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
  65 static INLINE int
  66 subpixel_snap(float a)
  67 {
  68    return util_iround(FIXED_ONE * a);
  69 }
  70
  71 static INLINE float
  72 fixed_to_float(int a)
  73 {
  74    return a * (1.0 / FIXED_ONE);
  75 }
  76
  77
  78
  79 /**
  80  * Compute a0 for a constant-valued coefficient (GL_FLAT shading).
  81  */
  82 static void constant_coef( struct lp_rast_triangle *tri,
  83                            unsigned slot,
  84                            const float value,
  85                            unsigned i )
  86 {
  87    tri->inputs.a0[slot][i] = value;
  88    tri->inputs.dadx[slot][i] = 0.0f;
  89    tri->inputs.dady[slot][i] = 0.0f;
  90 }
  91
  92
  93
  94 static void linear_coef( struct lp_rast_triangle *tri,
  95                          const struct tri_info *info,
  96                          unsigned slot,
  97                          unsigned vert_attr,
  98                          unsigned i)
  99 {
 100    float a0 = info->v0[vert_attr][i];
 101    float a1 = info->v1[vert_attr][i];
 102    float a2 = info->v2[vert_attr][i];
 103
 104    float da01 = a0 - a1;
 105    float da20 = a2 - a0;
 106    float dadx = (da01 * info->dy20 - info->dy01 * da20) * info->oneoverarea;
 107    float dady = (da20 * info->dx01 - info->dx20 * da01) * info->oneoverarea;
 108
 109    tri->inputs.dadx[slot][i] = dadx;
 110    tri->inputs.dady[slot][i] = dady;
 111
 112    /* calculate a0 as the value which would be sampled for the
 113     * fragment at (0,0), taking into account that we want to sample at
 114     * pixel centers, in other words (0.5, 0.5).
 115     *
 116     * this is neat but unfortunately not a good way to do things for
 117     * triangles with very large values of dadx or dady as it will
 118     * result in the subtraction and re-addition from a0 of a very
 119     * large number, which means we'll end up loosing a lot of the
 120     * fractional bits and precision from a0.  the way to fix this is
 121     * to define a0 as the sample at a pixel center somewhere near vmin
 122     * instead - i'll switch to this later.
 123     */
 124    tri->inputs.a0[slot][i] = (a0 -
 125                               (dadx * (info->v0[0][0] - info->pixel_offset) +
 126                                dady * (info->v0[0][1] - info->pixel_offset)));
 127 }
 128
 129
 130 /**
 131  * Compute a0, dadx and dady for a perspective-corrected interpolant,
 132  * for a triangle.
 133  * We basically multiply the vertex value by 1/w before computing
 134  * the plane coefficients (a0, dadx, dady).
 135  * Later, when we compute the value at a particular fragment position we'll
 136  * divide the interpolated value by the interpolated W at that fragment.
 137  */
 138 static void perspective_coef( struct lp_rast_triangle *tri,
 139                               const struct tri_info *info,
 140                               unsigned slot,
 141                               unsigned vert_attr,
 142                               unsigned i)
 143 {
 144    /* premultiply by 1/w  (v[0][3] is always 1/w):
 145     */
 146    float a0 = info->v0[vert_attr][i] * info->v0[0][3];
 147    float a1 = info->v1[vert_attr][i] * info->v1[0][3];
 148    float a2 = info->v2[vert_attr][i] * info->v2[0][3];
 149    float da01 = a0 - a1;
 150    float da20 = a2 - a0;
 151    float dadx = (da01 * info->dy20 - info->dy01 * da20) * info->oneoverarea;
 152    float dady = (da20 * info->dx01 - info->dx20 * da01) * info->oneoverarea;
 153
 154    tri->inputs.dadx[slot][i] = dadx;
 155    tri->inputs.dady[slot][i] = dady;
 156    tri->inputs.a0[slot][i] = (a0 -
 157                               (dadx * (info->v0[0][0] - info->pixel_offset) +
 158                                dady * (info->v0[0][1] - info->pixel_offset)));
 159 }
 160
 161
 162 /**
 163  * Special coefficient setup for gl_FragCoord.
