Source lightmap index reset to 0

ok i’ve just ported my game to UE4.5/shooter demo, copy/paste my content to the new folder/build

tried my maps and they looked very bad, further research showed that all my static meshes had the “source lightmap index” reset to 0.

maybe due to the way i move my content but just in case others have the same problem.

could be annoying if it happens if you have a lots of static meshes

Indeed, same here. Also the other settings like import materials and textures is now set as “on” to default. Looks like it doesn’t take in consideration previous settings. Now all my meshes imported in ue4.4, reimported in ue4.5 are getting broken. I have to recheck a lot of settings before reimporting other things I’m working on… so basically cannot rely on “reimport” as for now…
There is other thing, there is no way to turn off material importing. I have to drag from scratch fbx file to editor to be able get to this option again. Or do I miss something?

P.S. I have a silly question, maybe shouldn’t ask here, what is the difference between “source” and “destination” lightmap index?

Thanks in advance.

Hello Geodav,

Instead of copy and paste, try using the migrate tool which copies the entire asset and their dependencies to your new project. This helps safeguard your meshes and other imports from getting broken in the process. As for the settings of importing, they are reset to the default values when you use a new version of the engine.

Also source lightmap index is where you receive the index from which you can set for the destination lightmap index. In other words source is where it comes from, and destination is where it is applied.

Hope this helps,

Thanks for the info :slight_smile: I will try to be careful with reimporting after UE updates. But still, I would love to have the checkboxes for materials and textures importation in the future, since it would be nice to have possibility to change these settings without redropping the fbx to editor.
I know there are in plans many changes for the fbx importation for the future releases, so can you guys take it in consideration?

About the indexes, I’m still confused. They are also UV Indexes, right?
If I understood it right, it means it bakes shadows with “source” (probably where I should put my diffuse texture index) and than, once baked puts it to “destination”?
But I’m wondering what is happening with more complexy shaders, like blended two or three textures with vertex paint or a splat map? I’m probably over thinking it… I might be completely out of track here, just asking out of curiosity…

Thank you very much for your time :slight_smile:

Hey dzodzu,

We are glad to help, and there are indeed plans to improve upon .fbx importing options.

As for the Lightmap UV indexes here is a bit of clarification I pulled from the documentation website. By default, the first set of UVs (index 0) of a static mesh will be used when generating lightmaps for static lighting. This means the same set of coordinates that is used for applying materials to the mesh will also be used for lightmaps. This is quite often not ideal. One reason for this is that the UVs used for generating lightmaps need to be unique, meaning that each face of the mesh must not overlap any other face within the UV space.

The reason for this should be fairly obvious: if the faces share the same UV space, the portion of the lightmap corresponding to that space will be applied to both the faces. This can be great for diffuse and other textures as it allows the texture resolution to be higher for each face. It will result in inaccurate lighting, however. Static Meshes have a property called LightmapCoordinateIndex that allows a specific set of UVs to be used for lightmap generation. By setting this property to point to a set of UVs that are unique and properly set up for lightmaps, Static Meshes can enjoy the best of both worlds: better texture resolution for diffuse textures and accurate lighting from lightmaps.

Here is the link to the documentation for more information about unwrapping and lightmapping in general: