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
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	greg	2.2	static const char RCSid[] = "$Id$";
3	greg	1.1	#endif
4			/*
5			* Generate an N-dimensional Peano space-filling curve
6			* on the interval [0,1).
7	greg	2.2	*/
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	greg	1.1	*
60	greg	2.2	* 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	greg	1.1	*/
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	greg	1.2	register double p[];
100	greg	1.1	int n;
101			double t, e;
102			{
103			register int i;
104	greg	1.2	register int neg = 0;
105	greg	1.1
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			}