In maya I have the option to set the initial state of a dynamic object. This way I can put a glass on a table, let it calculate the collision and use this state after some frames as initial state for my dynamics.

Do I have something like that in houdini?

yes, you can simply simulate an object until it settles where you want, then cache it to disk (at the geometry level, right click the dop import node and save geometry).

once you've cached to disk, you can bring it back in (with a file node) and then plug the file node into your dop import node rather than whatever had been plugged into it.

Thanks a lot, I'll try.

Fine, you helped a lot. And because I now know how to read the node information, the example files are much more helpful than before

I could read something about a “Dynamics output driver”, that writes similiar to the file node the simulation data to disk. But I could not find this node.

Any tips?

Where did you see reference to this node?


I suspect that you're looking for the file dop, which will read/write simdata.

You can find it under “Render output nodes” -> “Dynamics render node”

I now use a dynamics file written with the file node to create an initial state .sim file.

Works fine.

But I have one problem. I have a simple scene. I have some cubes that build a wall. Then I want to shoot a sphere into the wall. In my dop I have the sphere as well as my cubes and the floor plane.

Because I first want the cubes to settle before I shoot the sphere into the wall, I first set the sphere rbd to not active.

Then I simulate. The boxes settle and the last written file is used as initial state for my dop network. But now I want the sphere to be an active rigid body and let it collide with my wall.

Unfortunatly my sphere does not move because the initial state seem to overwrite my active checkbox or something like this.

I hope I could explain what the problem is.

I've added the scene file. Simply go into the dop network, turn off the active setting for the sphere, let the simulation write some files and use one file as initial state. Then make the sphere active again and try to simulate. Nothing happens.

Any ideas?

Split your scene into layers. Your objects saved in sim files still can affect other objects. So simulate one part of your scene, then import it into another part. One branch comes from a previous sim and second has a RBD solver that solves reaction of new object on them self, gravity and previously saved object which are now passive.

In docs there should be an example of layered simulation I guess…

cheers,
sy.

Unfortunatly I was unable to find the example. Do you have an idea what name the example file maybe could have?

Hello, I am in the same situation, I dont know how to separete my initial state