//* 计算一个点是否在多边形里
//* @param {Object} pt 标注点 例: pt = {"lat":30,"lng":40}
//* @param {Object} poly 多边形数组
//例 poly = [{"lat":20,"lng":20},{"lat":40,"lng":40},{"lat":20,"lng":60}];
function isInsidePolygon(pt, poly) { ???????????for(var c = false, i = -1, l = poly.length, j = l - 1; ++i < l; j = i) ???????????????((poly[i].lat <= pt.lat && pt.lat < poly[j].lat) || (poly[j].lat <= pt.lat && pt.lat < poly[i].lat)) && ???????????????(pt.lng < (poly[j].lng - poly[i].lng) * (pt.lat - poly[i].lat) / (poly[j].lat - poly[i].lat) + poly[i].lng) && ???????????????(c = !c); ???????????return c; ???????}例：
<!DOCTYPE html><html> ???<head> ???????<meta charset="UTF-8"> ???????<title></title> ???????<script src="//apps.bdimg.com/libs/jquery/1.10.2/jquery.min.js"></script> ???????<style> ???????????*{ ???????????????padding: 0px; ???????????????margin: 0px; ???????????} ???????????#examp { ???????????????width: 500px; ???????????????height: 400px; ???????????????background: #aaa; ???????????????position: relative; ???????????} ???????????????????????#examp>div { ???????????????width: 10px; ???????????????height: 10px; ???????????????border-radius: 50%; ???????????????background: red; ???????????????position: absolute; ???????????} ???????????????????????#examp>.point1 { ???????????????left: 100px; ???????????????top: 10px; ???????????} ???????????????????????#examp>.point2 { ???????????????left: 130px; ???????????????top: 88px; ???????????} ???????????????????????#examp>.point3 { ???????????????left: 70px; ???????????????top: 122px; ???????????} ???????????????????????#examp>.point4 { ???????????????left: 55px; ???????????????top: 30px; ???????????} ???????</style> ???</head> ???<body> ???????<div id="examp"> ???????????<div class="point1">上</div> ???????????<div class="point2">右</div> ???????????<div class="point3">下</div> ???????????<div class="point4">左</div> ???????</div> ???</body> ???<script> ???????$(function(){ ???????????????$("#examp").on("mousemove", function(e) { ???????????????//鼠标坐标 ???????????????var MousePoint = { ???????????????????"lat": e.offsetX, ???????????????????"lng": e.offsetY ???????????????}; ???????????????//自定义 的4个点的坐标 ???????????????/* ???????????????* $("#examp>.point1").offset().left与$("#examp>.point1").offset().right可能存在小数点问题 ???????????????* 可以来个取整 ?parseInt($("#examp>.point1").offset().left+0.5) ???????????????* 我就不写了（重点是方法） ???????????????* pointArr的坐标点集合，是按照上、右、下、在的方式取的（顺时针方向 取坐标） ???????????????* 比如我取的顺序为point1=>point2=>point3=>point4 ???????????????* */ ???????????????var pointArr = [{ ???????????????????"lat":$("#examp>.point1").offset().left, ???????????????????"lng":$("#examp>.point1").offset().top ???????????????},{ ???????????????????"lat":$("#examp>.point2").offset().left, ???????????????????"lng":$("#examp>.point2").offset().top ???????????????},{ ???????????????????"lat":$("#examp>.point3").offset().left, ???????????????????"lng":$("#examp>.point3").offset().top ???????????????},{ ???????????????????"lat":$("#examp>.point4").offset().left, ???????????????????"lng":$("#examp>.point4").offset().top ???????????????}] ???????????????????????????????var loop = isInsidePolygon(MousePoint,pointArr);//是否在 多边形区域内 ???????????????console.log(loop);// ???????????}) ???????}) ???????function isInsidePolygon(pt, poly) { ???????????for(var c = false, i = -1, l = poly.length, j = l - 1; ++i < l; j = i) ???????????????((poly[i].lat <= pt.lat && pt.lat < poly[j].lat) || (poly[j].lat <= pt.lat && pt.lat < poly[i].lat)) && ???????????????(pt.lng < (poly[j].lng - poly[i].lng) * (pt.lat - poly[i].lat) / (poly[j].lat - poly[i].lat) + poly[i].lng) && ???????????????(c = !c); ???????????return c; ???????} ???</script></html>js+jQuery判断一个点是否在多边形中
原文地址：http://www.cnblogs.com/jaegerChong/p/7819633.html