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From: phorgan@cup.portal.com (Patrick John Horgan)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Graphics, clipping, and double-buffering in a window
Message-ID: <31739@cup.portal.com>
X-Local-Date: 14 Jul 90 18:41:14 PDT
Date: 15 Jul 90 01:41:14 GMT
References: <357@tlvx.UUCP>
Organization: The Portal System (TM)
Lines: 16

Gary Wolfe, SYSOP of the Temporal Vortex BBS said:

+..uflorida!unf7!tlvx!sysop, ..unf7!tlvx!sysop@bikini.cis.ufl.edu
+How slow are the built-in clipping routines?  I could always have my own
+draw function which clips the x & y before calling Draw(), but I'd rather
+use the system functions if there's nothing wrong with the performance.

I had an occasion to disassemble some of the graphics code awhile back,
(the first RKM's were wrong about how to do blitting of lines so I checked
to see how C= did it).  I was pleased to recognize the Cohen-Sutherland
Outcode algorithm used as the clipping algorithm.  You can't do much better
than that in a general clipping algorithm.  It's amazing how they can do
all that clipping constantly against damage-lists and still maintain such
good performance.  Way to got C=:)

Patrick Horgan                         phorgan@cup.portal.com