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From: jonabbey@cs.utexas.edu (Jonathan David Abbey)
Newsgroups: comp.sys.amiga.programmer
Subject: Re: Fast 3d Graphics
Keywords: fast 3d optimizing assembly cycles
Message-ID: <292@atacama.cs.utexas.edu>
Date: 5 Apr 91 18:49:15 GMT
References: <9529@star.cs.vu.nl> <1047@cbmger.UUCP> <20338@cbmvax.commodore.com> <9554@star.cs.vu.nl>
Organization: U. Texas CS Dept., Austin, Texas
Lines: 28

In article <9554@star.cs.vu.nl> mmblom@cs.vu.nl (Marc Blom) writes:
|I wish I knew how to use tables without taking too much memory: I'm using
|360 degrees around each angle, so to multiply a coordinate with a sin/cos
|(this is one table) value i would need 360 words PER coordinate, I'm now
|using coordinates that range from -16K to + 16K. I don't even want to
|calculate this ! (22.5 meg !) Offcourse i could use less percision, for
|instance only rotating by an even number of degrees (0,2,4...,360) and
|don't use such a large a coordinate system, but i don't want to compromise
|between speed/presicion just yet !
| 

Use quanta of rotation 1/256th of a circle.  That way you can do rotations
with a single indexed offset into your trig tables.  Short, sweet, and oh
so quick.

>+--------------------------------------------+------------------------+
>| Marc Blom        | Email: mmblom@cs.vu.nl  | What IS the question ? |
>| Gondel 14/13     |                         |                        |
>| 8243 BL Lelystad | Phone: 03200-46233 (NL) | TO OS OR NOT TO OS,    |
>| The Netherlands  |                         | that is the question ! |
>+------------------+-------------------------+------------------------+


-- 
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Jonathan David Abbey              \"Take your place on the great Mandela" P,P&M
the university of texas at austin  \  jonabbey@cs.utexas.edu     "Love me, love
computer science/math?/psychology?  \ (512) 472-2052              my Amiga" -Me