src/gallium/auxiliary/draw/draw_pipe_clip.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,
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  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  * \brief  Clipping stage
  30  *
  31  * \author  Keith Whitwell <keith@tungstengraphics.com>
  32  */
  33
  34
  35 #include "pipe/p_util.h"
  36 #include "pipe/p_shader_tokens.h"
  37
  38 #include "draw_vs.h"
  39 #include "draw_pipe.h"
  40
  41
  42 #ifndef IS_NEGATIVE
  43 #define IS_NEGATIVE(X) ((X) < 0.0)
  44 #endif
  45
  46 #ifndef DIFFERENT_SIGNS
  47 #define DIFFERENT_SIGNS(x, y) ((x) * (y) <= 0.0F && (x) - (y) != 0.0F)
  48 #endif
  49
  50 #ifndef MAX_CLIPPED_VERTICES
  51 #define MAX_CLIPPED_VERTICES ((2 * (6 + PIPE_MAX_CLIP_PLANES))+1)
  52 #endif
  53
  54
  55
  56 struct clipper {
  57    struct draw_stage stage;      /**< base class */
  58
  59    /* Basically duplicate some of the flatshading logic here:
  60     */
  61    boolean flat;
  62    uint num_color_attribs;
  63    uint color_attribs[4];  /* front/back primary/secondary colors */
  64
  65    float (*plane)[4];
  66 };
  67
  68
  69 /* This is a bit confusing:
  70  */
  71 static INLINE struct clipper *clipper_stage( struct draw_stage *stage )
  72 {
  73    return (struct clipper *)stage;
  74 }
  75
  76
  77 #define LINTERP(T, OUT, IN) ((OUT) + (T) * ((IN) - (OUT)))
  78
  79
  80 /* All attributes are float[4], so this is easy:
  81  */
  82 static void interp_attr( float *fdst,
  83                          float t,
  84                          const float *fin,
  85                          const float *fout )
  86 {
  87    fdst[0] = LINTERP( t, fout[0], fin[0] );
  88    fdst[1] = LINTERP( t, fout[1], fin[1] );
  89    fdst[2] = LINTERP( t, fout[2], fin[2] );
  90    fdst[3] = LINTERP( t, fout[3], fin[3] );
  91 }
  92
  93 static void copy_colors( struct draw_stage *stage,
  94                          struct vertex_header *dst,
  95                          const struct vertex_header *src )
  96 {
  97    const struct clipper *clipper = clipper_stage(stage);
  98    uint i;
  99    for (i = 0; i < clipper->num_color_attribs; i++) {
 100       const uint attr = clipper->color_attribs[i];
 101       COPY_4FV(dst->data[attr], src->data[attr]);
 102    }
 103 }
 104
 105
 106
 107 /* Interpolate between two vertices to produce a third.
 108  */
 109 static void interp( const struct clipper *clip,
 110                     struct vertex_header *dst,
 111                     float t,
 112                     const struct vertex_header *out,
 113                     const struct vertex_header *in )
 114 {
 115    const unsigned nr_attrs = clip->stage.draw->num_vs_outputs;
 116    unsigned j;
 117
 118    /* Vertex header.
 119     */
 120    {
 121       dst->clipmask = 0;
 122       dst->edgeflag = 0;        /* will get overwritten later */
 123       dst->pad = 0;
 124       dst->vertex_id = UNDEFINED_VERTEX_ID;
 125    }
 126
 127    /* Clip coordinates:  interpolate normally
 128     */
 129    {
 130       interp_attr(dst->clip, t, in->clip, out->clip);
 131    }
 132
 133    /* Do the projective divide and insert window coordinates:
 134     */
 135    {
 136       const float *pos = dst->clip;
 137       const float *scale = clip->stage.draw->viewport.scale;
 138       const float *trans = clip->stage.draw->viewport.translate;
 139       const float oow = 1.0f / pos[3];
 140
 141       dst->data[0][0] = pos[0] * oow * scale[0] + trans[0];
 142       dst->data[0][1] = pos[1] * oow * scale[1] + trans[1];
 143       dst->data[0][2] = pos[2] * oow * scale[2] + trans[2];
 144       dst->data[0][3] = oow;
 145    }
 146
 147    /* Other attributes
 148     * Note: start at 1 to skip winpos (data[0]) since we just computed
 149     * it above.
