Message-ID:	<F77915E7F086D31197F4009027CC81C903CA2A@ASL-NT-EXCH2>
From:	Shawn Hargreaves <SHargreaves AT acclaimstudios DOT co DOT uk>
To:	djgpp AT delorie DOT com
Subject:	Re: Error blitting to bitmap
Date:	Wed, 27 Oct 1999 12:08:08 +0100
MIME-Version:	1.0
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Reply-To:	djgpp AT delorie DOT com

Lasse Hassing writes:
> int main() {
>   FlukkiB = load_pcx("flukki.pcx", MyPal);
>   generate_optimized_palette(FlukkiB, MyPal, NULL);
[snip]
>  // init Allegro!!
>  allegro_init();

You have a nasty order of processing problem here: it is not a good
idea to be calling Allegro functions before you've initialised
Allegro! In fact, the docs explain that you must also set a graphics
mode before you try to load in any truecolor images, like you are
doing here.

>  // Set GFX driver
>  set_gfx_mode(GFX_AUTODETECT, 320, 240, 320, 240);
>  // Set color depth
>  set_color_depth(32);

Another order of processing error: set_gfx_mode() uses the current
color depth, so you must set the color depth before you call it,
rather than just after (what you are doing here has no effect).

>  // Set active palete
>  set_pallete(MyPal);

Not a bug, but there is no reason to use any palette stuff (or to
bother with the previous palette generation) since your program
is running in a truecolor mode.

>  install_int(BlitTimer, 1000);
[snip]
> void BlitTimer(void)
> {
>   DoBlit();
> }
> END_OF_FUNCTION(BlitTimer);

This is a very bad idea: you are calling lots of complex functions
from inside a timer handler, and haven't locked either the code or
any of the data that this code is using. Since much of this code
and data is buried down inside Allegro, it probably isn't even
possible for you to lock it, so the simple fix is not to do this.
Keep your timer handlers simple, just setting a few flags, and do
all your real work like graphics drawing from the mainline program
code.


	Shawn Hargreaves.

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