 164  * X and Y are trivial
 165  * Z and W are copied from position_coef which should have already been computed.
 166  * We could do a bit less work if we'd examine gl_FragCoord's swizzle mask.
 167  */
 168 static void
 169 setup_fragcoord_coef(struct lp_rast_triangle *tri,
 170                      const struct tri_info *info,
 171                      unsigned slot,
 172                      unsigned usage_mask)
 173 {
 174    /*X*/
 175    if (usage_mask & TGSI_WRITEMASK_X) {
 176       tri->inputs.a0[slot][0] = 0.0;
 177       tri->inputs.dadx[slot][0] = 1.0;
 178       tri->inputs.dady[slot][0] = 0.0;
 179    }
 180
 181    /*Y*/
 182    if (usage_mask & TGSI_WRITEMASK_Y) {
 183       tri->inputs.a0[slot][1] = 0.0;
 184       tri->inputs.dadx[slot][1] = 0.0;
 185       tri->inputs.dady[slot][1] = 1.0;
 186    }
 187
 188    /*Z*/
 189    if (usage_mask & TGSI_WRITEMASK_Z) {
 190       linear_coef(tri, info, slot, 0, 2);
 191    }
 192
 193    /*W*/
 194    if (usage_mask & TGSI_WRITEMASK_W) {
 195       linear_coef(tri, info, slot, 0, 3);
 196    }
 197 }
 198
 199
 200 /**
 201  * Setup the fragment input attribute with the front-facing value.
 202  * \param frontface  is the triangle front facing?
 203  */
 204 static void setup_facing_coef( struct lp_rast_triangle *tri,
 205                                unsigned slot,
 206                                boolean frontface,
 207                                unsigned usage_mask)
 208 {
 209    /* convert TRUE to 1.0 and FALSE to -1.0 */
 210    if (usage_mask & TGSI_WRITEMASK_X)
 211       constant_coef( tri, slot, 2.0f * frontface - 1.0f, 0 );
 212
 213    if (usage_mask & TGSI_WRITEMASK_Y)
 214       constant_coef( tri, slot, 0.0f, 1 ); /* wasted */
 215
 216    if (usage_mask & TGSI_WRITEMASK_Z)
 217       constant_coef( tri, slot, 0.0f, 2 ); /* wasted */
 218
 219    if (usage_mask & TGSI_WRITEMASK_W)
 220       constant_coef( tri, slot, 0.0f, 3 ); /* wasted */
 221 }
 222
 223
 224 /**
 225  * Compute the tri->coef[] array dadx, dady, a0 values.
 226  */
 227 static void setup_tri_coefficients( struct lp_setup_context *setup,
 228                                     struct lp_rast_triangle *tri,
 229                                     const struct tri_info *info)
 230 {
 231    unsigned fragcoord_usage_mask = TGSI_WRITEMASK_XYZ;
 232    unsigned slot;
 233    unsigned i;
 234
 235    /* setup interpolation for all the remaining attributes:
 236     */
 237    for (slot = 0; slot < setup->fs.nr_inputs; slot++) {
 238       unsigned vert_attr = setup->fs.input[slot].src_index;
 239       unsigned usage_mask = setup->fs.input[slot].usage_mask;
 240
 241       switch (setup->fs.input[slot].interp) {
 242       case LP_INTERP_CONSTANT:
 243          if (setup->flatshade_first) {
 244             for (i = 0; i < NUM_CHANNELS; i++)
 245                if (usage_mask & (1 << i))
 246                   constant_coef(tri, slot+1, info->v0[vert_attr][i], i);
 247          }
 248          else {
 249             for (i = 0; i < NUM_CHANNELS; i++)
 250                if (usage_mask & (1 << i))
 251                   constant_coef(tri, slot+1, info->v2[vert_attr][i], i);
 252          }
 253          break;
 254
 255       case LP_INTERP_LINEAR:
 256          for (i = 0; i < NUM_CHANNELS; i++)
 257             if (usage_mask & (1 << i))
 258                linear_coef(tri, info, slot+1, vert_attr, i);
 259          break;
 260
 261       case LP_INTERP_PERSPECTIVE:
 262          for (i = 0; i < NUM_CHANNELS; i++)
 263             if (usage_mask & (1 << i))
 264                perspective_coef(tri, info, slot+1, vert_attr, i);
 265          fragcoord_usage_mask |= TGSI_WRITEMASK_W;
 266          break;
 267
 268       case LP_INTERP_POSITION:
 269          /*
 270           * The generated pixel interpolators will pick up the coeffs from
 271           * slot 0, so all need to ensure that the usage mask is covers all
 272           * usages.
