[ODE] dBodyGetRotation

[Jon Watte (ODE)]

The FAQ for ODE, as well as the documentation, states that the "offset" 
part of the mass is ignored for a body.

Also, you're setting the rotation of the MASS, which only affects the 
inertia tensor. You want to set the body rotation matrix to a specific 
value if you want the body to be rotated to that orientation. If you 
want to introduce spinning (continuous rotation) to a body, you instead 
need to add a torque, or perhaps set the angular velocity.

Cheers,

          / h+


adastra at inorbit.com wrote:
>
> Hi Everyone,
> I have a problem with the dBodyGetRotation function (ode 4.2)
>
> I set the position and the rotation of my ode body to the correct 
> position/rotation, I know this because I checked it with TRACE.
> I got no collision figure so I checked that the body was infact 
> rotating according to the matrix I passed into it and, nope, nothing.
> Is this an ODE problem or a me problem?!
>
> Here's a bit of my code:
>
>  vtkMatrix4x4 *indexprot = transformIndexp->GetMatrix();
>  indexprot->GetElement(0,0),indexprot->GetElement(0,1),indexprot->GetElement(0,2),
>  indexprot->GetElement(1,0),indexprot->GetElement(1,1),indexprot->GetElement(1,2),
>  indexprot->GetElement(2,0),indexprot->GetElement(2,1),indexprot->GetElement(2,2));
>
>  dMatrix3 indexmatrix;
>
>  for (int indexmatrixrot1=0; indexmatrixrot1<3; indexmatrixrot1++) {
>   for (int indexmatrixrot2=0; indexmatrixrot2<3; indexmatrixrot2++) {
>    indexmatrix[indexmatrixrot1*3+indexmatrixrot2] = 
> indexprot->GetElement(indexmatrixrot1, indexmatrixrot2);
>   }
>  }
>
>     dReal odeip_x = indexprot->GetElement(0,3);
>     dReal odeip_y = indexprot->GetElement(1,3);
>     dReal odeip_z = indexprot->GetElement(2,3);
>    
>     dBodySetPosition(handbody[3], odeip_x, odeip_y, odeip_z);
>     dBodySetRotation(handbody[3],indexmatrix);
>     dMassTranslate(&m, odeip_x, odeip_y, odeip_z);
>     dMassRotate(&m, indexmatrix);
>
>     TRACE("ODE position is %f, %f, %f\n",odeip_x,odeip_y,odeip_z);
>     const dReal *bodyrot = dBodyGetRotation(handbody[3]);
>     TRACE("ODE rotation is\n %f, %f, %f,\n %f, %f, %f,\n %f, %f, %f\n",
>      indexmatrix[0], indexmatrix[1], indexmatrix[2],
>      indexmatrix[3], indexmatrix[4], indexmatrix[5],
>      indexmatrix[6], indexmatrix[7], indexmatrix[8]);
>    
>     TRACE("ODE rotation is\n %f, %f, %f,\n %f, %f, %f,\n %f, %f, %f\n 
> %f %f %f\n",
>      bodyrot[0], bodyrot[1], bodyrot[2],
>      bodyrot[3], bodyrot[4], bodyrot[5],
>      bodyrot[6], bodyrot[7], bodyrot[8],
>      bodyrot[9], bodyrot[10], bodyrot[11]);
>
> Cheers,
> Jemma
>
>
> -- 
>
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