# [ODE] FW: Quick dQuaternion question

Jon Watte (ODE) hplus-ode at mindcontrol.org
Mon Jun 12 10:03:02 MST 2006

```Please just check your math. Neither quaternions, nor matrices, nor ODE
have handedness. Only the interpretation of the data by you has
handedness. If you put in left-handed data into ODE, and run the
simulation, then the data you get out is left-handed. This is just a
basic truth of mathematics; ODE doesn't need to (and does not) interpret
the handedness of data at all.

Cheers,

/ h+

Auro wrote:
> Hi Jon,
>
> can u plz explain the "Handedness neutral" bit? How can ODE be
> handedness neutral - how can it even guess the handedness in the first
> place. Besides quaternions in themselves have no handedness - that comes
> into play only when u do a quat -> matrix conversion or the reverse. And
> looking at the ODE code (quat -> matrix conversion) I'd say that ODE is
> very much right-handed while DirectX is left-handed (OpenGL again is
> right handed).
> Thanks beforehand.
> Cheers,
>
>  -Auro
>
>
> On 6/5/06, *Jon Watte (ODE)* <hplus-ode at mindcontrol.org
> <mailto:hplus-ode at mindcontrol.org>> wrote:
>
>
>     No, you should not. You only need to change the order. ODE is
>     "handedness neutral" -- if you put in left-handed coordinates and data,
>     you will get out left-handed coordinates and data.
>
>     Cheers,
>
>     / h+
>
>
>     justinleung at imagi.com.hk <mailto:justinleung at imagi.com.hk> wrote:
>      > >From my expriement to integrate quaternion in ODE to DirectX,
>     beside the order
>      > of W X Y Z, i need to invert the sign of X Y Z ( i.e. -X, -Y and
>     -Z) for correct
>      > result. Is it normal?
>      >
>      > Justin
>      >
>      >
>
>
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```