 150     */
 151    for (j = 1; j < nr_attrs; j++) {
 152       interp_attr(dst->data[j], t, in->data[j], out->data[j]);
 153    }
 154 }
 155
 156
 157 static void emit_poly( struct draw_stage *stage,
 158                        struct vertex_header **inlist,
 159                        unsigned n,
 160                        const struct prim_header *origPrim)
 161 {
 162    struct prim_header header;
 163    unsigned i;
 164
 165    const ushort edge_first  = DRAW_PIPE_EDGE_FLAG_2;
 166    const ushort edge_middle = DRAW_PIPE_EDGE_FLAG_0;
 167    const ushort edge_last   = DRAW_PIPE_EDGE_FLAG_1;
 168
 169    /* later stages may need the determinant, but only the sign matters */
 170    header.det = origPrim->det;
 171    header.flags = DRAW_PIPE_RESET_STIPPLE | edge_first | edge_middle;
 172    header.pad = 0;
 173
 174    for (i = 2; i < n; i++, header.flags = 0) {
 175       header.v[0] = inlist[i-1];
 176       header.v[1] = inlist[i];
 177       header.v[2] = inlist[0];  /* keep in v[2] for flatshading */
 178
 179       if (i == n-1)
 180         header.flags |= edge_last;
 181
 182       if (0) {
 183          const struct draw_vertex_shader *vs = stage->draw->vertex_shader;
 184          uint j, k;
 185          debug_printf("Clipped tri:\n");
 186          for (j = 0; j < 3; j++) {
 187             for (k = 0; k < vs->info.num_outputs; k++) {
 188                debug_printf("  Vert %d: Attr %d:  %f %f %f %f\n", j, k,
 189                             header.v[j]->data[k][0],
 190                             header.v[j]->data[k][1],
 191                             header.v[j]->data[k][2],
 192                             header.v[j]->data[k][3]);
 193             }
 194          }
 195       }
 196
 197       stage->next->tri( stage->next, &header );
 198    }
 199 }
 200
 201 static INLINE float
 202 dot4(const float *a, const float *b)
 203 {
 204    return (a[0]*b[0] +
 205            a[1]*b[1] +
 206            a[2]*b[2] +
 207            a[3]*b[3]);
 208 }
 209
 210
 211 /* Clip a triangle against the viewport and user clip planes.
 212  */
 213 static void
 214 do_clip_tri( struct draw_stage *stage,
 215              struct prim_header *header,
 216              unsigned clipmask )
 217 {
 218    struct clipper *clipper = clipper_stage( stage );
 219    struct vertex_header *a[MAX_CLIPPED_VERTICES];
 220    struct vertex_header *b[MAX_CLIPPED_VERTICES];
 221    struct vertex_header **inlist = a;
 222    struct vertex_header **outlist = b;
 223    unsigned tmpnr = 0;
 224    unsigned n = 3;
 225    unsigned i;
 226
 227    inlist[0] = header->v[0];
 228    inlist[1] = header->v[1];
 229    inlist[2] = header->v[2];
 230
 231    while (clipmask && n >= 3) {
 232       const unsigned plane_idx = ffs(clipmask)-1;
 233       const float *plane = clipper->plane[plane_idx];
 234       struct vertex_header *vert_prev = inlist[0];
 235       float dp_prev = dot4( vert_prev->clip, plane );
 236       unsigned outcount = 0;
 237
 238       clipmask &= ~(1<<plane_idx);
 239
 240       inlist[n] = inlist[0]; /* prevent rotation of vertices */
 241
 242       for (i = 1; i <= n; i++) {
 243          struct vertex_header *vert = inlist[i];
 244
 245          float dp = dot4( vert->clip, plane );
 246
 247          if (!IS_NEGATIVE(dp_prev)) {
 248             outlist[outcount++] = vert_prev;
 249          }
 250
 251          if (DIFFERENT_SIGNS(dp, dp_prev)) {
 252             struct vertex_header *new_vert = clipper->stage.tmp[tmpnr++];
 253             outlist[outcount++] = new_vert;
 254
 255             if (IS_NEGATIVE(dp)) {
 256                /* Going out of bounds.  Avoid division by zero as we
 257                 * know dp != dp_prev from DIFFERENT_SIGNS, above.
