Drag the dots.
Here's the math written down nicely: b(A, B, C, D, p) = Ap^3 + 3Bp^2 - 3Bp^3 + 3Cp - 6Cp^2 - 3Cp^3 + D - 3Dp + 3Dp^2 - Dp^3 Where A, B, C, and D are points p is the target percentage of the curve. For some reason it starts at D instead of A. Not quite sure why; I guess I got something wrong in my math.
