src/common/peano.c

#ifndef lint
static const char       RCSid[] = "$Id$";
#endif
/*
 * Generate an N-dimensional Peano space-filling curve
 * on the interval [0,1).
 */

/* ====================================================================
 * The Radiance Software License, Version 1.0
 *
 * Copyright (c) 1990 - 2002 The Regents of the University of California,
 * through Lawrence Berkeley National Laboratory.   All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *         notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in
 *       the documentation and/or other materials provided with the
 *       distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *           if any, must include the following acknowledgment:
 *             "This product includes Radiance software
 *                 (http://radsite.lbl.gov/)
 *                 developed by the Lawrence Berkeley National Laboratory
 *               (http://www.lbl.gov/)."
 *       Alternately, this acknowledgment may appear in the software itself,
 *       if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Radiance," "Lawrence Berkeley National Laboratory"
 *       and "The Regents of the University of California" must
 *       not be used to endorse or promote products derived from this
 *       software without prior written permission. For written
 *       permission, please contact [email protected].
 *
 * 5. Products derived from this software may not be called "Radiance",
 *       nor may "Radiance" appear in their name, without prior written
 *       permission of Lawrence Berkeley National Laboratory.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.   IN NO EVENT SHALL Lawrence Berkeley National Laboratory OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of Lawrence Berkeley National Laboratory.   For more
 * information on Lawrence Berkeley National Laboratory, please see
 * <http://www.lbl.gov/>.
 */

extern double   floor();


static double
peanoC(n, t, e)                 /* compute Peano coordinate */
int     n;
double  t, e;
{
        register int    i;
        double  d;

        if (e >= 1./3.)
                return(t);
        d = 0.;
        while (t-d >= 1./3.)
                d += 1./3.;
        i = n;
        while (--i > 0)
                t *= 3.;
        t = 3.*(t - floor(t));
        i = 0;
        while (t >= 1.) {
                t -= 1.;
                i ^= 1;
        }
        t = peanoC(n, t, 3.*e);
        if (i)
                t = 1. - t;
        return(d + t/3.);
}


peano(p, n, t, e)               /* compute Peano point */
register double  p[];
int     n;
double  t, e;
{
        register int    i;
        register int  neg = 0;

        i = n;
        while (i-- > 0) {
                p[i] = peanoC(n, t, e);
                if (neg)
                        p[i] = 1. - p[i];
                t *= 3.;
                while (t >= 1.) {
                        t -= 1.;
                        neg ^= 1;
                }
        }
}
Revision:	2.2
Committed:	Sat Feb 22 02:07:22 2003 UTC (21 years, 2 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.1:	+57 -5 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	* Generate an N-dimensional Peano space-filling curve
6	* on the interval [0,1).
7	*/
8
9	/* ====================================================================
10	* The Radiance Software License, Version 1.0
11	*
12	* Copyright (c) 1990 - 2002 The Regents of the University of California,
13	* through Lawrence Berkeley National Laboratory. All rights reserved.
14	*
15	* Redistribution and use in source and binary forms, with or without
16	* modification, are permitted provided that the following conditions
17	* are met:
18	*
19	* 1. Redistributions of source code must retain the above copyright
20	* notice, this list of conditions and the following disclaimer.
21	*
22	* 2. Redistributions in binary form must reproduce the above copyright
23	* notice, this list of conditions and the following disclaimer in
24	* the documentation and/or other materials provided with the
25	* distribution.
26	*
27	* 3. The end-user documentation included with the redistribution,
28	* if any, must include the following acknowledgment:
29	* "This product includes Radiance software
30	* (http://radsite.lbl.gov/)
31	* developed by the Lawrence Berkeley National Laboratory
32	* (http://www.lbl.gov/)."
33	* Alternately, this acknowledgment may appear in the software itself,
34	* if and wherever such third-party acknowledgments normally appear.
35	*
36	* 4. The names "Radiance," "Lawrence Berkeley National Laboratory"
37	* and "The Regents of the University of California" must
38	* not be used to endorse or promote products derived from this
39	* software without prior written permission. For written
40	* permission, please contact [email protected].
41	*
42	* 5. Products derived from this software may not be called "Radiance",
43	* nor may "Radiance" appear in their name, without prior written
44	* permission of Lawrence Berkeley National Laboratory.
45	*
46	* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
47	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
48	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
49	* DISCLAIMED. IN NO EVENT SHALL Lawrence Berkeley National Laboratory OR
50	* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
51	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
52	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
53	* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
54	* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
55	* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
56	* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
57	* SUCH DAMAGE.
58	* ====================================================================
59	*
60	* This software consists of voluntary contributions made by many
61	* individuals on behalf of Lawrence Berkeley National Laboratory. For more
62	* information on Lawrence Berkeley National Laboratory, please see
63	* <http://www.lbl.gov/>.
64	*/
65
66	extern double floor();
67
68
69	static double
70	peanoC(n, t, e) /* compute Peano coordinate */
71	int n;
72	double t, e;
73	{
74	register int i;
75	double d;
76
77	if (e >= 1./3.)
78	return(t);
79	d = 0.;
80	while (t-d >= 1./3.)
81	d += 1./3.;
82	i = n;
83	while (--i > 0)
84	t *= 3.;
85	t = 3.*(t - floor(t));
86	i = 0;
87	while (t >= 1.) {
88	t -= 1.;
89	i ^= 1;
90	}
91	t = peanoC(n, t, 3.*e);
92	if (i)
93	t = 1. - t;
94	return(d + t/3.);
95	}
96
97
98	peano(p, n, t, e) /* compute Peano point */
99	register double p[];
100	int n;
101	double t, e;
102	{
103	register int i;
104	register int neg = 0;
105
106	i = n;
107	while (i-- > 0) {
108	p[i] = peanoC(n, t, e);
109	if (neg)
110	p[i] = 1. - p[i];
111	t *= 3.;
112	while (t >= 1.) {
113	t -= 1.;
114	neg ^= 1;
115	}
116	}
117	}