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/*************************************************************************
* Copyright (C) 2010-2014 Tavian Barnes <tavianator@tavianator.com> *
* *
* This file is part of The Dimension Library. *
* *
* The Dimension Library is free software; you can redistribute it and/ *
* or modify it under the terms of the GNU Lesser General Public License *
* as published by the Free Software Foundation; either version 3 of the *
* License, or (at your option) any later version. *
* *
* The Dimension Library is distributed in the hope that it will be *
* useful, but WITHOUT ANY WARRANTY; without even the implied warranty *
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU *
* Lesser General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public *
* License along with this program. If not, see *
* <http://www.gnu.org/licenses/>. *
*************************************************************************/
/**
* @file
* Checker pattern.
*/
#include "dimension-internal.h"
/** Checker pattern callback. */
static double
dmnsn_checker_pattern_fn(const dmnsn_pattern *checker, dmnsn_vector v)
{
double xmod = fmod(v.x, 2.0);
double ymod = fmod(v.y, 2.0);
double zmod = fmod(v.z, 2.0);
if (xmod < -dmnsn_epsilon)
xmod += 2.0;
if (ymod < -dmnsn_epsilon)
ymod += 2.0;
if (zmod < -dmnsn_epsilon)
zmod += 2.0;
/* Return 0 when an even number of coordinates are in [0, 1), 1 otherwise */
unsigned int n = 0;
if (xmod >= 1.0)
++n;
if (ymod >= 1.0)
++n;
if (zmod >= 1.0)
++n;
return (n%2 == 0) ? 0.0 : 1.0;
}
/** The singleton instance. */
static dmnsn_pattern dmnsn_checker_instance = {
.pattern_fn = dmnsn_checker_pattern_fn,
};
dmnsn_pattern *
dmnsn_new_checker_pattern(dmnsn_pool *pool)
{
return &dmnsn_checker_instance;
}
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