Box2D Forums

Hi,
I seem to be misunderstanding how to destroy joints and bodies. I have an ragdoll actor with multiple members and connecting joints (revolute). When a limb/member takes enough damage, I destroy one joint and the member detaches from the main body. When a leg is damaged then it detaches from pelvis, for example. But if damaged too much, the leg body is destroyed.

So, my code basically looks like:



This call to DestroyBody seems to cause a problem when it calls
b2World::DestroyJoint in the //'Remove from the doubly linked list'
area (j->m_prev->m_next = j->m_next;). I'm guessing this happens since I already destroyed the one of the joints on the body?

What is the right way to do this? Is it my job to remove the joint from the body's joint list when I explicitly destroy the joint?

Any tips appreciated.

You do not need do more that this. I think it most likely you are attempting to delete a body or joint twice. Bear in mind all joints on a body will be destroyed when the body is.

Indeed, you are right as usual. I see now that I am trying to destroy a joint twice, but I thought my code would handle it properly - famous last words! Here is what was happening.

I destroy the pelvis body, thus implicitly the right hip and left hip are also destroyed. I have the implicit destruction listener that looks like this


Then sometime later I try to destroy the right hip and boom goes the dynamite. Even though I'm checking for a null joint thusly:



So, this leads me to believe that the SayGoodbye method is incorrect somehow. Not sure why, I just want to be sure to nullify the pointers on implicit destruction...
Any help is appreciated. Thx

Your saygoodbye function does nothing. Read a good article on pointers and you'll see why.