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
40 * Compute a0 for a constant-valued coefficient (GL_FLAT shading).
42 static void constant_coef( struct lp_rast_triangle
*tri
,
47 tri
->inputs
.a0
[slot
][i
] = value
;
48 tri
->inputs
.dadx
[slot
][i
] = 0;
49 tri
->inputs
.dady
[slot
][i
] = 0;
53 * Compute a0, dadx and dady for a linearly interpolated coefficient,
56 static void linear_coef( struct lp_rast_triangle
*tri
,
64 float a1
= v1
[vert_attr
][i
];
65 float a2
= v2
[vert_attr
][i
];
66 float a3
= v3
[vert_attr
][i
];
70 float dadx
= (da12
* tri
->dy31
- tri
->dy12
* da31
) * tri
->oneoverarea
;
71 float dady
= (da31
* tri
->dx12
- tri
->dx31
* da12
) * tri
->oneoverarea
;
73 tri
->inputs
.dadx
[slot
][i
] = dadx
;
74 tri
->inputs
.dady
[slot
][i
] = dady
;
76 /* calculate a0 as the value which would be sampled for the
77 * fragment at (0,0), taking into account that we want to sample at
78 * pixel centers, in other words (0.5, 0.5).
80 * this is neat but unfortunately not a good way to do things for
81 * triangles with very large values of dadx or dady as it will
82 * result in the subtraction and re-addition from a0 of a very
83 * large number, which means we'll end up loosing a lot of the
84 * fractional bits and precision from a0. the way to fix this is
85 * to define a0 as the sample at a pixel center somewhere near vmin
86 * instead - i'll switch to this later.
88 tri
->inputs
.a0
[slot
][i
] = (v1
[vert_attr
][i
] -
89 (dadx
* (v1
[0][0] - 0.5f
) +
90 dady
* (v1
[0][1] - 0.5f
)));
95 * Compute a0, dadx and dady for a perspective-corrected interpolant,
97 * We basically multiply the vertex value by 1/w before computing
98 * the plane coefficients (a0, dadx, dady).
99 * Later, when we compute the value at a particular fragment position we'll
100 * divide the interpolated value by the interpolated W at that fragment.
102 static void perspective_coef( struct lp_rast_triangle
*tri
,
104 const float (*v1
)[4],
105 const float (*v2
)[4],
106 const float (*v3
)[4],
110 /* premultiply by 1/w (v[0][3] is always 1/w):
112 float a1
= v1
[vert_attr
][i
] * v1
[0][3];
113 float a2
= v2
[vert_attr
][i
] * v2
[0][3];
114 float a3
= v3
[vert_attr
][i
] * v3
[0][3];
115 float da12
= a1
- a2
;
116 float da31
= a3
- a1
;
117 float dadx
= (da12
* tri
->dy31
- tri
->dy12
* da31
) * tri
->oneoverarea
;
118 float dady
= (da31
* tri
->dx12
- tri
->dx31
* da12
) * tri
->oneoverarea
;
121 tri
->inputs
.dadx
[slot
][i
] = dadx
;
122 tri
->inputs
.dady
[slot
][i
] = dady
;
123 tri
->inputs
.a0
[slot
][i
] = (a1
-
124 (dadx
* (v1
[0][0] - 0.5f
) +
125 dady
* (v1
[0][1] - 0.5f
)));
130 * Special coefficient setup for gl_FragCoord.
131 * X and Y are trivial, though Y has to be inverted for OpenGL.
132 * Z and W are copied from position_coef which should have already been computed.
133 * We could do a bit less work if we'd examine gl_FragCoord's swizzle mask.
