求多边形区域内一点
this.locateBylonlat=function(featId,lons,lats,extendSelection){var lonArr=lons.split(',');var latArr=lats.split(',');var len=lonArr.length;var realLen=len-1;var lon;var lat;if(len<=4){var lonMide=(this.myParseFloat(lonArr[1])+this.myParseFloat(lonArr[2]))/2;var latMide=(this.myParseFloat(latArr[1])+this.myParseFloat(latArr[2]))/2; lon=(this.myParseFloat(lonArr[0])+lonMide)/2; lat=(this.myParseFloat(latArr[0])+latMide)/2;this.clickRightTree(featId,lon,lat,extendSelection)}else{var lonV=this.myParseFloat(lonArr[0]);var latV=this.myParseFloat(latArr[0]);var a;var b;var index=0; for(var i=1;i <len-1;i++){ //寻找一个凸顶点，最低点肯定是凸顶点 if(this.myParseFloat(lonArr[i]) <lonV){ lonV=this.myParseFloat(lonArr[i]); latV=this.myParseFloat(latArr[i]); index=i; } } a=(index-1+realLen)%realLen; //得到v的前一个顶点 b=(index+1)%realLen; //得到v的后一个顶点 var q; var latTri=[this.myParseFloat(latArr[a]),this.myParseFloat(latArr[index]),this.myParseFloat(latArr[b])]; var lonTri=[this.myParseFloat(lonArr[a]),this.myParseFloat(lonArr[index]),this.myParseFloat(lonArr[b])]; var md=Number.MAX_VALUE; var bin=false; for(var i=0;i <realLen;i++) { //寻找在三角形avb内且离顶点v最近的顶点q if(i==index)continue; if(i==(index-1+realLen)%realLen)continue; if(i==(index+1)%realLen)continue; if(!this.pnpoly(3,latTri,lonTri,this.myParseFloat(latArr[i]),this.myParseFloat(lonArr[i])))continue; bin=true; var distance=this.dist(lonArr,latArr,index,i); if(distance <md) { q=i; md=distance; } } if(!bin){ //没有顶点在三角形avb内，返回线段ab中点 lon1=(this.myParseFloat(lonArr[a])+this.myParseFloat(lonArr[b]))/2; lat1=(this.myParseFloat(latArr[a])+this.myParseFloat(latArr[b]))/2; lon=(this.myParseFloat(lonArr[index])+lon1)/2; lat=(this.myParseFloat(latArr[index])+lat1)/2; }else{ lon=(this.myParseFloat(lonArr[index])+this.myParseFloat(lonArr[q]))/2; //返回线段vq的中点 lat=(this.myParseFloat(latArr[index])+this.myParseFloat(latArr[q]))/2; } this.clickRightTree(featId,lon,lat,extendSelection)} }this.myParseFloat=function(num){return OpenLayers.Util.toFloat(num);}this.dist=function(lonArr,latArr,i,j){var num1=(lonArr[i]-lonArr[j])*(lonArr[i]-lonArr[j]);var num2=(latArr[i]-latArr[j])*(latArr[i]-latArr[j]);return Math.sqrt(num1+num2);} //google的判断点在不在多边形区域内this.pnpoly=function(nvert, vertx, verty,testx,testy){ var i, j, c = false; for (i = 0, j = nvert-1; i < nvert; j = i++) { if ( ((verty[i]>testy) != (verty[j]>testy)) && (testx < (vertx[j]-vertx[i]) * (testy-verty[i]) / (verty[j]-verty[i]) + vertx[i]) ) c = !c; } return c;}