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#ifndef lint |
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static const char RCSid[] = "$Id$"; |
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#endif |
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/* |
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* Anticorrelated random function due to Christophe Schlick |
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*/ |
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/* ==================================================================== |
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* The Radiance Software License, Version 1.0 |
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* |
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* Copyright (c) 1990 - 2002 The Regents of the University of California, |
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* through Lawrence Berkeley National Laboratory. All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in |
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* the documentation and/or other materials provided with the |
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* distribution. |
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* |
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* 3. The end-user documentation included with the redistribution, |
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* if any, must include the following acknowledgment: |
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* "This product includes Radiance software |
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* (http://radsite.lbl.gov/) |
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* developed by the Lawrence Berkeley National Laboratory |
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* (http://www.lbl.gov/)." |
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* Alternately, this acknowledgment may appear in the software itself, |
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* if and wherever such third-party acknowledgments normally appear. |
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* |
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* 4. The names "Radiance," "Lawrence Berkeley National Laboratory" |
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* and "The Regents of the University of California" must |
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* not be used to endorse or promote products derived from this |
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* software without prior written permission. For written |
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* permission, please contact [email protected]. |
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* |
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* 5. Products derived from this software may not be called "Radiance", |
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* nor may "Radiance" appear in their name, without prior written |
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* permission of Lawrence Berkeley National Laboratory. |
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* |
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED |
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
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* DISCLAIMED. IN NO EVENT SHALL Lawrence Berkeley National Laboratory OR |
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF |
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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* SUCH DAMAGE. |
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* ==================================================================== |
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* |
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* This software consists of voluntary contributions made by many |
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* individuals on behalf of Lawrence Berkeley National Laboratory. For more |
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* information on Lawrence Berkeley National Laboratory, please see |
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* <http://www.lbl.gov/>. |
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*/ |
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#include <stdlib.h> |
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greg |
1.1 |
#include "random.h" |
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greg |
2.5 |
#undef initurand |
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1.1 |
|
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gregl |
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#define MAXORDER (8*sizeof(unsigned short)) |
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unsigned short *urperm = NULL; /* urand() permutation */ |
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1.1 |
int urmask; /* bits used in permutation */ |
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gregl |
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int |
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greg |
1.1 |
initurand(size) /* initialize urand() for size entries */ |
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int size; |
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{ |
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int order, n; |
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register int i, offset; |
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if (urperm != NULL) |
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free((void *)urperm); |
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if (--size <= 0) { |
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urperm = NULL; |
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urmask = 0; |
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return(0); |
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} |
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greg |
1.1 |
for (i = 1; size >>= 1; i++) |
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; |
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gregl |
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order = i>MAXORDER ? MAXORDER : i; |
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greg |
1.1 |
urmask = (1<<i) - 1; |
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gregl |
2.4 |
urperm = (unsigned short *)malloc((urmask+1)*sizeof(unsigned short)); |
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greg |
1.1 |
if (urperm == NULL) { |
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eputs("out of memory in initurand\n"); |
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quit(1); |
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} |
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urperm[0] = 0; |
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for (n = 1, offset = 1; n <= order; n++, offset <<= 1) |
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for (i = offset; i--; ) { |
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urperm[i] = |
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urperm[i+offset] = 2*urperm[i]; |
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if (random() & 0x4000) |
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urperm[i]++; |
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else |
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urperm[i+offset]++; |
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} |
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gregl |
2.3 |
return(1<<order); |
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1.2 |
} |
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int |
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1.3 |
ilhash(d, n) /* hash a set of integer values */ |
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greg |
1.2 |
register int *d; |
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register int n; |
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{ |
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static int tab[8] = {13623,353,1637,5831,2314,3887,5832,8737}; |
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greg |
1.4 |
register int hval; |
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greg |
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hval = 0; |
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while (n-- > 0) |
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hval += *d++ * tab[n&7]; |
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greg |
1.3 |
return(hval); |
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greg |
1.1 |
} |