Doom3world

I had an idea when I was thinking about the wound decal( because they were not aesthetically pleasing during gameplay.) I was wondering if it is possible to have two material shaders on a model at once (with bump/spec maps for each too) and have one overlapping other, then have a decal have a pixel specific nodraw function with alpha(to avoid square decals). I dont know how to explain so here:

ex:

Hellknight throwin crap at me, I have a weapon whose projectiles leave wound decals, when the hellknight is shot the wound decals do not draw the top layer of the hellknight's (1s skin) and exposes the under-layer(2nd skin) which shows things like ribs, muscle, organs etc. So the decal acts as an eraser of the outer skin. I think that the lower-layer would be the primary skin(the flesh skin) and the secondary would be the original hellknight skin. The final product would be a hellknight that is still walking but has wounds that exposes ribs, tibia bone and other surrounding open wounds after taking alot of damage. Imaginethe fat zombie with his intestines showing.

With alpha test transparency and polygon offsetting to combat z-fighting the engine is nearly equipped to do it. The hurdle is the dynamic alpha texture. You'll need to work some magic with the source code.