/// <summary>
/// Rotates the matrix by the given amount.
/// </summary>
public void Rotate(Quaternion rot)
{
Matrix4D res = this * rot;
values = res.values;
}
/// <summary>
/// Multiplies two quaternions together.
/// </summary>
public static Quaternion operator *(Quaternion q1, Quaternion q2)
{
// Ignore nulls
if(q1 == null) return null;
if(q2 == null) return null;
// Create vectors from the values
Vector3D v1 = new Vector3D(q1.X, q1.Y, q1.Z);
Vector3D v2 = new Vector3D(q2.X, q2.Y, q2.Z);
double angle = ((q1.W * q2.W) - Vector3D.Dot(v1, v2));
Vector3D cross = Vector3D.Cross(v1, v2);
v1 *= q2.W;
v2 *= q1.W;
Quaternion result = new Quaternion(angle,
(v1.X + v2.X + cross.X),
(v1.Y + v2.Y + cross.Y),
(v1.Z + v2.Z + cross.Z));
return result;
}