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    tri_bytes = align(Offset(struct lp_rast_triangle, plane[nr_planes]), 16);
 346    bytes = tri_bytes + (3 * input_array_sz);
 347
 348    tri = lp_scene_alloc_aligned( scene, bytes, 16 );
 349
 350    if (tri) {
 351       inputs = ((char *)tri) + tri_bytes;
 352       tri->inputs.a0   = (float (*)[4]) inputs;
 353       tri->inputs.dadx = (float (*)[4]) (inputs + input_array_sz);
 354       tri->inputs.dady = (float (*)[4]) (inputs + 2 * input_array_sz);
 355
 356       *tri_size = bytes;
 357    }
 358
 359    return tri;
 360 }
 361
 362
 363 /**
 364  * Print triangle vertex attribs (for debug).
 365  */
 366 static void
 367 print_triangle(struct lp_setup_context *setup,
 368                const float (*v1)[4],
 369                const float (*v2)[4],
 370                const float (*v3)[4])
 371 {
 372    uint i;
 373
 374    debug_printf("llvmpipe triangle\n");
 375    for (i = 0; i < 1 + setup->fs.nr_inputs; i++) {
 376       debug_printf("  v1[%d]:  %f %f %f %f\n", i,
 377                    v1[i][0], v1[i][1], v1[i][2], v1[i][3]);
 378    }
 379    for (i = 0; i < 1 + setup->fs.nr_inputs; i++) {
 380       debug_printf("  v2[%d]:  %f %f %f %f\n", i,
 381                    v2[i][0], v2[i][1], v2[i][2], v2[i][3]);
 382    }
 383    for (i = 0; i < 1 + setup->fs.nr_inputs; i++) {
 384       debug_printf("  v3[%d]:  %f %f %f %f\n", i,
 385                    v3[i][0], v3[i][1], v3[i][2], v3[i][3]);
 386    }
 387 }
 388
 389
 390 lp_rast_cmd lp_rast_tri_tab[8] = {
 391    NULL,               /* should be impossible */
 392    lp_rast_triangle_1,
 393    lp_rast_triangle_2,
 394    lp_rast_triangle_3,
 395    lp_rast_triangle_4,
 396    lp_rast_triangle_5,
 397    lp_rast_triangle_6,
 398    lp_rast_triangle_7
 399 };
 400
 401 /**
 402  * Do basic setup for triangle rasterization and determine which
 403  * framebuffer tiles are touched.  Put the triangle in the scene's
 404  * bins for the tiles which we overlap.
 405  */
 406 static void
 407 do_triangle_ccw(struct lp_setup_context *setup,
 408                 const float (*v1)[4],
 409                 const float (*v2)[4],
 410                 const float (*v3)[4],
 411                 boolean frontfacing )
 412 {
 413
 414    struct lp_scene *scene = lp_setup_get_current_scene(setup);
 415    struct lp_fragment_shader_variant *variant = setup->fs.current.variant;
 416    struct lp_rast_triangle *tri;
 417    struct tri_info info;
 418    int area;
 419    int minx, maxx, miny, maxy;
 420    int ix0, ix1, iy0, iy1;
 421    unsigned tri_bytes;
 422    int i;
 423    int nr_planes = 3;
 424
 425    if (0)
 426       print_triangle(setup, v1, v2, v3);
 427
 428    if (setup->scissor_test) {
 429       nr_planes = 7;
 430    }
 431    else {
 432       nr_planes = 3;
 433    }
 434
 435
 436    tri = alloc_triangle(scene,
 437                         setup->fs.nr_inputs,
 438                         nr_planes,
 439                         &tri_bytes);
 440    if (!tri)
 441       return;
 442
 443 #ifdef DEBUG
 444    tri->v[0][0] = v1[0][0];
 445    tri->v[1][0] = v2[0][0];
 446    tri->v[2][0] = v3[0][0];
 447    tri->v[0][1] = v1[0][1];
 448    tri->v[1][1] = v2[0][1];
 449    tri->v[2][1] = v3[0][1];
 450 #endif
 451
 452    /* x/y positions in fixed point */
 453    info.x[0] = subpixel_snap(v1[0][0] - setup->pixel_offset);
 454    info.x[1] = subpixel_snap(v2[0][0] - setup->pixel_offset);
 455    info.x[2] = subpixel_snap(v3[0][0] - setup->pixel_offset);
 456    info.y[0] = subpixel_snap(v1[0][1] - setup->pixel_offset);
 457    info.y[1] = subpixel_snap(v2[0][1] - setup->pixel_offset);
 458    info.y[2] = subpixel_snap(v3[0][1] - setup->pixel_offset);
 459
 460    tri->plane[0].dcdy = info.x[0] - info.x[1];
 461    tri->plane[1].dcdy = info.x[1] - info.x[2];
 462    tri->plane[2].dcdy = info.x[2] - info.x[0];
 463
 464    tri->plane[0].dcdx = info.y[0] - info.y[1];
 465    tri->plane[1].dcdx = info.y[1] - info.y[2];
 466    tri->plane[2].dcdx = info.y[2] - info.y[0];
 467
 468    area = (tri->plane[0].dcdy * tri->plane[2].dcdx -
 469            tri->plane[2].dcdy * tri->plane[0].dcdx);
 470
 471    LP_COUNT(nr_tris);
 472
 473    /* Cull non-ccw and zero-sized triangles.
 474     *
 475     * XXX: subject to overflow??
 476     */
 477    if (area <= 0) {
 478       lp_scene_putback_data( scene, tri_bytes );
 479       LP_COUNT(nr_culled_tris);
 480       return;
 481    }
 482
 483    /* Bounding rectangle (in pixels) */
 484    {
 485       /* Yes this is necessary to accurately calculate bounding boxes
 486        * with the two fill-conventions we support.  GL (normally) ends
 487        * up needing a bottom-left fill convention, which requires
 488        * slightly different rounding.
 489        */
 490       int adj = (setup->pixel_offset != 0) ? 1 : 0;
 491
 492       minx = (MIN3(info.x[0], info.x[1], info.x[2]) + (FIXED_ONE-1)) >> FIXED_ORDER;
 493       maxx = (MAX3(info.x[0], info.x[1], info.x[2]) + (FIXED_ONE-1)) >> FIXED_ORDER;
 494       miny = (MIN3(info.y[0], info.y[1], info.y[2]) + (FIXED_ONE-1) + adj) >> FIXED_ORDER;
 495       maxy = (MAX3(info.y[0], info.y[1], info.y[2]) + (FIXED_ONE-1) + adj) >> FIXED_ORDER;
 496    }
 497
 498    if (setup->scissor_test) {
 499       minx = MAX2(minx, setup->scissor.current.minx);
 500       maxx = MIN2(maxx, setup->scissor.current.maxx);
 501       miny = MAX2(miny, setup->scissor.current.miny);
 502       maxy = MIN2(maxy, setup->scissor.current.maxy);
 503    }
 504    else {
 505       minx = MAX2(minx, 0);
 506       miny = MAX2(miny, 0);
 507       maxx = MIN2(maxx, scene->fb.width);
 508       maxy = MIN2(maxy, scene->fb.height);
 509    }
 510
 511
 512    if (miny >= maxy || minx >= maxx) {
 513       lp_scene_putback_data( scene, tri_bytes );
 514       LP_COUNT(nr_culled_tris);
 515       return;
 516    }
 517
 518    /*
 519     */
 520    info.pixel_offset = setup->pixel_offset;
 521    info.v0 = v1;
 522    info.v1 = v2;
 523    info.v2 = v3;
 524    info.dx01 = info.v0[0][0] - info.v1[0][0];
 525    info.dx20 = info.v2[0][0] - info.v0[0][0];
 526    info.dy01 = info.v0[0][1] - info.v1[0][1];
 527    info.dy20 = info.v2[0][1] - info.v0[0][1];
 528    info.oneoverarea = 1.0 / (info.dx01 * info.dy20 - info.dx20 * info.dy01);
 529    info.frontfacing = frontfacing;
 530
 531    /* Setup parameter interpolants:
 532     */
 533    setup_tri_coefficients( setup, tri, &info );
 534
 535    tri->inputs.facing = frontfacing ? 1.0F : -1.0F;
 536    tri->inputs.state = setup->fs.stored;
 537
 538
 539
 540    for (i = 0; i < 3; i++) {
 541       struct lp_rast_plane *plane = &tri->plane[i];
 542
 543       /* half-edge constants, will be interated over the whole render
 544        * target.
 545        */
 546       plane->c = plane->dcdx * info.x[i] - plane->dcdy * info.y[i];
 547
 548       /* correct for top-left vs. bottom-left fill convention.
 549        *
 550        * note that we're overloading gl_rasterization_rules to mean
 551        * both (0.5,0.5) pixel centers *and* bottom-left filling
 552        * convention.
 553        *
 554        * GL actually has a top-left filling convention, but GL's
 555        * notion of "top" differs from gallium's...
 556        *
 557        * Also, sometimes (in FBO cases) GL will render upside down
 558        * to its usual method, in which case it will probably want
 559        * to use the opposite, top-left convention.
 560        */
 561       if (plane->dcdx < 0) {
 562          /* both fill conventions want this - adjust for left edges */
 563          plane->c++;
 564       }
 565       else if (plane->dcdx == 0) {
 566          if (setup->pixel_offset == 0) {
 567             /* correct for top-left fill convention:
 568              */
 569             if (plane->dcdy > 0) plane->c++;
 570          }
 571          else {
 572             /* correct for bottom-left fill convention:
 573              */
 574             if (plane->dcdy < 0) plane->c++;
 575          }
 576       }
 577
 578       plane->dcdx *= FIXED_ONE;
 579       plane->dcdy *= FIXED_ONE;
 580
 581       /* find trivial reject offsets for each edge for a single-pixel
 582        * sized block.  These will be scaled up at each recursive level to
 583        * match the active blocksize.  Scaling in this way works best if
 584        * the blocks are square.
 585        */
 586       plane->eo = 0;
 587       if (plane->dcdx < 0) plane->eo -= plane->dcdx;
 588       if (plane->dcdy > 0) plane->eo += plane->dcdy;
 589
 590       /* Calculate trivial accept offsets from the above.
 591        */
 592       plane->ei = plane->dcdy - plane->dcdx - plane->eo;
 593
 594       plane->step = tri->step[i];
 595
 596       /* Fill in the inputs.step[][] arrays.
 597        * We've manually unrolled some loops here.
 598        */
 599 #define SETUP_STEP(j, x, y) \
 600       tri->step[i][j] = y * plane->dcdy - x * plane->dcdx
 601
 602       SETUP_STEP(0, 0, 0);
 603       SETUP_STEP(1, 1, 0);
 604       SETUP_STEP(2, 0, 1);
 605       SETUP_STEP(3, 1, 1);
 606
 607       SETUP_STEP(4, 2, 0);
 608       SETUP_STEP(5, 3, 0);
 609       SETUP_STEP(6, 2, 1);
 610       SETUP_STEP(7, 3, 1);
 611
 612       SETUP_STEP(8, 0, 2);
 613       SETUP_STEP(9, 1, 2);
 614       SETUP_STEP(10, 0, 3);
 615       SETUP_STEP(11, 1, 3);
 616
 617       SETUP_STEP(12, 2, 2);
 618       SETUP_STEP(13, 3, 2);
 619       SETUP_STEP(14, 2, 3);
 620       SETUP_STEP(15, 3, 3);
 621 #undef STEP
 622    }
 623
 624
 625    /*
 626     * When rasterizing scissored tris, use the intersection of the
 627     * triangle bounding box and the scissor rect to generate the
 628     * scissor planes.
 629     *
 630     * This permits us to cut off the triangle "tails" that are present
 631     * in the intermediate recursive levels caused when two of the
 632     * triangles edges don't diverge quickly enough to trivially reject
 633     * exterior blocks from the triangle.
 634     *
 635     * It's not really clear if it's worth worrying about these tails,
 636     * but since we generate the planes for each scissored tri, it's
 637     * free to trim them in this case.
 638     *
 639     * Note that otherwise, the scissor planes only vary in 'C' value,
 640     * and even then only on state-changes.  Could alternatively store
 641     * these planes elsewhere.