 273           */
 274          fragcoord_usage_mask |= usage_mask;
 275          break;
 276
 277       case LP_INTERP_FACING:
 278          setup_facing_coef(tri, slot+1, info->frontfacing, usage_mask);
 279          break;
 280
 281       default:
 282          assert(0);
 283       }
 284    }
 285
 286    /* The internal position input is in slot zero:
 287     */
 288    setup_fragcoord_coef(tri, info, 0, fragcoord_usage_mask);
 289
 290    if (0) {
 291       for (i = 0; i < NUM_CHANNELS; i++) {
 292          float a0   = tri->inputs.a0  [0][i];
 293          float dadx = tri->inputs.dadx[0][i];
 294          float dady = tri->inputs.dady[0][i];
 295
 296          debug_printf("POS.%c: a0 = %f, dadx = %f, dady = %f\n",
 297                       "xyzw"[i],
 298                       a0, dadx, dady);
 299       }
 300
 301       for (slot = 0; slot < setup->fs.nr_inputs; slot++) {
 302          unsigned usage_mask = setup->fs.input[slot].usage_mask;
 303          for (i = 0; i < NUM_CHANNELS; i++) {
 304             if (usage_mask & (1 << i)) {
 305                float a0   = tri->inputs.a0  [1 + slot][i];
 306                float dadx = tri->inputs.dadx[1 + slot][i];
 307                float dady = tri->inputs.dady[1 + slot][i];
 308
 309                debug_printf("IN[%u].%c: a0 = %f, dadx = %f, dady = %f\n",
 310                             slot,
 311                             "xyzw"[i],
 312                             a0, dadx, dady);
 313             }
 314          }
 315       }
 316    }
 317 }
 318
 319
 320
 321
 322
 323
 324 /**
 325  * Alloc space for a new triangle plus the input.a0/dadx/dady arrays
 326  * immediately after it.
 327  * The memory is allocated from the per-scene pool, not per-tile.
 328  * \param tri_size  returns number of bytes allocated
 329  * \param nr_inputs  number of fragment shader inputs
 330  * \return pointer to triangle space
 331  */
 332 static INLINE struct lp_rast_triangle *
 333 alloc_triangle(struct lp_scene *scene,
 334                unsigned nr_inputs,
 335                unsigned nr_planes,
 336                unsigned *tri_size)
 337 {
 338    unsigned input_array_sz = NUM_CHANNELS * (nr_inputs + 1) * sizeof(float);
 339    struct lp_rast_triangle *tri;
 340    unsigned tri_bytes, bytes;
 341    char *inputs;
 342
 343    tri_bytes = align(Offset(struct lp_rast_triangle, plane[nr_planes]), 16);
 344    bytes = tri_bytes + (3 * input_array_sz);
 345
 346    tri = lp_scene_alloc_aligned( scene, bytes, 16 );
 347
 348    if (tri) {
 349       inputs = ((char *)tri) + tri_bytes;
 350       tri->inputs.a0   = (float (*)[4]) inputs;
 351       tri->inputs.dadx = (float (*)[4]) (inputs + input_array_sz);
 352       tri->inputs.dady = (float (*)[4]) (inputs + 2 * input_array_sz);
 353
 354       *tri_size = bytes;
 355    }
 356
 357    return tri;
 358 }
 359
 360 void
 361 lp_setup_print_vertex(struct lp_setup_context *setup,
 362                       const char *name,
 363                       const float (*v)[4])
 364 {
 365    int i, j;
 366
 367    debug_printf("   wpos (%s[0]) xyzw %f %f %f %f\n",
 368                 name,
 369                 v[0][0], v[0][1], v[0][2], v[0][3]);
 370
 371    for (i = 0; i < setup->fs.nr_inputs; i++) {
 372       const float *in = v[setup->fs.input[i].src_index];
 373
 374       debug_printf("  in[%d] (%s[%d]) %s%s%s%s ",
 375                    i,
 376                    name, setup->fs.input[i].src_index,
 377                    (setup->fs.input[i].usage_mask & 0x1) ? "x" : " ",
 378                    (setup->fs.input[i].usage_mask & 0x2) ? "y" : " ",
 379                    (setup->fs.input[i].usage_mask & 0x4) ? "z" : " ",
 380                    (setup->fs.input[i].usage_mask & 0x8) ? "w" : " ");
 381
 382       for (j = 0; j < 4; j++)
 383          if (setup->fs.input[i].usage_mask & (1<<j))
 384             debug_printf("%.5f ", in[j]);
 385
 386       debug_printf("\n");
 387    }
 388 }
 389
 390
 391 /**
 392  * Print triangle vertex attribs (for debug).
