So after consulting the Search button here, and Google, i am lost. I need a tutorial on how to make those mesh overlays on displacements that valve likes to use for tire tracks. I've extracted a valve map and clicked the displacement and don't see really how it was made. If i stick an overlay onto a displacement in my own map, i get a compile error. I see valve warps the displacement to make the tracks turn and such, but i don't see how exactly. Can someone point me to a tutorial on this? Considering its in almost every valve map, someone has to have written one up. If not, can someone quickly explain how this is done? edit: this is what i'm talking about. thanks!