1 /**************************************************************************
3 * Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
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:
14 * The above copyright notice and this permission notice (including the
15 * next paragraph) shall be included in all copies or substantial portions
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.
26 **************************************************************************/
29 * Binning code for triangles
32 #include "lp_setup_context.h"
34 #include "util/u_math.h"
35 #include "util/u_memory.h"
37 #define NUM_CHANNELS 4
41 * Compute a0 for a constant-valued coefficient (GL_FLAT shading).
43 static void constant_coef( struct lp_rast_triangle
*tri
,
48 tri
->inputs
.a0
[slot
][i
] = value
;
49 tri
->inputs
.dadx
[slot
][i
] = 0.0f
;
50 tri
->inputs
.dady
[slot
][i
] = 0.0f
;
55 * Compute a0, dadx and dady for a linearly interpolated coefficient,
58 static void linear_coef( struct lp_rast_triangle
*tri
,
67 float a1
= v1
[vert_attr
][i
];
68 float a2
= v2
[vert_attr
][i
];
69 float a3
= v3
[vert_attr
][i
];
73 float dadx
= (da12
* tri
->dy31
- tri
->dy12
* da31
) * oneoverarea
;
74 float dady
= (da31
* tri
->dx12
- tri
->dx31
* da12
) * oneoverarea
;
76 tri
->inputs
.dadx
[slot
][i
] = dadx
;
77 tri
->inputs
.dady
[slot
][i
] = dady
;
79 /* calculate a0 as the value which would be sampled for the
80 * fragment at (0,0), taking into account that we want to sample at
81 * pixel centers, in other words (0.5, 0.5).
83 * this is neat but unfortunately not a good way to do things for
84 * triangles with very large values of dadx or dady as it will
85 * result in the subtraction and re-addition from a0 of a very
86 * large number, which means we'll end up loosing a lot of the
87 * fractional bits and precision from a0. the way to fix this is
88 * to define a0 as the sample at a pixel center somewhere near vmin
89 * instead - i'll switch to this later.
91 tri
->inputs
.a0
[slot
][i
] = (v1
[vert_attr
][i
] -
92 (dadx
* (v1
[0][0] - 0.5f
) +
93 dady
* (v1
[0][1] - 0.5f
)));
98 * Compute a0, dadx and dady for a perspective-corrected interpolant,
100 * We basically multiply the vertex value by 1/w before computing
101 * the plane coefficients (a0, dadx, dady).
102 * Later, when we compute the value at a particular fragment position we'll
103 * divide the interpolated value by the interpolated W at that fragment.
105 static void perspective_coef( struct lp_rast_triangle
*tri
,
108 const float (*v1
)[4],
109 const float (*v2
)[4],
110 const float (*v3
)[4],
114 /* premultiply by 1/w (v[0][3] is always 1/w):
116 float a1
= v1
[vert_attr
][i
] * v1
[0][3];
117 float a2
= v2
[vert_attr
][i
] * v2
[0][3];
118 float a3
= v3
[vert_attr
][i
] * v3
[0][3];
119 float da12
= a1
- a2
;
120 float da31
= a3
- a1
;
121 float dadx
= (da12
* tri
->dy31
- tri
->dy12
* da31
) * oneoverarea
;
122 float dady
= (da31
* tri
->dx12
- tri
->dx31
* da12
) * oneoverarea
;
124 tri
->inputs
.dadx
[slot
][i
] = dadx
;
125 tri
->inputs
.dady
[slot
][i
] = dady
;
126 tri
->inputs
.a0
[slot
][i
] = (a1
-
127 (dadx
* (v1
[0][0] - 0.5f
) +
128 dady
* (v1
[0][1] - 0.5f
)));
133 * Special coefficient setup for gl_FragCoord.
134 * X and Y are trivial
135 * Z and W are copied from position_coef which should have already been computed.
136 * We could do a bit less work if we'd examine gl_FragCoord's swizzle mask.
139 setup_fragcoord_coef(struct lp_rast_triangle
*tri
,
142 const float (*v1
)[4],
143 const float (*v2
)[4],
144 const float (*v3
)[4])
147 tri
->inputs
.a0
[slot
][0] = 0.0;
148 tri
->inputs
.dadx
[slot
][0] = 1.0;
149 tri
->inputs
.dady
[slot
][0] = 0.0;
151 tri
->inputs
.a0
[slot
][1] = 0.0;
152 tri
->inputs
.dadx
[slot
][1] = 0.0;
153 tri
->inputs
.dady
[slot
][1] = 1.0;
155 linear_coef(tri
, oneoverarea
, slot
, v1
, v2
, v3
, 0, 2);
157 linear_coef(tri
, oneoverarea
, slot
, v1
, v2
, v3
, 0, 3);
161 static void setup_facing_coef( struct lp_rast_triangle
*tri
,
165 constant_coef( tri
, slot
, 1.0f
- frontface
, 0 );
166 constant_coef( tri
, slot
, 0.0f
, 1 ); /* wasted */
167 constant_coef( tri
, slot
, 0.0f
, 2 ); /* wasted */
168 constant_coef( tri
, slot
, 0.0f
, 3 ); /* wasted */
173 * Compute the tri->coef[] array dadx, dady, a0 values.
