Path: chuka.playstation.co.uk!news
From: rs108@mdx.ac.uk (Robert Swan)
Newsgroups: scee.yaroze.programming.3d_graphics
Subject: strange results - please me
Date: Mon, 25 May 1998 12:43:09 GMT
Organization: PlayStation Net Yaroze (SCEE)
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Can someone help me on some very wierd effects.

Ive got a program, that places 627 models in the world, and everything
is fine. Then, I change some other code, (not related to their
position or orientation) recompile and run it, and they are all
slightly out. This may not sound major, but it is. If I can't get past
this, I may as well stop with my game.

A bit more info - the models make up the sections of track for a
racing game (which is why they need to align properly). I have a
feeling I may be using up to much memory or something (I seem to
remember someone saying you can only declare so many variables
globally). Here is what Ive got in my memory -

43 tmds (not a problem, I should be able to make about 200)
array of 627 u_shorts
array of 100 u_long pointers
various (about 20 max) other variables, u_long + long
627 structures, each of which comprises - GsDOBJ2 GsCOORDINATE2, and 8
u_shorts.

Is this way too much? and if so, why does it cause this slight error
in positioning?

I also have a feeling that maybe the processor loses the precision of
my long that is used to position each of the models, again why would
adding more instructions that dont affect it change its precision?

Anyway, this is a serious problem, and I beg of people to download my
file and have a look at the problem. the file is

http://www.netyaroze-europe.com/~middex2/ftp/HELPME.ZIP

if you unzip it, you get two directories - test1 is the correct
version, and test2 the knackered version (to get them to run go into
CODE directories and do siocons auto)

you can see the difference between the two by looking at the files
TRACK.C in the code directory. The first has lines 245 - 253 commented
out, the second hasn't. The variables im editing on those lines (fs1,
fe1, fs2, fs2) have nothing to do with the models positions. 

Id also better explain how to use the 'game'

up,down,left,right moves you.
L1, R1 rotate you
L2, R2 move you up and down.
circle takes you back to the start (but doesnt orientate you)
select quits
square gives an overhead view of the whole track

the game will work by only drawing sections of track around your
currect position, but at the moment that hasnt been implemented, so
you have to tell the computer which pieces of track to draw.
triangle moves the track forward,
and cross moves it back. Youll see what i mean when you try it

Please have a look, Im desperate - I have no ideas about memory and
stuff.

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