Hi, I'd like to kindly request an advice to a noob:

I have a packed RBD of random basic shapes (generated via copy stamping from some points) which undergoes some basic simulation of falling from the sky, being caught into a bowl.

Now - I am happy with the simulation and all my movements, but some of the objects fall out of the bowl. I would like to somehow select these particular outsiders (at any point in the simulation I pick - meaning NOT frame 1) and hide them, or at least be able to delete them.

I should be able filter them using their P.y on a specific frame.

However I seem to be completely oblivious as to how to manage to hide them, or even delete them. No matter which expression I write (in Group node's or Delete node's “Activation” parameter), I can only delete the whole packed RBD object (so, ALL of the simulated objects), despite them each clearly having a specific id.

As for the “hide” part (simulate, collide, but not show), I have no idea how to do that to the specific objects at all.

Please, help

The delete dop only deletes whole objects as you have found. To delete individual packs, you need to delete the geometry. Use a sop solver with a blast/delete sop to remove the group that meet your desired criteria for removal.

This type of edit is generally better and easier to perform after the simulation is complete. When deleting in simulation, or otherwise changing the number of pieces over the course of the simulation, proper deformation blur cannot be used to render motionblur. It is best to have a stable number of pieces when possible. To remove pieces for all time: import the simulation geometry, go to the last frame of the simulation, and select all the offending pieces by name, then blast this selection. The pieces will be removed from the entire simulation, allowing for proper motion blur.