Re: [MiNT] XaAES: detect pixel-format-problem

[Lonny Pursell <atari@bright.net>]

on 12/1/09 2:48 AM, Jo Even Skarstein wrote:

> -------------------------------------------------
> From: "Lonny Pursell" <atari@bright.net>
> Sent: Tuesday, December 01, 2009 5:52 AM
> To: "[MiNT] Mailing-List" <mint@fishpool.com>
> Subject: Re: [MiNT] XaAES: detect pixel-format-problem
> 
>>> If I use e.g.:
>>> 
>>>      {
>>>      RECT r = {0,0,v->screen.w,v->screen.h};
>>>      (*v->api->f_color)(v, 6 );
>>>      (*v->api->gbar)( v, 0, &r );
>>>      }
>>> 
>>> to set and draw a yellow color, the test succeeds and reports
>>> the correct motorola-format.
>>> 
>>> This is only reliable if the palette is set accordingly. I think the
>>> first
>>> 16
>>> colors are always defined, and no one changes the palette at this stage
>>> in the bootup-process, so it may be a working solution.
> 
> It is. In true-colour modes index 0-15 of the CLUT are always defined, and
> unless
> changed for the particular virtual workstation in use, they're always set to
> the
> standard Atari palette.
> 
>> Interesting.  So your saying ozks code it relying on some default values
>> in
>> the palette?  That is not good.  My method is to save the color , change
>> it
>> to white $FF, plot it, then restore that color back the way it was.
> 
> Your method is broken ;-) How do you know that $FF is white? You don't. The
> correct
> method is to use colour index 0, which is always white (or was that index
> 1?). Your
> method is exactly what causes LZH-Shell's background to be inverted on
> true-colour
> systems. It attempts to clear the background to white by writing $00, which
> happens
> to be black on most systems.
> 
> Jo Even 

It's not broken, and I don't know anything about LZH-Shell.  It's badly
phrased.  What I meant to say (I was referring to TC) is...

Interesting.  So your saying ozks code it relying on some default values
In the palette?  That is not good.  My method is to save the color , change
it to R, G, or B , plot it, then restore that color pen back to the way it
was.  I make no assumptions about the contents of the palette, so no chance
of error.

I don't know why I wrote white or $FF cause my code don't use white.  :o)


-- 
Lonny Pursell    http://www.bright.net/~gfabasic/