Applying materials differently to one spot of an object based on a bool (ie. use a cube to determine which parts get material A vs. B)?

Question

I am wondering if there is an easy nondestructive way to determine which faces of an object get one material vs. another.

For example, if I have a low poly mountain created by adding the "landscape" add-on and then I want to apply a "snow" material to the upper faces without manually assigning them by selection, can I use a hidden cube to overlap the ones I want the "snow" material for and then have that determine the assignment?

Can this be done in geometry nodes or material nodes somehow?

I always prefer nondestructive editing as it provides much faster prototyping and experimentation.

Thanks for any ideas.

Answer 1

This is a "typical" use case for shader nodes and a little math.

You could e.g. use this node tree to give water to you landscape:

It simply chooses the color by using the z coordinate. Everything which is less then a value you choose will be painted blue.

By using this method you could add different colors to different ares like this:

if you then add a noise texture to make it more random and look more realistic, you could even animate your snow ;)

of course you can always tweak and tune it more and more...like giving waves to your ocean and animating it with color ramp and wave texture:

if you want to control the color by another object e.g. a plane, you can use this node setup:

result: