I am trying to recreate a glass water shatter effect, I am quiet new to houdini.
I can fracture my object and write it out as files. But it does not collide with the flip fluid afterwards.

Is there a special way i should write the geometry files.

I figured it would be easier for houdini to simulate the fracturing first and after using the file node to export animated geometry and add flip fluids over it. So the houdini wouldnt have to simulate fracturing and the flip fluid together at the same time.

Exporting .obj will do no good since there will be no velocity vectors. Saving sequence in MDD file format seems to be good way to do this but you need mdd loader for maya, but never tryed this myself.
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Terribly New to Houdini, intermediate knowledge on 3D mostly Maya

The way houdini works is simply great, but tell me if my approach is correct for redoing the glass breaking with a bullet simulation.

I assume it would be a problem to simulate both the auto fracture and flip fluid in the same DOP node, either because I think it would take forever to simulate, or it would crash.

My step by step approach was this until I got stuck.

1.)Make a glass obj in maya or from revoled curves within maya.
2.)Add a ground object.
3.)Add Active RBD to glass
4.)Make a bullet and add RBD also input initial speed and make them collide
5.)Add auto fracture play with the settings and simulate.

Until here all good.

1.)With in the glass node add a file node and write out .bgeo files( should I be using ROP Output driver or even Can I )

2.)Within the autodop node add a DOP Dynamics Output driver after gravity and write out the .sim files.

Reason for above two points:

Make another file with flip fluid water settled in the glass, add inside that autodop network the glass shattering .sim files and collide with the flip fluid.

If so why do I need the .sim files for fracturing, cant I just use the .bgeo files of the shattering glass.

or do I only add a file node in in the autodop for fluid simulation, and choose my shattering .bgeo files. and add the .sim file to that and just before the gravity node do I merge them with a merge node with collide relationship on.


Help me out here… Please

I also assumed if I can carry somehow the velocity information to maya with a .bgeo loader plugin, I can also work this out with realflow.

I know I cant explain my question good but thats because I new to Houdini.

nice man.., explained it in briefly..,

tricecold
1.)With in the glass node add a file node and write out .bgeo files( should I be using ROP Output driver or even Can I )

Whatever it takes to write out the geometry to disk post DOP Import SOPs. There are a few ways to do that. It is common to follow the last SOP in the fractured object with a ROP Output Driver SOP and write out the geometry to disk.

tricecold
2.)Within the autodop node add a DOP Dynamics Output driver after gravity and write out the .sim files.

The main reason for writing out the sim data files is if the simulation terminates through the simulation and you need to continue on.

tricecold
Make another file with flip fluid water settled in the glass, add inside that autodop network the glass shattering .sim files and collide with the flip fluid.

If so why do I need the .sim files for fracturing, cant I just use the .bgeo files of the shattering glass.

or do I only add a file node in in the autodop for fluid simulation, and choose my shattering .bgeo files. and add the .sim file to that and just before the gravity node do I merge them with a merge node with collide relationship on.

You can use the actual geometry to fracture the glass. Use a Static RBD object and point it at an Object that contains your fractured geometry. Set the Static RBD to dynamic geometry. This will force the collision volumes to be re-built every frame. You can cache out the sdf collision volumes from the original simulation as well to disk. This is done right from the RBD object in the first simulation: in the Collision tab.

In the second fluid simulation, you can load in the sdf collision volumes written to disk in the first fracture simlation right in to the RBD Passive object so that they won't be calculated all the time.

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You can also simulate the rbd fractures and the flip fluids if the data is manageable in memory. The Merge DOP builds relationships. It defaults to “Mutual” which means that both the fluid and the rbd pieces will interact. If you set the Merge DOP bringing the two solvers together to “Left Inputs Affect Right Inputs” and the RBD solver is wired in first, then the fluid will be affected by the RBD objects but not itself impart forces on the RBD objects.


There are a great many tutorials on RBD and DOPs in general. Check out the various vimeo videos by Peter Quint on DOPs.