在系统开发中，有时会用到一些常用的空间算法，引用一些类库是可以解决问题，但是有时类库的运行效率比较慢，引用的东西比较多，如果需要的方法不多，可以写一些简单的计算方法。
下边分享几个常用的gis计算方法：
//判断点是否在面里
public bool IsPointInPolygon(List<CVector> poly, CVector point)
{
int i, j;
bool c = false;
for (i = 0, j = poly.Count - 1; i < poly.Count; j = i++)
{
if ((((poly[i].VY <= point.VY) && (point.VY < poly[j].VY))
|| ((poly[j].VY <= point.VY) && (point.VY < poly[i].VY)))
&& (point.VX < (poly[j].VX - poly[i].VX) * (point.VY - poly[i].VY)
/ (poly[j].VY - poly[i].VY) + poly[i].VX))
{
c = !c;
}
}
return c;
}
//计算弧度
public double Rad(double d)
{
return d * Math.PI / 180.0;
}
//计算角度
public static double RAngle(double d)
{
return d * 180.0 / Math.PI;
}
//计算两个坐标的中心点
public double[] ComputeMidPoint(double lat1, double long1, double lat2, double long2)
{
lat1 = Rad(lat1);
long1 = Rad(long1);
lat2 = Rad(lat2);
long2 = Rad(long2);
var Bx = Math.Cos(lat2) * Math.Cos(long2 - long1);
var By = Math.Cos(lat2) * Math.Sin(long2 - long1);
var _rlat = Math.Atan2(Math.Sin(lat1) + Math.Sin(lat2), Math.Sqrt((Math.Cos(lat1) + Bx) * (Math.Cos(lat1) + Bx) + By * By));
var _rlong = long1 + Math.Atan2(By, Math.Cos(lat1) + Bx);
return new double[] { _rlat, _rlong };
}
//计算一批点的四至坐标
public OCExtent GetPointsExtent(List<CVector> PList)
{
OCExtent cET = new OCExtent();
for (int i = 0; i < PList.Count; i++)
{
CVector aP = PList[i];
if (i == 0)
{
cET.minX = aP.VX;
cET.maxX = aP.VX;
cET.minY = aP.VY;
cET.maxY = aP.VY;
}
else
{
if (cET.minX > aP.VX)
{
cET.minX = aP.VX;
}
else if (cET.maxX < aP.VX)
{
cET.maxX = aP.VX;
}
if (cET.minY > aP.VY)
{
cET.minY = aP.VY;
}
else if (cET.maxY < aP.VY)
{
cET.maxY = aP.VY;
}
}
}
return cET;
}
