Rigidbody doesn't move with transform!!

I realized that sometimes my Rigidbody is not being moved along with my transform's position. This is with a trigger collider and kinematic rigidbody.

I move my gameobject with the rigidbody from position 1 to position 2 in the editor:
The editor gizmos shows the collider is allegedly moved to position 2, however it's not being detected by my OnTriggerEnter function, instead OnTriggerEnter is being called in the position 1 where the collider/transform started(position 1).

What can I do to update the Rigidbody's position to always be on the transform's position?

PS: Whenever I edit the Rigidbody in the inspector, it syncs back and teleports to position 2.

 

How do you guys make your triggers interact with each other?
If you don't know the answer to the first post it's alright. I just want to make a hitbox(trigger) always hit a hurtbox(trigger).

In 2D, I added a rigidbody2D on both the triggers and it worked without problems. But somehow in 3D, it seems different.

 

I'm definitely having the same issue as the first post. This issue was definitely not present for the same project and scene in 2018.2, but after upgrading to 2019.1, my kinematic rigidbodies do not move along with their parents. Their gizmos say they and their colliders are moving, but in the physics inspector, those colliders do not move.

If anyone has a workaround or knows if this is intentional or is being fixed let me know!! ty

Edit: Another Detail:
This is occuring for me with a few examples of a Kinematic Rigidbody that is a child of a Rigidbody. When the parent rigidbody moves, the child thinks it has not moved. If i remove that Kinematic Rigidbody, its collider updates correctly in the physics debugger.

It's as if the kinematic rigidbody is falling asleep even though its parent has momentum. This sounds like a reasonable thing for a rigidbody to do, but it definitely wasn't happening before.

 

Make a quick check that you still have the issue when Auto Sync Transforms turned on.
This did not solve the problem for me, but I'm curious.

 

I do have Auto Sync Transforms on! This does seem like exactly what this checkbox is for haha

 

Yes, I have this issue as well.

 

I tried using Physics.SyncTransforms() in LateUpdate() to see if maybe the checkbox just wasn't doing anything, but the collider is still not syncing. What does work is toggling gameObject.active on the kinematic rigidbody - but this is an unsatisfying solution because i have important OnDisable and OnEnable events on these objects, and i don't otherwise want to be toggling a gameobject's active state every frame for multiple objects.

 

I read this thread @swanijam https://answers.unity.com/questions/199347/rigidbody-and-parenting-kinematic-rigidbodies.html

Basically it is said that :
it's not allowed to have a non-kinematic rigidbody in a structure when there is already a parent that has a rigibody.
However, in my case, there are 2 rigidbodies (a "real" one on the parent, and a kinematic one on one of the children). Meaning that the I'm following the rule but I still get the issue mentioned above.

I checked the documentation but I don't see information about this rule however. Do you mind clearing this up for us @Bunny83?

 

Yep, i think i've seen this rule as well. My child rigidbodies are strictly kinematic and are mainly there to direct collision events between different parts of a complicated VR boat setup. It's been working perfectly for a long time and only broke in 2019, but i haven't seen any mention of the rules changing for 2019!

 

You should never parent rigidbody to another rigidbody. It will lead to unexpected behaviour.

 

It's always worked before with kinematic rigidbodies - a kinematic rigidbody should just maintain its localPosition at all times, right?

I wouldn't dream of using a non-kinematic nested rigidbody, though.

 

And it seems like the kinematic rigidbody does know that its collider belongs at its localposition&rotation, too. When i turn the gameobject on and off, or toggle isKinematic, the collider updates to where it should be. It seems that the collider-transform syncing just isn't happening when a parent moves, which doesn't seem intentional as it's afaik an undocumented change.

 

Maybe this is related to the upgrade from physX 3.3 to 3.4 that occured in Unity 2018.3? I jumped from 2018.2 to 2019.1, so it's possible the issue began in 2018.3 and not 2019.1 as I said.

 

Hi guys,
Also experiencing the same issue. It was alright in 2018.3.XX, however after swapping editor to 2019 all my "car drivers" behave as mentioned above.

Does anyone found a solution?

 

I think it's like Vergil said:

"You should never parent rigidbody to another rigidbody. It will lead to unexpected behaviour."

 

Maybe not exactly the same but, I had similar issue and ended up in this thread while looking for a solution.

Basically, I am shooting cannonballs with rigidbodies from a ship with a main rigidbody. When they collide with a target, I make them kinematic rigidbody, disable their colliders and renderers to finally reset their transfrom positions back to start position. When doing it I realised similar behaviour like the one mentioned in this thread. Although their transforms are set to initial start positions, sometimes they move on spot, but sometimes they stay in between position 1 and 2 along with their colliders.

Thinking about the whole process during reading this thread, I realised that first the cannonballs moving with physics update and then for an instant after the collision, resetting them in normal update might create this issue. Therefore adding a small and short co-routine for 0.1 second as a buffer for the transition solved my problem instantly. Maybe the reason is something else, but at least it solved my problem.

 

Possible solution: https://forum.unity.com/threads/rigidbody-addforce-not-moving-the-object.539865/#post-3559413
Answer 8

 

I got around this by using Physics.SyncTransforms()