[ODE] vector has zero size

[Hampus Soderstrom]

Hi,

I think the best way to get rid of this is to fine tune ERP and CFM  
values.

If it is a case of exploding simulation that causes this, adding  
damping and making sure the mass of objects isn't to small can also  
help.

/Hampa

On 18 Oct 2006, at 8:20 PM, Wouter Mollemans wrote:

> Thx I will try to use your solution, but this is of course only a work
> around.  Does anyone has an idea what causes these infinite values?
>
> Is it the collision detection algorithm? I noticed that the collision
> algorithm (dCollide()) frequently reports a NaN value for the position
> value of the first contact (contact[0]).
>
>
> Alex Green wrote:
>> Apporx once every 12000 simulations I get the same error. The  
>> error can
>> be detected. I run a function called 'checkPhysicsForError()' per  
>> frame.
>> It works as follows:
>>
>> bool checkPhysicsForError(void){
>> dReal *pos = (dReal*) dBodyGetPosition(bodyID of one of my boxes);
>> if(!(pos[0]==pos[0]) || !(_finite(pos[0])))
>> {
>>     dWorldDestroy(world);
>>     reset all my stuff
>>     create everything again;
>>     rewind one test (ie do the one that failed from the beginning);
>>     return true;
>> }
>> else return false;
>> }
>>
>> Notes:
>> pos[0] == pos[0] checks for NAN (not a number);
>> _finite() is windows, is there a cross platform check?
>>
>> Cheers -alex
>>
>> Wouter Mollemans wrote:
>>> After some debugging, I noted that some of the collision points are
>>> lying at infinity. This causes dNormalize4() to go nuts. Has anyone
>>> seen this problem before and do you know what causes this effect?
>>>
>>> Greetz
>>> Wouter
>>>> Hi,
>>>>
>>>> In my simulator I try to fit two rigid objects into eachother (a
>>>> little bit like a 3D puzzle).  The rigid objects are trimeshes
>>>> (around 4000 triangles) and all my joint are of the type contact.
>>>> Sometimes this works nicely, but mostly I get following message:  
>>>> "ODE
>>>> message 2 : vector has zero size" emmtted by dNormalize4().
>>>> Consequently the velocity becomes Nan and my simulation is ruined.
>>>>
>>>> Is there a solution? Is there a maximum number of triangles that  
>>>> can
>>>> be used or what is the source of the error?
>>>>
>>>> Thanks
>>>> Greetz
>>>> Wouter
>>>>
>>>>
>>>> -- 
>>>> _______________________________________________
>>>> ODE mailing list
>>>> ODE at q12.org
>>>> http://q12.org/mailman/listinfo/ode
>>>>
>>>>
>>>
>>> _______________________________________________
>>> ODE mailing list
>>> ODE at q12.org
>>> http://q12.org/mailman/listinfo/ode
>>>
>>
> _______________________________________________
> ODE mailing list
> ODE at q12.org
> http://q12.org/mailman/listinfo/ode
>