RE: [Plib-users] ssg coordinate system convention

[Paul B. <pbl...@di...>]

Hey Steve,

Where does the "Z is up" affect code?  i.e. "Z is up" to me 
means that there are assumptions in the code like "the 'floor' 
is in the XY plane", "gravity has the unit vector (0,0,-1)",
and such.  It could also affect what roll, pitch and yaw mean.
(But I thought there were de facto standards for that in the
vizsim industry.  Are they Z is up?)

It's been a while since I was in the ssg code, so this may
seem obvious to others.  


Thanks,
Paul


> -----Original Message-----
> From: Steve Baker [mailto:sjb...@ai...]
> Sent: Wednesday, February 23, 2000 11:50 PM
> To: pli...@li...
> Subject: Re: [Plib-users] ssg coordinate system convention
> 
> 
> Rahul Choudhury wrote:
> > 
> > Just started looking into the ssg src code. I was
> > wondering whether the coordinate system convention
> > used in SSG is same as OpenGL or something different.
> 
> SSG's coordinate system is the same 'handedness' as OpenGL,
> but uses Z-is-up instead of Y-is-up.   I'm afraid that's
> because I come from a flight simulation background (where
> Z-is-up has always been the convention) - and there are really
> too many users to change it at this late stage.
> 
> SSG is not alone in this - SGI's Performer scene graph library
> is also a Z-is-up system that's based on OpenGL.
> 
> -- 
> Steve Baker                  http://web2.airmail.net/sjbaker1
> sjb...@ai... (home)  http://www.woodsoup.org/~sbaker
> sj...@ht...      (work)
> 
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