百度地圖API 判斷點是否在圓形內

jopen 9年前發布 | 4K 次閱讀 JavaScript
 /**

@fileoverview GeoUtils類提供若干幾何算法，用來幫助用戶判斷點與矩形、
圓形、多邊形線、多邊形面的關系,并提供計算折線長度和多邊形的面積的公式。 
主入口類是<a href="symbols/BMapLib.GeoUtils.html">GeoUtils</a>，
基于Baidu Map API 1.2。
*
@author Baidu Map Api Group 
@version 1.2
*/
/**

@namespace BMap的所有library類均放在BMapLib命名空間下
*/
var BMapLib = window.BMapLib = BMapLib || {};
(function() { 

/**

地球半徑
*/
var EARTHRADIUS = 6370996.81; 

/**

@exports GeoUtils as BMapLib.GeoUtils 
*/
var GeoUtils =
/**
GeoUtils類，靜態類，勿需實例化即可使用
@class GeoUtils類的<b>入口</b>。
該類提供的都是靜態方法，勿需實例化即可使用。

*/
BMapLib.GeoUtils = function(){

}
/**

判斷點是否在矩形內
@param {Point} point 點對象
@param {Bounds} bounds 矩形邊界對象
@returns {Boolean} 點在矩形內返回true,否則返回false
*/
GeoUtils.isPointInRect = function(point, bounds){
 //檢查類型是否正確
 if (!(point instanceof BMap.Point) || 
 !(bounds instanceof BMap.Bounds)) {
 return false;

 }
 var sw = bounds.getSouthWest(); //西南腳點
 var ne = bounds.getNorthEast(); //東北腳點
 return (point.lng >= sw.lng && point.lng <= ne.lng && point.lat >= sw.lat && point.lat <= ne.lat);
}

/**

判斷點是否在圓形內
@param {Point} point 點對象
@param {Circle} circle 圓形對象
@returns {Boolean} 點在圓形內返回true,否則返回false
*/
GeoUtils.isPointInCircle = function(point, circle){
 //檢查類型是否正確
 if (!(point instanceof BMap.Point) ||

 !(circle instanceof BMap.Circle)) {
 return false;

}
//point與圓心距離小于圓形半徑，則點在圓內，否則在圓外
 var c = circle.getCenter();
 var r = circle.getRadius();
var dis = GeoUtils.getDistance(point, c);
 if(dis <= r){

 return true;

} else {

 return false;

}
}


/**

判斷點是否在折線上
@param {Point} point 點對象
@param {Polyline} polyline 折線對象
@returns {Boolean} 點在折線上返回true,否則返回false
*/
GeoUtils.isPointOnPolyline = function(point, polyline){
 //檢查類型
 if(!(point instanceof BMap.Point) ||

 !(polyline instanceof BMap.Polyline)){
 return false;

}
//首先判斷點是否在線的外包矩形內，如果在，則進一步判斷，否則返回false
 var lineBounds = polyline.getBounds();
 if(!this.isPointInRect(point, lineBounds)){

 return false;

}
//判斷點是否在線段上，設點為Q，線段為P1P2 ，
 //判斷點Q在該線段上的依據是：( Q - P1 ) × ( P2 - P1 ) = 0，且 Q 在以 P1，P2為對角頂點的矩形內
 var pts = polyline.getPath();
 for(var i = 0; i < pts.length - 1; i++){

var curPt = pts[i];
var nextPt = pts[i + 1];
//首先判斷point是否在curPt和nextPt之間，即：此判斷該點是否在該線段的外包矩形內
if (point.lng >= Math.min(curPt.lng, nextPt.lng) && point.lng <= Math.max(curPt.lng, nextPt.lng) &&
    point.lat >= Math.min(curPt.lat, nextPt.lat) && point.lat <= Math.max(curPt.lat, nextPt.lat)){
    //判斷點是否在直線上公式
    var precision = (curPt.lng - point.lng) * (nextPt.lat - point.lat) - 
        (nextPt.lng - point.lng) * (curPt.lat - point.lat);                
    if(precision < 2e-10 && precision > -2e-10){//實質判斷是否接近0
        return true;
    }                
}

