[ODE] dBodyGetRotation returns what?

Bram Stolk bram at sara.nl
Sun Mar 6 00:03:44 MST 2005

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.


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