Path: utzoo!attcan!uunet!fernwood!hercules!apple!fox!portal!cup.portal.com!Sullivan
From: Sullivan@cup.portal.com (sullivan - segall)
Newsgroups: comp.sys.amiga.tech
Subject: Re: 3D-graphics (Quaternions)
Message-ID: <24201@cup.portal.com>
Date: 18 Nov 89 21:53:52 GMT
References: <1470@cc.helsinki.fi>
Distribution: na
Organization: The Portal System (TM)
Lines: 30

>
>		I am going to make a program, which uses filled 3D vector
>	graphics with hidden-surface removal. Normal methods - transform and
>        rotation matrices - aren't fast enough for my purposes. I have planned
>	to build a whole city with vector graphics. Can anybody recommend
>	any good books about this subject? Does someboby know better ways
>	to calculate the necessary transformations and rotations?
>		I haven't yet decided what kind of graphics routine to use.
>	It should make possible to move anywhere in arbitrary 3D-world in
>	real time. Does anybody have good ideas how to do this?
>		Right now I'm learning how to make use of Blitter and Copper
>	directly through hardware. It is in all probability the fastest way
>	to draw graphics. On the other hand, it's also quite difficult and
>	troublesome. So, I don't know whether or not to utilize it. If
>	somebody has any comments, I would be pleased to hear them.
>
>
>					Petri Kontkanen
>
>				                               
If direction of motion is important, use quaternions (20 FLOPS) instead of
matric representations (24 FLOPS).  If direction is unimportant you can 
use either body axis angles, or Pitch, Yaw, Roll sequences.  If Roll is 
unnneccessary, try SARA/SADEC angles (Right Ascention, and declination.)
SARA and SADEC will allow you to point toward any object, but won't include
any information about your attitude.  PYR sequences include your attitude
but don't describe transitions (eg: 180, 180, 0 == 0, 0, 180)  quaternions
are your best bet if you need to preserve the method of translation.  As
for where to find them?  I have no idea.  All are used in satellite attitude
control.  Perhaps NASA literature would suffice. -ss