From:	Shawn Hargreaves <Shawn AT talula DOT demon DOT co DOT uk>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: create/show_video_bitmap problem (Allegro3+WIP)
Date:	Fri, 26 Jun 1998 20:49:02 +0100
Organization:	None
Message-ID:	<oyttGTAus$k1Ew78@talula.demon.co.uk>
References:	<6mqofm$63o$1 AT news2 DOT isdnet DOT net>
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To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

JCx writes:
>I recently installed the May, 30 WIP of Allegro 3.0, and have problems using
>the new video bitmaps. I'm using double buffering for my game, and what I do
>is create a standard memory bitmap where I store the background, and a
>video_bitmap as a temporary one to draw sprites and other things onto the
>background. 

When you create a video bitmap object, this is just allocating part of
the main screen bitmap, that covers your entire video memory. The first
time you allocate a video bitmap, it will probably come from the top
left corner of the larger surface, which is the same place you are using
when you write directly to 'screen', so your two regions will overlap.

Moral: use either video bitmaps, or 'screen', but not both at the same
time. If you want two individual video memory surfaces, call
create_video_bitmap() twice to allocate them both.


--
Shawn Hargreaves - shawn AT talula DOT demon DOT co DOT uk - http://www.talula.demon.co.uk/
"Miracles are nothing if you've got the wrong intentions" - Mike Keneally

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