[4.12] Weird Actor Transform Behaviour

Development Platform & Builds
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1

Hi,

Since upgrading to 4.12, we have been experiencing several issues with actor movement and actor rotations.

In the editor, trying to move parented blueprints, results in the following behaviour:

Additionally, in packaged builds, multiple meshes seem to have been randomly rotated or moved slightly. Like so:

1920×1080 399 KB

We did not have any of these issues in 4.11. Please help! We need 4.12 for various platform specific bug fixes, and we are aiming to release very soon.

Thanks,
.

2

Hey PB-,

Are you able to reproduce this issue in a clean project? I’ve not been able to reproduce this myself. If you are able to reproduce it, please provide the steps that you’ve followed.

3

Hi Sean, thanks for the reply!

I have been trying to reproduce it, but I haven’t been able to yet. I’ll keep trying in the clean project. In the meantime, is there anything else I can provide that may be useful?

This behavior has only been happening since we upgraded to 4.12, and I haven’t seen any breaking changes that would effect this in the release notes. We’re a bit clueless as to what could be going on.

Edit: Just a little bit more information on what’s going on there in our project. We have a “BP_Movebetween” object, that moves between two given actors, childed to that have a standard static mesh, and childed to that we have about 9 Blueprints with 3D Widgets as components. While trying to figure out why some of these widget’s weren’t displaying properly, I figured out that their rotations are behaving strangely (For instance, if I tried to flip them from 90 to -90, the rotation would act weird and the value on all axis would change slightly). We have also had a few other BP’s acting this way: For instance a blueprint that was supposed to follow/look at a certain object was also behaving this way.

Edit 2: I have attached another gif, showing the weird sort of rotation behavior I was getting:

Edit 3: While recording the above footage, I got this in the output log:

“LogText:Warning: Failed to parse argument “DropTarget” as a number (using “0” as a fallback). Please check your format string for errors: “{DropTarget}. {AttachMessage}”.
LogText:Warning: Failed to parse argument “AttachMessage” as a number (using “1” as a fallback). Please check your format string for errors: “{DropTarget}. {AttachMessage}”.”

Hope that helps!

4

Thanks for providing the additional information. In terms of what else could be useful, the thing we’ll need to get is either repro steps that we can use to reproduce the issue in a clean project, or a simplified test project that you can send us so we can see the issue and determine what is causing it. Let me know if you are able to figure out that repro, or if you have any other information you can provide that might lead to figuring it out.

5

Hello,

I am marking this topic as resolved for tracking purposes, as we have not heard from you in a few days. If this issue persists, feel free to respond to this thread. For any new issues, please create a new Answerhub topic.

Have a great day

6

Hi Sean,

I have been doing some more testing, and I have found what was causing the issue, and I have reproduced it in an empty project.

The issue is caused when moving, (and in some, but not all cases, rotating) a childed object, where the parent has a negative value in it’s scale.

The rotation of the actor seems to bounce between the +ve and -ve of the value of a certain rotation axis, depending on which axis has been scaled to a -ve value on the parent. It is also causing the strange movement when adjusting the location via the transform gizmo, when it is set to local space.

This was reproduced using 4.12.3 (Or specifically, Github changelist 4.12-3010846)

Steps I used to reproduce:

  1. Create a project with the Starter Content.
  2. Load map “Minimal_Default”
  3. Child one of the two chair objects to the other.
  4. Set the Parent objects scale to (-1,1,1)
  5. Set the transform gizmo co-ordinate system to local (object) space.
  6. Try moving and then rotating the childed object, via the transform gizmo.

The rotating flickering bug seems to be less consistent than the strange movement, but they do both occur eventually!

Thanks,
.

Edit: Hi again. I just wanted to note, that while I did do the steps above on that github changelist, the bug was present in 4.12.0.

Edit 2: This has also been causing us issues on packaged builds for consoles, but not PC.

7

Thanks for the steps. I’ve followed them using the launcher build of 4.12.4, and I was unable to see the issue occur. Could you please test it on your end in 4.12.4 and see if you are seeing the same results?

8

I downloaded the launcher version of 4.12.4, and I can confirm the steps I did above are still working. Did you remember to change into Local (Object) Space?

I’ll record a gif of me reproducing it in the 4.12.4 launcher build.

9

I uploaded a video of the process here: - YouTube

10

Thank you for providing the video. It was my mistake, I realized I had the parent object selected instead of the child during my initial test. I have reproduced the issue, and have entered a bug report, UE-32674. Thank you for your report and for providing the information needed to reproduce the issue.

Have a great day