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Bug / Crash  Error Destroy ObiCollider
Hi Jose,

I spotted something weird when the ObiCollider are destroyed in my project.
I procedurally generate a rope and its blueprint at runtime (similar to your scene RopeGrapplingHook ). Everything looks good and it's working.
However, every time when I turn off the play mode, I got this error :

ArgumentNullException: Value cannot be null.
Parameter name: key
System.Collections.Generic.Dictionary`2[TKey,TValue].Remove (TKey key) (at <599589bf4ce248909b8a14cbe4a2034e>:0)
Obi.ObiMeshShapeTracker.Destroy () (at Assets/Obi/Scripts/Common/Collisions/ColliderTrackers/Trackers3D/ObiMeshShapeTracker.cs:131)
Obi.ObiColliderBase.RemoveCollider () (at Assets/Obi/Scripts/Common/Collisions/ObiColliderBase.cs:216)
Obi.ObiColliderBase.OnDestroy () (at Assets/Obi/Scripts/Common/Collisions/ObiColliderBase.cs:276)

The issues doesn't appear on all ObiCollider, I've more than 1000 ObiCollider in my scene and this error appears on about 100 of them.
So I fixed that by adding an additional check before the Remove in the Destroy method of the ObiMeshShapeTracker class (line 121) :

public override void Destroy()

    MeshCollider meshCollider = collider as MeshCollider;

    if (meshCollider != null && handles != null)

        handles.Unref(); // Decrease handles refcount.

        if (handles.RefCount <= 0)
            if (meshCollider.sharedMesh != null && meshDataCache.ContainsKey(meshCollider.sharedMesh))


Moreover, although my rope is well initialized and works fine, if I turn off the play mode and turn it on again, I get this error :

NullReferenceException: Object reference not set to an instance of an object
Obi.ObiRopeBlueprint+<Initialize>d__2.MoveNext () (at Assets/Obi/Scripts/RopeAndRod/Blueprints/ObiRopeBlueprint.cs:56)
Obi.ObiActorBlueprint+<Generate>d__68.MoveNext () (at Assets/Obi/Scripts/Common/Blueprints/ObiActorBlueprint.cs:300)
Obi.ObiActorBlueprint.GenerateImmediate () (at Assets/Obi/Scripts/Common/Blueprints/ObiActorBlueprint.cs:278)
Obi.ObiRopeBlueprintBase.OnValidate () (at Assets/Obi/Scripts/RopeAndRod/Blueprints/ObiRopeBlueprintBase.cs:50) 

I suppose it's could be related to the rope creation at runtime or maybe a memory leak during the rope or blueprint destruction ?

Thanks in advance
Hi there,

I could reproduce the first one. It will happen when a MeshCollider whose sharedMesh is null is destroyed. This is a bug in Obi (thanks for finding and reporting it!), and the fix is as easy as checking if the sharedMesh is null before looking for it in the meshDataCache -just like you did- as it's not necessary to reduce the reference count of a mesh that does not exist. However it's pretty unusual to have a collider referencing no mesh, so this might be indicative of a deeper problem in your scene.

The second one I could not reproduce, though. The error points to the rope being unable to destroy its first particle group (first control point), but a rope should always have at least 2 control points, this is ensured throughout the code. Can you share how you're initializing the rope at runtime?
Thanks Jose, indeed I've probably something not logic in my scene, I'll take a look !
Finally for the second point, I just tried my code on the last version of Obi (5.5) and I don't have the error. So yes, I think that's is probably an issue with my version of Obi (5.2) or Unity (2019.2). But for technical reasons I prefer to stay on Unity 2019.2, so I will not upgrade to the 5.5 which is tagged 2019.3.1 on the asset store.

That's strange because before I didn't have this error, it suddenly appeared. I wonder if my Obi plugin is probably corrupted. I would appreciate it if you could send me the 5.2 version or the last version compatible with Unity 2019.2.7. I will mail you on the Obi support email.

Thank you  !