Problem is, the skybox (the 6 images that make up the sky) cannot be changed dynamically. Therefore, the sky would never actually change. The rest is perfectly possible.

It's not impossible to do all of that, but it is complicated; I know of a map that has a cycle, but doesn't have a sun, though I guess a big enough light_dynamic could fix that.

Posted by birjolaxew

Problem is, the skybox (the 6 images that make up the sky) cannot be changed dynamically. Therefore, the sky would never actually change. The rest is perfectly possible.

What you can probably do is an animated texture for the skybox, outside Hammer.

Posted by alexandrovich

Devieus, what's that map you mentioned?

rp_apocalypse_hl2dm, but it has a million devices to prevent you from doing anything with it; you'd probably be better off contacting the author, if you can find him.

I've made a rotating skybox surf_foldingworlds I did it by making a box with a space texture on the inside, tied the box to func_rotating, and placed a 3d sky camera inside it.

Simples

Moving suns however is impossible in the source engine, as far as i know.

edit - You can change the skybox, and there is a tutorial somewhere which shows you how to flick through various different skybox's in game with a few buttons. it wont be graduate but it'll still change to night time and day time if you use timers.

If I was doing it I'd play with the following:

• Color Correction Volumes (save extra light styles on faces) triggered at various points with long fade-in-out times.
• Avoid strong shadows (overcast-ish level).
• Use my custom skybox model prefab parented to a SLOW func_rotate. Probably 2-5 of those models to use more texture sets for nicer fade from light to dark.
• Add in animated cloud texture to help hide transitions.
• env_sprite for faint sun appearance (again, overcast day).