From: ao950 AT FreeNet DOT Carleton DOT CA (Paul Derbyshire)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Some Allegro questions (Shawn?)
Date: 7 Mar 1997 08:46:08 GMT
Organization: The National Capital FreeNet
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George Foot (gfoot AT mc31 DOT merton DOT ox DOT ac DOT uk) writes:
> Paul Derbyshire (ao950 AT FreeNet DOT Carleton DOT CA) wrote:
> 
> : I have several questions about Allegro, mostly out of curiosity...
> 
> : * Why, when using a SVGA mode e.g. GFX_AUTODETECT 640x480, does a
> :   fade_in(palette) or a fade_out() seem to do 4 fades in series instead of
> :   just 1? Fades work as expected in GFX_MODEX. Is it a bug or a "feature"?
> 
> Most likely, you're defining the colour strenghts in your palette from 
> 0 to 255; this is incorrect, the VGA hardware only recognises values from
> 0 to 63. For example, white is (63,63,63) [R,G,B], red is (63,0,0), orange
> is (63,31,0), ...

I'm not defining them anywhere. They are coming straight from a .pcx.
Also, all the example code for Allegro uses 0-256.

> : * When an allegro program that uses sound starts, there is a popping noise.
> :   The noise also happens at exit. I have learned to dread this pop, since
> :   usually if it happens when I'm not expecting it, I find myself staring at
> :   a stack dump a few seconds later. What is it?
> 
> It's your sound card; probably objecting to the change in mixer settings.
> Some cards make a pop when they receive initialisation commands, some don't.

hm. (As for dreading it, it's not that I think it causes gpf's, it's
because I know it comes from allegro_init and allegro_exit, and if it
happens unexpectedly it's the Allegro signal handler handling a crash.)



--
    .*.  Where feelings are concerned, answers are rarely simple [GeneDeWeese]
 -()  <  When I go to the theater, I always go straight to the "bag and mix"
    `*'  bulk candy section...because variety is the spice of life... [me]
Paul Derbyshire ao950 AT freenet DOT carleton DOT ca, http://chat.carleton.ca/~pderbysh