {
 851 }
 852
 853
 854 void
 855 lp_setup_choose_triangle( struct lp_setup_context *setup )
 856 {
 857    switch (setup->cullmode) {
 858    case PIPE_FACE_NONE:
 859       setup->triangle = triangle_both;
 860       break;
 861    case PIPE_FACE_BACK:
 862       setup->triangle = setup->ccw_is_frontface ? triangle_ccw : triangle_cw;
 863       break;
 864    case PIPE_FACE_FRONT:
 865       setup->triangle = setup->ccw_is_frontface ? triangle_cw : triangle_ccw;
 866       break;
 867    default:
 868       setup->triangle = triangle_nop;
 869       break;
 870    }
 871 }