LBS——地理圍欄(JS)
阿新 • • 發佈:2018-12-21
/*
圍欄計算
*/
var GPS_EleFence = {
IsPtInPoly: function (ALon, ALat, APoints) {
var iSum = 0,
iCount;
var dLon1, dLon2, dLat1, dLat2, dLon;
if (APoints.length < 3) return false;
iCount = APoints.length;
for (var i = 0; i < iCount; i++) {
if (i == iCount) {
dLon1 = APoints[i].lng;
dLat1 = APoints[i].lat;
dLon2 = APoints[0].lng;
dLat2 = APoints[0].lat;
} else {
dLon1 = APoints[i].lng;
dLat1 = APoints[i].lat;
dLon2 = APoints[i + 1].lng;
dLat2 = APoints[i + 1].lat;
}
//以下語句判斷A點是否在邊的兩端點的水平平行線之間,在則可能有交點,開始判斷交點是否在左射線上
if (((ALat >= dLat1) && (ALat < dLat2)) || ((ALat >= dLat2) && (ALat < dLat1))) {
if (Math.abs(dLat1 - dLat2) > 0) {
//得到 A點向左射線與邊的交點的x座標:
dLon = dLon1 - ((dLon1 - dLon2) * (dLat1 - ALat)) / (dLat1 - dLat2);
if (dLon < ALon)
iSum++;
}
}
}
if (iSum % 2 != 0)
return true;
return false;
}
};