Projecting Polygons to a mesh through Material

Hi there!

How would I render polygons (eg. runtime calculated from cpp/bp) on another mesh through a material.

The idea is to have multiple colored polygons project onto a landscape for example as an overlay through emissive color.

Here is a Unity Forum post that kind of shows what I want to achieve: “How to project a mesh onto another mesh”

Would it be easier to have the polygons rendered into a render target so the material can just sample from there? I don’t know how that would perform with large scale landscapes though.

Thanks in advance and cheers!