136 setup_fragcoord_coef(struct lp_rast_triangle
*tri
,
138 const float (*v1
)[4],
139 const float (*v2
)[4],
140 const float (*v3
)[4])
143 tri
->inputs
.a0
[slot
][0] = 0.0;
144 tri
->inputs
.dadx
[slot
][0] = 1.0;
145 tri
->inputs
.dady
[slot
][0] = 0.0;
147 tri
->inputs
.a0
[slot
][1] = 0.0;
148 tri
->inputs
.dadx
[slot
][1] = 0.0;
149 tri
->inputs
.dady
[slot
][1] = 1.0;
151 linear_coef(tri
, slot
, v1
, v2
, v3
, 0, 2);
153 linear_coef(tri
, slot
, v1
, v2
, v3
, 0, 3);
157 static void setup_facing_coef( struct lp_rast_triangle
*tri
,
161 constant_coef( tri
, slot
, 1.0f
- frontface
, 0 );
162 constant_coef( tri
, slot
, 0.0f
, 1 ); /* wasted */
163 constant_coef( tri
, slot
, 0.0f
, 2 ); /* wasted */
164 constant_coef( tri
, slot
, 0.0f
, 3 ); /* wasted */
169 * Compute the tri->coef[] array dadx, dady, a0 values.
171 static void setup_tri_coefficients( struct setup_context
*setup
,
172 struct lp_rast_triangle
*tri
,
173 const float (*v1
)[4],
174 const float (*v2
)[4],
175 const float (*v3
)[4],
180 /* The internal position input is in slot zero:
182 setup_fragcoord_coef(tri
, 0, v1
, v2
, v3
);
184 /* setup interpolation for all the remaining attrbutes:
186 for (slot
= 0; slot
< setup
->fs
.nr_inputs
; slot
++) {
187 unsigned vert_attr
= setup
->fs
.input
[slot
].src_index
;
190 switch (setup
->fs
.input
[slot
].interp
) {
191 case LP_INTERP_CONSTANT
:
192 for (i
= 0; i
< NUM_CHANNELS
; i
++)
193 constant_coef(tri
, slot
+1, v3
[vert_attr
][i
], i
);
196 case LP_INTERP_LINEAR
:
197 for (i
= 0; i
< NUM_CHANNELS
; i
++)
198 linear_coef(tri
, slot
+1, v1
, v2
, v3
, vert_attr
, i
);
201 case LP_INTERP_PERSPECTIVE
:
202 for (i
= 0; i
< NUM_CHANNELS
; i
++)
203 perspective_coef(tri
, slot
+1, v1
, v2
, v3
, vert_attr
, i
);
206 case LP_INTERP_POSITION
:
207 /* XXX: fix me - duplicates the values in slot zero.
209 setup_fragcoord_coef(tri
, slot
+1, v1
, v2
, v3
);
212 case LP_INTERP_FACING
:
213 setup_facing_coef(tri
, slot
+1, frontface
);
224 static inline int subpixel_snap( float a
)
226 return util_iround(FIXED_ONE
* a
);
230 #define MIN3(a,b,c) MIN2(MIN2(a,b),c)
231 #define MAX3(a,b,c) MAX2(MAX2(a,b),c)
234 * Do basic setup for triangle rasterization and determine which
235 * framebuffer tiles are touched. Put the triangle in the bins for the
236 * tiles which we overlap.
239 do_triangle_ccw(struct setup_context
*setup
,
240 const float (*v1
)[4],
241 const float (*v2
)[4],
242 const float (*v3
)[4],
243 boolean frontfacing
)
245 /* x/y positions in fixed point */
246 const int x1
= subpixel_snap(v1
[0][0]);
247 const int x2
= subpixel_snap(v2
[0][0]);
248 const int x3
= subpixel_snap(v3
[0][0]);
249 const int y1
= subpixel_snap(v1
[0][1]);
250 const int y2
= subpixel_snap(v2
[0][1]);
251 const int y3
= subpixel_snap(v3
[0][1]);
253 struct lp_rast_triangle
*tri
= get_data( &setup
->data
, sizeof *tri
);
255 int minx
, maxx
, miny
, maxy
;
265 area
= (tri
->dx12
* tri
->dy31
-
266 tri
->dx31
* tri
->dy12
);
268 /* Cull non-ccw and zero-sized triangles.
270 * XXX: subject to overflow??