 258                 */
 259                float t = dp / (dp - dp_prev);
 260                interp( clipper, new_vert, t, vert, vert_prev );
 261
 262                /* Force edgeflag true in this case:
 263                 */
 264                new_vert->edgeflag = 1;
 265             } else {
 266                /* Coming back in.
 267                 */
 268                float t = dp_prev / (dp_prev - dp);
 269                interp( clipper, new_vert, t, vert_prev, vert );
 270
 271                /* Copy starting vert's edgeflag:
 272                 */
 273                new_vert->edgeflag = vert_prev->edgeflag;
 274             }
 275          }
 276
 277          vert_prev = vert;
 278          dp_prev = dp;
 279       }
 280
 281       {
 282          struct vertex_header **tmp = inlist;
 283          inlist = outlist;
 284          outlist = tmp;
 285          n = outcount;
 286       }
 287    }
 288
 289    /* If flat-shading, copy color to new provoking vertex.
 290     */
 291    if (clipper->flat && inlist[0] != header->v[2]) {
 292       if (1) {
 293          inlist[0] = dup_vert(stage, inlist[0], tmpnr++);
 294       }
 295
 296       copy_colors(stage, inlist[0], header->v[2]);
 297    }
 298
 299
 300
 301    /* Emit the polygon as triangles to the setup stage:
 302     */
 303    if (n >= 3)
 304       emit_poly( stage, inlist, n, header );
 305 }
 306
 307
 308 /* Clip a line against the viewport and user clip planes.
 309  */
 310 static void
 311 do_clip_line( struct draw_stage *stage,
 312               struct prim_header *header,
 313               unsigned clipmask )
 314 {
 315    const struct clipper *clipper = clipper_stage( stage );
 316    struct vertex_header *v0 = header->v[0];
 317    struct vertex_header *v1 = header->v[1];
 318    const float *pos0 = v0->clip;
 319    const float *pos1 = v1->clip;
 320    float t0 = 0.0F;
 321    float t1 = 0.0F;
 322    struct prim_header newprim;
 323
 324    while (clipmask) {
 325       const unsigned plane_idx = ffs(clipmask)-1;
 326       const float *plane = clipper->plane[plane_idx];
 327       const float dp0 = dot4( pos0, plane );
 328       const float dp1 = dot4( pos1, plane );
 329
 330       if (dp1 < 0.0F) {
 331          float t = dp1 / (dp1 - dp0);
 332          t1 = MAX2(t1, t);
 333       }
 334
 335       if (dp0 < 0.0F) {
 336          float t = dp0 / (dp0 - dp1);
 337          t0 = MAX2(t0, t);
 338       }
 339
 340       if (t0 + t1 >= 1.0F)
 341          return; /* discard */
 342
 343       clipmask &= ~(1 << plane_idx);  /* turn off this plane's bit */
 344    }
 345
 346    if (v0->clipmask) {
 347       interp( clipper, stage->tmp[0], t0, v0, v1 );
 348
 349       if (clipper->flat)
 350          copy_colors(stage, stage->tmp[0], v0);
 351
 352       newprim.v[0] = stage->tmp[0];
 353    }
 354    else {
 355       newprim.v[0] = v0;
 356    }
 357
 358    if (v1->clipmask) {
 359       interp( clipper, stage->tmp[1], t1, v1, v0 );
 360       newprim.v[1] = stage->tmp[1];
 361    }
 362    else {
 363       newprim.v[1] = v1;
 364    }
 365
 366    stage->next->line( stage->next, &newprim );
 367 }
 368
 369
 370 static void
 371 clip_point( struct draw_stage *stage,
 372             struct prim_header *header )
 373 {
 374    if (header->v[0]->clipmask == 0)
 375       stage->next->point( stage->next, header );
 376 }
 377
 378
 379 static void
 380 clip_line( struct draw_stage *stage,
 381            struct prim_header *header )
 382 {
 383    unsigned clipmask = (header->v[0]->clipmask |
 384                         header->v[1]->clipmask);
 385
 386    if (clipmask == 0) {
 387       /* no clipping needed */
 388       stage->next->line( stage->next, header );
 389    }
 390    else if ((header->v[0]->clipmask &
 391              header->v[1]->clipmask) == 0) {
 392       do_clip_line(stage, header, clipmask);
 393    }
 394    /* else, totally clipped */
 395 }
 396
 397
 398 static void
 399 clip_tri( struct draw_stage *stage,
 400           struct prim_header *header )
 401 {
 402    unsigned clipmask = (header->v[0]->clipmask |
 403                         header->v[1]->clipmask |
 404                         header->v[2]->clipmask);
 405
 406    if (clipmask == 0) {
 407       /* no clipping needed */
 408       stage->next->tri( stage->next, header );
 409    }
 410    else if ((header->v[0]->clipmask &
 411              header->v[1]->clipmask &
 412              header->v[2]->clipmask) == 0) {
 413       do_clip_tri(stage, header, clipmask);
 414    }
 415 }
 416
 417 /* Update state.  Could further delay this until we hit the first
 418  * primitive that really requires clipping.
