I’m sure many of you who use Hammer glance at the “Only Entities” setting for VBSP in the compile menu and just skip over it. I’m fairly certain at least a few of you have tried setting VBSP to compile Only Entities and have noticed that VVIS and VRAD start throwing errors because of it. This is a fairly short guide on how to properly use the Only Entities compile option. Before I jump right in, however, I do want to explain exactly what this option does. When you run VBSP as Only Entities, it skips over a very large portion of the VBSP process. the BSP tree isn’t created, visleafs aren’t cut up, detail sprites aren’t placed, and all those other little things that VBSP does to compile a map are not done. VBSP simply overwrites all the entity values stored in the currently compiled map. Attempting to re-run VVIS or VRAD over it will return errors because of the way those tools work, something a little bit more complicated than I really want to go over in this guide.
