How to get Joint connectedBody OnJointBreak

Question

I have multiple joints connected to a group of objects. If a joint breaks I want the original object and the connected object to respond. The method OnJointBreak doesn't give me any indication of the Joint connectedBody. How can I find the body that was connected?

Why the heck would they only give break Force!? Please help.

Answer 1

I created a work around that is not what i want, but until someone can suggest something better this is what i did.

created an array of connections

 //joints
 public ArrayList<Part> connections;

then as i create joints i add them to both parts, the original and the connectedBody.

 parts[i, j].connections.Add(parts[i + 1, j]);
 parts[i + 1, j].connections.Add(parts[i, j]);

then when a joint breaks i flip a flag and wait:

 void OnJointBreak(float breakForce) {
     JointBroken = true;
 }

in the next update (when the joint has been destroyed) I the go looking for the missing joint:

 if (JointBroken) {
     Ship.EvaluateJointBreak(this);
     JointBroken = false;
 }

then i can find and act on missing joint

     public static void EvaluateJointBreak(Part part) {
         foreach (Part sp in part.connections) {
             if (sp == null) 
                 continue;
             Joint j = findJoint(part,sp);
             if (j == null) {
                 //missing joint
             }
         }
     }    
 
     public static Joint findJoint(Part part1, Part part2) {
         foreach (Joint j in part1.GetComponents<Joint>()) {
             Part temp = j.connectedBody.GetComponent<Part>();
             if (temp == part2) {
                 return j;
             }
         }
         foreach (Joint j in part2.GetComponents<Joint>()) {
             Part temp = j.connectedBody.GetComponent<Part>();
             if (temp == part1) {
                 return j;
             }
         }
         
         return null;
     }

There you go.

Answer 2

Answer by mrlinds · Mar 23, 2018 at 08:18 PM

I recently ran into this issue, but found a better solution, likely because of Unity updates. In Unity 2018 you can now check joint.currentForce. Not sure when that was added

 private void OnJointBreak(float breakForce) {
         for ( int i = 0; i < joints.Count; i++ ) {//have list of joints
             ConfigurableJoint joint = joints[i];
             if (breakForce != joint.currentForce.magnitude ) {
                 continue;
             }
             RemoveJoint(joint); //do joint cleanup
             break;
         }
     }

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LorenzoValente · Nov 30, 2020 at 11:20 AM 0

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It is not a good idea to check inequality between two floats using the != operator. Floats may have precision errors. You should use $$anonymous$$athf.Approximately

How to get Joint connectedBody OnJointBreak

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