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48 lines
1.6 KiB
48 lines
1.6 KiB
"use strict";
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Object.defineProperty(exports, "__esModule", { value: true });
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exports.isPointInPolygon = isPointInPolygon;
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// 多边形的射线检测，参考：https://blog.csdn.net/WilliamSun0122/article/details/77994526
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var tolerance = 1e-6;
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// 三态函数，判断两个double在eps精度下的大小关系
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function dcmp(x) {
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if (Math.abs(x) < tolerance) {
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return 0;
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}
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return x < 0 ? -1 : 1;
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}
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// 判断点Q是否在p1和p2的线段上
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function onSegment(p1, p2, q) {
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if ((q[0] - p1[0]) * (p2[1] - p1[1]) === (p2[0] - p1[0]) * (q[1] - p1[1]) &&
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Math.min(p1[0], p2[0]) <= q[0] &&
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q[0] <= Math.max(p1[0], p2[0]) &&
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Math.min(p1[1], p2[1]) <= q[1] &&
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q[1] <= Math.max(p1[1], p2[1])) {
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return true;
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}
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return false;
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}
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// 判断点P在多边形内-射线法
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function isPointInPolygon(points, x, y) {
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var isHit = false;
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var n = points.length;
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if (n <= 2) {
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// svg 中点小于 3 个时，不显示，也无法被拾取
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return false;
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}
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for (var i = 0; i < n; i++) {
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var p1 = points[i];
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var p2 = points[(i + 1) % n];
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if (onSegment(p1, p2, [x, y])) {
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// 点在多边形一条边上
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return true;
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}
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// 前一个判断min(p1[1],p2[1])<P.y<=max(p1[1],p2[1])
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// 后一个判断被测点 在 射线与边交点 的左边
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if (dcmp(p1[1] - y) > 0 !== dcmp(p2[1] - y) > 0 &&
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dcmp(x - ((y - p1[1]) * (p1[0] - p2[0])) / (p1[1] - p2[1]) - p1[0]) < 0) {
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isHit = !isHit;
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}
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}
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return isHit;
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}
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//# sourceMappingURL=is-point-in-polygon.js.map
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