This has probably been asked before, but anyway.
I would like to know how to make it so when a player shoots through very thick(unbreakable) glass instead of the standard bulletholes you see a cracked glass mark instead, or like when you shoot a wooden crate the impact mark looks like damaged wood, etc.

I've never done this, but since nobody else replied -- perhaps SCAN_TEXTURE in trace() would do the trick? You could potentially call the trace() on bullet impact, then check TEX_NAME against a list of "special" textures. If it's in the list, apply the appropriate decal.

Hope that helps any.

- Tesanders

It has been a while since I used GameStudio but a trace will return details about what was hit. YOu can check special flags and the texture name. The flags can be set through WED so you could set up certain surfaces to have that flag turned on and when you scan check that flag.