Path: chuka.playstation.co.uk!news
From: "Peter" <cybersmurf@btinternet.com>
Newsgroups: scee.yaroze.freetalk.english
Subject: Re: Quadtrees - am I missing something
Date: Wed, 21 Feb 2001 01:13:51 -0000
Organization: PlayStation Net Yaroze (SCEE)
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Message-ID: <96v4i6$17p3@www.netyaroze-europe.com>
References: <96kfp8$rfo1@www.netyaroze-europe.com>
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Here's a link to a paper called "Faster 3D Game Graphics
by Not Drawing What Is Not Seen" that you may find useful.

http://www.cs.unc.edu/~hoff/papers/vfc/vfc.html

Hugz, Peter

"John ( QuietBloke )" <quietbloke@btinternet.com> wrote in message
news:96kfp8$rfo1@www.netyaroze-europe.com...
> OK.. I've just been looking into Quadtrees today. Part of my 3d self
> training course. I can see its a very simple concept but I must be being
> real dim tonight because I cant see the point of them.
>
> Reason...
> OK.. the main example I saw was a small example terrain of a 16x16 grid.
The
> reasoning was you dont want to draw the whole terrain just the bit the
> camera can see.
> This is the bit I dont get.. the tutorial then goes through how with a
> quadtree you start from the root and check the camera in the four quarters
> and eliminate the ones its not in.. then sub divide again etc etc and
> eventually you end up with just the leaf(s) that the camera is in and the
> leafs point to triangle data to draw the scene.
> Thats all fine and dandy but if its a grid then surely you can just do a
> quick calculation to figure out which leaf the camera is in...
>
> ie.. the camera x and y position will tell you exactly what cell the
camera
> is in.
>
> So what has this tutorial missed out ?... anyone ?.. why would I need to
use
> an quadtree when drawing a terrain ?
>
> Also... what happens next ?.. I know what leaf the camera is in but how do
> you decide what cells are visible going out to the horizon ( or a fair
> distance at least ) ?
>
> Im sure some of you have done this and its obvious and sorry for being dim
> but this really is all new to me and from what I've discovered I have a
> awful lot to learn !
>
> Ahhh who knows.. by tommorow morning I may have it figured out.
>
> Cheers
> John
>
>