[ODE] cylinder plane bug

Jon Watte (ODE) hplus-ode at mindcontrol.org
Wed Sep 20 13:29:56 MST 2006

Sorry, I should have said "a plane, as defined by a half-space, is 
infinitely thick." Sometimes, these are called half-planes, too.

My point is: in ODE, you can get thin walls already through trimeshes or 
through boxes. The only way to get a half-space is through the Plane 
primitive. If you wanted to remove the behavior for plane as half-space, 
you'd have to update all the existing primitives.

If you really want a wafer-thin barrier, that would probably better be 
implemented as a separate, new primitive.


			/ h+

Jean-Sebastien Guay wrote:
> Hello,
>> A plane is well defined as infinitely thick.
> Err, sorry? In 3D a plane has no volume, just as in 2D a line has no area... At
> least mathematically.
> http://en.wikipedia.org/wiki/Plane_%28mathematics%29
> Specifically, http://en.wikipedia.org/wiki/Plane_%28disambiguation%29 states:
> "Plane (mathematics), theoretical surface which has infinite width and length,
> zero thickness, and zero curvature".
> If collision detection makes different assumptions than does geometry, they
> should be documented, because people not familiar with collision detection will
> use ODE.
> Now that I know that different assumptions are made, I will of course use a very
> thin box or a trimesh to do what I would normally do with a plane. Now I know
> why the "water surface" plane I made once gave really weird results...
> J-S
> --
> ______________________________________________________
> Jean-Sebastien Guay     jean-sebastien.guay at polymtl.ca
>                         http://whitestar02.webhop.org/

More information about the ODE mailing list