Hi there,

I have a sop based animation on a breakable obj.
How can the Dop simulation fallow inherit the sop movment, and not just drop as if the sop movment would not exist.
tried to run the Velocity Transfer in the Voronoi Fracture Parameters, but I don't get it work!

Any advice or suggestions would be nice!

(enclosed the hip file)

Thanks a lot

I would get the animation hand off working before introducing the fracturing tools. Read this section [sidefx.com] in the Houdini docs about transferring animation to DOPs.
The VelocityTransfer on the fracture node controls how the pieces inherit velocity from the intact object at fracture time.

At the moment you have a tranform at the Object level, and animation at the SOPs level. I would consolidate those to the object level, or, since you want to fracture things later, maybe move it all to an RBD Keyframe Active node.

I copied your animation channels to an RBD Keyframe Active node, and that seems to work fine. Just set the Bypass flag on the fractureParms node while tweaking the animation.

I also set the DOPnet Substeps to 2 since the fracturing transition is smoother when you do that.

Thanks for your reply johner!!!,

The reason i dont didnt go that way was because I need the aniamtion on a sop level.
The main obj I working on is more complex and so I can't go with object Transformation way.

Any suggestions?

Thanks!

For SOP level animation it depends on whether you want to simulate deforming geometry, or hand off the animation of the object completely to DOPs at some point.

In the first case you can turn on “Use Deforming Geometry”, which does what it sounds like but can be slow as the collision SDF needs to be re-computed each timestep.

For the second case, append a Trail SOP set to Compute Velocity, which adds a velocity attribute to each point of your geometry, then turn on “Inherit Velocity from Point Velocity” on the RBD Object. Then set the “Creation Frame” to the frame when your SOP-level animation ends. See attached for an example of this technique.

thanks a lot johner!!!

Thats what i am looking for!!!…but it seem that merge sop and the two incomming dops are somehow erroneous ..or the fechting doesnt work correctly!?

So I used a switch node to blend the situation befor and after the break in one seemless sequenc.
Is there a more elegant way to feed the data back to work properly?

Thanks!

Yes, you can't fetch the object from DOPs until after its Creation Frame. So a Switch SOP like you've done is a good way to go. For motion blur you'll want to turn on “Geometry Velocity Blur” at the Object level, which will use the point velocities from the Trail SOP and the DOPImport SOPs.

Thanks johner!