Water Demo

[TJ the HedgeScout]

So, i saw the GIF on trello that shows water physics, will it be able to collect at the bottom?
Even if it has to do it slowly, i would be fine with that, as having it collect in real time would be too demanding. Plus if it doesn't that would probably mean if you drilled a hole in the ocean to hell the ocean would eventually vanish... ^^;

[red51]

Originally posted by TJ the HedgeScout:

So, i saw the GIF on trello that shows water physics, will it be able to collect at the bottom?

Yes it will ;) However, over distance, flowing water gets absorbed by the ground - this is mostly done for performance reasons, otherwise drilling a hole in the ocean to hell would indeed flood it (which would be kinda funny, but would certainly kill performance, especially on multiplayer servers) ^^

[TJ the HedgeScout]

I hope that wont cause a water shortage though.
But here is hoping you find a breakthrough on water calculation.
Can't wait to try out the water when the update comes.

[Menzagitat]

Originally posted by red51:

Originally posted by TJ the HedgeScout:

So, i saw the GIF on trello that shows water physics, will it be able to collect at the bottom?

Yes it will ;) However, over distance, flowing water gets absorbed by the ground - this is mostly done for performance reasons, otherwise drilling a hole in the ocean to hell would indeed flood it (which would be kinda funny, but would certainly kill performance, especially on multiplayer servers) ^^

You definitely play and enjoy things we might never see...
I want a secret setting which would adjust that. If you put it in the C# part of the code is fine ;)

[Menzagitat]

An ingame profiler, if there isn't already, would be useful, to see what the CPU and GPU are bussy with.

[Draven Crow]

Water pouring into hell to douse the flames, that's Rising World's Armageddon ;)

[Yaro]

Important question: Can we make waterfalls?

[Menzagitat]

Like here?
https://twitter.com/Vuthric/status/1512640001472962565
Probably not. :)

[TJ the HedgeScout]

That depends on Red's skills. But i think he might be able to do it, I trust him. ;)

[red51]

Originally posted by TJ the HedgeScout:

I hope that wont cause a water shortage though.

This is a good point, although I don't think it will be a huge issue... for large bodies of water, we will probably implement a special "infinite" water type - otherwise draining an ocean would keep the game (or server in multiplayer) busy for weeks ^^

Originally posted by Menzagitat:

You definitely play and enjoy things we might never see...

Hehe, well, tbh I didn't actually test it :D But based on the the current flow behaviour and performance implications, it's safe to assume that this would be a performance killer :D

Originally posted by Menzagitat:

I want a secret setting which would adjust that.

Maybe it's not a bad idea to have a hidden option for that ^^

Originally posted by Menzagitat:

An ingame profiler, if there isn't already, would be useful, to see what the CPU and GPU are bussy with.

That's a good idea (irrespective of water), I will put that on our to-do list :)

Although the water system in RW is CPU bound (since all flow calculations happen on the CPU). The water system definitely benefits from many CPU cores.

Originally posted by Captain "The Hermit" Yero:

Important question: Can we make waterfalls?

Most likely yes: Placing a regular water block somewhere will not work in this case (it will just flow away), However, we will probably implement a special "infinite" water block (which acts as an infinite source of water), which would be suitable for a water fall. We still have to run some tests to get a better idea of the overall performance implications of such a feature ^^

Originally posted by Menzagitat:

Like here?
https://twitter.com/Vuthric/status/1512640001472962565
Probably not. :)

Unfortunately this is indeed not the type of fluid simulation we will see in RW =/ This is definitely a very impressive fluid simulation the Epic dev is showing there, but you have to take it with a grain of salt: This kind of water simulation isn't possible on a larger scale, e.g. having a lake or even an ocean with this type of water. It's great for small scale water simulations though (filling a room with water, for example, or maybe a swimming pool with dynamic water).
This is basically a GPU based particle simulation: There are tens or hundreds of thousands of individual water "particles" (like small blobs) simulated on the GPU (which is good for parallelizable tasks). A special type of renderer is then responsible to visually "merge" these individual blobs (so they look like a continuous body of water).
This has a few limitations though: Even a powerful graphics card will struggle if there are too many water particles (a powerful modern GPU will probably be able to handle a few millions of particles, but that's still not enough to fill a lake, for example).
Another issue are persistent worlds: If you want to store the current state of the water, you need to get the data back to the CPU. This will be a bit problematic if there are really millions of water particles out there - this results in way too much data. In multiplayer, this also needs to be synced across all clients. This isn't necessarily impossible to do, but it opens up a whole new can of worms ^^

