Build Geometry vs Build Lighting Only

I read the docs but they dont really go into the details as to what is covered in a Geo and Lighting Build. I understand the basics between these two builds. If you add new meshes, you build geo and if you make changes to the lights, you build lighting only.
My question is can you just build lighting only if you add lights to the level or do you need to build geo also?
Likewise, if you import new textures, create new materials, and assign materials to objects, can you perform just a Build Light Only or do you also need to Build Geo?

Hi Haskellf,

The build Geometry option is referring to BSP and building that. It’s really not an option you have to worry about unless you’ve disabled “Update BSP Automatically” in the Editor Preferences > Level Editor > Miscellaneous.

If you’ve disabled this, then BSP/Geometry will not update automatically and you will need to use Build Geometry to make it appear. Other than that there is no need to worry about this option. 99% of the time it’s fine just to hit Build and let it do all the things. If you’re using HLOD or Precomputed Visibility Volumes there may be an additional added time, but if you’re not it’s nothing to worry about then.

I hope this helps.


Thanks! I did not know that. I rarely use BSPs. So build geometry only is only for BSP not also meshes? Good to know.
So then what is the difference between executing/compiling with Build All vs build Light Only? I find that build All takes much longer than build lights only and that’s why I want to limit it’s use.
If I create a new light, can I just build light only?

Build Lighting will only compile the lighting for the scene again whereas build all will look at each of the options in the drop down for Lighting, Reflection Captures, Precomputed Visibility, Geometry, Navigation, and HLODs.

If you add a new light you can use just the Build Lighting option if that is all you need. Personally, I did not notice a difference in using Build All vs Build Lighting only if I only added a new light. If it’s quicker for you, then I think that’s the way to go.

Sorry for very late post, but this kind of applies…why is am I getting ‘build geometry’ to start ,when I click build lighting only ? Do I have wrong settings somewhere?I’ve looked in docs and videos and can find no info about this.