}
return false;
}


/**

判斷點是否多邊形內
@param {Point} point 點對象
@param {Polyline} polygon 多邊形對象
@returns {Boolean} 點在多邊形內返回true,否則返回false
*/
GeoUtils.isPointInPolygon = function(point, polygon){
 //檢查類型
 if(!(point instanceof BMap.Point) ||

 !(polygon instanceof BMap.Polygon)){
 return false;

}
//首先判斷點是否在多邊形的外包矩形內，如果在，則進一步判斷，否則返回false
 var polygonBounds = polygon.getBounds();
 if(!this.isPointInRect(point, polygonBounds)){

 return false;

}
var pts = polygon.getPath();//獲取多邊形點
//下述代碼來源：http://paulbourke.net/geometry/insidepoly/，進行了部分修改
 //基本思想是利用射線法，計算射線與多邊形各邊的交點，如果是偶數，則點在多邊形外，否則
 //在多邊形內。還會考慮一些特殊情況，如點在多邊形頂點上，點在多邊形邊上等特殊情況。
var N = pts.length;
 var boundOrVertex = true; //如果點位于多邊形的頂點或邊上，也算做點在多邊形內，直接返回true
 var intersectCount = 0;//cross points count of x 
 var precision = 2e-10; //浮點類型計算時候與0比較時候的容差
 var p1, p2;//neighbour bound vertices
 var p = point; //測試點
p1 = pts[0];//left vertex

 for(var i = 1; i <= N; ++i){//check all rays

 if(p.equals(p1)){
     return boundOrVertex;//p is an vertex
 }

 p2 = pts[i % N];//right vertex            
 if(p.lat < Math.min(p1.lat, p2.lat) || p.lat > Math.max(p1.lat, p2.lat)){//ray is outside of our interests                
     p1 = p2; 
     continue;//next ray left point
 }

 if(p.lat > Math.min(p1.lat, p2.lat) && p.lat < Math.max(p1.lat, p2.lat)){//ray is crossing over by the algorithm (common part of)
     if(p.lng <= Math.max(p1.lng, p2.lng)){//x is before of ray                    
         if(p1.lat == p2.lat && p.lng >= Math.min(p1.lng, p2.lng)){//overlies on a horizontal ray
             return boundOrVertex;
         }

         if(p1.lng == p2.lng){//ray is vertical                        
             if(p1.lng == p.lng){//overlies on a vertical ray
                 return boundOrVertex;
             }else{//before ray
                 ++intersectCount;
             } 
         }else{//cross point on the left side                        
             var xinters = (p.lat - p1.lat) * (p2.lng - p1.lng) / (p2.lat - p1.lat) + p1.lng;//cross point of lng                        
             if(Math.abs(p.lng - xinters) < precision){//overlies on a ray
                 return boundOrVertex;
             }

             if(p.lng < xinters){//before ray
                 ++intersectCount;
             } 
         }
     }
 }else{//special case when ray is crossing through the vertex                
     if(p.lat == p2.lat && p.lng <= p2.lng){//p crossing over p2                    
         var p3 = pts[(i+1) % N]; //next vertex                    
         if(p.lat >= Math.min(p1.lat, p3.lat) && p.lat <= Math.max(p1.lat, p3.lat)){//p.lat lies between p1.lat & p3.lat
             ++intersectCount;
         }else{
             intersectCount += 2;
         }
     }
 }            
 p1 = p2;//next ray left point

}
if(intersectCount % 2 == 0){//偶數在多邊形外

 return false;

} else { //奇數在多邊形內

 return true;

}

}


/**

將度轉化為弧度
@param {degree} Number 度     
@returns {Number} 弧度
/
GeoUtils.degreeToRad =  function(degree){
 return Math.PI  degree/180;

}

/**

將弧度轉化為度
@param {radian} Number 弧度     
@returns {Number} 度
/
GeoUtils.radToDegree = function(rad){
 return (180  rad) / Math.PI;

}

/**

將v值限定在a,b之間，緯度使用
*/
function _getRange(v, a, b){
 if(a != null){
   v = Math.max(v, a);
 }
 if(b != null){
   v = Math.min(v, b);
 }
 return v;
}

/**

將v值限定在a,b之間，經度使用
*/
function _getLoop(v, a, b){
 while( v > b){
   v -= b - a
 }
 while(v < a){
   v += b - a
 }
 return v;
}

