Path: chuka.playstation.co.uk!news
From: rs108@mdx.ac.uk (Robert Swan)
Newsgroups: scee.yaroze.programming.3d_graphics
Subject: reducing polygon overlap
Date: Fri, 13 Mar 1998 23:32:36 GMT
Organization: PlayStation Net Yaroze (SCEE)
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this is the result of not getting enough sleep.

In my next project Im going to do a driving game. Seeing as cars are
always on the ground, then overlapping z depths is quite a problem.
Theres nothing worse than having your car driving forwards only to
have half of it obliterated by the ground it should be on. This is my
solution, follwed by two questions at the end.

Create OT(1) and OT(2)

sort all the world (except your car) into OT(1)
sort your car int OT(2)

now comes the silly part...

through trial and error (!) I would find whereabouts in the middle of
OT(1) the car would be if I registered in there instead of OT(2). This
leads to being able to

draw OT(1) from distance where car would be to end of OT(1)
draw OT(2)
draw OT(1) from start to distance where car would be

In my mind that would work. The reason I've thought of such a
convoluted method over just bit shifting the car more than the scenery
when it is registered with OT(1) is becuase it means objects in front
othe car get obscured by the car. Not good when your world isn' flat.

The questions are -

1) has anyone tried to set up a 'fake' OT. For example, create a large
OT(1) and then make OT(3) use only the last half of the PACKET array
and OT(4) the first half? There is an offset member of GsOT, but
apparently it doesn't work.

2) In my minds eye it would be worth doing this to eliminate overlap.
Would it really though?!

Robert Swan
rs108@mdx.ac.uk
http://www.netyaroze-europe.com/~middex2