I s it the same as the algorithm to subdive the control points of Bezier curve?

No, use the Cox De-Boor algorithm for any order curve, or use,

Q(t) = { ((1-t)^3)/6) * P0 }

+ { (3t^3 - 6t^2 + 4)/6 * P1 }

+ { (-3t^3 - 6t^2 +3t +1)/6 * P2 }

+ { (t^3/6) * P3 }

for a single cubic segment. (by the way I’m using ^ to represent a power, ie t^3 means t to the power of 3)

[This message has been edited by Rob The Bloke (edited 07-19-2001).]