Js判断点在几何内算法

本文转载自：CSDN博客

JS判断点在几何内部

---

重新编辑我

点击查看详细内容

  var checkPoint = [120.94816,31.28292];
  var polygonPoints =[ 
    [ 118.2216439660001, 33.940503869000054 ],
    [ 118.22536301900004, 33.94065932400002 ],
    [ 118.22544694300007, 33.93926268600006 ],
    [ 118.22175661300003, 33.939258077000034 ],
    [ 118.22175552400006, 33.93926727100006 ],
    [ 118.2217219050001, 33.93983108300006 ],
    [ 118.22171830600007, 33.93987282300003 ],
    [ 118.2217123260001, 33.939914291000036 ],
    [ 118.22170407500005, 33.93995548700008 ],
    [ 118.22168107000005, 33.94005563700006 ],
    [ 118.2216728200001, 33.940096924000045 ],
    [ 118.221666948, 33.94013839200005 ],
    [ 118.22166324000011, 33.94018013200008 ],
    [ 118.2216439660001, 33.940503869000054 ] 
  ];
function isInPolygon(checkPoint, polygonPoints) {
    var counter = 0;
    var i;
    var xinters;
    var p1, p2;
    var pointCount = polygonPoints.length;
    p1 = polygonPoints[0];
 
    for (i = 1; i <= pointCount; i++) {
        p2 = polygonPoints[i % pointCount];
        if (
            checkPoint[0] > Math.min(p1[0], p2[0]) &&
            checkPoint[0] <= Math.max(p1[0], p2[0])
        ) {
            if (checkPoint[1] <= Math.max(p1[1], p2[1])) {
                if (p1[0] != p2[0]) {
                    xinters =
                        (checkPoint[0] - p1[0]) *
                            (p2[1] - p1[1]) /
                            (p2[0] - p1[0]) +
                        p1[1];
                    if (p1[1] == p2[1] || checkPoint[1] <= xinters) {
                        counter++;
                    }
                }
            }
        }
        p1 = p2;
    }
    if (counter % 2 == 0) {
        return false;
    } else {
        return true;
    }
}

---

指的一提的是，参数checkPoint, polygonPoints不论是经纬度坐标还是空间直角坐标系XYZ都能够运行。