 393  */
 394 void
 395 lp_setup_print_triangle(struct lp_setup_context *setup,
 396                         const float (*v0)[4],
 397                         const float (*v1)[4],
 398                         const float (*v2)[4])
 399 {
 400    debug_printf("triangle\n");
 401
 402    {
 403       const float ex = v0[0][0] - v2[0][0];
 404       const float ey = v0[0][1] - v2[0][1];
 405       const float fx = v1[0][0] - v2[0][0];
 406       const float fy = v1[0][1] - v2[0][1];
 407
 408       /* det = cross(e,f).z */
 409       const float det = ex * fy - ey * fx;
 410       if (det < 0.0f)
 411          debug_printf("   - ccw\n");
 412       else if (det > 0.0f)
 413          debug_printf("   - cw\n");
 414       else
 415          debug_printf("   - zero area\n");
 416    }
 417
 418    lp_setup_print_vertex(setup, "v0", v0);
 419    lp_setup_print_vertex(setup, "v1", v1);
 420    lp_setup_print_vertex(setup, "v2", v2);
 421 }
 422
 423
 424 lp_rast_cmd lp_rast_tri_tab[8] = {
 425    NULL,               /* should be impossible */
 426    lp_rast_triangle_1,
 427    lp_rast_triangle_2,
 428    lp_rast_triangle_3,
 429    lp_rast_triangle_4,
 430    lp_rast_triangle_5,
 431    lp_rast_triangle_6,
 432    lp_rast_triangle_7
 433 };
 434
 435 /**
 436  * Do basic setup for triangle rasterization and determine which
 437  * framebuffer tiles are touched.  Put the triangle in the scene's
 438  * bins for the tiles which we overlap.
