DestructibleActor leftovers


i run into some nifty problems using the wonderful feature of destructing meshes.

Setup: 20x20 boxes â la Minecraft, each one DM (Destructible Mesh) with ~50 chunks.

So far so good, it works and i love it.

There are two things mocking me and i just can’t get over it, i have to fix it somehow:

a) After the DM is gone in-game…in fact i destroyed every chunk and nothing “visible” is left in the scene (even checking player collison in PIE) - the DM is still there in the World Outliner. How can i kill the actor? Because this seems to produce another problem:

b) At the same place where the DM was, i can’t fully pass with my character (Tunnel for example) since the DM got some invisible collision “leftovers”. Even in a free floating environment, the cube’s collision got some invisible chunks.

Neither any threshold or different custom physics are working here - something is seriously odd with the DM actor.

I know Destruction 2.0 is not around the corner…but maybe you can take a look at it. I can’t provide any example data, pictures or videos (NDA) but at least i can tell that its a random reproduce-able behavior.

Thank you and have a nice sunday!


Hi Tim, at first…a big thank you for taking a look into it. (regarding your post some minutes ago).

I’m going to ask our coders what kind of player-character system we’re using. In short, its a custom 6DOF flight system with a sphere collision. Once these chunks are gone and i try to fly through the area where the DM actor was (and still is…inside world outliner) the ship starts to get stuck into small invisible pieces.

The base DM actor is just a regular 6 sides FBX cube from 3dsmax, fractured inside UE4. I tried it with other assets and still get the same behavior. I’m just a 3D Artist, maybe it’s a button i forgot to check to “delete” the actor once the chunks are gone, actually tried every possible setup over the weekend, no luck.

One of our coders said that this is a known issue, a reason why they implanted a BP to just shoot and delete the actor, destructing the DM in one shot (looks odd). We’re really looking forward to destroy assets into small pieces like intended. Strangely, the Large Chunk Threshold is not working either (maybe that could solve the issue) - need to investigate why, keeping you updated if you like.

Another small thing i figured out: I wanted to build a small BP with more than one DM. Seems like there is no way to use more than one DM inside a BP to get recognized. Is this a correct behavior?

Best, Toby

If you don’t mind, i place a post inside UDN with everything i found out. Some of our team may response on that, too.

Hi Tobias,

Have you tried using the PXVIS Collision? When you use this you’ll be able to see the PhysX collision for the scene. This should give you a better representation of any issues with collision and your Destructible that you’re having issues with.

Large Chunk Threshold: This should only apply to the a player character being blocked so that the player is not blocked by chunks, but this should not apply to other meshes in the scene.

Destruction 2.0: probably a few more corners as well. :confused:

A) I have a few questions in regards to how you’re adding these to your scene.

  • Are you spawning them in and then destroying?
  • Is there anything special about the way they are being spawned in or removed?
  • Can you share any specific DM settings you’re using?

B) Questions:

  • With a large chunk threshold, do you have a special setup for your character?
  • Is the playable character using a capsule?
  • the PXVIS Collision view should show any collision issues happening here and if the graphics mesh is being destroyed, but leaving behind a collision mesh.

Some things to be aware of with DMs.

  • Scaling is not really recommended, especially non-uniform scaling as this will completely skew the collisions ability to stay with the graphics mesh.
  • There has been scaling and BP spawning issues in the past, but I’m fairly certain these were resolved, but I can’t find the tickets at the moment. They were issues from a while back.
  • Scaling the mesh in BP event graph will not update the collision correctly for the graphics mesh. This is reported with UE-6407, and as with many destructible bugs is backlogged.

Understandably you can’t post anything within your NDA, but if you have a test scene that has basic objects you need feedback on or can reproduce there this can sometimes be very helpful as well. Also, if it’s specific to your scene only and you need help/feedback and your NDA allows you can privately share anything without worry as well via messaging on the forums.

Let me know what you find.

**Also, looking forward the final release of D:U. :slight_smile:

Hey Tim, yeah its gonna be awesome - promise!

I continue messaging you on UDN.

Thanks, Tobias. I’ve assigned myself to the question and will follow up there.

Once we get a resolution, I’ll copy the answer back here with any relevant information in the event that anyone else on AnswerHub has this same issue.