Mail Archives: djgpp/1998/07/18/14:16:58
>I'm programming a very nice game with DJGPP and allegro. I use SVGA
>640*480*256 colors, so graphic looks good. But the problem is the
>double buffering. It's just too slow.
>That is a the only way I can think of, but itsn't fast enough.
>So is there any faster way to do that 'blit(buffer, screen, ...)' ???
Right, so you think double-buffering is too slow in hi-res... TRUE!! I've
begun to code with DJGPP and Allegro just about two weeks ago, but I've
already a lot of experiences in game programming (visit my page!); I've done
a few experiments in SVGA 640x480x65K colors... I wanted to achieve a decent
scrolling engine, but the problem was double buffering... Blitting to the
screen a bitmap as large as the screen itself requires about 5 or 10 bank
switchings depending if you are in 640x480x256 or 640x480x65K mode. For the
scroll I used to make a memory bitmap 4x4 screens wide, and then to blit to
the screen only the visible portion of it, passing to the blit() function
the x and y offset where to begin to copy data from the memory bitmap. This
is pretty fast even in 65K hires mode! If you're going to move some sprites
(you'll surely need this in a game!), I strongly suggest you to use the
dirty blocks method: before drawing every sprite, just get their background
blocks, then put them onto the memory bitmap. Blit this large bitmap to the
screen just like you want, then to move the sprites, before moving them,
draw back their backgrounds on the memory bitmap. Well, now you can move
your sprites and repeat the process as you want.
Using this method you can achieve a fast animation, even if it's a bit more
difficult to code.
Remember: double buffering is a great techinque, but it's fast enough only
in low-res video modes... I think you already experienced that!
Hope this will help you!
bye
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