Automatic fog settings

Hi again.
I would like to tell Uru to set automatically the fog of an Age depending of a precise number of hour, in order to have a daytime/nighttime cycle.
It would set the line "Graphics.Renderer.Fog.SetDefColor" (and "Graphics.Renderer.Setyon" if possible).
Gira, Kemo and Payiferen already use it, but it seems it doesn't use any Python file for this. Is it in the PRP and how can I reproduce it ? Thanks a lot.
I would like to tell Uru to set automatically the fog of an Age depending of a precise number of hour, in order to have a daytime/nighttime cycle.
It would set the line "Graphics.Renderer.Fog.SetDefColor" (and "Graphics.Renderer.Setyon" if possible).
Gira, Kemo and Payiferen already use it, but it seems it doesn't use any Python file for this. Is it in the PRP and how can I reproduce it ? Thanks a lot.