 439  */
 440 static void
 441 do_triangle_ccw(struct lp_setup_context *setup,
 442                 const float (*v1)[4],
 443                 const float (*v2)[4],
 444                 const float (*v3)[4],
 445                 boolean frontfacing )
 446 {
 447
 448    struct lp_scene *scene = lp_setup_get_current_scene(setup);
 449    struct lp_fragment_shader_variant *variant = setup->fs.current.variant;
 450    struct lp_rast_triangle *tri;
 451    struct tri_info info;
 452    int area;
 453    int minx, maxx, miny, maxy;
 454    int ix0, ix1, iy0, iy1;
 455    unsigned tri_bytes;
 456    int i;
 457    int nr_planes = 3;
 458
 459    if (0)
 460       lp_setup_print_triangle(setup, v1, v2, v3);
 461
 462    if (setup->scissor_test) {
 463       nr_planes = 7;
 464    }
 465    else {
 466       nr_planes = 3;
 467    }
 468
 469
 470    tri = alloc_triangle(scene,
 471                         setup->fs.nr_inputs,
 472                         nr_planes,
 473                         &tri_bytes);
 474    if (!tri)
 475       return;
 476
 477 #ifdef DEBUG
 478    tri->v[0][0] = v1[0][0];
 479    tri->v[1][0] = v2[0][0];
 480    tri->v[2][0] = v3[0][0];
 481    tri->v[0][1] = v1[0][1];
 482    tri->v[1][1] = v2[0][1];
 483    tri->v[2][1] = v3[0][1];
 484 #endif
 485
 486    /* x/y positions in fixed point */
 487    info.x[0] = subpixel_snap(v1[0][0] - setup->pixel_offset);
 488    info.x[1] = subpixel_snap(v2[0][0] - setup->pixel_offset);
 489    info.x[2] = subpixel_snap(v3[0][0] - setup->pixel_offset);
 490    info.y[0] = subpixel_snap(v1[0][1] - setup->pixel_offset);
 491    info.y[1] = subpixel_snap(v2[0][1] - setup->pixel_offset);
 492    info.y[2] = subpixel_snap(v3[0][1] - setup->pixel_offset);
 493
 494    tri->plane[0].dcdy = info.x[0] - info.x[1];
 495    tri->plane[1].dcdy = info.x[1] - info.x[2];
 496    tri->plane[2].dcdy = info.x[2] - info.x[0];
 497
 498    tri->plane[0].dcdx = info.y[0] - info.y[1];
 499    tri->plane[1].dcdx = info.y[1] - info.y[2];
 500    tri->plane[2].dcdx = info.y[2] - info.y[0];
 501
 502    area = (tri->plane[0].dcdy * tri->plane[2].dcdx -
 503            tri->plane[2].dcdy * tri->plane[0].dcdx);
 504
 505    LP_COUNT(nr_tris);
 506
 507    /* Cull non-ccw and zero-sized triangles.
 508     *
 509     * XXX: subject to overflow??
 510     */
 511    if (area <= 0) {
 512       lp_scene_putback_data( scene, tri_bytes );
 513       LP_COUNT(nr_culled_tris);
 514       return;
 515    }
 516
 517    /* Bounding rectangle (in pixels) */
 518    {
 519       /* Yes this is necessary to accurately calculate bounding boxes
 520        * with the two fill-conventions we support.  GL (normally) ends
 521        * up needing a bottom-left fill convention, which requires
 522        * slightly different rounding.
 523        */
 524       int adj = (setup->pixel_offset != 0) ? 1 : 0;
 525
 526       minx = (MIN3(info.x[0], info.x[1], info.x[2]) + (FIXED_ONE-1)) >> FIXED_ORDER;
 527       maxx = (MAX3(info.x[0], info.x[1], info.x[2]) + (FIXED_ONE-1)) >> FIXED_ORDER;
 528       miny = (MIN3(info.y[0], info.y[1], info.y[2]) + (FIXED_ONE-1) + adj) >> FIXED_ORDER;
 529       maxy = (MAX3(info.y[0], info.y[1], info.y[2]) + (FIXED_ONE-1) + adj) >> FIXED_ORDER;
 530    }
 531
 532    if (setup->scissor_test) {
 533       minx = MAX2(minx, setup->scissor.current.minx);
 534       maxx = MIN2(maxx, setup->scissor.current.maxx);
 535       miny = MAX2(miny, setup->scissor.current.miny);
 536       maxy = MIN2(maxy, setup->scissor.current.maxy);
 537    }
 538    else {
 539       minx = MAX2(minx, 0);
 540       miny = MAX2(miny, 0);
 541       maxx = MIN2(maxx, scene->fb.width);
 542       maxy = MIN2(maxy, scene->fb.height);
 543    }
 544
 545
 546    if (miny >= maxy || minx >= maxx) {
 547       lp_scene_putback_data( scene, tri_bytes );
 548       LP_COUNT(nr_culled_tris);
 549       return;
 550    }
 551
 552    /*
 553     */
 554    info.pixel_offset = setup->pixel_offset;
 555    info.v0 = v1;
 556    info.v1 = v2;
 557    info.v2 = v3;
 558    info.dx01 = info.v0[0][0] - info.v1[0][0];
 559    info.dx20 = info.v2[0][0] - info.v0[0][0];
 560    info.dy01 = info.v0[0][1] - info.v1[0][1];
 561    info.dy20 = info.v2[0][1] - info.v0[0][1];
 562    info.oneoverarea = 1.0f / (info.dx01 * info.dy20 - info.dx20 * info.dy01);
 563    info.frontfacing = frontfacing;
 564
 565    /* Setup parameter interpolants:
 566     */
 567    setup_tri_coefficients( setup, tri, &info );
 568
 569    tri->inputs.facing = frontfacing ? 1.0F : -1.0F;
 570    tri->inputs.state = setup->fs.stored;
 571
 572
 573
 574    for (i = 0; i < 3; i++) {
 575       struct lp_rast_plane *plane = &tri->plane[i];
 576
 577       /* half-edge constants, will be interated over the whole render
 578        * target.
