src/gen/hermite3.c

/* Copyright (c) 1986 Regents of the University of California */

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

/*
 *  hermite.c - routines for 3D hermite curves.
 *
 *     10/29/85
 */

#include  <stdio.h>


hermite3(hp, p0, p1, r0, r1, t)         /* compute point on hermite curve */
double  hp[3];          /* returned hermite point */
double  p0[3];          /* first endpoint */
double  p1[3];          /* second endpoint */
double  r0[3];          /* tangent at p0 */
double  r1[3];          /* tangent at p1 */
double  t;              /* position parameter */
{
        register int  i;
        double  tmh[4];
        
        tmh[0] = (2.0*t - 3.0)*t*t + 1.0;
        tmh[1] = (-2.0*t + 3.0)*t*t;
        tmh[2] = ((t - 2.0)*t + 1.0)*t;
        tmh[3] = (t - 1.0)*t*t;
        
        for (i = 0; i < 3; i++)
                hp[i] = p0[i]*tmh[0] + p1[i]*tmh[1] +
                        r0[i]*tmh[2] + r1[i]*tmh[3];
}


htan3(ht, p0, p1, r0, r1, t)            /* compute tangent on hermite curve */
double  ht[3];          /* returned hermite tangent */
double  p0[3];          /* first endpoint */
double  p1[3];          /* second endpoint */
double  r0[3];          /* tangent at p0 */
double  r1[3];          /* tangent at p1 */
double  t;              /* position parameter */
{
        register int  i;
        double  tpmh[4];
        
        tpmh[0] = (6.0*t - 6.0)*t;
        tpmh[1] = (-6.0*t + 6.0)*t;
        tpmh[2] = (3.0*t - 4.0)*t + 1.0;
        tpmh[3] = (3.0*t - 2.0)*t;
        
        for (i = 0; i < 3; i++)
                ht[i] = p0[i]*tpmh[0] + p1[i]*tpmh[1] +
                        r0[i]*tpmh[2] + r1[i]*tpmh[3];
}
Revision:	2.1
Committed:	Tue Nov 12 17:04:40 1991 UTC (33 years, 11 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.1:	+0 -0 lines
Log Message:	updated revision number for release 2.0
#	User	Rev	Content
1	greg	1.1	/* Copyright (c) 1986 Regents of the University of California */
2
3			#ifndef lint
4			static char SCCSid[] = "$SunId$ LBL";
5			#endif
6
7			/*
8			* hermite.c - routines for 3D hermite curves.
9			*
10			* 10/29/85
11			*/
12
13			#include <stdio.h>
14
15
16			hermite3(hp, p0, p1, r0, r1, t) /* compute point on hermite curve */
17			double hp[3]; /* returned hermite point */
18			double p0[3]; /* first endpoint */
19			double p1[3]; /* second endpoint */
20			double r0[3]; /* tangent at p0 */
21			double r1[3]; /* tangent at p1 */
22			double t; /* position parameter */
23			{
24			register int i;
25			double tmh[4];
26
27			tmh[0] = (2.0t - 3.0)t*t + 1.0;
28			tmh[1] = (-2.0t + 3.0)t*t;
29			tmh[2] = ((t - 2.0)t + 1.0)t;
30			tmh[3] = (t - 1.0)tt;
31
32			for (i = 0; i < 3; i++)
33			hp[i] = p0[i]tmh[0] + p1[i]tmh[1] +
34			r0[i]tmh[2] + r1[i]tmh[3];
35			}
36
37
38			htan3(ht, p0, p1, r0, r1, t) /* compute tangent on hermite curve */
39			double ht[3]; /* returned hermite tangent */
40			double p0[3]; /* first endpoint */
41			double p1[3]; /* second endpoint */
42			double r0[3]; /* tangent at p0 */
43			double r1[3]; /* tangent at p1 */
44			double t; /* position parameter */
45			{
46			register int i;
47			double tpmh[4];
48
49			tpmh[0] = (6.0t - 6.0)t;
50			tpmh[1] = (-6.0t + 6.0)t;
51			tpmh[2] = (3.0t - 4.0)t + 1.0;
52			tpmh[3] = (3.0t - 2.0)t;
53
54			for (i = 0; i < 3; i++)
55			ht[i] = p0[i]tpmh[0] + p1[i]tpmh[1] +
56			r0[i]tpmh[2] + r1[i]tpmh[3];
57			}