Better fog API structure (visible, colours etc)

[Zughy]

Problem

Currently, MT fog is quite limited, with people in these years requesting features like colour (#7284) and tweakable cloud fog (#7838). Also, players can turn it off by just pressing F3, breaking whatever aim the modder had (#14163)

Solutions

First of all, I suggest a visible parameter, both to create coherence with other celestial vault elements (sun, moon, stars and clouds) and to avoid this -1 hack on fog_distance, fog_start and whatever parameter may come next. I maintain a mod that includes an in-game editor for the celestial vault, and implementing fog hasn't been fun as I had to treat these parameters as a special case. Furthermore, it can be a nice way to tackle #14163, enforcing visible when declared (no matter if true or false)

Then I'd move fog_sun_tint, fog_moon_tint and fog_tint_type into fog

Last but not least, I wonder why fog is in set_sky. Like, in my mind is a weather condition, not a component of the celestial vault. Wouldn't be better to have a separate set_fog() function?

Alternatives

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Additional context

No response

[lhofhansl]

I agree with most of your suggestions. Where to put it in the API is always hard. Is it where you set clouds? Is it where you set lighting?

[Zughy]

Definitely not lighting, it's not a light phenomenon. It's humidity coming from the soil, so it doesn't belong to the celestial vault either. In my mind it's something on its own, related to visibility