 579        */
 580       plane->c = plane->dcdx * info.x[i] - plane->dcdy * info.y[i];
 581
 582       /* correct for top-left vs. bottom-left fill convention.
 583        *
 584        * note that we're overloading gl_rasterization_rules to mean
 585        * both (0.5,0.5) pixel centers *and* bottom-left filling
 586        * convention.
 587        *
 588        * GL actually has a top-left filling convention, but GL's
 589        * notion of "top" differs from gallium's...
 590        *
 591        * Also, sometimes (in FBO cases) GL will render upside down
 592        * to its usual method, in which case it will probably want
 593        * to use the opposite, top-left convention.
 594        */
 595       if (plane->dcdx < 0) {
 596          /* both fill conventions want this - adjust for left edges */
 597          plane->c++;
 598       }
 599       else if (plane->dcdx == 0) {
 600          if (setup->pixel_offset == 0) {
 601             /* correct for top-left fill convention:
 602              */
 603             if (plane->dcdy > 0) plane->c++;
 604          }
 605          else {
 606             /* correct for bottom-left fill convention:
 607              */
 608             if (plane->dcdy < 0) plane->c++;
 609          }
 610       }
 611
 612       plane->dcdx *= FIXED_ONE;
 613       plane->dcdy *= FIXED_ONE;
 614
 615       /* find trivial reject offsets for each edge for a single-pixel
 616        * sized block.  These will be scaled up at each recursive level to
 617        * match the active blocksize.  Scaling in this way works best if
 618        * the blocks are square.
 619        */
 620       plane->eo = 0;
 621       if (plane->dcdx < 0) plane->eo -= plane->dcdx;
 622       if (plane->dcdy > 0) plane->eo += plane->dcdy;
 623
 624       /* Calculate trivial accept offsets from the above.
 625        */
 626       plane->ei = plane->dcdy - plane->dcdx - plane->eo;
 627    }
 628
 629
 630    /*
 631     * When rasterizing scissored tris, use the intersection of the
 632     * triangle bounding box and the scissor rect to generate the
 633     * scissor planes.
 634     *
 635     * This permits us to cut off the triangle "tails" that are present
 636     * in the intermediate recursive levels caused when two of the
 637     * triangles edges don't diverge quickly enough to trivially reject
 638     * exterior blocks from the triangle.
 639     *
 640     * It's not really clear if it's worth worrying about these tails,
 641     * but since we generate the planes for each scissored tri, it's
 642     * free to trim them in this case.
 643     *
 644     * Note that otherwise, the scissor planes only vary in 'C' value,
 645     * and even then only on state-changes.  Could alternatively store
 646     * these planes elsewhere.
 647     */
 648    if (nr_planes == 7) {
 649       tri->plane[3].dcdx = -1;
 650       tri->plane[3].dcdy = 0;
 651       tri->plane[3].c = 1-minx;
 652       tri->plane[3].ei = 0;
 653       tri->plane[3].eo = 1;
 654
 655       tri->plane[4].dcdx = 1;
 656       tri->plane[4].dcdy = 0;
 657       tri->plane[4].c = maxx;
 658       tri->plane[4].ei = -1;
 659       tri->plane[4].eo = 0;
 660
 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].dcdx = 0;
 668       tri->plane[6].dcdy = -1;
 669       tri->plane[6].c = maxy;
 670       tri->plane[6].ei = -1;
 671       tri->plane[6].eo = 0;
 672    }
 673
 674
 675    /*
 676     * All fields of 'tri' are now set.  The remaining code here is
 677     * concerned with binning.