 419  */
 420 static void
 421 clip_init_state( struct draw_stage *stage )
 422 {
 423    struct clipper *clipper = clipper_stage( stage );
 424
 425    clipper->flat = stage->draw->rasterizer->flatshade ? TRUE : FALSE;
 426
 427    if (clipper->flat) {
 428       const struct draw_vertex_shader *vs = stage->draw->vertex_shader;
 429       uint i;
 430
 431       clipper->num_color_attribs = 0;
 432       for (i = 0; i < vs->info.num_outputs; i++) {
 433          if (vs->info.output_semantic_name[i] == TGSI_SEMANTIC_COLOR ||
 434              vs->info.output_semantic_name[i] == TGSI_SEMANTIC_BCOLOR) {
 435             clipper->color_attribs[clipper->num_color_attribs++] = i;
 436          }
 437       }
 438    }
 439
 440    stage->tri = clip_tri;
 441    stage->line = clip_line;
 442 }
 443
 444
 445
 446 static void clip_first_tri( struct draw_stage *stage,
 447                             struct prim_header *header )
 448 {
 449    clip_init_state( stage );
 450    stage->tri( stage, header );
 451 }
 452
 453 static void clip_first_line( struct draw_stage *stage,
 454                              struct prim_header *header )
 455 {
 456    clip_init_state( stage );
 457    stage->line( stage, header );
 458 }
 459
 460
 461 static void clip_flush( struct draw_stage *stage,
 462                              unsigned flags )
 463 {
 464    stage->tri = clip_first_tri;
 465    stage->line = clip_first_line;
 466    stage->next->flush( stage->next, flags );
 467 }
 468
 469
 470 static void clip_reset_stipple_counter( struct draw_stage *stage )
 471 {
 472    stage->next->reset_stipple_counter( stage->next );
 473 }
 474
 475
 476 static void clip_destroy( struct draw_stage *stage )
 477 {
 478    draw_free_temp_verts( stage );
 479    FREE( stage );
 480 }
 481
 482
 483 /**
 484  * Allocate a new clipper stage.
 485  * \return pointer to new stage object
 486  */
 487 struct draw_stage *draw_clip_stage( struct draw_context *draw )
 488 {
 489    struct clipper *clipper = CALLOC_STRUCT(clipper);
 490    if (clipper == NULL)
 491       goto fail;
 492
 493    if (!draw_alloc_temp_verts( &clipper->stage, MAX_CLIPPED_VERTICES+1 ))
 494       goto fail;
 495
 496    clipper->stage.draw = draw;
 497    clipper->stage.point = clip_point;
 498    clipper->stage.line = clip_first_line;
 499    clipper->stage.tri = clip_first_tri;
 500    clipper->stage.flush = clip_flush;
 501    clipper->stage.reset_stipple_counter = clip_reset_stipple_counter;
 502    clipper->stage.destroy = clip_destroy;
 503
 504    clipper->plane = draw->plane;
 505
 506    return &clipper->stage;
 507
 508  fail:
 509    if (clipper)
 510       clipper->stage.destroy( &clipper->stage );
 511
 512    return NULL;
 513 }