src/gen/hermite3.c

#ifndef lint
static const char       RCSid[] = "$Id$";
#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:	2.2
Committed:	Sat Feb 22 02:07:23 2003 UTC (21 years, 2 months ago) by greg
Content type:	text/plain
Branch:	MAIN
CVS Tags:	rad3R5
Changes since 2.1:	+1 -4 lines
Log Message:	Changes and check-in for 3.5 release Includes new source files and modifications not recorded for many years See ray/doc/notes/ReleaseNotes for notes between 3.1 and 3.5 release
#	Content
1	#ifndef lint
2	static const char RCSid[] = "$Id$";
3	#endif
4	/*
5	* hermite.c - routines for 3D hermite curves.
6	*
7	* 10/29/85
8	*/
9
10	#include <stdio.h>
11
12
13	hermite3(hp, p0, p1, r0, r1, t) /* compute point on hermite curve */
14	double hp[3]; /* returned hermite point */
15	double p0[3]; /* first endpoint */
16	double p1[3]; /* second endpoint */
17	double r0[3]; /* tangent at p0 */
18	double r1[3]; /* tangent at p1 */
19	double t; /* position parameter */
20	{
21	register int i;
22	double tmh[4];
23
24	tmh[0] = (2.0t - 3.0)t*t + 1.0;
25	tmh[1] = (-2.0t + 3.0)t*t;
26	tmh[2] = ((t - 2.0)t + 1.0)t;
27	tmh[3] = (t - 1.0)tt;
28
29	for (i = 0; i < 3; i++)
30	hp[i] = p0[i]tmh[0] + p1[i]tmh[1] +
31	r0[i]tmh[2] + r1[i]tmh[3];
32	}
33
34
35	htan3(ht, p0, p1, r0, r1, t) /* compute tangent on hermite curve */
36	double ht[3]; /* returned hermite tangent */
37	double p0[3]; /* first endpoint */
38	double p1[3]; /* second endpoint */
39	double r0[3]; /* tangent at p0 */
40	double r1[3]; /* tangent at p1 */
41	double t; /* position parameter */
42	{
43	register int i;
44	double tpmh[4];
45
46	tpmh[0] = (6.0t - 6.0)t;
47	tpmh[1] = (-6.0t + 6.0)t;
48	tpmh[2] = (3.0t - 4.0)t + 1.0;
49	tpmh[3] = (3.0t - 2.0)t;
50
51	for (i = 0; i < 3; i++)
52	ht[i] = p0[i]tpmh[0] + p1[i]tpmh[1] +
53	r0[i]tpmh[2] + r1[i]tpmh[3];
54	}