Physics Objects Lose Solidity after pickup

[Finn]

I think this is a bug, because I notice this happens within the ContentExample projects, version 4.2 currently. There isn’t a ContentExamples for 4.3 as of this posting.

What I’m doing is creating a physics based game. I have been working on this in UDK, and then switched to UE4. The physics seemed to be working fine until recently, and I"m not sure where they broke. This is not isolated to my game though, it is in the ContentExamples/Physics project which I have not altered.

What happens is this. In the first block of the Physics sampler, you can pick up an object, drop it, and push it.

I’m using physics objects to solve problems, so climbing onto an object you move into place, is part of the game. However, you can interact with the objects normally at first You can push them with your player body, and jump on them. Then if you use the LMB or RMB to interact with the object and place it where needed, you will see it no longer acts the same. It reacts to physics and the environment, but it doesn’t let you push it with the player body or climb on etc.

I’ve combed through the PlayerCharacter to see if there is something I can change to no avail. I’ve investigated the mesh object and have seen no improvement.

Ultimately though, this gets back to the ContentExamples, where it no longer works either.

If anyone has seen this issue and has a solution I would appreciate it as I’m stuck in development without it. If it’s a bug that I’ve uncovered I just want to bring it to the team’s attention.

thanks

[Tim_Hobson]

Hi Finn,

I’ve been able to get this to reproduce. I’ll spend some time looking into this tomorrow for further testing to make sure this isn’t something that is just a setting vs being an actual bug. I’ll get back to you soon on this.

Thanks!

Tim

[Finn]

Hi Tim,

Thanks for responding to this. Let me know if it’s just a setting, i’ve never seen anything like this before in UDK or UE4 so I’ve been perplexed as I’ve been relying on the physics. Holding off on physics puzzles while a solution come through.

-Daev

[TJ_V]

Hi Finn,

It’s a missing node. Double-click to open the GrabObject that is in the Event Graph. At the very end of the chain you will see that on grab the SetCollisionResponseToChannel sets the New Response to Ignore. This is correct, it keeps the box from colliding with your player capsule while picked up. The problem is, the Collision Response never gets set back when the object is dropped.

To do this, double-click the DropObject in the Event Graph. Add a SetCollisionResponeToChannel to the end and make sure the target is the PhysicsObject variable. Set the New Response back to Block.

We’re going to log this in our tracking software as well and get this corrected. I hope this fixes the issue for you. If you have any other questions, please feel free to post them here.

Thanks, TJ