/**

計算兩點之間的距離,兩點坐標必須為經緯度
@param {point1} Point 點對象
@param {point2} Point 點對象
@returns {Number} 兩點之間距離，單位為米
*/
GeoUtils.getDistance = function(point1, point2){
 //判斷類型
 if(!(point1 instanceof BMap.Point) ||

 !(point2 instanceof BMap.Point)){
 return 0;

}
point1.lng = _getLoop(point1.lng, -180, 180);
 point1.lat = _getRange(point1.lat, -74, 74);
 point2.lng = _getLoop(point2.lng, -180, 180);
 point2.lat = _getRange(point2.lat, -74, 74);
var x1, x2, y1, y2;
 x1 = GeoUtils.degreeToRad(point1.lng);
 y1 = GeoUtils.degreeToRad(point1.lat);
 x2 = GeoUtils.degreeToRad(point2.lng);
 y2 = GeoUtils.degreeToRad(point2.lat);
return EARTHRADIUS  Math.acos((Math.sin(y1)  Math.sin(y2) + Math.cos(y1)  Math.cos(y2)  Math.cos(x2 - x1)));

}


/**

計算折線或者點數組的長度
@param {Polyline|Array<Point>} polyline 折線對象或者點數組
@returns {Number} 折線或點數組對應的長度
*/
GeoUtils.getPolylineDistance = function(polyline){
 //檢查類型
 if(polyline instanceof BMap.Polyline ||

 polyline instanceof Array){
 //將polyline統一為數組
 var pts;
 if(polyline instanceof BMap.Polyline){
     pts = polyline.getPath();
 } else {
     pts = polyline;
 }

 if(pts.length < 2){//小于2個點，返回0
     return 0;
 }

 //遍歷所有線段將其相加，計算整條線段的長度
 var totalDis = 0;
 for(var i =0; i < pts.length - 1; i++){
     var curPt = pts[i];
     var nextPt = pts[i + 1]
     var dis = GeoUtils.getDistance(curPt, nextPt);
     totalDis += dis;
 }

 return totalDis;


} else {

 return 0;

}
}


/**

計算多邊形面或點數組構建圖形的面積,注意：坐標類型只能是經緯度，且不適合計算自相交多邊形的面積
@param {Polygon|Array<Point>} polygon 多邊形面對象或者點數組
@returns {Number} 多邊形面或點數組構成圖形的面積
*/
GeoUtils.getPolygonArea = function(polygon){
 //檢查類型
 if(!(polygon instanceof BMap.Polygon) &&

 !(polygon instanceof Array)){
 return 0;

}
 var pts;
 if(polygon instanceof BMap.Polygon){

 pts = polygon.getPath();

}else{

 pts = polygon;    

}
if(pts.length < 3){//小于3個頂點，不能構建面

 return 0;

}
var totalArea = 0;//初始化總面積
 var LowX = 0.0;
 var LowY = 0.0;
 var MiddleX = 0.0;
 var MiddleY = 0.0;
 var HighX = 0.0;
 var HighY = 0.0;
 var AM = 0.0;
 var BM = 0.0;
 var CM = 0.0;
 var AL = 0.0;
 var BL = 0.0;
 var CL = 0.0;
 var AH = 0.0;
 var BH = 0.0;
 var CH = 0.0;
 var CoefficientL = 0.0;
 var CoefficientH = 0.0;
 var ALtangent = 0.0;
 var BLtangent = 0.0;
 var CLtangent = 0.0;
 var AHtangent = 0.0;
 var BHtangent = 0.0;
 var CHtangent = 0.0;
 var ANormalLine = 0.0;
 var BNormalLine = 0.0;
 var CNormalLine = 0.0;
 var OrientationValue = 0.0;
 var AngleCos = 0.0;
 var Sum1 = 0.0;
 var Sum2 = 0.0;
 var Count2 = 0;
 var Count1 = 0;
 var Sum = 0.0;
 var Radius = EARTHRADIUS; //6378137.0,WGS84橢球半徑 
 var Count = pts.length;

