[ODE] dBodyGetRotation returns what?

[Megan Fox]

The last time this came up, I thought it was decided that what ODE is
putting out is a row-major matrix of 3 vectors, each 4 floats long,
with the trailing floats just existing as 0's - but I could very well
be misremembering.  You might want to take a peak in the archives in
any case, I'm sure this was brought up somewhat recently.

-Megan Fox

On Sun, 06 Mar 2005 00:03:44 +0100, Bram Stolk <bram at sara.nl> wrote:
> Aaron Cameron wrote:
> > On Sat, 2005-03-05 at 04:26 +0530, Kuldip wrote:
> >
> >>HI all,
> >>
> >>It is written in the documentation of ODE that dBodyGetRotation
> >>returns a 4x3 martix. but what does each value in this array
> >>signifies? what is this matrix actually?
> >>
> >
> >
> > It is a standard rotation matrix.  You might find it helpful to brush up
> > on your matrix transforms.  A good place to start is this page:
> 
> this 4x3 ode matrix is not so 'standard' as you make it out to be.
> In computer graphics, almost all matrices are 4x4.
> 
> The ode documentation is unclear about the 4x3 values.
> Are these 3 vectors of length 4 (simply a 4x4 matrix with the 4th
> translational vector removed?) or 4 vectors of length 3?
> 
> Orientations can be expressed as 4 floats of a quaternion, or
> with 9 floats from the full 4x4 mat. Why use 12 floats?
> I agree with the original poster that the docs are not clear.
> 
>    bram
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