Question Vertex Displacement only at the bottom of the object

I am trying to make ice hanging down from objects. I took Vertext displacement shader from this tutorial https://blogs.unity3d.com/2019/02/12/creating-an-interactive-vertex-effect-using-shader-graph/ and i dont know how to merge this with it

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Shader should deform only the bottom part.

 

What you need to do is take the position node and split it. You can then take the x and z (or r and b as they are listed in the split) and feed those unchanged into a vector3 node. Take the g of the split (which is the y value of the vertex position) use that as a mask by feeding it into a smooth step node. There are a number of tutorials on youtube that use this technique. I'm attaching two screen grabs of a graph I made that hopefully will help. The first shows the set up for the gradient noise I'm using for displacement. The second shows how that ties into isolating the the vertices I am displacing. In my case I am doing the opposite of what you are trying to achieve, so you could add a one minus node after the leap near the end.

Hope this helps.

 

im confused why did you transform from world to object on the end instead of just using object mode during each position node in the graph?