In 4.14 p3, Merge Actors creates an empty illegal static mesh asset when none of the selected actors has LightMap channel set to 1 and a corresponding Channel to begin with.
- Import Box Mesh from 3dsMax (or any other DCC-app) without Lightmap-Generation on (and without collision in my case) but of course proper UV0. For example box mapping done in 3dsmax for the first channel.
- Add actors of that Box to the scene
- Open Merge-Actors Dialog and Merge Actors. No matter the settings, the merge fails and an error is thrown in the output log that the raw mesh is corrupted. (The static mesh is empty). my settings: No Material Merge activated. Rest as default.
- Open the Box_Asset and create a 2nd (lightmap) channel. Save the asset.
- Try to merge again. The merged asset is still corrupted.
- Now Open the Box-Asset again and set the Lightmap Coordinate Index to 1. The merge will now succeed.
From what I understand this is a bug. Especially because the Merge-Dialog includes an option to generate a Lightmap Channel for the merged mesh. So this should always succeed and there shouldn’t be an error when the Actor assets dont have a lightmap.
Also interesting observation: If you have multiple different assets (actors) and ONLY 1 has a proper second UV channel + LM-index set to 1, the merge works, too. So at least 1 actors needs a “proper” setup.
If this is no bug and by design, there should be at least a helping output log error message. Atm. only a “raw mesh is corrupted” message from RawMesh.cpp is generated for the merged static mesh, which does not help at all.