1 |
/* Copyright (c) 1994 Regents of the University of California */ |
2 |
|
3 |
#ifndef lint |
4 |
static char SCCSid[] = "$SunId$ LBL"; |
5 |
#endif |
6 |
|
7 |
/* |
8 |
* Routines for 3-d vectors |
9 |
*/ |
10 |
|
11 |
#include <stdio.h> |
12 |
#include <math.h> |
13 |
#include "parser.h" |
14 |
|
15 |
|
16 |
double |
17 |
normalize(v) /* normalize a vector, return old magnitude */ |
18 |
register FVECT v; |
19 |
{ |
20 |
static double len; |
21 |
|
22 |
len = DOT(v, v); |
23 |
|
24 |
if (len <= 0.0) |
25 |
return(0.0); |
26 |
|
27 |
if (len <= 1.0+FTINY && len >= 1.0-FTINY) |
28 |
len = 0.5 + 0.5*len; /* first order approximation */ |
29 |
else |
30 |
len = sqrt(len); |
31 |
|
32 |
v[0] /= len; |
33 |
v[1] /= len; |
34 |
v[2] /= len; |
35 |
|
36 |
return(len); |
37 |
} |
38 |
|
39 |
|
40 |
fcross(vres, v1, v2) /* vres = v1 X v2 */ |
41 |
register FVECT vres, v1, v2; |
42 |
{ |
43 |
vres[0] = v1[1]*v2[2] - v1[2]*v2[1]; |
44 |
vres[1] = v1[2]*v2[0] - v1[0]*v2[2]; |
45 |
vres[2] = v1[0]*v2[1] - v1[1]*v2[0]; |
46 |
} |