 642     */
 643    if (nr_planes == 7) {
 644       tri->plane[3].step = step_scissor_minx;
 645       tri->plane[3].dcdx = -1;
 646       tri->plane[3].dcdy = 0;
 647       tri->plane[3].c = 1-minx;
 648       tri->plane[3].ei = 0;
 649       tri->plane[3].eo = 1;
 650
 651       tri->plane[4].step = step_scissor_maxx;
 652       tri->plane[4].dcdx = 1;
 653       tri->plane[4].dcdy = 0;
 654       tri->plane[4].c = maxx;
 655       tri->plane[4].ei = -1;
 656       tri->plane[4].eo = 0;
 657
 658       tri->plane[5].step = step_scissor_miny;
 659       tri->plane[5].dcdx = 0;
 660       tri->plane[5].dcdy = 1;
 661       tri->plane[5].c = 1-miny;
 662       tri->plane[5].ei = 0;
 663       tri->plane[5].eo = 1;
 664
 665       tri->plane[6].step = step_scissor_maxy;
 666       tri->plane[6].dcdx = 0;
 667       tri->plane[6].dcdy = -1;
 668       tri->plane[6].c = maxy;
 669       tri->plane[6].ei = -1;
 670       tri->plane[6].eo = 0;
 671    }
 672
 673
 674    /*
 675     * All fields of 'tri' are now set.  The remaining code here is
 676     * concerned with binning.
 677     */
 678
 679    /* Convert to tile coordinates, and inclusive ranges:
 680     */
 681    ix0 = minx / TILE_SIZE;
 682    iy0 = miny / TILE_SIZE;
 683    ix1 = (maxx-1) / TILE_SIZE;
 684    iy1 = (maxy-1) / TILE_SIZE;
 685
 686    /*
 687     * Clamp to framebuffer size
 688     */
 689    assert(ix0 == MAX2(ix0, 0));
 690    assert(iy0 == MAX2(iy0, 0));
 691    assert(ix1 == MIN2(ix1, scene->tiles_x - 1));
 692    assert(iy1 == MIN2(iy1, scene->tiles_y - 1));
 693
 694    /* Determine which tile(s) intersect the triangle's bounding box
 695     */
 696    if (iy0 == iy1 && ix0 == ix1)
 697    {
 698       /* Triangle is contained in a single tile:
 699        */
 700       lp_scene_bin_command( scene, ix0, iy0,
 701                             lp_rast_tri_tab[nr_planes],
 702                             lp_rast_arg_triangle(tri, (1<<nr_planes)-1) );
 703    }
 704    else
 705    {
 706       int c[7];
 707       int ei[7];
 708       int eo[7];
 709       int xstep[7];
 710       int ystep[7];
 711       int x, y;
 712
 713       for (i = 0; i < nr_planes; i++) {
 714          c[i] = (tri->plane[i].c +
 715                  tri->plane[i].dcdy * iy0 * TILE_SIZE -
 716                  tri->plane[i].dcdx * ix0 * TILE_SIZE);
 717
 718          ei[i] = tri->plane[i].ei << TILE_ORDER;
 719          eo[i] = tri->plane[i].eo << TILE_ORDER;
 720          xstep[i] = -(tri->plane[i].dcdx << TILE_ORDER);
 721          ystep[i] = tri->plane[i].dcdy << TILE_ORDER;
 722       }
 723
 724
 725
 726       /* Test tile-sized blocks against the triangle.
 727        * Discard blocks fully outside the tri.  If the block is fully
 728        * contained inside the tri, bin an lp_rast_shade_tile command.
 729        * Else, bin a lp_rast_triangle command.