tl;dr Flowing water with this level of detail is only suitable for small-scale scenarios nowadays (small river / waterfall, ponds, swimming pool etc). It will take ~ 10-20 years until we can see something like that on a large scale (e.g. as a full water solution in a game like Rising World) ;)

[TJ the HedgeScout]

If Unity ever decides to try and copy UE5's Water, then Rising World could have better water that isn't as demanding on resources, but that is only if the people behind Unity consider adding it.
Also yeah i think we should have a setting that controls water updates per second, based on the GIF we saw, it looks like water updates 20 times per second which is like 20 FPS?
People with weaker CPUs could lower the number, water physics will act more janky but it would be less taxing, also the setting is server side, if you join a server where the water update is 10, then it only updates 10 times per second, even if a player's water update is say 60 (would be 60 FPS) it would still be 10 times per second since the server controls it. But if a player's water update was 5, then for them it would only be 5 times per second, server still has it at 10, but players with a lower number than the server will take priority for performance reasons.

[red51]

Originally posted by TJ the HedgeScout:

If Unity ever decides to try and copy UE5's Water, then Rising World could have better water that isn't as demanding on resources, but that is only if the people behind Unity consider adding it.

That would be great, although it wouldn't really help for the actual water system... it would be useful for smaller things though (e.g. having a nice effect when pouring a bucket of water, for example). The limitations mentioned above are basically irrespective of the engine, so even in UE5, you couldn't use the GPU-particle-based water on a large scale =/

Originally posted by TJ the HedgeScout:

Also yeah i think we should have a setting that controls water updates per second, based on the GIF we saw, it looks like water updates 20 times per second which is like 20 FPS?

Well observed ;) The water on the gif is updated approx. every 50 ms, resulting in 20 updates per second. This value is already configurable, and indeed, reducing the update interval definitely takes some load from the CPU.

Originally posted by TJ the HedgeScout:

also the setting is server side, if you join a server where the water update is 10, then it only updates 10 times per second, even if a player's water update is say 60 (would be 60 FPS) it would still be 10 times per second since the server controls it.

Exactly: In multiplayer, water flow is calculated on the server, so only the server setting is relevant in that case.

Originally posted by TJ the HedgeScout:

But if a player's water update was 5, then for them it would only be 5 times per second, server still has it at 10, but players with a lower number than the server will take priority for performance reasons.

Currently this is unsupported (the player cannot force the game to update the water less frequently than the server), but I agree that it would be quite helpful if the client could at least lower the update frequency on his end... it's a bit tricky to implement though, because water updates are basically like regular world edits, and we have to make sure the world is still properly synced if the client skips certain world edit packets. But it's on our to-do list :)

[Menzagitat]

Now I saw too that water animation gif on Trello.
It looks much better than I expected, when we first talked about water in another old thread.
Great job!

[TJ the HedgeScout]

I do need to ask though, what about other liquids? My guess would be that lava would flow slower than water since... well it's liquid rock.

[red51]

Originally posted by Menzagitat:

Now I saw too that water animation gif on Trello.
It looks much better than I expected, when we first talked about water in another old thread.
Great job!

Thanks a lot for your feedback :)

Originally posted by TJ the HedgeScout:

I do need to ask though, what about other liquids? My guess would be that lava would flow slower than water since... well it's liquid rock.

Our water system is written in a way that it can basically handle various liquids with different viscosity - so oil or even lava could flow slower than regular water ^^

[VaderDFXB]

The only issue I have with the dynamic water in the .gif is how quickly it dissipates into the ground. If it took a minute or so, with options to adjust it of course, then that'd be better than it basically vanishing instantly. Otherwise it looks quite good and I'll be happy to have it.