Game Programming: Faster techniques to draw double layered tilebased maps!

["GameProgrammer.Com" <bob@pendleton.com>]

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GameProgrammer.Com: Game Programming: Faster techniques to
draw double layered tilebased maps!
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By Mike Hammer on Wednesday, June 28, 2000 - 04:19 pm:

 Hiya, Me & a friend of mine,are writing on a platform game,
I handle the drawing techniques.
I have written 2 different routines, 1 who draws the
background tiles (drawing the tiles while looking at the map
for which tile to draw) and another one which draws the
front tiles (does the same as the first one but also checks
what kind of tile it is). The tiles used in the frontlayer
are checked when they are first loaded and are given a
number that tells if they are transparent, half-transparent
or solid. This way they can be drawn with optimal speed as
you don't have to (for example) check every pixel in
solidity, instead you can just write it much faster with a
doubleword. Since these 2 layers are seperate you can have
different speeds on them as you walk, making it look more
realistic, or 3rd dimensional, call it what you want.

Anywayz, I have been thinking alot if these two steps are
possible to draw in one go. As it is now, it first draws the
background layer and then the foreground.

I've seen some emulators, emulating different game machines
and I have a hard time understanding how they can EMULATE a
game machine that draws multiple layers (like 3 or 4 layers)
and do that so fast!

I have been thinking of using a technique, where you draw
everything in one go but as I see it, it would be slower
than what I do no. I also do not know how I should code it,
thinking of that the layers could have completely different
positions.

Heh, this is getting a rather long letter so my question is,
do you think I use the fastest way to draw those 2 layers or
what? Tips on other fast techniques with multilayered
tilemaps are very welcome! I'll keep in touch!

(and btw, of course the routines are written in ASM)

/// Mike Hammer

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