 678     */
 679
 680    /* Convert to tile coordinates, and inclusive ranges:
 681     */
 682    if (nr_planes == 3) {
 683       int ix0 = minx / 16;
 684       int iy0 = miny / 16;
 685       int ix1 = (maxx-1) / 16;
 686       int iy1 = (maxy-1) / 16;
 687
 688       if (iy0 == iy1 && ix0 == ix1)
 689       {
 690
 691          /* Triangle is contained in a single 16x16 block:
 692           */
 693          int mask = (ix0 & 3) | ((iy0 & 3) << 4);
 694
 695          lp_scene_bin_command( scene, ix0/4, iy0/4,
 696                                lp_rast_triangle_3_16,
 697                                lp_rast_arg_triangle(tri, mask) );
 698          return;
 699       }
 700    }
 701
 702    ix0 = minx / TILE_SIZE;
 703    iy0 = miny / TILE_SIZE;
 704    ix1 = (maxx-1) / TILE_SIZE;
 705    iy1 = (maxy-1) / TILE_SIZE;
 706
 707    /*
 708     * Clamp to framebuffer size
 709     */
 710    assert(ix0 == MAX2(ix0, 0));
 711    assert(iy0 == MAX2(iy0, 0));
 712    assert(ix1 == MIN2(ix1, scene->tiles_x - 1));
 713    assert(iy1 == MIN2(iy1, scene->tiles_y - 1));
 714
 715    /* Determine which tile(s) intersect the triangle's bounding box
 716     */
 717    if (iy0 == iy1 && ix0 == ix1)
 718    {
 719       /* Triangle is contained in a single tile:
 720        */
 721       lp_scene_bin_command( scene, ix0, iy0,
 722                             lp_rast_tri_tab[nr_planes],
 723                             lp_rast_arg_triangle(tri, (1<<nr_planes)-1) );
 724    }
 725    else
 726    {
 727       int c[7];
 728       int ei[7];
 729       int eo[7];
 730       int xstep[7];
 731       int ystep[7];
 732       int x, y;
 733
 734       for (i = 0; i < nr_planes; i++) {
 735          c[i] = (tri->plane[i].c +
 736                  tri->plane[i].dcdy * iy0 * TILE_SIZE -
 737                  tri->plane[i].dcdx * ix0 * TILE_SIZE);
 738
 739          ei[i] = tri->plane[i].ei << TILE_ORDER;
 740          eo[i] = tri->plane[i].eo << TILE_ORDER;
 741          xstep[i] = -(tri->plane[i].dcdx << TILE_ORDER);
 742          ystep[i] = tri->plane[i].dcdy << TILE_ORDER;
 743       }
 744
 745
 746
 747       /* Test tile-sized blocks against the triangle.
 748        * Discard blocks fully outside the tri.  If the block is fully
 749        * contained inside the tri, bin an lp_rast_shade_tile command.
 750        * Else, bin a lp_rast_triangle command.
