[ODE] FW: Quick dQuaternion question

[Jon Watte (ODE)]

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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