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Path: utzoo!henry
From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: net.graphics
Subject: Re: Y positive up or down?
Message-ID: <7291@utzoo.UUCP>
Date: Thu, 6-Nov-86 14:06:08 EST
Article-I.D.: utzoo.7291
Posted: Thu Nov  6 14:06:08 1986
Date-Received: Thu, 6-Nov-86 14:06:08 EST
References: <478@vaxb.calgary.UUCP>, <5139@brl-smoke.ARPA>
Organization: U of Toronto Zoology
Lines: 16

> Henry stated that the Blit was 4th-quadrant; I believe the Blit
> was originally 1st-quadrant, changed to 4th-quadrant for the DMD
> (which is NOT a Blit!).  There is evidence for this in some of
> the older DMD software.

Tsk, tsk, Doug, obviously reading all the DMD software has affected your
mind!  :-)  To quote from "Hardware/Software Trade-offs for Bitmap Graphics
on the Blit", Pike/Locanthi/Reiser, Software-Practice&Experience Feb 1985:

" ... (The Teletype DMD 5620 is a commercial product based on the Blit,
but this paper is about the Blit itself.) ...  All bitmaps share a single
coordinate space, with (0,0) in the upper left.  (The orientation of the
y-axis is one thing we might change were we to do it again.)"
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,decvax,pyramid}!utzoo!henry