Eric, I need a function to return the distance along a spline, given a 3d point. So kind of the opposite of GetPoint3D. Without a better idea (i.e. the reason for this post), I plan to do something like this: 1) check to see if the input 3d point is in the splines points3. I'll do this with a for loop, using Vector3.Distance to see if they are close within some tolerance. 2) if this returns a point, I'll infer a distance by dividing the returned point's position in the points3 array by the total number of points in points3. Just wonder what you think. Is there something for this already. If not, is my logic reasonable or is there a better way? Thanks!