Spline maths question

Hi there,

maybe some of the math gurus flying around here know an answer to my "little" problem:
If I have a spline (say a catmull rom with 6 controlpoints), is there any way to calculate the coords based on "distance travelled"?

Hmm, hard to explain...think of this spline as a rope between CP2 and CP5 (with CP1 and CP6 beeing "modifiers"). So how do I manage to get the coords of the rope after 50% of its length?

Found some papers on the net with serious math involved. Seems like I will stick with an approximation using line-segments, unless anyone knows an easier way to do this.

I'm probably missing what you're asking for, but most spline algorithms I've seen interpolate between 0 (the start) and 1 (the end). Just feed in d=0.5 to get the co-ords at 50% of the length of the rope.

I'm not familiar with catmull Rom with 6 control points, only with four. When I wrote a bunch of spline interpolation functions ( which I conveniently can't find at the moment ) I'm pretty sure I used this page as a reference :

http://www.mvps.org/directx/articles/catmull/

You should also be able to find some functions in the code archives for spline interpolation. I know they had cosine, but I thought they had hermite splines or something as well.