public static void ToAxisAngle(this __type__ r, ref __v3t__ axis, ref __ftype__ angleInRadians)
{
angleInRadians = 2 * Fun.Acos(r.W);
var s = Fun.Sqrt(1 - r.W * r.W); // assuming quaternion normalised then w is less than 1, so term always positive.
if (s < 0.001)
{ // test to avoid divide by zero, s is always positive due to sqrt
// if s close to zero then direction of axis not important
axis.X = r.X; // if it is important that axis is normalised then replace with x=1; y=z=0;
axis.Y = r.Y;
axis.Z = r.Z;
}
else
{
axis.X = r.X / s; // normalise axis
axis.Y = r.Y / s;
axis.Z = r.Z / s;
}
}
