The asset that is giving me trouble is the industrial fencing. I have not tried the others to see if they suffer from the same issue. The editor hack is to have the engine iterate through all of the actors and components and call GetNumUncachedStaticLightingInteractions() checking for a return value greater than 0.
The level which is having troubles has about 90 fences in it. This is due to the auto pole spacing not placing the barbed wire supports on top of the poles except for the first and last pole.
Four of the placed fences are having problems. The hack reports that each of the problem segments have multiple spline components which failed to build lighting. Deleting the segment allows the build to complete without error.
The fences look normal in screen shots.
This is what the hack is reporting when a fence segment goes bad:
Finding actors which need lighting rebuild…
There are 0 lighting unbuilt actors
Checked 1306 actors for lighting.
Finding components which need lighting rebuild…
Object Name: SplineMeshComponent_913
Object Owner: IndustrialFence_Spline63_1923
Num Interactions: 1
Object Name: SplineMeshComponent_1581
Object Owner: IndustrialFence_Spline63_1923
Num Interactions: 1
Object Name: SplineMeshComponent_1580
Object Owner: IndustrialFence_Spline63_1923
Num Interactions: 1
Object Name: SplineMeshComponent_913
Object Owner: IndustrialFence_Spline63_1923
Num Interactions: 1
Object Name: SplineMeshComponent_1581
Object Owner: IndustrialFence_Spline63_1923
Num Interactions: 1
Object Name: SplineMeshComponent_1580
Object Owner: IndustrialFence_Spline63_1923
Num Interactions: 1
Checked 5219 object components for lighting.
I’m a little confused why there seems to be duplicate components for the same actor. For example, why is the more than one “SplineMeshComponent_1580”? This might be a clue, especially if the issue is duplicate components overlapping each other and preventing the lighting to build. Or it could be a red herring from the engine.
This is another minor bug:
http://www.roboticgladiator.com/images/FenceProblem.jpg
In this bug, the segment has the post turned off, but the support is still there which causes a duplicate support to be added. I offset the segment to reveal the double support.
FYI: This is running on UE4 v4.10 which has it’s own set of gremlins including some bad behavior with shadows. So the lighting issue may be a problem with the engine itself.