Rendering wireframe over a filled mesh

I’m attempting to render landscape similar to what you would see in Darwinia. I’m more or less looking for a filled in wireframe. I found a suggestion for using the cartoon edge filter, but I want to draw all of the triangles used in a mesh, not just the edge. That or somehow overlaying a second material set to wireframe over the mesh. Any help is greatly appreciated!

First rendering it as a fully shaded material and then rendering it with Wireframe Material and setting the background to transparent should do the trick, shoudlnt it?

Thats the naive attempt, i guess.

Sounds like a job for a custom shader. Draw the lines black, draw between the lines in colour, etc.