How can you copy joints?

[garfi43]

I am trying to copy a joint but there are some errors.

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Json::Value jointValue;
b2Joint *tmpJoint;
tmpJoint=json->getJointByName("jointName");
jointValue=json->b2j(tmpJoint);
json->j2b2Joint(World,jointValue);

But it is like the b2j function does not return anything, crushing the program at line 185 on b2Joint.cpp

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b2Assert(def->bodyA != def->bodyB);

Does anyone have managed to do this?

[iforce2d]

I had some discussion with garfi about this, and it looks like a slightly different version of the b2j and j2b2Joint functions might do the job. See the pastebin here for a summary of my suggestion: http://pastebin.com/x1DDNXKx

[garfi43]

Helpful suggestion Chris, it worked out. Thank you.

on b2dJson.h

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//reading functions
...
b2Joint* j2b2NewJoint(b2World* world, Json::Value jointValue, b2Body *bodyA, b2Body *bodyB);
...

on b2dJson.cpp

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b2Joint* b2dJson::j2b2NewJoint(b2World* world, Json::Value jointValue, b2Body *bodyA, b2Body *bodyB)
{
    b2Joint* joint = NULL;

    ////////////* comment out these four lines *////

//    int bodyIndexA = jointValue["bodyA"].asInt();
//    int bodyIndexB = jointValue["bodyB"].asInt();
//    if ( bodyIndexA >= (int)m_bodies.size() || bodyIndexB >= (int)m_bodies.size() )
//        return NULL;
    
    ...
    
    if ( jointDef ) {
        //set features common to all joints
        
        ////////////* replace with parameters *////
        jointDef->bodyA = bodyA;//m_bodies[bodyIndexA];
        jointDef->bodyB = bodyB;//m_bodies[bodyIndexB];
    
       ...
    }
    
    return joint;
}

on code:

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json->j2b2NewJoint(World,jointValue,bodyA,bodyB);