cv/mgflib/fvect.c

/* Copyright (c) 1994 Regents of the University of California */

#ifndef lint
static char SCCSid[] = "$SunId$ LBL";
#endif

/*
 * Routines for 3-d vectors
 */

#include <stdio.h>
#include <math.h>
#include "parser.h"


double
normalize(v)                    /* normalize a vector, return old magnitude */
register FVECT  v;
{
        static double  len;
        
        len = DOT(v, v);
        
        if (len <= 0.0)
                return(0.0);
        
        if (len <= 1.0+FTINY && len >= 1.0-FTINY)
                len = 0.5 + 0.5*len;    /* first order approximation */
        else
                len = sqrt(len);

        v[0] /= len;
        v[1] /= len;
        v[2] /= len;

        return(len);
}


void
fcross(vres, v1, v2)            /* vres = v1 X v2 */
register FVECT  vres, v1, v2;
{
        vres[0] = v1[1]*v2[2] - v1[2]*v2[1];
        vres[1] = v1[2]*v2[0] - v1[0]*v2[2];
        vres[2] = v1[0]*v2[1] - v1[1]*v2[0];
}
Revision:	1.3
Committed:	Tue Mar 18 11:05:33 1997 UTC (27 years, 1 month ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.2:	+1 -0 lines
Log Message:	added fh entity and general cleanup
#	User	Rev	Content
1	greg	1.1	/* 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	greg	1.2	len = DOT(v, v);
23	greg	1.1
24			if (len <= 0.0)
25			return(0.0);
26
27	greg	1.2	if (len <= 1.0+FTINY && len >= 1.0-FTINY)
28			len = 0.5 + 0.5len; / first order approximation */
29			else
30			len = sqrt(len);
31	greg	1.1
32			v[0] /= len;
33			v[1] /= len;
34			v[2] /= len;
35
36			return(len);
37			}
38
39
40	greg	1.3	void
41	greg	1.1	fcross(vres, v1, v2) /* vres = v1 X v2 */
42			register FVECT vres, v1, v2;
43			{
44			vres[0] = v1[1]v2[2] - v1[2]v2[1];
45			vres[1] = v1[2]v2[0] - v1[0]v2[2];
46			vres[2] = v1[0]v2[1] - v1[1]v2[0];
47			}