Proposal: Decals and Nameplatesprops to Tomo for the ideaFor some subset of the object's polygons, store an additional set of UV coords. These are the coordinates to be used by the decal texture.
These polygons are then drawn with the following render state info:
- Texture: the nameplate or decal texture
- Texture wrap: Wrap mode for both texture coordinates should be clamp (or possibly clamp to edge); there should be a 1-pixel transparent border*
- Depth: Depth testing enabled, depth function should be "equal", depth mask false (but it doesn't really matter)
- Blending: Blending enabled, alpha-opacity based blending
Because the polygons' vertices are identical to those of the model, there's no need to worry about z-fighting; the depth for the nameplate/decal is exactly the same as the depth for the 'hull' polygons.
*I've never used it, but OpenGL has some texture parameter options relating to a "border", which from my reading of the documentation, would let you control what color stuff is in the repeating portion of the texture (when it's set to not tile)