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
|
/*
* FUNCTION:
* This file contains a number of utilities useful to 3D graphics in
* general, and to the generation of tubing and extrusions in particular
*
* HISTORY:
* Written by Linas Vepstas, August 1991
*/
#include "gutil.h"
#include "intersect.h"
/* ========================================================== */
/*
* The macro and subroutine INTERSECT are designed to compute the
* intersection of a line (defined by the points v1 and v2) and a plane
* (defined as plane which is normal to the vector n, and contains the
* point p). Both sect the array "sect", which is the point of
* interesection.
*
* The subroutine returns a value indicating if the specified inputs
* represented a degenerate case. Valid is TRUE if the computed
* intersection is valid, else it is FALSE.
*/
/* ========================================================== */
void intersect (gleDouble sect[3], /* returned */
gleDouble p[3], /* input */
gleDouble n[3], /* input */
gleDouble v1[3], /* input */
gleDouble v2[3]) /* input */
{
INTERSECT (sect, p, n, v1, v2);
}
/* ========================================================== */
/*
* The macro and subroutine BISECTING_PLANE compute a normal vecotr that
* describes the bisecting plane between three points (v1, v2 and v3).
* This bisecting plane has the following properties:
* 1) it contains the point v2
* 2) the angle it makes with v21 == v2 - v1 is equal to the angle it
* makes with v32 == v3 - v2
* 3) it is perpendicular to the plane defined by v1, v2, v3.
*
* Having input v1, v2, and v3, it returns a vector n.
* Note that n is NOT normalized (is NOT of unit length).
*
* The subroutine returns a value indicating if the specified inputs
* represented a degenerate case. Valid is TRUE if the computed
* intersection is valid, else it is FALSE.
*/
int bisecting_plane (gleDouble n[3], /* returned */
gleDouble v1[3], /* input */
gleDouble v2[3], /* input */
gleDouble v3[3]) /* input */
{
int valid;
BISECTING_PLANE (valid, n, v1, v2, v3);
return (valid);
}
/* ========================================================== */
|
