[Bug?] Movable Lights inside Movable Objects breaks in 4.16?

It appears that in Unreal 4.16 one loses the ability to place movable light sources inside movable shadow-casting objects.

You can see this by comparing the placement of a movable spotlight in a movable cylinder in 4.15 vs 4.16 as shown in the image below:



You can clearly see that the dynamic spotlight is weirdly cut down to a really small radius in 4.16 now. It goes back to it’s old proper rendering if moved outside of the movable cylinder though.

This unfortunately, breaks lighting for many scenarios: In one example case of mine, I have a spotlight inside a (shadow-casting) flashlight mesh. Both are moveable. The flashlight can no longer shine light in my game (worked fine in 4.15).


I could of course disable shadow-casting from the flashlight mesh, but the lack of shadows is very noticeable when placed on a surface like a table or the floor.

I’m open to any suggestions for workarounds. It would also be nice to hear confirmation if this is indeed a bug, or just intended behavior, so that I’ll be able to figure out what to do about it for my game.

Thanks so much!

Hi nrossol,

Thank you for the report. I was able to reproduce this behavior so I’ve created JIRA UE-45646. Follow that link to monitor the status. I’m not sure if this was an intentional change on our part or not but our developers will be investigating this further.

As for a workaround, disabling Dynamic Shadow on your flashlight mesh does seem to give similar results. Will this work with your setup?


Thanks for the quick reply, I’ll keep an eye out for updates on this!

As a work-around for now, I’ve disabled dynamic shadows on the original mesh, and created a hidden, simpler cylinder mesh in the blueprint that has has hidden-shadows set to true. This is only a partial solution, though, as the hidden cylinder is only covering the back part of the flashlight, making the front of the flashlight non-shadow casting.