ofxBullet how to make a spring mesh

I have been looking at the ofxBullet Cloth example.
It’s so beautiful.

I am wondering if it is possible to make the cloth act like the surface of a water pool.
The connections between the separate nodes are seem to be fixed in length right now.
Is it possible to make them elastic so they can stretch up and down, but not side ways?
Water particles move up and down and get pulled and push in the z axis but stay rather fixed in their xy position. At least in what i am trying to do.

Can ->generateBendingConstraints() be used to set this?

in the end i am hoping for something like this:
http://zonalandeducation.com/mstm/physics/waves/interference/twoSource3D/twoSource3D.html

thanks. stephan.