Xref:	news2.mv.net comp.os.msdos.djgpp:5478
From:	Shawn Hargreaves <slh100 AT york DOT ac DOT uk>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Allegro - tile graphics
Date:	Thu, 27 Jun 1996 17:57:00 +0100
Organization:	The University of York, UK
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To:	djgpp AT delorie DOT com
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On Tue, 25 Jun 1996, Nicholas Marrone wrote:

> 1) When viewing the screen, there is a 1 pixel black line between the
> first and second tile rows, and also one between the 1rst and 2nd
....
> 	 blit(data[map[ver][hor]].dat, screen, 0, 0,
> 	      hor * 20, ver * 20, hor * 20 + 19, ver * 20 + 19);

You are passing the wrong size parameters to blit(). The last two 
parameters should be the width and height of the area to blit, ie. both 
20, regardless of where on the screen you are blitting the image.

> 2) Although I'm sure my video card has enough memory, I cannot make a
> virtual screen that is 640x480 wide! The largest I can get is 640x409,

Mode-X can only address 256k of video memory, regardless of how much you 
have in your card, because it uses the standard VGA memory addressing 
scheme. If you want to access more than 256k, you'll have to use an SVGA 
mode. Unfortunately there isn't a standard way of accessing low resolution 
SVGA modes, but SciTech have implemented these in UniVBE for most cards. 
I think UniVBE will give you a 320x240 resolution with a 640x480 virtual 
screen on almost anything, and this will work with Allegro's VESA 
drivers. But then you'd need UniVBE to run your program...


/*
 *	Shawn Hargreaves.        Why is 'phonetic' spelt with a ph?
 *	Check out Allegro and FED on http://www.york.ac.uk/~slh100/
 */

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