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ekan de

Simulating flip from bottle

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Hello everyone.

Long time since last post here when i was dealing with the same thing.

After watching some tutorials and learning some more in houdini i decided it was time to go back and see if i could get some better results.


There is still some big questionmarks that im seeking answers for.

Here goes.

This is the simulation i want to do.


Animating a beer bottle (prefferable in maya since i have a rigged character and i have made a animation that matches footage so i know that the animation is timed correctly and so on.

The bottle will be pouring beer into a pretty standard glass.

When i have a stable flipsim i would want to go on and simulating bubbles and foam.


So on to the questions.

1. I have noticed some differences between using collision geometry made in houdini or imported geometry.

    Making the geometry in houdini seems to work much better for some strange reason. Can anyone confirm this? It seems that i get away with much higher settings on particle separation and gridscale then using similar objects imported from maya.


2. Scale seems very important here. Simulating in real scale gives a lot of trouble. therefor i scaled the bottle up so that it is around 1 meter high. However, this gives some problems when it comes to actually using the animation i made in maya. Everything in maya is done in       centimeters and when importing it to houdini its way to big. I ended up matching the animation inside houdini from the imported file and used that instead. Wich is the best way to get around this? Usually in production everything is modeled in correct scale in maya.


3. Setting up the flip source. Is this the correct way?

Import the fbx file with the bottle. --> create a new geo node --> create a box big enough to cover the bottle and up to the level where the liquid should end at the bottleneck.

Object merge the bottle into this geo and connecting a boolean with subtract b-a settings.

Then i blast the exterior so i have only the interior of the box minus the bottle.


4. In the bottle geo i have a transform and after that a null. i put the displayflag on the null and then create a deforming object from that.


5. finally i create a static object from the imported glass.


Now all is setup to start simulating. ofcourse there is alot of tweaking of particle separation and collision settings to be done but overall is this a good setup?

I can post a file if that helps.


Finally some other questions.

When caching out the flip to simfiles i only want the particles to be cached. where do i set this up? 

Regarding substeps, if i raise the substeps INSIDE the dopnet on the flipsolver will this generate more substeps when caching it out or is it only the substes on the dopnode that sets substeps in caches?


Sorry for kinda of a long post but if anything can be answered i would be grateful! THX!









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