From:	T DOT Harte AT btinternet DOT com (Thomas Harte)
Newsgroups:	comp.os.msdos.djgpp
Subject:	The Allegro get_camera_matrix_f 'aspect' variable
Date:	Fri, 13 Jun 1997 18:35:13 GMT
Organization:	BT Internet
Message-ID:	<33a192dd.3930277@news.btinternet.com>
NNTP-Posting-Host:	host5-99-51-161.btinternet.com
Lines:	21
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

	All the Allegro readme file says about this is :-

> Finally, the aspect ratio is used to scale the Y dimensions of 
> the image relative to the X axis, so you can use it to adjust the 
> proportions of the output image (set it to 1 for no scaling).

	which doesn't help a lot. Firstly, does this mean I'm just supposed to
pass SCREEN_H/SCREEN_W (presuming I am projecting a full screen view) ? I tried
this, but it does not seem to work. When I run the ex25 program, I notice it
starts with a 320x240 window and an aspect ratio of 1. Am I supposed to allow
for the fact that the normal monitor screen is of the 4:3 aspect ratio?

	Basically, I guess my question is - am I supposed to presume square
pixels, or 4:3 ratio pixels when I calculate this value? Or can someone just
give me a simple formula which does what I want? I tried one in 320x200 mode,
and this definitely wasn't right, but then it doesn't appear correct within the
ex25 demo when it is set to 1 with the 4:3 ratio window (ie 320x240). I remember
one game, Car & Driver, had an option where you could set it yourself by
correcting an ellipse to be a circle. Do I need to include one of these?

		-Thomas

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