/// <summary>
/// This function takes in a destination double vector, and I will tell you how much you need to rotate me in order for me to end up
/// along that destination double vector.
/// </summary>
/// <remarks>
/// This function is a mutated copy of MyVector.GetAngleBetweenVectors. It is almost identical, but slightly more complex :)
///
/// If I am already aligned with the vector passed in, then I will return an arbitrary orthoganal, and an angle of zero.
/// </remarks>
/// <param name="destination">This is the double vector you want me to align myself with</param>
public MyQuaternion GetAngleAroundAxis(DoubleVector destination)
{
#region Standard
// Get the angle
double rotationRadians = MyVector.GetAngleBetweenVectors(this.Standard, destination.Standard);
if (Double.IsNaN(rotationRadians))
{
rotationRadians = 0d;
}
// I need to pull the cross product from me to the vector passed in
MyVector rotationAxis = MyVector.Cross(this.Standard, destination.Standard);
// If the cross product is zero, then there are two possibilities. The vectors point in the same direction, or opposite directions.
if (rotationAxis.IsNearZero)
{
// If I am here, then the angle will either be 0 or PI.
if (Utility3D.IsNearZero(rotationRadians))
{
// The vectors sit on top of each other. I will set the orthoganal to an arbitrary value, and return zero for the radians
rotationAxis.X = 1d;
rotationAxis.Y = 0d;
rotationAxis.Z = 0d;
rotationRadians = 0d;
}
else
{
// The vectors are pointing directly away from each other, because this is a double vector, I must rotate along an axis that
// is orthogonal to my standard and orth
rotationAxis = this.Orth; //MyVector.Cross(this.Standard, this.Orth);
}
}
MyQuaternion quatStandard = new MyQuaternion(rotationAxis, rotationRadians);
//return quatStandard;
#endregion
// I only need to rotate the orth, because I already know where the standard will be
MyVector rotatedOrth = quatStandard.GetRotatedVector(this.Orth, true);
#region Orthogonal
// Grab the angle
rotationRadians = MyVector.GetAngleBetweenVectors(rotatedOrth, destination.Orth);
if (Double.IsNaN(rotationRadians))
{
rotationRadians = 0d;
}
// Since I've rotated the standards onto each other, the rotation axis of the orth is the standard (asumming it was truely orthogonal
// to begin with)
rotationAxis = destination.Standard.Clone();
MyQuaternion quatOrth = new MyQuaternion(rotationAxis, rotationRadians);
#endregion
// Exit Function
//return MyQuaternion.Multiply(quatOrth, quatStandard);
return(MyQuaternion.Multiply(quatStandard, quatOrth));
}