 751        */
 752       for (y = iy0; y <= iy1; y++)
 753       {
 754          boolean in = FALSE;  /* are we inside the triangle? */
 755          int cx[7];
 756
 757          for (i = 0; i < nr_planes; i++)
 758             cx[i] = c[i];
 759
 760          for (x = ix0; x <= ix1; x++)
 761          {
 762             int out = 0;
 763             int partial = 0;
 764
 765             for (i = 0; i < nr_planes; i++) {
 766                int planeout = cx[i] + eo[i];
 767                int planepartial = cx[i] + ei[i] - 1;
 768                out |= (planeout >> 31);
 769                partial |= (planepartial >> 31) & (1<<i);
 770             }
 771
 772             if (out) {
 773                /* do nothing */
 774                if (in)
 775                   break;  /* exiting triangle, all done with this row */
 776                LP_COUNT(nr_empty_64);
 777             }
 778             else if (partial) {
 779                /* Not trivially accepted by at least one plane -
 780                 * rasterize/shade partial tile
 781                 */
 782                int count = util_bitcount(partial);
 783                in = TRUE;
 784                lp_scene_bin_command( scene, x, y,
 785                                      lp_rast_tri_tab[count],
 786                                      lp_rast_arg_triangle(tri, partial) );
 787
 788                LP_COUNT(nr_partially_covered_64);
 789             }
 790             else {
 791                /* triangle covers the whole tile- shade whole tile */
 792                LP_COUNT(nr_fully_covered_64);
 793                in = TRUE;
 794                if (variant->opaque &&
 795                    !setup->fb.zsbuf) {
 796                   lp_scene_bin_reset( scene, x, y );
 797                }
 798                lp_scene_bin_command( scene, x, y,
 799                                      lp_rast_shade_tile,
 800                                      lp_rast_arg_inputs(&tri->inputs) );
 801             }
 802
 803             /* Iterate cx values across the region:
 804              */
 805             for (i = 0; i < nr_planes; i++)
 806                cx[i] += xstep[i];
 807          }
 808
 809          /* Iterate c values down the region:
 810           */
 811          for (i = 0; i < nr_planes; i++)
 812             c[i] += ystep[i];
 813       }
 814    }
 815 }
 816
 817
 818 /**
 819  * Draw triangle if it's CW, cull otherwise.
 820  */
 821 static void triangle_cw( struct lp_setup_context *setup,
 822                          const float (*v0)[4],
 823                          const float (*v1)[4],
 824                          const float (*v2)[4] )
 825 {
 826    do_triangle_ccw( setup, v1, v0, v2, !setup->ccw_is_frontface );
 827 }
 828
 829
 830 /**
 831  * Draw triangle if it's CCW, cull otherwise.
 832  */
 833 static void triangle_ccw( struct lp_setup_context *setup,
 834                          const float (*v0)[4],
 835                          const float (*v1)[4],
 836                          const float (*v2)[4] )
 837 {
 838    do_triangle_ccw( setup, v0, v1, v2, setup->ccw_is_frontface );
 839 }
 840
 841
 842
 843 /**
 844  * Draw triangle whether it's CW or CCW.
 845  */
 846 static void triangle_both( struct lp_setup_context *setup,
 847                            const float (*v0)[4],
 848                            const float (*v1)[4],
 849                            const float (*v2)[4] )
 850 {
 851    /* edge vectors e = v0 - v2, f = v1 - v2 */
 852    const float ex = v0[0][0] - v2[0][0];
 853    const float ey = v0[0][1] - v2[0][1];
 854    const float fx = v1[0][0] - v2[0][0];
 855    const float fy = v1[0][1] - v2[0][1];
 856
 857    /* det = cross(e,f).z */
 858    const float det = ex * fy - ey * fx;
 859    if (det < 0.0f)
 860       triangle_ccw( setup, v0, v1, v2 );
 861    else if (det > 0.0f)
 862       triangle_cw( setup, v0, v1, v2 );
 863 }
 864
 865
 866 static void triangle_nop( struct lp_setup_context *setup,
 867                           const float (*v0)[4],
 868                           const float (*v1)[4],
 869                           const float (*v2)[4] )
 870 {
 871 }
 872
 873
 874 void
 875 lp_setup_choose_triangle( struct lp_setup_context *setup )
 876 {
 877    switch (setup->cullmode) {
 878    case PIPE_FACE_NONE:
 879       setup->triangle = triangle_both;
 880       break;
 881    case PIPE_FACE_BACK:
 882       setup->triangle = setup->ccw_is_frontface ? triangle_ccw : triangle_cw;
 883       break;
 884    case PIPE_FACE_FRONT:
 885       setup->triangle = setup->ccw_is_frontface ? triangle_cw : triangle_ccw;
 886       break;
 887    default:
 888       setup->triangle = triangle_nop;
 889       break;
 890    }
 891 }