Path: chuka.playstation.co.uk!news
From: "Nick Slaven" <NickSlaven@compuserve.com>
Newsgroups: scee.yaroze.beginners
Subject: Re: angles, angles
Date: Sat, 21 Nov 1998 17:40:14 -0000
Organization: PlayStation Net Yaroze (SCEE)
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Message-ID: <736vpv$ekm8@chuka.playstation.co.uk>
References: <72spa7$dvm12@chuka.playstation.co.uk> <72sr28$dvm13@chuka.playstation.co.uk> <3652971c.228584498@news.playstation.co.uk> <731up3$olq9@chuka.playstation.co.uk>
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Darren Jackson wrote in message <731up3$olq9@chuka.playstation.co.uk>...
>I understand the maths, no problem, its just the fixed point trig that I am
>trying to get my head around.
>At the moment I am trying to use the rotation element of the sprite
>structure to give me an angle ? And then using this in the trig equations
to
>give x and y. But what do I have to do to the rotation value to make it
>meaningful to use in trig.
>
>ONE=4096=1degree, right?


for sprite rotation 4096=1 degree
for rotation transforms in 3D space 4096=360 degrees
does anyone know why this is like this??

I wrote trig lib with 4096=360 degrees for the PSX functions.
and the function values in fixed point where 4096=1.0

eg
sin(45deg)=0.707

using trig lib
SinD(45)=0.707*4096=2897
SinP(512)=2897

ASinD(2897)=45;        // mul by 4096 to use in sprite stuff
ASinP(2897)=512;      // mul by 360 to use in sprite stuff

in trig lib the PSX functions are quicker as the degree
functions all do a conversion 1st on the angle to get it in PSX
units.

cheers

Nick S