Rear faces of modular geometry - keep or delete?

motionblur

I created this thread on Eat3D and the Unity forums as well - if you see it there please ignore two of the three

I don't know if the problem is specific to a game engine or more of a general rule. If you create tileable assets for levels/environments - do you keep the rear faces of walls and roofs that nobody will ever see or not?

So far I simply deleted the rear faces of walls the player/camera will never be able to view anyways. I'm working in Unity and Be

SlyRipper

I would also remove them, why should you keep them if nobody ever sees them? It's always good to remove unneeded parts to save performance on other locations where you can't that easily delete unneeded parts.

To make it safe, I would also recommend you to keep a basic file stored somewhere, that has all the faces (also the deleted ones). This way you could easily recreate that part again with the needed parts when it causes some errors in the engine or whatever. I would always keep a full version of every part so you can edit it later on.

Guess the rest is just trial and error, to get best balance between needed and uneeded parts

Eric Chadwick

Depends on how modular your pieces are. If they're whole walls, then no need for backfaces. But if they are sections of walls, columns, arches, etc., then you can reuse them more if they have backfaces. Then you can rotate them 90 or 180 degrees for more variety. So, depends on how the level is filled out with your pieces.

http://wiki.polycount.com/CategoryEnvironmentModularity

leleuxart

Aren't meshes without backfaces more likely to have light bleeding? Especially with UDK...

Lloydyy89

When I've used modular pieces in UDK, if the model was lit from the back where the missing faces where, then there's no shadows. I had to make the material 2 sided to get shadows back.

motionblur

So if the backfaces are still there it might reduce bleeding in the lightmaps?
That's actually an interesting thing to try out.

I know that ProBuilder for Unity mimics Valve's Hammer Editor in lots of ideas. The backfaces of geometry created with PB can be set to "invisible" so they aren't in the final light map. I don't know if that is only because of Pro Builder's internal structure or if this also increases light map quality. It's an interesting idea, though.
In general - at least in Unity the Lightmapper catches shadows even if there is no rear geometry. So maybe it actually is an UDK specific thing.