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,
  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  * \brief  Clipping stage
  30  *
  31  * \author  Keith Whitwell <keith@tungstengraphics.com>
  32  */
  33
  34
  35 #include "util/u_memory.h"
  36 #include "util/u_math.h"
  37
  38 #include "pipe/p_shader_tokens.h"
  39
  40 #include "draw_vs.h"
  41 #include "draw_pipe.h"
  42
  43
  44 #ifndef IS_NEGATIVE
  45 #define IS_NEGATIVE(X) ((X) < 0.0)
  46 #endif
  47
  48 #ifndef DIFFERENT_SIGNS
  49 #define DIFFERENT_SIGNS(x, y) ((x) * (y) <= 0.0F && (x) - (y) != 0.0F)
  50 #endif
  51
  52 #ifndef MAX_CLIPPED_VERTICES
  53 #define MAX_CLIPPED_VERTICES ((2 * (6 + PIPE_MAX_CLIP_PLANES))+1)
  54 #endif
  55
  56
  57
  58 struct clip_stage {
  59    struct draw_stage stage;      /**< base class */
  60
  61    /* Basically duplicate some of the flatshading logic here:
  62     */
  63    boolean flat;
  64    uint num_color_attribs;
  65    uint color_attribs[4];  /* front/back primary/secondary colors */
  66
  67    float (*plane)[4];
  68 };
  69
  70
  71 /* This is a bit confusing:
  72  */
  73 static INLINE struct clip_stage *clip_stage( struct draw_stage *stage )
  74 {
  75    return (struct clip_stage *)stage;
  76 }
  77
  78
  79 #define LINTERP(T, OUT, IN) ((OUT) + (T) * ((IN) - (OUT)))
  80
  81
  82 /* All attributes are float[4], so this is easy:
  83  */
  84 static void interp_attr( float *fdst,
  85                          float t,
  86                          const float *fin,
  87                          const float *fout )
  88 {
  89    fdst[0] = LINTERP( t, fout[0], fin[0] );
  90    fdst[1] = LINTERP( t, fout[1], fin[1] );
  91    fdst[2] = LINTERP( t, fout[2], fin[2] );
  92    fdst[3] = LINTERP( t, fout[3], fin[3] );
  93 }
  94
  95
  96 static void copy_colors( struct draw_stage *stage,
  97                          struct vertex_header *dst,
  98                          const struct vertex_header *src )
  99 {
 100    const struct clip_stage *clipper = clip_stage(stage);
 101    uint i;
 102    for (i = 0; i < clipper->num_color_attribs; i++) {
 103       const uint attr = clipper->color_attribs[i];
 104       COPY_4FV(dst->data[attr], src->data[attr]);
 105    }
 106 }
 107
 108
 109
 110 /* Interpolate between two vertices to produce a third.
 111  */
 112 static void interp( const struct clip_stage *clip,
 113                     struct vertex_header *dst,
 114                     float t,
 115                     const struct vertex_header *out,
 116                     const struct vertex_header *in )
 117 {
 118    const unsigned nr_attrs = draw_current_shader_outputs(clip->stage.draw);
 119    const unsigned pos_attr = draw_current_shader_position_output(clip->stage.draw);
 120    unsigned j;
 121
 122    /* Vertex header.
