Event bindings are incorrectly copied on duplicate of an actor

Development Programming & Scripting Blueprint
, , ,
1

Hi there,

Found a serious bug in BPs to do with event bindings:

  • Create an actor BP
  • Add a trigger box property to this BP and make it editable
  • Add an event handler for actor overlap for this new property
  • Place this new actor in level
  • Create a trigger for it and set that trigger on player
  • Duplicate actor and create another new trigger
  • Assign this new trigger to newly duplicated actor
  • Now move another player controlled actor between triggers
  • Note that first trigger calls first BP actor and duplicated one.
  • duplicated actor retains binding to original trigger not matter what you do

I believe this is a bug.

2

Hi TommyBear,

I haven’t been able to reproduce this in 4.7.2. Which version of engine are you using? Can you post a screenshot of your BP Event Graph so I can make sure I’m following along correctly? Thanks!

3

Hi TommyBear,

We haven’t heard back from you in a while, so I’m resolving this post for tracking purposes. Please let us know if you’re still experiencing this issue with information requested above, and we can continue investigating. Thanks!

4

I’m going to try to get a repro project for you . Sorry been a bit busy!

5

Sounds good, thanks!

6

Okay I have a repro! Uploading to my dropbox now. Will share link ASAP. So here are distilled steps:

  • I used third person project type with no content
  • Create an empty actor and place it somewhere in level (ActorA)
  • Create a Box Trigger (TriggerA) and place it in your level
  • Create a BP on actorA (create/edit BP button on actor)
  • Save this BP somewhere in your project
  • Create a new property of type BoxTrigger on your actor BP and make it editable
  • Call it MyBoxTrigger
  • In properties for MyBoxTrigger, click green “+” button for OnActorBeginOverlap
  • Connect node up to notify you on screen. I used this (note that my boxtrigger propery was call MyTriggerVolume):

33935-screen+shot+2015-03-13+at+1.00.01+pm.png
33935-screen+shot+2015-03-13+at+1.00.01+pm.png1160×445 73.5 KB

  • Save
  • In your level, assign triggerA to MyBoxTrigger property on actorA’s details
  • Run game and run character over trigger
  • You should get a message like “Player blah triggered triggerA”
  • Now alt-drag actorA somewhere to duplicate it, rename it to actorB
  • alt-drag triggerA somewhere to duplicate it and rename it triggerB
  • Click on actorB, and set that MyBoxTrigger property to point to triggerB
  • Run game and run over to trigger B, you get something like “Player has triggered triggerB”, perfect
  • Now run over to triggerA, notice that you get two messages! “Player triggered triggerA” followed by “Player triggered triggerB”
  • That is bug :slight_smile:
7

Here is link to repro:

8

Well, after opening project I first tested your original repro steps with, it looks like I’m seeing same bug. Maybe it has something to do with closing/reopening project? I’m going to test with your new repro steps as well, and then check in our main internal branch. I’ll get back to you when I have some more information. Thanks!

9

Awesome! Thanks!

10

Hey TommyBear,

Thanks for detailed repro steps! I was able to reproduce this both in 4.7.2 and in our main internal build, and I have entered a bug report for it (UE-11819). I’ll let you know when I see an update on it. For now, dropping a new BP instance into level (rather than duplicating an existing one) seems to avoid this bug. Thanks again!

11

Hey ! Awesome news. Thank you very much for confirming bug, glad you can see it internally!

12

I just experienced this bug myself in 4.10.1 so it’s still not fixed. I think this is a rather serious bug because you spend a lot of time to find out what’s actually going wrong.

13

Hi ,

I just tested this again in 4.10.2, and bug no longer occurs using steps described above. This was marked as fixed in 4.8, so it hasn’t been happening for a while. Can you give me some detailed steps to follow that reproduces bug for you? Thanks!

14

Thank you for your fast reply.
I uploaded a project for you to easily reproduce bug:

http://we.tl/iTSOGzoIif

Notice that events broadcasted are arriving in all actors, not just in one that broadcasted it. I included owner as a parameter to easily see that wrong event is arriving. Like original bug mentioned in this thread this only happens if you duplicate actors.

Also important: This only happens if base class which holds component is a C++ class.
Maybe bug also occurs if you leave out one level of inheritance but I reconstructed it way it is in our project.

Thanks again and good luck with bug hunting!

15

Hi ,

This appears to be a separate bug, as what was fixed involved a simple variable reference. They may be related, so I’ll reference fixed bug report in new one when I enter it. If you wouldn’t mind, please create a new post with this information and this same link, so I can follow up with it there. Please also include specific steps you took to reproduce in a fresh project. I’ll attempt same here and see what we get. Thank you!

16

OK, I did so:

17

Excellent, thank you! I’ve got someone assigned to it, and we’ll post there if we have any follow-up questions and let you know if we enter a bug report. Thanks!