 730        */
 731       for (y = iy0; y <= iy1; y++)
 732       {
 733          boolean in = FALSE;  /* are we inside the triangle? */
 734          int cx[7];
 735
 736          for (i = 0; i < nr_planes; i++)
 737             cx[i] = c[i];
 738
 739          for (x = ix0; x <= ix1; x++)
 740          {
 741             int out = 0;
 742             int partial = 0;
 743
 744             for (i = 0; i < nr_planes; i++) {
 745                int planeout = cx[i] + eo[i];
 746                int planepartial = cx[i] + ei[i] - 1;
 747                out |= (planeout >> 31);
 748                partial |= (planepartial >> 31) & (1<<i);
 749             }
 750
 751             if (out) {
 752                /* do nothing */
 753                if (in)
 754                   break;  /* exiting triangle, all done with this row */
 755                LP_COUNT(nr_empty_64);
 756             }
 757             else if (partial) {
 758                /* Not trivially accepted by at least one plane -
 759                 * rasterize/shade partial tile
 760                 */
 761                int count = util_bitcount(partial);
 762                in = TRUE;
 763                lp_scene_bin_command( scene, x, y,
 764                                      lp_rast_tri_tab[count],
 765                                      lp_rast_arg_triangle(tri, partial) );
 766
 767                LP_COUNT(nr_partially_covered_64);
 768             }
 769             else {
 770                /* triangle covers the whole tile- shade whole tile */
 771                LP_COUNT(nr_fully_covered_64);
 772                in = TRUE;
 773                if (variant->opaque &&
 774                    !setup->fb.zsbuf) {
 775                   lp_scene_bin_reset( scene, x, y );
 776                }
 777                lp_scene_bin_command( scene, x, y,
 778                                      lp_rast_shade_tile,
 779                                      lp_rast_arg_inputs(&tri->inputs) );
 780             }
 781
 782             /* Iterate cx values across the region:
 783              */
 784             for (i = 0; i < nr_planes; i++)
 785                cx[i] += xstep[i];
 786          }
 787
 788          /* Iterate c values down the region:
 789           */
 790          for (i = 0; i < nr_planes; i++)
 791             c[i] += ystep[i];
 792       }
 793    }
 794 }
 795
 796
 797 /**
 798  * Draw triangle if it's CW, cull otherwise.
 799  */
 800 static void triangle_cw( struct lp_setup_context *setup,
 801                          const float (*v0)[4],
 802                          const float (*v1)[4],
 803                          const float (*v2)[4] )
 804 {
 805    do_triangle_ccw( setup, v1, v0, v2, !setup->ccw_is_frontface );
 806 }
 807
 808
 809 /**
 810  * Draw triangle if it's CCW, cull otherwise.
 811  */
 812 static void triangle_ccw( struct lp_setup_context *setup,
 813                          const float (*v0)[4],
 814                          const float (*v1)[4],
 815                          const float (*v2)[4] )
 816 {
 817    do_triangle_ccw( setup, v0, v1, v2, setup->ccw_is_frontface );
 818 }
 819
 820
 821
 822 /**
 823  * Draw triangle whether it's CW or CCW.
 824  */
 825 static void triangle_both( struct lp_setup_context *setup,
 826                            const float (*v0)[4],
 827                            const float (*v1)[4],
 828                            const float (*v2)[4] )
 829 {
 830    /* edge vectors e = v0 - v2, f = v1 - v2 */
 831    const float ex = v0[0][0] - v2[0][0];
 832    const float ey = v0[0][1] - v2[0][1];
 833    const float fx = v1[0][0] - v2[0][0];
 834    const float fy = v1[0][1] - v2[0][1];
 835
 836    /* det = cross(e,f).z */
 837    if (ex * fy - ey * fx < 0.0f)
 838       triangle_ccw( setup, v0, v1, v2 );
 839    else
 840       triangle_cw( setup, v0, v1, v2 );
 841 }
 842
 843
 844 static void triangle_nop( struct lp_setup_context *setup,
 845                           const float (*v0)[4],
 846                           const float (*v1)[4],
 847                           const float (*v2)[4] )
 848 {
 849 }
 850
 851
 852 void
 853 lp_setup_choose_triangle( struct lp_setup_context *setup )
 854 {
 855    switch (setup->cullmode) {
 856    case PIPE_FACE_NONE:
 857       setup->triangle = triangle_both;
 858       break;
 859    case PIPE_FACE_BACK:
 860       setup->triangle = setup->ccw_is_frontface ? triangle_ccw : triangle_cw;
 861       break;
 862    case PIPE_FACE_FRONT:
 863       setup->triangle = setup->ccw_is_frontface ? triangle_cw : triangle_ccw;
 864       break;
 865    default:
 866       setup->triangle = triangle_nop;
 867       break;
 868    }
 869 }