Bifrost - particle life?

[Anonymous]

Hey guys, I was wondering how to make liquid dissipate faster?

I guess in the particle world, you'd call it particle life/age.

[pshwayka]

Hi digi3gg,

Have you tried the Bifrost->add killplane feature?  You can position them in your scene where you want the liquid "particles" to die...

[Anonymous]

Yeah I use that for the ground most of the time but, they seem to just delete the particle off.

I'd like the lquid to get smaller to a scale of 0 and then die.

[syracoj]

One thing that you could try...

and this is for hardware rendering only...

is you could add an expression to the sphere particle display type (on the bifrostShape node - Particles > Type: Sphere > Sphere Radius attribute)

something along the lines of:

bifrostShape1.sphereRadius = 1 + (frame * -.01);

but then you would have to add some sort of logic statement to test to see if the particle sphere was already at a radius of 0 to just use a radius of 0 because, other than a killplane, there is no way to explicitly kill bifrost particles at the perParticle level and since this is using the 'frame' function as it progresses it will factor to 0 and then step into the negative range so the particles will appear to grow again. (essentially the particles scale themselves inside to out)

you would not be able to mesh this sim. The only rendering option would be to render it out in hw2 sequence.

very limited but in its current implementation bifrost simulation is a fluid simulator not a particle one (in the classic sense of particle simulation that is).

hope this helps.

[Anonymous]

ok cool, I'll try that out!

[agraham]

This isn't something that Bifrost can currently do. When you think about it, this isn't something that non-compressible liquids can do either!

What kind of effect are you trying to achieve? Evaporation?

[Anonymous]

Hi Im trying to create a boat foam system with bifrost and I would really like for my particles to die after a period of time.. right now after a long period of sim my trail gets bigger and bigger and longer is my simulation. I've got a wide shot camera and I dont need the trail to be that huge.

It would be nice to be able to delete the particles after a certain time (randomly) putting a kill plane just makes my sim squard and sharp cut in the particles with is not nice.

any solution on that? thanks

Eric

[agraham]

Foam particles will die once their density drops below the Kill Density Threshold. Foam particles are always born with a density > 1, and depending on where they are below the surface, they will have a density even higher (roughly equal to their depth in voxels + 1).

Foam particles' density will dissipate every frame (as controlled by the Dissipation Rate). The rate at which the density value dissipates is somewhat complicated, but increasing the dissipation rate will help the foam particles to dissipate faster, thereby killing them off faster.

So it's not a matter of killing your particles sooner, it's a matter of aging them faster. Sort of.

[timdan]

Is this still the case with Bifrost? I need the particles to die after a certain amount of time. I realise this post is 5 years old, and I see nothing else regarding this topic. Is there still no way to kill particles after a certain amount of time? This is a very standard behavior for particles. 

[syracoj]

Timdan,

is this for the legacy BifrostFX (liquid and aero) tools or the newer Bifrost Graph Toolset?

For BifrostFX you should be able to create a killField and set it to lifeSpan. min 1 and max 1.1 will kill the particles within a second (after 24th frame on a 24fps rate). The bounding box should encompass the entire sim.

For Bifrost Graph, using basic_particle_graph if you select the source_particles node has an age limit parameter that can be set. Default is 2 (so particles get killed at the 48th frame). 

[timdan]

@syracojOh, this is exactly what I was looking for! You've just saved my Christmas! Thank you.

(Also, to answer your question it's for the "legacy" Bifrost Liquid, and not Graph. )

[Anonymous]

How do I embed the disappearance of points into this graph? I need them to disappear after 20 frames.
Maya 2022 

[syracoj]

do you need all of them to disappear or just the particles that have reached their 20 frame life span?