 123     */
 124    {
 125       dst->clipmask = 0;
 126       dst->edgeflag = 0;        /* will get overwritten later */
 127       dst->pad = 0;
 128       dst->vertex_id = UNDEFINED_VERTEX_ID;
 129    }
 130
 131    /* Clip coordinates:  interpolate normally
 132     */
 133    {
 134       interp_attr(dst->clip, t, in->clip, out->clip);
 135    }
 136
 137    /* Do the projective divide and insert window coordinates:
 138     */
 139    {
 140       const float *pos = dst->clip;
 141       const float *scale = clip->stage.draw->viewport.scale;
 142       const float *trans = clip->stage.draw->viewport.translate;
 143       const float oow = 1.0f / pos[3];
 144
 145       dst->data[pos_attr][0] = pos[0] * oow * scale[0] + trans[0];
 146       dst->data[pos_attr][1] = pos[1] * oow * scale[1] + trans[1];
 147       dst->data[pos_attr][2] = pos[2] * oow * scale[2] + trans[2];
 148       dst->data[pos_attr][3] = oow;
 149    }
 150
 151    /* Other attributes
 152     */
 153    for (j = 0; j < nr_attrs; j++) {
 154       if (j != pos_attr)
 155          interp_attr(dst->data[j], t, in->data[j], out->data[j]);
 156    }
 157 }
 158
 159
 160 static void emit_poly( struct draw_stage *stage,
 161                        struct vertex_header **inlist,
 162                        unsigned n,
 163                        const struct prim_header *origPrim)
 164 {
 165    struct prim_header header;
 166    unsigned i;
 167    ushort edge_first, edge_middle, edge_last;
 168
 169    if (stage->draw->rasterizer->flatshade_first) {
 170       edge_first  = DRAW_PIPE_EDGE_FLAG_0;
 171       edge_middle = DRAW_PIPE_EDGE_FLAG_1;
 172       edge_last   = DRAW_PIPE_EDGE_FLAG_2;
 173    }
 174    else {
 175       edge_first  = DRAW_PIPE_EDGE_FLAG_2;
 176       edge_middle = DRAW_PIPE_EDGE_FLAG_0;
 177       edge_last   = DRAW_PIPE_EDGE_FLAG_1;
 178    }
 179
 180    /* later stages may need the determinant, but only the sign matters */
 181    header.det = origPrim->det;
 182    header.flags = DRAW_PIPE_RESET_STIPPLE | edge_first | edge_middle;
 183    header.pad = 0;
 184
 185    for (i = 2; i < n; i++, header.flags = edge_middle) {
 186       /* keep in provoking vertex for flatshading */
 187       if (stage->draw->rasterizer->flatshade_first) {
 188          header.v[0] = inlist[0];
 189          header.v[1] = inlist[i-1];
 190          header.v[2] = inlist[i];
 191       }
 192       else {
 193          header.v[0] = inlist[i-1];
 194          header.v[1] = inlist[i];
 195          header.v[2] = inlist[0];
 196       }
 197
 198       if (i == n-1)
 199          header.flags |= edge_last;
 200
 201       if (0) {
 202          const struct draw_vertex_shader *vs = stage->draw->vs.vertex_shader;
 203          uint j, k;
 204          debug_printf("Clipped tri:\n");
 205          for (j = 0; j < 3; j++) {
 206             for (k = 0; k < vs->info.num_outputs; k++) {
 207                debug_printf("  Vert %d: Attr %d:  %f %f %f %f\n", j, k,
 208                             header.v[j]->data[k][0],
 209                             header.v[j]->data[k][1],
 210                             header.v[j]->data[k][2],
 211                             header.v[j]->data[k][3]);
 212             }
 213          }
 214       }
 215
 216       stage->next->tri( stage->next, &header );
 217    }
 218 }
 219
 220
 221 static INLINE float
 222 dot4(const float *a, const float *b)
 223 {
 224    return (a[0] * b[0] +
 225            a[1] * b[1] +
 226            a[2] * b[2] +
 227            a[3] * b[3]);
 228 }
 229
 230
 231 /* Clip a triangle against the viewport and user clip planes.
 232  */
 233 static void
 234 do_clip_tri( struct draw_stage *stage,
 235              struct prim_header *header,
 236              unsigned clipmask )
 237 {
 238    struct clip_stage *clipper = clip_stage( stage );
 239    struct vertex_header *a[MAX_CLIPPED_VERTICES];
 240    struct vertex_header *b[MAX_CLIPPED_VERTICES];
 241    struct vertex_header **inlist = a;
 242    struct vertex_header **outlist = b;
 243    unsigned tmpnr = 0;
 244    unsigned n = 3;
 245    unsigned i;
 246
 247    inlist[0] = header->v[0];
 248    inlist[1] = header->v[1];
 249    inlist[2] = header->v[2];
 250
 251    while (clipmask && n >= 3) {
 252       const unsigned plane_idx = ffs(clipmask)-1;
 253       const float *plane = clipper->plane[plane_idx];
 254       struct vertex_header *vert_prev = inlist[0];
 255       float dp_prev = dot4( vert_prev->clip, plane );
 256       unsigned outcount = 0;
 257
 258       clipmask &= ~(1<<plane_idx);
 259
 260       inlist[n] = inlist[0]; /* prevent rotation of vertices */
 261
 262       for (i = 1; i <= n; i++) {
 263          struct vertex_header *vert = inlist[i];
 264
 265          float dp = dot4( vert->clip, plane );
 266
 267          if (!IS_NEGATIVE(dp_prev)) {
 268             outlist[outcount++] = vert_prev;
 269          }
 270
 271          if (DIFFERENT_SIGNS(dp, dp_prev)) {
 272             struct vertex_header *new_vert = clipper->stage.tmp[tmpnr++];
 273             outlist[outcount++] = new_vert;
 274
 275             if (IS_NEGATIVE(dp)) {
 276                /* Going out of bounds.  Avoid division by zero as we
 277                 * know dp != dp_prev from DIFFERENT_SIGNS, above.
