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/*
* Sobol sequence direction vectors.
*
* This file contains code to create direction vectors for generating sobol
* sequences in high dimensions. It is adapted from code on this webpage:
*
* http://web.maths.unsw.edu.au/~fkuo/sobol/
*
* From these papers:
*
* S. Joe and F. Y. Kuo, Remark on Algorithm 659: Implementing Sobol's quasirandom
* sequence generator, ACM Trans. Math. Softw. 29, 49-57 (2003)
*
* S. Joe and F. Y. Kuo, Constructing Sobol sequences with better two-dimensional
* projections, SIAM J. Sci. Comput. 30, 2635-2654 (2008)
*/
/* Copyright (c) 2008, Frances Y. Kuo and Stephen Joe
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * 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.
*
* * Neither the names of the copyright holders nor the names of the
* University of New South Wales and the University of Waikato
* and its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``AS IS'' AND ANY
* EXPRESS 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 THE COPYRIGHT HOLDERS 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.
*/
#include "util/util_types.h"
#include "scene/sobol.h"
CCL_NAMESPACE_BEGIN
#include "sobol.tables"
void sobol_generate_direction_vectors(uint vectors[][SOBOL_BITS], int dimensions)
{
assert(dimensions <= SOBOL_MAX_DIMENSIONS);
const uint L = SOBOL_BITS;
/* first dimension is exception */
uint *v = vectors[0];
for (uint i = 0; i < L; i++)
v[i] = 1 << (31 - i); // all m's = 1
for (int dim = 1; dim < dimensions; dim++) {
const SobolDirectionNumbers *numbers = &SOBOL_NUMBERS[dim - 1];
const uint s = numbers->s;
const uint a = numbers->a;
const uint *m = numbers->m;
v = vectors[dim];
if (L <= s) {
for (uint i = 0; i < L; i++)
v[i] = m[i] << (31 - i);
}
else {
for (uint i = 0; i < s; i++)
v[i] = m[i] << (31 - i);
for (uint i = s; i < L; i++) {
v[i] = v[i - s] ^ (v[i - s] >> s);
for (uint k = 1; k < s; k++)
v[i] ^= (((a >> (s - 1 - k)) & 1) * v[i - k]);
}
}
}
}
CCL_NAMESPACE_END
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