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57 lines
2.0 KiB
C
57 lines
2.0 KiB
C
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/*
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* p2d_contains_point.c - Determine whether polygon contains point/polygon
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*
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* Based on the algorithm by W. Randolph Franklin
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* http://www.ecse.rpi.edu/Homepages/wrf/Research/Short_Notes/pnpoly.html
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* which is distributed under the following license, similar to the 3-clause
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* BSD license:
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*
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* Copyright (c) 1970-2003, Wm. Randolph Franklin
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimers.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice in the documentation and/or other materials provided with the
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* distribution.
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* 3. The name of W. Randolph Franklin may not be used to endorse or promote
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* products derived from this Software without specific prior written
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* permission.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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* DEALINGS IN THE SOFTWARE.
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*/
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#include "poly2d.h"
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int p2d_contains_point(const struct p2d *p, const struct v2d *v)
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{
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const struct v2d *j, *i;
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int in = 0;
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j = p->v;
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do {
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i = j->next;
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if (((i->y > v->y) != (j->y > v->y)) &&
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(v->x < (j->x-i->x)*(v->y-i->y)/
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(j->y-i->y)+i->x))
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in = !in;
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j = i;
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}
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while (j != p->v);
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return in;
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}
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