175 static void setup_tri_coefficients( struct setup_context
*setup
,
176 struct lp_rast_triangle
*tri
,
178 const float (*v1
)[4],
179 const float (*v2
)[4],
180 const float (*v3
)[4],
183 struct lp_scene
*scene
= lp_setup_get_current_scene(setup
);
186 /* Allocate space for the a0, dadx and dady arrays
189 unsigned bytes
= (setup
->fs
.nr_inputs
+ 1) * 4 * sizeof(float);
190 tri
->inputs
.a0
= lp_scene_alloc_aligned( scene
, bytes
, 16 );
191 tri
->inputs
.dadx
= lp_scene_alloc_aligned( scene
, bytes
, 16 );
192 tri
->inputs
.dady
= lp_scene_alloc_aligned( scene
, bytes
, 16 );
195 /* The internal position input is in slot zero:
197 setup_fragcoord_coef(tri
, oneoverarea
, 0, v1
, v2
, v3
);
199 /* setup interpolation for all the remaining attributes:
201 for (slot
= 0; slot
< setup
->fs
.nr_inputs
; slot
++) {
202 unsigned vert_attr
= setup
->fs
.input
[slot
].src_index
;
205 switch (setup
->fs
.input
[slot
].interp
) {
206 case LP_INTERP_CONSTANT
:
207 for (i
= 0; i
< NUM_CHANNELS
; i
++)
208 constant_coef(tri
, slot
+1, v3
[vert_attr
][i
], i
);
211 case LP_INTERP_LINEAR
:
212 for (i
= 0; i
< NUM_CHANNELS
; i
++)
213 linear_coef(tri
, oneoverarea
, slot
+1, v1
, v2
, v3
, vert_attr
, i
);
216 case LP_INTERP_PERSPECTIVE
:
217 for (i
= 0; i
< NUM_CHANNELS
; i
++)
218 perspective_coef(tri
, oneoverarea
, slot
+1, v1
, v2
, v3
, vert_attr
, i
);
221 case LP_INTERP_POSITION
:
222 /* XXX: fix me - duplicates the values in slot zero.
224 setup_fragcoord_coef(tri
, oneoverarea
, slot
+1, v1
, v2
, v3
);
227 case LP_INTERP_FACING
:
228 setup_facing_coef(tri
, slot
+1, frontface
);
239 static inline int subpixel_snap( float a
)
241 return util_iround(FIXED_ONE
* a
- (FIXED_ONE
/ 2));
246 * Do basic setup for triangle rasterization and determine which
247 * framebuffer tiles are touched. Put the triangle in the scene's
248 * bins for the tiles which we overlap.
251 do_triangle_ccw(struct setup_context
*setup
,
252 const float (*v1
)[4],
253 const float (*v2
)[4],
254 const float (*v3
)[4],
255 boolean frontfacing
)
257 /* x/y positions in fixed point */
258 const int x1
= subpixel_snap(v1
[0][0]);
259 const int x2
= subpixel_snap(v2
[0][0]);
260 const int x3
= subpixel_snap(v3
[0][0]);
261 const int y1
= subpixel_snap(v1
[0][1]);
262 const int y2
= subpixel_snap(v2
[0][1]);
263 const int y3
= subpixel_snap(v3
[0][1]);
265 struct lp_scene
*scene
= lp_setup_get_current_scene(setup
);
266 struct lp_rast_triangle
*tri
= lp_scene_alloc_aligned( scene
, sizeof *tri
, 16 );
267 float area
, oneoverarea
;
268 int minx
, maxx
, miny
, maxy
;
278 area
= (tri
->dx12
* tri
->dy31
-
279 tri
->dx31
* tri
->dy12
);
281 /* Cull non-ccw and zero-sized triangles.
283 * XXX: subject to overflow??
