Path: utzoo!utgpu!water!watmath!clyde!bellcore!tness7!tness1!sugar!peter
From: peter@sugar.uu.net (Peter da Silva)
Newsgroups: comp.sys.amiga.tech
Subject: Re: IFF form for 2D drawings (again)
Message-ID: <2435@sugar.uu.net>
Date: 11 Aug 88 01:48:33 GMT
References: <11640003@hpfcdc.HP.COM> <11640004@hpfcdc.HP.COM>
Organization: Sugar Land Unix - Houston, TX
Lines: 16

In article ... cunniff@hpfcdc.HP.COM (Ross Cunniff) writes:
> Actually, every object *is* rotatable; simply rotate the actual points
> of the data. ...  My rationale for precomputing the rotation is that
> it is faster to render objects whose position and rotation are precomputed
> rather than rotating and traslating them on the fly...

That's fine for a rendering standard. I thought, though, that you were working
on a data transmission standard. For that, the rotation angle is important.

Why? Floating point operations are not commutative. The rotated points for the
rectangle will be off by a small amount, whereas the unrotated rectangle may
be exact. If it's stored and transmitted in an exact format, then errors will
not accumulate as the iterations progress.
-- 
		Peter da Silva  `-_-'  peter@sugar.uu.net
		 Have you hugged  U  your wolf today?