goldfish in a plastic bag filled with water

#1

Hello
I hope I’m asking in the right place
I’m an animator by profession so I’m not very experienced with solving vfx problems

anyways,goldfish in a plastic bag filled with water,how do i attack this problem?
if i want to test and see if its doable…
do i model a bag in its “filled” form,fill it with fluid and move the bag artificially by a rig?
(the bag should be on a table or floor,it doesn’t move much,but the fish in it should
move a lot.

do i use cloth for the bag,and there’s a way for the fluid to deform the bag from the inside?

other creative solutions?

comments and advice are welcome,
thank you

Hagar

#2

Hi HagarE,

I’d suggest you to take a look to this rig (you can download it for free):
[VIMEO]91109929[/VIMEO]

I don’t know anything about fluid/clothes simulation but it seems hard to set whereas this rig is rather simple. Of course this won’t look like realistic water because it’s just a rigged polygon but it could be a good alternative solution.
In my opinion, you should create the bag in it’s “filled form” and the water in the shape of the bag and then create a rig based on Carlos Contreras’s.

Hope this helped! :slight_smile:

#3

thank you
yes helps a lot,its a clever solution, if all else fails ill take this one
i tried to test the dynamics stuff,apparently it seems doable
on the first the cloth can act like a bag filled with liquid or something plastic
and on the second,the cloth can be filled with particles
(it took me a long time to figure out they will only react together if they have
the same nucleus)
[VIMEO]109314492[/VIMEO]
[VIMEO]109314183[/VIMEO]
but I’m a complete idiot on those(for now),ill have to do all the tutorials on the internet

I’m still contemplating…

if i fill a cloth bag with particles…
should i go straight for using real flow?i saw that maya fluids act more like voxels
like smoke or fire

or should i maybe just convert particles to a mesh,since it doesn’t move a lot

also a stupid question(because i transferred to maya just a year ago)
when playing simulation,should i use “play every frame” or “realtime”?

#4

Every frame.

You can Convert particles to mesh and make a detailed enough water blob if you dont need a realflow style splash. Or if you wanted you could use a fluid as a solid, also converted to geo.

Is this a realistic shot or something cartoonish?

You could even try to venture into using Bifrost if you have 2015 :wink:

#5

ok,thank you

the fish are cartoony,but the render is realistic
basically its 2 plastic bags with one fish in each ,put next to each other
and the endless stupid\interesting gags you can do with that

for now i think ill try to go for the simulation and learn it because in a realistic render
the still mesh might look frozen,and it would be nice if in the beginning there would be one
bag and the second one would drop next to it,so it will need to splash

some projects in process are still anchored in 2012 so i cant change version for now
even though the bifrost thing thing looks like a very attractive toy

ill probably come back to cry and complain when stuff don’t work :slight_smile:

#6

You could probably get OK liquid by enabling liquid on the particles and turning off self collision. Then use the mesh out on the particle shape and carefully set the mesh output settings(triangle size, blobby threshold, etc). Also depending on the size of the particles and the relative density of the cloth mesh adjust the mass value on the particles. Higher and it will push the bag more.

Or if you want really realistic water you could use the nParticles just to influence the shape of the bag and make it behave like it is full of liquid, then hide the particles and use bifrost for the actual liquid, colliding with the output cloth. You might finish the full animation with the fish just using nParticles then as a last step use bifrost if you need more accurate liquid. Although note that bifrost doesn’t have surface tension in the current release, so this might be an issue, as otherwise the liquid might look too much like large scale liquid with fine droplets.

#7

thank you
that is a lot of useful information
didn’t know about the possibility of the mass value

in case of using nParticles to deform the bag,hiding them and filling the bag using
bifrost or other fluid simulation,that simulation will take to the deformed bag?
or to the original bag?

i considered the first option,until yesterday,when i got “it would be great if the fish
jump up and move the bag with them”…and “they will blow out bubbles”…
so I’m thinking,in case i need the bag to roll or jump or god knows what,
do i have the fluid affect the bag or just rig the bag,animate it convincingly enough
and fill it with fluid
but ill know better when i have a storyboard

soo…i have enough time until i need to start the project,i will start by learning maya
dynamics and particles
unfortunately ,I’m limited to versions 2012 and 2014(not my decision)
so it will probably be realflow,so any tips for that one would help too

cheers…