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
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
|
/**************************************************************************
*
* 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 "util/u_memory.h"
#include "pipe/p_defines.h"
#include "draw_pipe.h"
struct cull_stage {
struct draw_stage stage;
unsigned winding; /**< which winding(s) to cull (one of PIPE_WINDING_x) */
};
static INLINE struct cull_stage *cull_stage( struct draw_stage *stage )
{
return (struct cull_stage *)stage;
}
static void cull_tri( struct draw_stage *stage,
struct prim_header *header )
{
const unsigned pos = draw_current_shader_position_output(stage->draw);
/* Window coords: */
const float *v0 = header->v[0]->data[pos];
const float *v1 = header->v[1]->data[pos];
const float *v2 = header->v[2]->data[pos];
/* edge vectors: e = v0 - v2, f = v1 - v2 */
const float ex = v0[0] - v2[0];
const float ey = v0[1] - v2[1];
const float fx = v1[0] - v2[0];
const float fy = v1[1] - v2[1];
/* det = cross(e,f).z */
header->det = ex * fy - ey * fx;
if (header->det != 0) {
/* if det < 0 then Z points toward the camera and the triangle is
* counter-clockwise winding.
*/
unsigned winding = (header->det < 0) ? PIPE_WINDING_CCW : PIPE_WINDING_CW;
if ((winding & cull_stage(stage)->winding) == 0) {
/* triangle is not culled, pass to next stage */
stage->next->tri( stage->next, header );
}
}
}
static void cull_first_tri( struct draw_stage *stage,
struct prim_header *header )
{
struct cull_stage *cull = cull_stage(stage);
cull->winding = stage->draw->rasterizer->cull_mode;
stage->tri = cull_tri;
stage->tri( stage, header );
}
static void cull_flush( struct draw_stage *stage, unsigned flags )
{
stage->tri = cull_first_tri;
stage->next->flush( stage->next, flags );
}
static void cull_reset_stipple_counter( struct draw_stage *stage )
{
stage->next->reset_stipple_counter( stage->next );
}
static void cull_destroy( struct draw_stage *stage )
{
draw_free_temp_verts( stage );
FREE( stage );
}
/**
* Create a new polygon culling stage.
*/
struct draw_stage *draw_cull_stage( struct draw_context *draw )
{
struct cull_stage *cull = CALLOC_STRUCT(cull_stage);
if (cull == NULL)
goto fail;
if (!draw_alloc_temp_verts( &cull->stage, 0 ))
goto fail;
cull->stage.draw = draw;
cull->stage.name = "cull";
cull->stage.next = NULL;
cull->stage.point = draw_pipe_passthrough_point;
cull->stage.line = draw_pipe_passthrough_line;
cull->stage.tri = cull_first_tri;
cull->stage.flush = cull_flush;
cull->stage.reset_stipple_counter = cull_reset_stipple_counter;
cull->stage.destroy = cull_destroy;
return &cull->stage;
fail:
if (cull)
cull->stage.destroy( &cull->stage );
return NULL;
}
|
