Let a dot move along a mesh

Hi everyone!

I don’t know how to solve this problem:
I have a simple mesh (see image) and I want to let a quad move along the border of this mesh. Can you give me an approach?

https://vvvv.org/sites/default/files/imagecache/large/images/example_0.png

Thanks in advance!

Try B-Spline

works! thank you