I'm planning to fade my flashlight code(based on XD1v0 FFP TextProjection), and I found that using mip-map is the only thing I can think of using A7 extra.
The theory is to have different bitmap for different range(mipmap), so the further the range from the camera(in this case, flashlight) the darker the map. But I cant find the way to assign the bmap to mipmap, is this possible?

Maybe, you can do that with a .dds file and an editor that allows you to edit each of its mipmaps seperately.
But, I don't know whether the texture projection fixed fucntion uses the mipmaps.

Ah, yes! DDS, how could I miss that... Thanks mate.
Now to find the dds plugins for GIMP, I know I found it somewhere...
[EDIT]
Yes, the projected texture can use mipmaping.