Ghost of Tsushima's blood in water effect. How?

ilyatheartist

So I've spent the last few days trying to figure out how to do blood particle with water interaction like in Ghost of Tsushima but in Unreal Engine 5, but I can't seem to figure it out. 

I know the particles are dynamic according to this blog (need to use waybackmachine to enable gifs) , but how do they turn into clouds after they interact with the water, and most importantly, how does the effect gets picked up by the river's flow and dissipates? It's just incredible to me. If anyone can help me figure it out, I'd very much appreciate it. Thanks.

MikeF

Im not familiar with the specifics of unreal's particle system but i would break it down like this
1)initial blood splatter particle with collision enabled
2)on collision with water, emit a new sub system that is aligned to the surface normal of the water. If this isnt possible then just allign horizontally . At the same time the origi al system should be destroyed
3)over the lifetime of this secondary system, scale up and gradually fade out the individual splat billboards

For controlling the direction you would likely need to retrieve some data from the hit water surface that can give you a flow vector and speed that you can then use to control the position of the billboards as they scale and fade out. You could also randomize the influence of this value slightly to give the effect of an uneven dilution in the water

dimwalker

At the start of flowing, splatter looks like it stretches (by velocity or maybe trails), then turns to more traditional puffy particle cloud before disappearing.

poopipe

I think you could get fairly close with niagara - getting the flow vector out of the water might be tricky/impossible but if you can it should be relatively simple. 

I'm pretty certain the developers made engine mods to achieve this effect though

Klunk

Think I would approach this by first creating a good blood in the water effect, with flow and without.... and with random area initialization. Then go from there.