From:	"Christopher Nelson" <paradox AT gye DOT satnet DOT net>
To:	<djgpp AT delorie DOT com>
Subject:	Re: Allegro - why doesnt this work??
Date:	Fri, 26 Mar 1999 15:06:28 -0700
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Reply-To:	djgpp AT delorie DOT com

-----Original Message-----
From: Shawn Hargreaves <ShawnH AT Probe DOT co DOT uk>
To: djgpp AT delorie DOT com <djgpp AT delorie DOT com>
Date: Thursday, March 25, 1999 8:14 PM
Subject: Re: Allegro - why doesnt this work??


>Christopher Nelson writes:
>> On my system, this causes problems because the driver
>> in DD doesn't work right. Try to explicity set it to
>> GFX_VGA. That ought to do it.
>
>Hardcoding a particular driver name into your executable is not a
>very good idea. That may work around a particular problem on your
>machine, but it is also a good way to make sure your program won't
>work correctly for anyone else, who might have different hardware to
>you and thus need different drivers.


I realize that.  i was simply suggesting that he(?) try to explicity check
to see if he can set the VGA mode and write to the screen.  That way, if it
does work, then the person knows that it was the mode they were trying to
use, and not a library installation or coding problem.

>If the autodetect isn't working properly, the best thing to do would
>be to investigate and find out why. If there is a bug in Allegro, try
>to locate exactly what is going wrong so it can be fixed. If the
>problem is with your system setup, try to remove whatever driver is
>causing the problem, eg. to disable those modes in Display Doctor,
>or contact SciTech and get them to fix the problem if it turns out
>to be their error.

In this case, it wasn't precisely a Display Doctor problem because they were
extended VESA modes which my computer's SVGA DAC supports in theory, but
since it's a portable, doesn't support in practice.  In fact, none of the
DD's modes set properly (not even the ones that I was using before I
installed it.) The mode will set, but will not appear correctly, and will
have symptoms similiar to those described by the person who I was replying
to.  The person didn't sound as if they had a lot of experience in either
graphics programming or Allegro in general, so I didn't suggest something
that they may not even know how to do.  That can be very frustrating to a
beginner.

>If you don't have the time or inclination to fix it properly, use the
>config file to specify what drivers you want to use on your machine
>(see Allegro docs for details). This sort of thing belongs in a
>per-machine config file, not the sources for a program that may be
>run on more than one machine.

This is a point well taken, but in this instance wasn't applicable, because
the person was simply writing a "hello world" type test program.  :-)  If
you were simply taking the opportunity to make a point (which, by the way,
is excellent considering how many times I've downloaded software that I
can't run because the person didn't put in a flexible video driver option)
then that's fine.  But in this particular instance, it wasn't as drastic as
all that.  :-)

        -={C}=-

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