Sequencer + CineCamera + Lookat Tracking => can't save sequence

Development Cinematics & Media
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1

Hello,

first of all, the new sequencer is absolutely fantastic :slight_smile:

Unfortunately, I think I found a bug where using in-sequencer spawned camera (cinecam), using it’s Lookat Tracking feature and assigning a scene object (which is not spawned in that sequencer) leads to a sequence save error which can be resolved only by removing the Lookat Tracking object or by converting the object to spawnable.

Interestingly one time when trying to reproduce the bug, and possibly by first removing the look at target, then assigning it again, saving (with the mentioned error), then converting the object to spawnable I got cought up in a chain reaction where trying to save the sequnce led to many errors with scene objects being marked as “external” (basically same error like with the lookat tracking target).

Steps to reproduce:

  1. Startup 4.12.4, New Project, Blank is ok, using “Starter Content” preferable
  2. Keep the default map with the table, chairs and statue
  3. Create new Sequence in Content Browser
  4. In Sequencer, click the 4th button on the toolbar - “Create a new camera and set it…” (so this camera is spawned by Sequencer and is not “part of the scene”)
  5. Select the camera in the Sequencer and in “Details” tab, “Lookat Tracking Settings”, turn on “Enable Look at Tracking”, in “Actor to Track” select the statue (or some other object)
  6. In Sequencer, click the save button and you should get the error saying "Can’t save… Graph is linked to objects in external map… External Object: Statue… "
  7. If you click OK, then Continue and convert the statue to Spawnable, it should be possible to save the sequence.

Unfortunately, when I was writing the repro steps, and trying the bug again, I was not able to save the sequence even if converted the statue to spawnable because now I started to get errors about other scene objects being externally referenced. So I’m not sure what’s the root cause of the problem, but those repro steps will take you to the problem :slight_smile:

2

Hi ,

Because the level sequence (and any spawnables within) are independent of the level you are putting them in, spawnable actors can only reference other spawnables and vice versa. Did you clear and replace the look at actor in the camera details after you converted it to spawnable? This was reported a few weeks ago here. I have entered UE-32231, which is a request for more clarity in the error message and possibly resolving some of those persistent errors.

3

A workaround (or the correct/intended way to do it, I guess):

  • create a spawnable actor (empty actor or any mesh set to not visible). You can Shift+drag one from the Modes window to automatically add it as a spawnable to sequencer;
  • use the spawnable’s attach track to attach it to the lookat/focus target actor and position it as needed;
  • set the camera to track the new spawnable.

Sequencer will add the parent actor to the sequence and the attach track reference to it won’t prevent you from saving the sequence.