[ODE] Rotation about two axes

[Martin C. Martin]

Hey Josh,

If the first rotation is 90 degrees, does the second cause the cylinder to
rotate about its own axis?  I assume that's not the effect you want.

Either way, you could try using dRFromEulerAngles().  You'd have to set
one of them to a constant (zero or 90 degrees or something), not sure
which one though.

Joshua Bongard wrote:
> 
> Hi,
>   I've been trying to automate a way of rotating a cylinder about the
> horizontal and vertical axis. The user supplies two parameters,
> rotation[0] and rotation[1], which are these two rotations. The
> orientation of the cylinder is then calculated as follows:
> 
>                 dMatrix3 Rx, Ry, Ryx;
> 
>                 dRFromAxisAndAngle(Rx,1.0,0.0,0.0,rotation[0]);
>                 dRFromAxisAndAngle(Ry,0.0,1.0,0.0,rotation[1]);
> 
>                 dMULTIPLY0_333(Ryx,Ry,Rx);
> 
>                 dBodySetRotation(body,Ryx);
> 
> The orientation is always _almost_ right, but is always off by a small
> amount. Does anyone have any ideas what I'm doing wrong?
> 
> Thanks,
> Josh