/// <summary>
/// Gets the angle in degrees for a ray that extends from the center
/// of the circle through the given point. An exception will occur,
/// however, if the point specified is the same point as the center
/// of the circle.
/// </summary>
/// <param name="pt">The point.</param>
public decimal AngleThroughPoint(Point2D pt)
{
decimal a = 0m;
// Shift point so it's relative to the origin.
pt += new Vector2D(-Center.X, -Center.Y);
// Do check here after we've translated the point
// to account for small precision rounding.
if (pt == Point2D.Origin)
{
throw new Exception("No angle through given point since point is at center of circle!");
}
// Special case for 0 and 180 where we would get
// a divide by zero below.
if (pt.Y == 0)
{
if (pt.X > 0)
{
return(0);
}
else
{
return(180);
}
}
// Special case for 90 and 270 where we can't
// determine quadrant below.
if (pt.X == 0)
{
if (pt.Y > 0)
{
return(90);
}
else
{
return(270);
}
}
a = DecimalEx.ToDeg(DecimalEx.ATan(pt.X / pt.Y));
switch (pt.Quadrant)
{
case 1:
case 2:
a = 90 - a;
break;
case 3:
case 4:
a = 270 - a;
break;
}
return(a);
}
/// <summary>
/// Gets the angle in degrees between this vector and another.
/// </summary>
/// <param name="other">The other vector to get the angle to.</param>
/// <remarks>See http://en.wikipedia.org/wiki/Dot_product</remarks>
public decimal AngleTo(Vector2D other)
{
if (this.IsNull || other.IsNull)
{
throw new Exception("Can't find angle when one or both vectors are null vectors!");
}
// Cos(theta) = DotProduct(v1,v2) / (length(v1) * length(v2))
// aka theta = acos(v.normalize.dot(other.normalize)), however, the equation
// used gives us better precision
return(DecimalEx.ToDeg(DecimalEx.ACos(this.Dot(other) / (this.Magnitude * other.Magnitude))));
}
/// <summary>
/// Gets the angle of the vector in degrees from the X+ axis. Will return result in the range
/// -180 to +180. Will return 0 for null vector.
/// </summary>
public decimal Angle()
{
return(DecimalEx.ToDeg(DecimalEx.ATan2(Y, X)));
}
/// <summary>
/// Gets angle in degrees from the adjacent side and the hypotenuse.
/// </summary>
/// <param name="adjacentSide">Length of the known side adjacent to the angle.</param>
/// <param name="hypotenuse">Length of the hypotenuse.</param>
public static decimal GetAngleFromAdjSideHyp(decimal adjacentSide, decimal hypotenuse)
{
// cos(a) = adjacentSide / hypotenuse
// a = acos(adjacentSide / hypotenuse)
return(DecimalEx.ToDeg(DecimalEx.ACos(adjacentSide / hypotenuse)));
}
/// <summary>
/// Gets angle in degrees from the opposite side and the hypotenuse.
/// </summary>
/// <param name="oppositeSide">Length of the known side opposite the angle.</param>
/// <param name="hypotenuse">Length of the hypotenuse.</param>
public static decimal GetAngleFromOppSideHyp(decimal oppositeSide, decimal hypotenuse)
{
// sin(a) = oppositeSide / hypotenuse
// a = asin(oppositeSide / hypotenuse)
return(DecimalEx.ToDeg(DecimalEx.ASin(oppositeSide / hypotenuse)));
}
/// <summary>
/// Gets angle in degrees from the two known sides.
/// </summary>
/// <param name="oppositeSide">Length of the known side opposite the angle.</param>
/// <param name="adjacentSide">Length of the known side adjacent to the angle.</param>
public static decimal GetAngleFromSides(decimal oppositeSide, decimal adjacentSide)
{
// tan(a) = opposideSide / adjacentSide
// a = atan(opposideSide / adjacentSide)
return(DecimalEx.ToDeg(DecimalEx.ATan(oppositeSide / adjacentSide)));
}