286 lp_scene_putback_data( scene
, sizeof *tri
);
290 /* Bounding rectangle (in pixels) */
291 minx
= (MIN3(x1
, x2
, x3
) + (FIXED_ONE
-1)) >> FIXED_ORDER
;
292 maxx
= (MAX3(x1
, x2
, x3
) + (FIXED_ONE
-1)) >> FIXED_ORDER
;
293 miny
= (MIN3(y1
, y2
, y3
) + (FIXED_ONE
-1)) >> FIXED_ORDER
;
294 maxy
= (MAX3(y1
, y2
, y3
) + (FIXED_ONE
-1)) >> FIXED_ORDER
;
296 if (setup
->scissor_test
) {
297 minx
= MAX2(minx
, setup
->scissor
.current
.minx
);
298 maxx
= MIN2(maxx
, setup
->scissor
.current
.maxx
);
299 miny
= MAX2(miny
, setup
->scissor
.current
.miny
);
300 maxy
= MIN2(maxy
, setup
->scissor
.current
.maxy
);
305 lp_scene_putback_data( scene
, sizeof *tri
);
311 oneoverarea
= ((float)FIXED_ONE
) / (float)area
;
313 /* Setup parameter interpolants:
315 setup_tri_coefficients( setup
, tri
, oneoverarea
, v1
, v2
, v3
, frontfacing
);
317 /* half-edge constants, will be interated over the whole render target.
319 tri
->c1
= tri
->dy12
* x1
- tri
->dx12
* y1
;
320 tri
->c2
= tri
->dy23
* x2
- tri
->dx23
* y2
;
321 tri
->c3
= tri
->dy31
* x3
- tri
->dx31
* y3
;
323 /* correct for top-left fill convention:
325 if (tri
->dy12
< 0 || (tri
->dy12
== 0 && tri
->dx12
> 0)) tri
->c1
++;
326 if (tri
->dy23
< 0 || (tri
->dy23
== 0 && tri
->dx23
> 0)) tri
->c2
++;
327 if (tri
->dy31
< 0 || (tri
->dy31
== 0 && tri
->dx31
> 0)) tri
->c3
++;
329 tri
->dy12
*= FIXED_ONE
;
330 tri
->dy23
*= FIXED_ONE
;
331 tri
->dy31
*= FIXED_ONE
;
333 tri
->dx12
*= FIXED_ONE
;
334 tri
->dx23
*= FIXED_ONE
;
335 tri
->dx31
*= FIXED_ONE
;
337 /* find trivial reject offsets for each edge for a single-pixel
338 * sized block. These will be scaled up at each recursive level to
339 * match the active blocksize. Scaling in this way works best if
340 * the blocks are square.
343 if (tri
->dy12
< 0) tri
->eo1
-= tri
->dy12
;
344 if (tri
->dx12
> 0) tri
->eo1
+= tri
->dx12
;
347 if (tri
->dy23
< 0) tri
->eo2
-= tri
->dy23
;
348 if (tri
->dx23
> 0) tri
->eo2
+= tri
->dx23
;
351 if (tri
->dy31
< 0) tri
->eo3
-= tri
->dy31
;
352 if (tri
->dx31
> 0) tri
->eo3
+= tri
->dx31
;
354 /* Calculate trivial accept offsets from the above.
356 tri
->ei1
= tri
->dx12
- tri
->dy12
- tri
->eo1
;
357 tri
->ei2
= tri
->dx23
- tri
->dy23
- tri
->eo2
;
358 tri
->ei3
= tri
->dx31
- tri
->dy31
- tri
->eo3
;
361 const int xstep1
= -tri
->dy12
;
362 const int xstep2
= -tri
->dy23
;
363 const int xstep3
= -tri
->dy31
;
365 const int ystep1
= tri
->dx12
;
366 const int ystep2
= tri
->dx23
;
367 const int ystep3
= tri
->dx31
;
372 for (qy
= 0; qy
< 2; qy
++) {
373 for (qx
= 0; qx
< 2; qx
++) {
374 for (iy
= 0; iy
< 2; iy
++) {
375 for (ix
= 0; ix
< 2; ix
++, i
++) {
378 tri
->inputs
.step
[0][i
] = x
* xstep1
+ y
* ystep1
;
379 tri
->inputs
.step
[1][i
] = x
* xstep2
+ y
* ystep2
;
380 tri
->inputs
.step
[2][i
] = x
* xstep3
+ y
* ystep3
;
388 * All fields of 'tri' are now set. The remaining code here is
389 * concerned with binning.
392 /* Convert to tile coordinates:
394 minx
= minx
/ TILE_SIZE
;
395 miny
= miny
/ TILE_SIZE
;
396 maxx
= maxx
/ TILE_SIZE
;
397 maxy
= maxy
/ TILE_SIZE
;
399 /* Clamp maxx, maxy to framebuffer size
401 maxx
= MIN2(maxx
, scene
->tiles_x
- 1);
402 maxy
= MIN2(maxy
, scene
->tiles_y
- 1);
404 /* Determine which tile(s) intersect the triangle's bounding box
406 if (miny
== maxy
&& minx
== maxx
)
408 /* Triangle is contained in a single tile:
410 lp_scene_bin_command( scene
, minx
, miny
, lp_rast_triangle
,
411 lp_rast_arg_triangle(tri
) );
416 tri
->dx12
* miny
* TILE_SIZE
-
417 tri
->dy12
* minx
* TILE_SIZE
);
419 tri
->dx23
* miny
* TILE_SIZE
-
420 tri
->dy23
* minx
* TILE_SIZE
);
422 tri
->dx31
* miny
* TILE_SIZE
-
423 tri
->dy31
* minx
* TILE_SIZE
);
425 int ei1
= tri
->ei1
<< TILE_ORDER
;
426 int ei2
= tri
->ei2
<< TILE_ORDER
;
427 int ei3
= tri
->ei3
<< TILE_ORDER
;
429 int eo1
= tri
->eo1
<< TILE_ORDER
;
430 int eo2
= tri
->eo2
<< TILE_ORDER
;
431 int eo3
= tri
->eo3
<< TILE_ORDER
;
433 int xstep1
= -(tri
->dy12
<< TILE_ORDER
);
434 int xstep2
= -(tri
->dy23
<< TILE_ORDER
);
435 int xstep3
= -(tri
->dy31
<< TILE_ORDER
);
437 int ystep1
= tri
->dx12
<< TILE_ORDER
;
438 int ystep2
= tri
->dx23
<< TILE_ORDER
;
439 int ystep3
= tri
->dx31
<< TILE_ORDER
;
443 /* Trivially accept or reject blocks, else jump to per-pixel
446 for (y
= miny
; y
<= maxy
; y
++)
451 boolean in
= FALSE
; /* are we inside the triangle? */
453 for (x
= minx
; x
<= maxx
; x
++)
461 break; /* exiting triangle, all done with this row */
463 else if (cx1
+ ei1
> 0 &&
468 /* triangle covers the whole tile- shade whole tile */
469 if(setup
->fs
.current
.opaque
) {
470 lp_scene_bin_reset( scene
, x
, y
);
471 lp_scene_bin_command( scene
, x
, y
,
473 lp_rast_arg_state(setup
->fs
.stored
) );
475 lp_scene_bin_command( scene
, x
, y
,
477 lp_rast_arg_inputs(&tri
->inputs
) );
482 /* shade partial tile */
483 lp_scene_bin_command( scene
, x
, y
,
485 lp_rast_arg_triangle(tri
) );
488 /* Iterate cx values across the region:
495 /* Iterate c values down the region:
505 static void triangle_cw( struct setup_context
*setup
,
506 const float (*v0
)[4],
507 const float (*v1
)[4],
508 const float (*v2
)[4] )
510 do_triangle_ccw( setup
, v1
, v0
, v2
, !setup
->ccw_is_frontface
);
514 static void triangle_ccw( struct setup_context
*setup
,
515 const float (*v0
)[4],
516 const float (*v1
)[4],
517 const float (*v2
)[4] )
519 do_triangle_ccw( setup
, v0
, v1
, v2
, setup
->ccw_is_frontface
);
523 static void triangle_both( struct setup_context
*setup
,
524 const float (*v0
)[4],
525 const float (*v1
)[4],
526 const float (*v2
)[4] )
528 /* edge vectors e = v0 - v2, f = v1 - v2 */
529 const float ex
= v0
[0][0] - v2
[0][0];
530 const float ey
= v0
[0][1] - v2
[0][1];
531 const float fx
= v1
[0][0] - v2
[0][0];
532 const float fy
= v1
[0][1] - v2
[0][1];
534 /* det = cross(e,f).z */
535 if (ex
* fy
- ey
* fx
< 0.0f
)
536 triangle_ccw( setup
, v0
, v1
, v2
);
538 triangle_cw( setup
, v0
, v1
, v2
);
542 static void triangle_nop( struct setup_context
*setup
,
543 const float (*v0
)[4],
544 const float (*v1
)[4],
545 const float (*v2
)[4] )
551 lp_setup_choose_triangle( struct setup_context
*setup
)
553 switch (setup
->cullmode
) {
554 case PIPE_WINDING_NONE
:
555 setup
->triangle
= triangle_both
;
557 case PIPE_WINDING_CCW
:
558 setup
->triangle
= triangle_cw
;
560 case PIPE_WINDING_CW
:
561 setup
->triangle
= triangle_ccw
;
564 setup
->triangle
= triangle_nop
;