Is there a formula? Or must i approximate it by dividing the curve into line segments and summing them up?

You could analytically divide the curve into n segments and take the limit of the sum as n goes to infinity, this should give you the formula. Or use the integral form which would give the same result (by definition). Did you try this (google cache since the site seems to be down/dead)?

Wow, i tried it and it works, thanks, but i have a question,



what is the D in the b = 2P1 - 2DP0? And why is there no line above P0? I need to understand this so that i could simplify this equation, because i have a very simple case of a bezier curve.

i figured it out from the code.. no need to explain, thanks again.