[modeless]

GPUs can definitely handle more than 700 entities. Here's 100k in a web browser: http://david.li/fluid/

But even most offline rendered fluid simulations are not that convincing to my eyes, let alone real time ones. It will be a long, long time before we have truly realistic behavior of real time water in unconstrained settings for games.

[lossolo]

Have you seen RealFlow? I was having fun with their fluid physics simulator a few years ago, it's really good.

https://realflow.com/

[modeless]

It looks cool, but I find that there's a characteristic "blobby" look to these simulations, especially visible in mostly flat parts or whenever thin sheets of liquid form and break apart. I imagine that increased resolution can mitigate it but the cost eventually becomes prohibitive even for offline simulation so people settle for "good enough". And I think foam/bubbles are usually kind of hacky (when present at all) rather than being simulated in a principled way.

[hnuser123456]

Yeah, it must be something specific about the overhead in the Source engine when drawing entities, but it doesn't matter if I render the particles as 2D sprites or as 3D models, both of them have a similar performance impact over not rendering them at all when there's 700, and there's no way it's a hardware limitation.

The GP shared some links below from other indie devs, there is a realtime water simulation that looks pretty dang good, though it looks to be on the scale of a human-sized tub.