 for (var i = 0; i < Count; i++) {

 if (i == 0) {
     LowX = pts[Count - 1].lng * Math.PI / 180;
     LowY = pts[Count - 1].lat * Math.PI / 180;
     MiddleX = pts[0].lng * Math.PI / 180;
     MiddleY = pts[0].lat * Math.PI / 180;
     HighX = pts[1].lng * Math.PI / 180;
     HighY = pts[1].lat * Math.PI / 180;
 }
 else if (i == Count - 1) {
     LowX = pts[Count - 2].lng * Math.PI / 180;
     LowY = pts[Count - 2].lat * Math.PI / 180;
     MiddleX = pts[Count - 1].lng * Math.PI / 180;
     MiddleY = pts[Count - 1].lat * Math.PI / 180;
     HighX = pts[0].lng * Math.PI / 180;
     HighY = pts[0].lat * Math.PI / 180;
 }
 else {
     LowX = pts[i - 1].lng * Math.PI / 180;
     LowY = pts[i - 1].lat * Math.PI / 180;
     MiddleX = pts[i].lng * Math.PI / 180;
     MiddleY = pts[i].lat * Math.PI / 180;
     HighX = pts[i + 1].lng * Math.PI / 180;
     HighY = pts[i + 1].lat * Math.PI / 180;
 }
 AM = Math.cos(MiddleY) * Math.cos(MiddleX);
 BM = Math.cos(MiddleY) * Math.sin(MiddleX);
 CM = Math.sin(MiddleY);
 AL = Math.cos(LowY) * Math.cos(LowX);
 BL = Math.cos(LowY) * Math.sin(LowX);
 CL = Math.sin(LowY);
 AH = Math.cos(HighY) * Math.cos(HighX);
 BH = Math.cos(HighY) * Math.sin(HighX);
 CH = Math.sin(HighY);
 CoefficientL = (AM * AM + BM * BM + CM * CM) / (AM * AL + BM * BL + CM * CL);
 CoefficientH = (AM * AM + BM * BM + CM * CM) / (AM * AH + BM * BH + CM * CH);
 ALtangent = CoefficientL * AL - AM;
 BLtangent = CoefficientL * BL - BM;
 CLtangent = CoefficientL * CL - CM;
 AHtangent = CoefficientH * AH - AM;
 BHtangent = CoefficientH * BH - BM;
 CHtangent = CoefficientH * CH - CM;
 AngleCos = (AHtangent * ALtangent + BHtangent * BLtangent + CHtangent * CLtangent) / (Math.sqrt(AHtangent * AHtangent + BHtangent * BHtangent + CHtangent * CHtangent) * Math.sqrt(ALtangent * ALtangent + BLtangent * BLtangent + CLtangent * CLtangent));
 AngleCos = Math.acos(AngleCos);            
 ANormalLine = BHtangent * CLtangent - CHtangent * BLtangent;
 BNormalLine = 0 - (AHtangent * CLtangent - CHtangent * ALtangent);
 CNormalLine = AHtangent * BLtangent - BHtangent * ALtangent;
 if (AM != 0)
     OrientationValue = ANormalLine / AM;
 else if (BM != 0)
     OrientationValue = BNormalLine / BM;
 else
     OrientationValue = CNormalLine / CM;
 if (OrientationValue > 0) {
     Sum1 += AngleCos;
     Count1++;
 }
 else {
     Sum2 += AngleCos;
     Count2++;
 }

}

 var tempSum1, tempSum2;
 tempSum1 = Sum1 + (2  Math.PI  Count2 - Sum2);
 tempSum2 = (2  Math.PI  Count1 - Sum1) + Sum2;
 if (Sum1 > Sum2) {

 if ((tempSum1 - (Count - 2) * Math.PI) < 1)
     Sum = tempSum1;
 else
     Sum = tempSum2;

}
 else {

 if ((tempSum2 - (Count - 2) * Math.PI) < 1)
     Sum = tempSum2;
 else
     Sum = tempSum1;

}
 totalArea = (Sum - (Count - 2)  Math.PI)  Radius * Radius;
return totalArea; //返回總面積
}




})();//閉包結束</pre> 

 使用方法：
var point = new BMap.Point(x,y)
var circle = new BMap.Circle(mPoint,1000,{fillColor:"blue", strokeWeight: 1 ,fillOpacity: 0.3, strokeOpacity: 0.3});
if(BMapLib.GeoUtils.isPointInCircle(point,circle)){
    alert("該point在circle內");
}</pre> 

 鏈接：
GeoUtils.js 

 作者：
itmyhome
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JavaScript
百度地圖API 判斷點是否在圓形內

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