[ODE] how to stopbody enabling by joint

[Mark Williams]

> Krystian Ligenza wrote:
>   
>> I have look more in mailing list archive, and see that this topic was 
>> many times discussed. Main problem is how to set that joint should only 
>> affect  one body and other  left  unforced.  Maybe we should think about 
>> adding flag for this, by adding dJointSetXXXParam with dParamAffectBoth, 
>> dParamAffectFirst, dParamAffectSecond? If joint can link with world, 
>> this should not be impossible to do - correct me if I'm wrong?
>>   
>>     
>
>
> Why wouldn't you just create the joint attached to the affected body and 
> the world (NULL), then? I do that for collisions in certain cases, for 
> example.
>   

If you attach a joint to a null-body, then the joint considers that body 
to have zero velocity. This is a potential source of error when 
colliding against non-simulated yet animated geoms. I think Krystian's 
patch has a great deal of value.

Cheers,
Mark