[ODE] Changing the 3D coordinate system to left-handed

skjold@cistron.nl skjold at cistron.nl
Thu Feb 13 06:53:01 2003


Yes, afaik, ODE is completely without preference when it comes to any of its units (distance, mass, time), as long as it's consistent. The same goes for the organization of your coordinate axes. You can think of X pointing downards, Z extending to the left and Y pointing out of the screen, and it will work normally as long as you stick with that decision (e.g. downwards gravity would mean a positive force along the X axis).

But keep in mind that these decisions extend to the graphics engine as well. And as it so happens with the included drawstuff library, Z is interpreted as pointing up, etc. So if you use the drawstuff library you'll have to stick to that system, or swap axis values to convert your own coordinates to that system.

Greets,
Mark

> Isnt it just a matter of changing at which direction the gravity pulls?
> I changed my system from right to left, and only updated my gravity vector -
> everything looked right after that - also the collisions.
> As far as i know ODE hasnt got any preference.
> 
> Tobias Thorsen
> www.spacetimefoam.com
> 
> ----- Original Message -----
> From: "Michal Bacik" <michal@lonelycatgames.com>
> To: "ODE mailing list" <ode@q12.org>
> Sent: Thursday, February 13, 2003 10:55 AM
> Subject: [ODE] Changing the 3D coordinate system to left-handed
> 
> 
> > Hi all,
> > I noticed ODE uses right-handed coord system (Z pointing up), while I'm
> used
> > to left-handed one (Y pointing up).
> >
> > Is there some switch in header files swapping the Y and Z axes?
> >
> > Optionally I could treat the system as left-handed (setting gravitation
> > to -Y axis instead of -Z), but I suppose this would break collision
> > functions, or other parts of system.
> >
> > Any idea?
> > Thanks
> >
> > - Michal
> >
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