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
128
129
130
|
/**************************************************************************
*
* 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.
*
**************************************************************************/
/**
* \brief Drawing stage for polygon culling
*/
/* 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; /**< one of PIPE_WINDING_x */
};
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: */
const GLfloat *v0 = header->v[0]->data[0];
const GLfloat *v1 = header->v[1]->data[0];
const GLfloat *v2 = header->v[2]->data[0];
/* edge vectors e = v0 - v2, f = v1 - v2 */
GLfloat ex = v0[0] - v2[0];
GLfloat ey = v0[1] - v2[1];
GLfloat fx = v1[0] - v2[0];
GLfloat fy = v1[1] - v2[1];
/* det = cross(e,f).z */
header->det = ex * fy - ey * fx;
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;
}
|