 278                 */
 279                float t = dp / (dp - dp_prev);
 280                interp( clipper, new_vert, t, vert, vert_prev );
 281
 282                /* Force edgeflag true in this case:
 283                 */
 284                new_vert->edgeflag = 1;
 285             } else {
 286                /* Coming back in.
 287                 */
 288                float t = dp_prev / (dp_prev - dp);
 289                interp( clipper, new_vert, t, vert_prev, vert );
 290
 291                /* Copy starting vert's edgeflag:
 292                 */
 293                new_vert->edgeflag = vert_prev->edgeflag;
 294             }
 295          }
 296
 297          vert_prev = vert;
 298          dp_prev = dp;
 299       }
 300
 301       /* swap in/out lists */
 302       {
 303          struct vertex_header **tmp = inlist;
 304          inlist = outlist;
 305          outlist = tmp;
 306          n = outcount;
 307       }
 308    }
 309
 310    /* If flat-shading, copy color to new provoking vertex.
 311     */
 312    if (clipper->flat) {
 313       if (stage->draw->rasterizer->flatshade_first) {
 314          if (inlist[0] != header->v[0]) {
 315             inlist[0] = dup_vert(stage, inlist[0], tmpnr++);
 316             copy_colors(stage, inlist[0], header->v[0]);
 317          }
 318       }
 319       else {
 320          if (inlist[0] != header->v[2]) {
 321             inlist[0] = dup_vert(stage, inlist[0], tmpnr++);
 322             copy_colors(stage, inlist[0], header->v[2]);
 323          }
 324       }
 325    }
 326
 327    /* Emit the polygon as triangles to the setup stage:
 328     */
 329    if (n >= 3)
 330       emit_poly( stage, inlist, n, header );
 331 }
 332
 333
 334 /* Clip a line against the viewport and user clip planes.
 335  */
 336 static void
 337 do_clip_line( struct draw_stage *stage,
 338               struct prim_header *header,
 339               unsigned clipmask )
 340 {
 341    const struct clip_stage *clipper = clip_stage( stage );
 342    struct vertex_header *v0 = header->v[0];
 343    struct vertex_header *v1 = header->v[1];
 344    const float *pos0 = v0->clip;
 345    const float *pos1 = v1->clip;
 346    float t0 = 0.0F;
 347    float t1 = 0.0F;
 348    struct prim_header newprim;
 349
 350    while (clipmask) {
 351       const unsigned plane_idx = ffs(clipmask)-1;
 352       const float *plane = clipper->plane[plane_idx];
 353       const float dp0 = dot4( pos0, plane );
 354       const float dp1 = dot4( pos1, plane );
 355
 356       if (dp1 < 0.0F) {
 357          float t = dp1 / (dp1 - dp0);
 358          t1 = MAX2(t1, t);
 359       }
 360
 361       if (dp0 < 0.0F) {
 362          float t = dp0 / (dp0 - dp1);
 363          t0 = MAX2(t0, t);
 364       }
 365
 366       if (t0 + t1 >= 1.0F)
 367          return; /* discard */
 368
 369       clipmask &= ~(1 << plane_idx);  /* turn off this plane's bit */
 370    }
 371
 372    if (v0->clipmask) {
 373       interp( clipper, stage->tmp[0], t0, v0, v1 );
 374
 375       if (clipper->flat)
 376          copy_colors(stage, stage->tmp[0], v0);
 377
 378       newprim.v[0] = stage->tmp[0];
 379    }
 380    else {
 381       newprim.v[0] = v0;
 382    }
 383
 384    if (v1->clipmask) {
 385       interp( clipper, stage->tmp[1], t1, v1, v0 );
 386       newprim.v[1] = stage->tmp[1];
 387    }
 388    else {
 389       newprim.v[1] = v1;
 390    }
 391
 392    stage->next->line( stage->next, &newprim );
 393 }
 394
 395
 396 static void
 397 clip_point( struct draw_stage *stage,
 398             struct prim_header *header )
 399 {
 400    if (header->v[0]->clipmask == 0)
 401       stage->next->point( stage->next, header );
 402 }
 403
 404
 405 static void
 406 clip_line( struct draw_stage *stage,
 407            struct prim_header *header )
 408 {
 409    unsigned clipmask = (header->v[0]->clipmask |
 410                         header->v[1]->clipmask);
 411
 412    if (clipmask == 0) {
 413       /* no clipping needed */
 414       stage->next->line( stage->next, header );
 415    }
 416    else if ((header->v[0]->clipmask &
 417              header->v[1]->clipmask) == 0) {
 418       do_clip_line(stage, header, clipmask);
 419    }
 420    /* else, totally clipped */
 421 }
 422
 423
 424 static void
 425 clip_tri( struct draw_stage *stage,
 426           struct prim_header *header )
 427 {
 428    unsigned clipmask = (header->v[0]->clipmask |
 429                         header->v[1]->clipmask |
 430                         header->v[2]->clipmask);
 431
 432    if (clipmask == 0) {
 433       /* no clipping needed */
 434       stage->next->tri( stage->next, header );
 435    }
 436    else if ((header->v[0]->clipmask &
 437              header->v[1]->clipmask &
 438              header->v[2]->clipmask) == 0) {
 439       do_clip_tri(stage, header, clipmask);
 440    }
 441 }
 442
 443
 444 /* Update state.  Could further delay this until we hit the first
 445  * primitive that really requires clipping.
 446  */
 447 static void
 448 clip_init_state( struct draw_stage *stage )
 449 {
 450    struct clip_stage *clipper = clip_stage( stage );
 451
 452    clipper->flat = stage->draw->rasterizer->flatshade ? TRUE : FALSE;
 453
 454    if (clipper->flat) {
 455       const struct draw_vertex_shader *vs = stage->draw->vs.vertex_shader;
 456       uint i;
 457
 458       clipper->num_color_attribs = 0;
 459       for (i = 0; i < vs->info.num_outputs; i++) {
 460          if (vs->info.output_semantic_name[i] == TGSI_SEMANTIC_COLOR ||
 461              vs->info.output_semantic_name[i] == TGSI_SEMANTIC_BCOLOR) {
 462             clipper->color_attribs[clipper->num_color_attribs++] = i;
 463          }
 464       }
 465    }
 466
 467    stage->tri = clip_tri;
 468    stage->line = clip_line;
 469 }
 470
 471
 472
 473 static void clip_first_tri( struct draw_stage *stage,
 474                             struct prim_header *header )
 475 {
 476    clip_init_state( stage );
 477    stage->tri( stage, header );
 478 }
 479
 480 static void clip_first_line( struct draw_stage *stage,
 481                              struct prim_header *header )
 482 {
 483    clip_init_state( stage );
 484    stage->line( stage, header );
 485 }
 486
 487
 488 static void clip_flush( struct draw_stage *stage,
 489                              unsigned flags )
 490 {
 491    stage->tri = clip_first_tri;
 492    stage->line = clip_first_line;
 493    stage->next->flush( stage->next, flags );
 494 }
 495
 496
 497 static void clip_reset_stipple_counter( struct draw_stage *stage )
 498 {
 499    stage->next->reset_stipple_counter( stage->next );
 500 }
 501
 502
 503 static void clip_destroy( struct draw_stage *stage )
 504 {
 505    draw_free_temp_verts( stage );
 506    FREE( stage );
 507 }
 508
 509
 510 /**
 511  * Allocate a new clipper stage.
 512  * \return pointer to new stage object
 513  */
 514 struct draw_stage *draw_clip_stage( struct draw_context *draw )
 515 {
 516    struct clip_stage *clipper = CALLOC_STRUCT(clip_stage);
 517    if (clipper == NULL)
 518       goto fail;
 519
 520    if (!draw_alloc_temp_verts( &clipper->stage, MAX_CLIPPED_VERTICES+1 ))
 521       goto fail;
 522
 523    clipper->stage.draw = draw;
 524    clipper->stage.name = "clipper";
 525    clipper->stage.point = clip_point;
 526    clipper->stage.line = clip_first_line;
 527    clipper->stage.tri = clip_first_tri;
 528    clipper->stage.flush = clip_flush;
 529    clipper->stage.reset_stipple_counter = clip_reset_stipple_counter;
 530    clipper->stage.destroy = clip_destroy;
 531
 532    clipper->plane = draw->plane;
 533
 534    return &clipper->stage;
 535
 536  fail:
 537    if (clipper)
 538       clipper->stage.destroy( &clipper->stage );
 539
 540    return NULL;
 541 }