Path: chuka.playstation.co.uk!news
From: SCEE Developer Support <ps_yaroze@interactive.sony.com>
Newsgroups: scee.yaroze.programming.3d_graphics
Subject: Re: The camera
Date: Mon, 21 Apr 1997 12:33:05 +0100
Organization: Sony Computer Entertainment Europe
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Alex Amsel wrote:
> 
> Can someone answer a quick question?
> 
> I was playing around with the gsview stuff yesterday (not well
> documented) and I realised I really wasn't sure of a number of things!
> 
> 1) Some demos uses lw and ls, others just use ls. Howcome, and what is
> the real difference?
> 2) When calculating lw/ls do you pass the pointer to the objects
> GsCoordinate2?
> 3) I thought gsview2 would allow me to point the camera somewhere and
> translate it. I was wrong of course! So I have linked it to a GsCoord2
> which I can then move around an environment. However, how can I move
> the camera along the axes of a local coordinate system ? It is
> probably something obvious but I did a few combinations and didn't get
> it. However, it was 7am this morning!
> 
> Regards
> 
> * Alex Amsel * Into Beyond Web Design & JAVA Programming *
> * http://www.intobeyond.com  *  WWFC Utter Rubbish 1996-7*
> MM - "Steve Corica is every bit as good as that Kinkladze"

Viewing is done under one basic setup with two ways to
manipulate in software; GsVIEW or GsRVIEW.

GsRVIEW2 uses: a pointer to super coordinate system to specify the
viewing space; viewpoint and looked-at point in that space;
and a view-orientation angle specifier.

Easiest way to move a view along the axis of a local coordinate
system: set view.super to the coordinate system of the object
(the GsCOORDINATE2 structure), set the reference (looked-at)
point to the centre of the object (ie 0, 0, 0 in that coordinate
system) and the viewpoint to the object's z axis (0, 0, K in that
coordinate space). Then you will look along the object's z axis,
towards the object itself. If it doesn't seem to work, make
projection distance variable by controller; too-high projection
will result in your object being clipped for being too-close-to-view.

The solar and solar2 demos do alot of (albeit unpolished)
viewpoint manipulations (local, external, circling, flyby).

Lewis