Can a decal material be used with Vertex paint the same way a regular material can? I made some graffiti decals, and wanted to add a way to paint parts of them out so that I could get more mileage from one material, but since the decal basically rests "on top" of the geo it doesn't appear to be letting me paint it. Is it…
You wont be able to paint the textures behind the decal onto the decal to make it fade away but you should be able to blend off the decal from showing to not showing. Example. White is 100% showing decal, black is 0% showing decal (ie 100% alphaed out) and then paint away parts you dont want.
I've never tried doing what you're suggesting but I don't think it will be possible. Decals technically are meshes, they need to be to render, but they're typically generated at run-time. In the editor you only have the decal actor, or basically the projector, but not the mesh.
So how do you paint it? I only know how to use the "Mesh Paint" brush, and I can't even paint on a decal on that since there is no Mesh I guess to paint on?