summaryrefslogtreecommitdiff
path: root/src/mesa/pipe/draw/draw_cull.c
blob: d27d33a40ded1e434e4265a31cca2a692ca97347 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
/**************************************************************************
 * 
 * Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sub license, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 * 
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
 * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 * 
 **************************************************************************/

/* Authors:  Keith Whitwell <keith@tungstengraphics.com>
 */

#include "main/imports.h"
#include "pipe/p_defines.h"
#include "draw_private.h"



struct cull_stage {
   struct prim_stage stage;
   GLuint mode;
};



static INLINE struct cull_stage *cull_stage( struct prim_stage *stage )
{
   return (struct cull_stage *)stage;
}


static void cull_begin( struct prim_stage *stage )
{
   struct cull_stage *cull = cull_stage(stage);

   cull->mode = stage->draw->setup.cull_mode;

   stage->next->begin( stage->next );
}


static void cull_tri( struct prim_stage *stage,
		      struct prim_header *header )
{
   /* Window coords: */
   GLfloat *v0 = (GLfloat *)&(header->v[0]->data[0]);
   GLfloat *v1 = (GLfloat *)&(header->v[1]->data[0]);
   GLfloat *v2 = (GLfloat *)&(header->v[2]->data[0]);

   GLfloat ex = v0[0] - v2[0];
   GLfloat ey = v0[1] - v2[1];
   GLfloat fx = v1[0] - v2[0];
   GLfloat fy = v1[1] - v2[1];
   
   header->det = ex * fy - ey * fx;

   _mesa_printf("%s %f\n", __FUNCTION__, header->det );

   if (header->det != 0) {
      /* non-zero area */
      GLuint mode = (header->det < 0) ? PIPE_WINDING_CW : PIPE_WINDING_CCW;

      if ((mode & cull_stage(stage)->mode) == 0) {
         /* triangle is not culled, pass to next stage */
	 stage->next->tri( stage->next, header );
      }
   }
}


static void cull_line( struct prim_stage *stage,
		       struct prim_header *header )
{
   stage->next->line( stage->next, header );
}


static void cull_point( struct prim_stage *stage,
			struct prim_header *header )
{
   stage->next->point( stage->next, header );
}


static void cull_end( struct prim_stage *stage )
{
   stage->next->end( stage->next );
}


/**
 * Create a new polygon culling stage.
 */
struct prim_stage *prim_cull( struct draw_context *draw )
{
   struct cull_stage *cull = CALLOC_STRUCT(cull_stage);

   prim_alloc_tmps( &cull->stage, 0 );

   cull->stage.draw = draw;
   cull->stage.next = NULL;
   cull->stage.begin = cull_begin;
   cull->stage.point = cull_point;
   cull->stage.line = cull_line;
   cull->stage.tri = cull_tri;
   cull->stage.end = cull_end;

   return &cull->stage;
}