How to fix object on curve to move smoothly in geometry nodes?

[saintecaroline]

Hello,

I have created a geometry nodes setup to make a moving sine wave that follows a bezier curve, which then modifies the object (like a curve modifier, but built in geometry nodes). However, I’m having trouble with the animation.

This is the first part of the GN setup for creating the sine wave:

And this is the result, which moves smoothly:

Then, I add a setup to modify the object along that sine wave (the set position nodes are the same in both images). The GN setup is applied directly to the object that is being modified.

The model curves as it should, but the animation isn’t smooth. I keep getting this “inchworming” effect. It is best seen on the tail, where it moves, stops, and then rapidly moves again.

I’m not very proficient with GN, and since most of this was built by following tutorials, I just can’t figure out how to make the movement consistent without that inchworming effect.

I would really appreciate any insights!

[BlenderTimer (Daniel Roberts)]

It’s “inchworming” because the length of your sine wave curve is changing but your mesh object is a fixed length. You can see as the sine curves go around a bend, waves pointing toward the inside make the overall curve shorter and waves pointing toward the outside make the overall curve longer. I think all you need to do to fix this is to use the value from the first Curve Length node you have rather than retrieving the length again after the sine wave is generated.

[saintecaroline]

Ah, so simple and it worked Thank you so much!