So I've implemented hash grid based fluid simulation in VRChat - its absolutely incredible. Because its hash based its literally boundless, so fluid can occupy the entire world. Currently I only have the "Mentos" particle rendering, but I plan on trying to make isosurface work

Its absolutely mental when you set gravity to low, fluid literally flyes everywhere

I have put 1M particles as limit in the world for now, which can fill a decently large space

I've also added a bunch of "manipulator" objects, like this attractor sphere, you can make globes of fluid

Here's high viscosity goop liquid

Inverting gravity direction is also quite insane when you dont have bounds

I've also been improving the isosurface ray tracer, make it a bit more PBR based, also basic screen space effects. Its currently only functional in bounded simulation mode. Making it work in hash sparse boundless would be the next problem. Not sure if even feasible with good perf

Regarding the technical side, I think hash based particle simulation is much better than sparse tree grid based one, sparse tree's require indirections to get neighbor, while with hash grids the only drawback is hash collisions, but the bottleneck is latency so its much better

Making a hash based grid however is tricky, I think I'm going to try making a "N-slot texture" where each sparse cell can hold up to N voxels, it should hopefully work most of the time if the "hash" has few collisions. But yeah making it ray trace fast is tricky

Soo what exactly do you expect vrchat players to do with a fluid sim...

dont worry about that 🫡

Please dont add white color, i beg you

You did, didn't you

How did he made the water physics work I mean is there a tutorial for it

tutorial? not really, more like papers:

VR chat? How many request for a sticky white version you got so far?

yes

Will you be releasing this anywhere? I'd love to learn from your work.

Hi! I've been working on a very similar thing with ThreeJS + Box3D! This is MIT

VRC Splatoon and DrainSim. Good potential here.

Portal 2 map incoming xD

This is the future

@GuusDeKroonVR - we need to check this out sometime 😁

watch this be used for you know what

The bandwidth required to display this for all players must be enormous.

Not really, sim is run locally. As long as the inputs and interaction matches it looks similar enough for people to be fooled that its synced

Wonder if it'd be possible to use this to do something like SpaceSim in VRChat (Example of SpaceSim: 1M Solar mass black hole eating Mercury)

Unfortunately it is possible, and I've been considering something like that. But I would need on top of sorting to build a sparse octree for Barns-Hut, or multipole method, that would be tricky. Much harder simulation wise than sparse hash fluid

Don't know about you, but I'm one of those people who love pushing a platform not made for physics deep into physics Same with mechanical engineering stuff, just seeing things move and be interactive So difficult yes, cool also yes.

external gravity is easy with this simulation, its just self gravity which is ass to work with due to nonlocality

Ah, got it. So basically VRChat is being VRChat like always, a pain in the ass to do anything cool in without having to get around a mess

honestly? this would be hard even outside of vrchat 😅

Yeah... I'll come back and reread after I get sleep so I'm not on 2% battery mode and actually comprehend things Until then imma go read up on some more whatever I was doing... I forgot

That's really cool!

world?

work in progress, release later

Add white color PLEASEEE i uhhh need it for scientific research

これはまだVRChatで公開されていませんか？ワールドを知りたいです

@SadlyItsBradley Can it run on potato pc ?

@SadlyItsBradley potentially with a small amount of liquid

@SadlyItsBradley Never really tried VRchat. you made me want to play it !

I wanna play in the virtual water so bad ngl

What the fuck

Really strong technical work, respect.

Fiuld simulation in such a performance limited world is really an incredible work. Next step should be adding Cola fiuld into the world.

This will 100% eventually be used for VR furry sex cum physics

Great. Another thing that could crash my game.

millions of gallons...

That's waaay too cool. I seem to have very similar things under the hood, but the visualization and constants make yours look so much better

Yaaay, gooop :3333

@SadlyItsBradley this is awesome! 👏

I also implement hash, how funny

I know what you VRChat guys are targeting with fluids. So keep up the good work.

You are having too much fun over there.

How do you replicate data of 1 million particles, or it's not a concern?

Woah this is impressive. Even with "only" the Mentos. I dont know how VRChat works since i rather play DCV or Valheim in VR but where is the Workload of this sim? Is this Standalone VR or are there Servers from VRChat which handles the calculations? impressive video 🤩👍

its locally simulated, not synced. it looks similar for players, but not the "same"

Ah. So it is PCVR and every Chatter has its own simulation result. Still impressive. Nice work

If this was a separate game it could potentially be synced, but youd likely need * Deterministic simulation, probably on CPU * Lockstep handling on all players * Exact matching of simulation inputs between players