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48 lines
1.7 KiB
JavaScript
48 lines
1.7 KiB
JavaScript
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/*
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The MIT License (MIT)
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Copyright (c) 2016 James Halliday
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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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 THE
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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 FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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*/
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function pointIsInPolygon (point, polygon) {
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// ray-casting algorithm based on
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// http://www.ecse.rpi.edu/Homepages/wrf/Research/Short_Notes/pnpoly.html
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var x = point[0], y = point[1];
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var inside = false;
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for (var i = 0, j = polygon.length - 1; i < polygon.length; j = i++) {
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var xi = polygon[i][0], yi = polygon[i][1];
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var xj = polygon[j][0], yj = polygon[j][1];
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var intersect = ((yi > y) != (yj > y))
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&& (x < (xj - xi) * (y - yi) / (yj - yi) + xi);
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if (intersect) inside = !inside;
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}
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return inside;
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};
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