Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!olivea!oliveb!amiga!jimm
From: jimm@amiga.UUCP (Jim Mackraz)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: Using the copper (was Re: 3d Graphics)
Message-ID: <6457@amiga.UUCP>
Date: 3 Apr 91 21:17:51 GMT
References: <7183@harrier.ukc.ac.uk> <mykes.0830@amiga0.SF-Bay.ORG> <1042@cbmger.UUCP>
Organization: I and I Computing, Palo Alto, CA
Lines: 37

(Peter Kittel GERMANY) writes:
)(Mike Schwartz) writes:
)>First of all, you don't need TWO copper lists to do double buffering.  
)>All you need to do is change the plane pointers in a single copper list.
)
)And this is considered one of the big NO-NOs for system-friendly
)programs! Thou shalt not do this (sp?).

You cannot believe that the Amiga has gotten this far without people
doing substantially more with the hardware, Copper in particular, than
is supported by the OS.  User Copper Lists are pretty useless; you can't
even provide different copper instructions for the two interlaced fields,
which means no Copper assisted smooth scrolling, playfield swaps, or
mode changes in "TV" modes.

Most of these effects would conflict with other screens, if present, anyway
even if you used the user copper lists.  Even color gradients, which
the user coplists can do, conflicts with other screens.

Clearly, since the system copper lists are dynamically reallocated and
disposed, you can't poke their contents, but if you're telling programmers
that they cannot and should (shalt) not use custom hardware copper lists of
their own construction, you're way off base.

The Copper is the biggest technical advantage the Amiga has in many
application areas, including video, titling, and presentations.
The difference in overhead between double-buffering displays using the
copper and not using the system support

Use it.

	jimm

-- 
--- opinions expressed herein are my own. ---
"... Because they can."
		- profound punchline to joke about dogs