It does that at 2048 for me. I thought it might be a max texture limit but I tried glGetIntegerv(GL_MAX_TEXTURE_SIZE, &texSize); and it showed 16384.
It seems like it's limited by the resolution. Make sure the game resolution is larger than the texture size (ie if your resolution is 1024x768 the max is 512). I've added a check to make sure texture size stays below resolution.
There are other ways to make nicer looking textures but the algorithm would need to be changed and for an RTS I don't think it's a big priority.
Created
ticket 328.