Rendering pretty sky in Around The World game | Hacker News Reader

Rendering pretty sky in Around The World game

frozenfractal.com

163 pointsibobev20 comments

Oh wow, thanks for this. I'm working on a game with some similarities to this (at least in the sense of "includes ocean travel"). Just this week I was working on a sky shader in Godot, and have yet to implement clouds. That whole series of articles looks relevant to my interests... ocean/wave rendering is also on my to-do list.

Game itself sounds interesting and I look forward to playing.

> "On Earth, exploration often meant gruesome exploitation and violence, whose effects can be felt even today... However, this game is not about any of that; it shows how things could have gone, if people had behaved more kindly towards each other."

I love this concept. The world I'm building is almost the inverse of this, taking the reckless real-world exploitation of Earth to its logical conclusions and challenging the player to find a better way of life in the ruins. But despite the different approaches, I think we're both trying to imagine how this world could be better, instead of giving in to bleak, helpless doomerism. We need more fiction like this.

Thanks! I want my game to bring some positive feelings into the world, but I picked a rather bad setting for that, so this is my compromise :)

About cloud rendering: In 2008 a college friend wrote his thesis on real-time realistic rendering of clouds: https://maverick.inria.fr/Publications/2008/BN08b/

You can see screenshots of that work in his thesis defense slides https://theses.hal.science/tel-00319974/file/defense.pdf

That's where I learned about the transference phase function (slide 24), which includes two spikes on the return angle that correspond to the relatively unknown Glory rainbow: https://en.wikipedia.org/wiki/Glory_(optical_phenomenon)

I don't know if this method is what is used in video games today.

Incidentally, you may recognize his advisor Fabrice Neyret as someone very active in the Shadertoy community https://www.shadertoy.com/user/FabriceNeyret2

Thanks for the pointer! It seems like my approach is similar to, but much more simplified than, what is described in the slides (the thesis itself is not loading for me right now). I'm using a 4D function (LUT) rather than 5D. The correspondences are: size/thickness (of a sphere, not a slab), lighting angle, view angle. I additionally use the surface normal, they use viewpoint depth and scattering order.

The observation of different behaviours for different scattering orders is interesting. I could try adding a cheap approximate first-order term to the shader to get more pronounced silver linings.

My LUT is calculated using the Henyey-Greenstein phase function, so without the backward spikes. Since this is all computed offline, I could easily add the more accurate Mie function.

What is used in games today is more raycast-based, e.g. Nubis³: https://www.guerrilla-games.com/read/nubis-cubed

And Neyret's name is well known to me, yes :)

An interesting read, given nowadays no one seem to care anymore how things are actually done in detail.

Doing a pretty sky in my game? Just delegate the entire process to AI.

If it doesn’t look good just keep prompting your way to a pretty sky. Learn nothing while you do it, and when you need to do a simulated 3D sky again, have zero reusable knowledge, after all you can just point your codex at your successful previous attempt.

Thanks! Fsck AI. Keep caring. It's all we have.

Another game that has amazing clouds, where you move around them horizontally and vertically, is the recently released Ace Combat 8. The game itself is UE5 but clouds seem to be completely custom made, volumetric, and look amazing, especially noticeable as you're flying around/through them in the game. Examples: https://x.com/PROJECT_ACES/status/2042437413260443803 - https://www.youtube.com/watch?v=BG7DLLdQf1k

The game is even more amazing in VR where you really get a better spatial understanding of the entire sky, environment and the clouds.

Super pretty indeed, but that AAA look is way out of my league :) Probably took several rendering engineers several months. And it wouldn't fit my art style anyway.

The light is also reflected from the Earth back into the sky, e.g. over bodies of water.

Yes, and my approach does capture that to some extent. Or rather, Godot's ambient lighting approach does. The (ir?)radiance cube map(s?) cover all directions, including the ground. Right now I'm using a uniform gray from below — [albedo 0.39](https://en.wikipedia.org/wiki/Albedo_0.39), but I just learned that this value is outdated. For slightly more realism, I could colour this according to the terrain underneath. Future work!

Of course, there's a chicken-and-egg problem here that isn't captured: the very presence of the clouds also affects how much light is reflected back onto them. That would be a bit harder to achieve.

I'd love to play the game when it's ready. I don't play much of anything but was searching for open-world sailing/exploration games very recently on Steam.

Sounds like exactly what I was looking for... Strange coincidence.

I had a lot of fun with Sailwind, maybe give it a try

https://store.steampowered.com/app/1764530/Sailwind/

There are a couple of ships you can sail with a simple economic engine - you start small and work up. It has some simple sail handling - its not enough to just turn right/left and manage sails up/down. Multi-sail ships are an interesting challenge but manageable.

It's pretty slow-paced, but like I said, I had a lot of fun with it for ~20 hours.

Looks awesome (I actually had found it in my research, but didn't see a ton about it). I'm gonna give it a go, thanks for the recommendation!

Thanks, I (as the developer of Around The World) am always looking for inspiration, so I'll check it out too!

I'm maintaining a list of early testers. Would you like to be on it? Let me know preferably by e-mail (contact details are on my site).

I love this as a concept for a game.

this is gem.

I particularly enjoyed the post about cloud, and I also watched Ten Skies lately... Strange coincidence.

This is excellent work!

Looks awesome (and puts my 2d Godot efforts to shame :)).

The fun part for me is that you managed to get 2 comments out of 9 to end their reply with <end statement>... Strange coincidence.

...Stranger coincidence.

Interestingly, these kinds of insights into how light around us really works are still flying under the radar of modern digital photography.

In Fujifilm online communities ‘film simulation’ is peaking at this moment. Thing with Fuji cameras is, you can tweak many settings in-camera, including built-in simulations for the film look, white balance color shifts, and more. When you take a photo, camera applies these tweaks on the fly, resulting in a photo that does not need much extra post-processing.

For the past 2-3 years this got viral on socials, with the influx of new Fuji owners, and the exponential rise of "film recipes" - set of settings that lead to a specific photo look. The interesting part is, in most cases people share example photos that are taken in vastly different geographies.

What gets lost is that a recipe is mostly just a fixed color shift: more blue or yellow, more red or cyan, plus a tone curve on top of a film sim. That’s it. Many popular recipes are one or two notches apart from each other. The dramatic differences people see in the example photos come from the light where those photos were taken, not from the settings.

And light is far more complex than most of us think we understand. As the post shows, direct sun gets yellower the more atmosphere it passes through, so it changes with latitude, season and time of day. Shadows, meanwhile, are lit by blue skylight. So one photo already contains light of different colors, and a single fixed shift can’t correct all of them the same way. The "Wes Anderson" recipe that looks great in California turns yellow and muted in Finland.

People blame the settings, or even buy another recipe, when the thing they’re actually trying to copy is the sun and atmospheric scatter.

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