That's a task for a script, no need to make the material configuration unnecessarily complex for a specialty like this.
Make sense at some point. However, I bet not many 3d modelers, making static model, will go to scripting to make automatic on/off lights.
And when Outerra will be filled with cities, you'll end up with few lights ON at night.
If it's mostly done at your end, with option provided to user, then there will be more will to go for this on user side.
In the end most of cities will light up at night.
But it's definitely must be a "spend an extra minute" option - For this reason I even thought not to mention time ranges - just to make Automatic (at sunset-sunrise) on/off if the texture have certain tag in name (ex. "
N_windows_illumination.dds".
Then all that user need to worry about when doing illumination map, is to add that tag to name.
But still - Will the scripting will be available for static models?
hmm, maybe some kind of a system generated random map usable in materials? But it would require multiple channels with varying periods.
A mask map for illumination map. Basically every element on this mask is in different color (Object ID Pass):
At start time (Sunset) randomly (or even linearly) start to unmask illumination map by gradually revealing Object ID map color parts.