273 putback_data( &setup
->data
, sizeof *tri
);
277 /* Bounding rectangle (in pixels) */
278 tri
->minx
= (MIN3(x1
, x2
, x3
) + 0xf) >> FIXED_ORDER
;
279 tri
->maxx
= (MAX3(x1
, x2
, x3
) + 0xf) >> FIXED_ORDER
;
280 tri
->miny
= (MIN3(y1
, y2
, y3
) + 0xf) >> FIXED_ORDER
;
281 tri
->maxy
= (MAX3(y1
, y2
, y3
) + 0xf) >> FIXED_ORDER
;
283 if (tri
->miny
== tri
->maxy
||
284 tri
->minx
== tri
->maxx
) {
285 putback_data( &setup
->data
, sizeof *tri
);
289 tri
->inputs
.state
= setup
->fs
.stored
;
293 tri
->oneoverarea
= ((float)FIXED_ONE
) / (float)area
;
295 /* Setup parameter interpolants:
297 setup_tri_coefficients( setup
, tri
, v1
, v2
, v3
, frontfacing
);
299 /* half-edge constants, will be interated over the whole
302 tri
->c1
= tri
->dy12
* x1
- tri
->dx12
* y1
;
303 tri
->c2
= tri
->dy23
* x2
- tri
->dx23
* y2
;
304 tri
->c3
= tri
->dy31
* x3
- tri
->dx31
* y3
;
306 /* correct for top-left fill convention:
308 if (tri
->dy12
< 0 || (tri
->dy12
== 0 && tri
->dx12
> 0)) tri
->c1
++;
309 if (tri
->dy23
< 0 || (tri
->dy23
== 0 && tri
->dx23
> 0)) tri
->c2
++;
310 if (tri
->dy31
< 0 || (tri
->dy31
== 0 && tri
->dx31
> 0)) tri
->c3
++;
312 tri
->dy12
*= FIXED_ONE
;
313 tri
->dy23
*= FIXED_ONE
;
314 tri
->dy31
*= FIXED_ONE
;
316 tri
->dx12
*= FIXED_ONE
;
317 tri
->dx23
*= FIXED_ONE
;
318 tri
->dx31
*= FIXED_ONE
;
320 /* find trivial reject offsets for each edge for a single-pixel
321 * sized block. These will be scaled up at each recursive level to
322 * match the active blocksize. Scaling in this way works best if
323 * the blocks are square.
326 if (tri
->dy12
< 0) tri
->eo1
-= tri
->dy12
;
327 if (tri
->dx12
> 0) tri
->eo1
+= tri
->dx12
;
330 if (tri
->dy23
< 0) tri
->eo2
-= tri
->dy23
;
331 if (tri
->dx23
> 0) tri
->eo2
+= tri
->dx23
;
334 if (tri
->dy31
< 0) tri
->eo3
-= tri
->dy31
;
335 if (tri
->dx31
> 0) tri
->eo3
+= tri
->dx31
;
337 /* Calculate trivial accept offsets from the above.
339 tri
->ei1
= tri
->dx12
- tri
->dy12
- tri
->eo1
;
340 tri
->ei2
= tri
->dx23
- tri
->dy23
- tri
->eo2
;
341 tri
->ei3
= tri
->dx31
- tri
->dy31
- tri
->eo3
;
344 int xstep1
= -tri
->dy12
;
345 int xstep2
= -tri
->dy23
;
346 int xstep3
= -tri
->dy31
;
348 int ystep1
= tri
->dx12
;
349 int ystep2
= tri
->dx23
;
350 int ystep3
= tri
->dx31
;
359 for (iy
= 0; iy
< 4; iy
++) {
364 for (ix
= 0; ix
< 4; ix
++, i
++) {
365 tri
->step
[0][i
] = cx1
;
366 tri
->step
[1][i
] = cx2
;
367 tri
->step
[2][i
] = cx3
;
380 * All fields of 'tri' are now set. The remaining code here is
381 * concerned with binning.
384 /* Convert to tile coordinates:
386 minx
= tri
->minx
/ TILE_SIZE
;
387 miny
= tri
->miny
/ TILE_SIZE
;
388 maxx
= tri
->maxx
/ TILE_SIZE
;
389 maxy
= tri
->maxy
/ TILE_SIZE
;
391 /* Determine which tile(s) intersect the triangle's bounding box
393 if (miny
== maxy
&& minx
== maxx
)
395 /* Triangle is contained in a single tile:
397 bin_command( &setup
->tile
[minx
][miny
], lp_rast_triangle
,
398 lp_rast_arg_triangle(tri
) );
403 tri
->dx12
* miny
* TILE_SIZE
-
404 tri
->dy12
* minx
* TILE_SIZE
);
406 tri
->dx23
* miny
* TILE_SIZE
-
407 tri
->dy23
* minx
* TILE_SIZE
);
409 tri
->dx31
* miny
* TILE_SIZE
-
410 tri
->dy31
* minx
* TILE_SIZE
);
412 int ei1
= tri
->ei1
<< TILE_ORDER
;
413 int ei2
= tri
->ei2
<< TILE_ORDER
;
414 int ei3
= tri
->ei3
<< TILE_ORDER
;
416 int eo1
= tri
->eo1
<< TILE_ORDER
;
417 int eo2
= tri
->eo2
<< TILE_ORDER
;
418 int eo3
= tri
->eo3
<< TILE_ORDER
;
420 int xstep1
= -(tri
->dy12
<< TILE_ORDER
);
421 int xstep2
= -(tri
->dy23
<< TILE_ORDER
);
422 int xstep3
= -(tri
->dy31
<< TILE_ORDER
);
424 int ystep1
= tri
->dx12
<< TILE_ORDER
;
425 int ystep2
= tri
->dx23
<< TILE_ORDER
;
426 int ystep3
= tri
->dx31
<< TILE_ORDER
;
430 /* Trivially accept or reject blocks, else jump to per-pixel
433 for (y
= miny
; y
<= maxy
; y
++)
440 for (x
= minx
; x
<= maxx
; x
++)
450 else if (cx1
+ ei1
> 0 &&
455 /* triangle covers the whole tile- shade whole tile */
456 bin_command( &setup
->tile
[x
][y
],
458 lp_rast_arg_inputs(&tri
->inputs
) );
463 /* shade partial tile */
464 bin_command( &setup
->tile
[x
][y
],
466 lp_rast_arg_triangle(tri
) );
469 /* Iterate cx values across the region:
476 /* Iterate c values down the region:
485 static void triangle_cw( struct setup_context
*setup
,
486 const float (*v0
)[4],
487 const float (*v1
)[4],
488 const float (*v2
)[4] )
490 do_triangle_ccw( setup
, v1
, v0
, v2
, !setup
->ccw_is_frontface
);
493 static void triangle_ccw( struct setup_context
*setup
,
494 const float (*v0
)[4],
495 const float (*v1
)[4],
496 const float (*v2
)[4] )
498 do_triangle_ccw( setup
, v0
, v1
, v2
, setup
->ccw_is_frontface
);
501 static void triangle_both( struct setup_context
*setup
,
502 const float (*v0
)[4],
503 const float (*v1
)[4],
504 const float (*v2
)[4] )
506 /* edge vectors e = v0 - v2, f = v1 - v2 */
507 const float ex
= v0
[0][0] - v2
[0][0];
508 const float ey
= v0
[0][1] - v2
[0][1];
509 const float fx
= v1
[0][0] - v2
[0][0];
510 const float fy
= v1
[0][1] - v2
[0][1];
512 /* det = cross(e,f).z */
513 if (ex
* fy
- ey
* fx
< 0)
514 triangle_ccw( setup
, v0
, v1
, v2
);
516 triangle_cw( setup
, v0
, v1
, v2
);
519 static void triangle_nop( struct setup_context
*setup
,
520 const float (*v0
)[4],
521 const float (*v1
)[4],
522 const float (*v2
)[4] )
528 lp_setup_choose_triangle( struct setup_context
*setup
)
530 switch (setup
->cullmode
) {
531 case PIPE_WINDING_NONE
:
532 setup
->triangle
= triangle_both
;
534 case PIPE_WINDING_CCW
:
535 setup
->triangle
= triangle_cw
;
537 case PIPE_WINDING_CW
:
538 setup
->triangle
= triangle_ccw
;
541 setup
->triangle
= triangle_nop
;