/// <summary>
/// Initializes the quaternion so that it orients an object so it faces in te provided direction.
/// </summary>
/// <param name="forward">Direction to orient the object towards.</param>
/// <param name="up">Axis that determines the upward direction of the object.</param>
public void SetLookRotation(Vector3 forward, Vector3 up)
{
Vector3 forwardNrm = Vector3.Normalize(forward);
Vector3 upNrm = Vector3.Normalize(up);
if (MathEx.ApproxEquals(Vector3.Dot(forwardNrm, upNrm), 1.0f))
{
SetLookRotation(forwardNrm);
return;
}
Vector3 x = Vector3.Cross(forwardNrm, upNrm);
Vector3 y = Vector3.Cross(x, forwardNrm);
x.Normalize();
y.Normalize();
this = Quaternion.FromAxes(x, y, -forwardNrm);
}