计算两点连线与X轴正方向的夹角

 ///
<summary>

       
/// 计算两点连线与X轴正方向的夹角

       
/// </summary>

       
/// <param
name="startpt">三维点</param>

       
/// <param
name="endPt">三维点</param>

       
///
<returns>两点连线与X轴正方向的夹角（弧度）</returns>

       
public double GetRealAngle(Point3d startpt, Point3d endPt)

       
{

           
// 两点与X轴正向的夹角

           
double angle = 0.0;

           
if (endPt.Y >= startpt.Y)

           
{

               
Vector3d vec = new Vector3d(endPt.X - startpt.X, endPt.Y -
startpt.Y, 0);

               
angle = vec.GetAngleTo(Vector3d.XAxis);

               
return angle;

           
}

           
else

           
{

               
Vector3d vec = new Vector3d(endPt.X - startpt.X, endPt.Y -
startpt.Y, 0);

               
angle = 2 * Math.PI - vec.GetAngleTo(Vector3d.XAxis);

               
return angle;

           
}

       
}

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