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| 1 | /* |
| 2 | * p2d_contains_point.c - Determine whether polygon contains point/polygon |
| 3 | * |
| 4 | * Based on the algorithm by W. Randolph Franklin |
| 5 | * http://www.ecse.rpi.edu/Homepages/wrf/Research/Short_Notes/pnpoly.html |
| 6 | * which is distributed under the following license, similar to the 3-clause |
| 7 | * BSD license: |
| 8 | * |
| 9 | * Copyright (c) 1970-2003, Wm. Randolph Franklin |
| 10 | * |
| 11 | * Permission is hereby granted, free of charge, to any person obtaining a |
| 12 | * copy of this software and associated documentation files (the "Software"), |
| 13 | * to deal in the Software without restriction, including without limitation |
| 14 | * the rights to use, copy, modify, merge, publish, distribute, sublicense, |
| 15 | * and/or sell copies of the Software, and to permit persons to whom the |
| 16 | * Software is furnished to do so, subject to the following conditions: |
| 17 | * |
| 18 | * 1. Redistributions of source code must retain the above copyright notice, |
| 19 | * this list of conditions and the following disclaimers. |
| 20 | * 2. Redistributions in binary form must reproduce the above copyright |
| 21 | * notice in the documentation and/or other materials provided with the |
| 22 | * distribution. |
| 23 | * 3. The name of W. Randolph Franklin may not be used to endorse or promote |
| 24 | * products derived from this Software without specific prior written |
| 25 | * permission. |
| 26 | * |
| 27 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| 28 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| 29 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
| 30 | * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| 31 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
| 32 | * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER |
| 33 | * DEALINGS IN THE SOFTWARE. |
| 34 | */ |
| 35 | |
| 36 | |
| 37 | #include <stdbool.h> |
| 38 | |
| 39 | #include "poly2d.h" |
| 40 | |
| 41 | |
| 42 | bool p2d_contains_point(const struct p2d *p, const struct v2d *v) |
| 43 | { |
| 44 | const struct v2d *j, *i; |
| 45 | bool in = 0; |
| 46 | |
| 47 | j = p->v; |
| 48 | do { |
| 49 | i = j->next; |
| 50 | if (((i->y > v->y) != (j->y > v->y)) && |
| 51 | (v->x < (j->x-i->x)*(v->y-i->y)/ |
| 52 | (j->y-i->y)+i->x)) |
| 53 | in = !in; |
| 54 | j = i; |
| 55 | } |
| 56 | while (j != p->v); |
| 57 | return in; |
| 58 | } |
| 59 |
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