2 textures 1 box

[Zethariel]

After that horrible, horrible pun for which I will not apologise, I'd like to ask advice on how to go about rendering a texture with an additional overlay to a model?

 

For example, in my races mod, there will be a race that will require the texture to be slightly transparent (so OpenGL blending) and with an additional layer of texture over that (cracks and crevices to simulate a rocky surface)

 

I don't want to add this as an armor layer type, since it needs to stick on the skin, not float above it. Is there any OpenGL function I'm missing specifically designed to applying a texture over another, or do I need to actually generate a separate bindable texture?

 

I mean, doing that wouldn't be such a horrible way out (because I could just apply the overlay during image processing after download from server) but I'd like to know if there is a cost efficient way that would allow me to retiain the original texture (and thus allow for instant race change without having to re-download the texture each time the change occurs)

 

Any help or guidance is very appreciated!