After exhaustively trying to get to the bottom of this issue, I’ve finally thrown my hands up in frustration—there seems to be a discrepancy in how UE4 renders skeletal mesh components vs poseable mesh components. If both meshes are located at the exact same location and are alternately toggled hidden on/off, there is a slight brightness variation between them. Can’t be sure, but it seems to be caused by the indirect lighting cache affecting each differently.
The issue is easily reproducible:
- Create a new default level. Delete the fog, directional light, and sky sphere.
- Add a spotlight and raise it so it’s pointing directly down from about 350cm. (stationary or static doesn’t matter)
- Create an actor BP with a poseable mesh component and skeletal mesh component, both parented to the default scene component. All should be at 0,0,0.
- Set the skeletal mesh on both components to be the TutorialTPP (show engine content must be checked in the content broswer).
- In the event graph on begin play, set a 2 second looping event timer that flip flops between 1. Hiding the poseable mesh and unhiding the skeletal mesh, and 2. Hiding the skeletal mesh and unhiding the poseable mesh.
At this point, just hit play. It can sometimes be very subtle, and other times extremely obvious, depending on lighting and viewport position. Just fly around and watch as they swap. You can also eject and move the BP while playing.
If anyone has any insight, I’d love to hear it. Thanks.