How to make a slider mechanism at crv in kangaroo

Hello, I want to do some physic simulation in kangaroo.
I know how to make a slider mechanism at static trail in kangaroo, like this below:

It works fine.
But the slider won’t follow the trail when the trail’s position has changed (ex. the trail is moved by grab force in kangaroo), like this below:

Is it possible to achieve the goal that the slider mechanism can follow a curvy trail moving by kangaroo force ? (19.6 KB)

I think you should add the pull point on crv tool to keep the end point on the curve.
(just my 2 cent)

After I move the trail crv, it can’t work.

right, and this is expected.
you should create the line starting from a point on the crv. this way the point remain on it while working.

I can’t get “after kangaroo force moved crv” as input crv to create line. Because it will be output to input looping, which is wrong in grasshopper.

I can only get the first original crv as input , which is still the static crv, not moving. So it will get the same wrong resault as before.