
Images stored in special format, in RGB triplets.

       
       +---------+---------+---------+
       |lite|colr|lite|colr|lite|colr|
       +---------+---------+---------+
           Red	    Green      Blue

Top half of each byte contains lighting information (brightness)
ranging from 0 to 15 (0x0 - 0xf).

Bottom half contains colour information.  16 * 16 * 16 = 4096 colours.

We tell Allegro that these are 8 bpp images (only, three times are
wide), so for a pixel to be transparent, it must contain zero in all
three RGB components (no light or colour information).



Normal solid colour SPRITES have zero'd out lighting information, and
only contain colour information.  i.e. they give off no light of their
own.

	e.g. tiles, players, pickups


LIGHTMAPS contain zero'd out colour information, and only contain
lighting information.  They light up other objects (as well as
tinting), but do not add any colour to the scene.  Coloured light is
done by varying the amounts of RGB lighting, NOT by adding colour
information (e.g. a red light would have more red than green and
blue).

	e.g. environmental lights, player lights


GLOWBALLS (or plasmas?  I don't have a term for these yet) are a
combination of the two, containing colour and light information.

       e.g. for things like flickering torches, etc (though this is
       probably better done with two separate sprite + lightmap
       combo), and glowing fireballs, missles, bullets, sparks, etc.



[ add a bit on translucency ]
