Jump to content

Solved - Using sphere to contain POPs


Recommended Posts

Hi Everyone, 


I'm working through Stop Being Afraid of Houdini, by Mograph.com, and in the POPs section I created some particles and would like to contain them inside a sphere. I've made a polygon sphere, extruded it and made it a Static Collider and the particles seem to teleport outside the sphere and collide with the outside of the sphere (I then tried inverting normals but that didn't work). I'm sure it's a simple fix but I'm very new to Houdini and not sure where to go with solving this.


Also, what's a good way to either hide or ghost the sphere once inside the DOP network? 


I've attached my scene here, I apologies it it's not organized correctly.


Thank you! 


Edited by james_conkle
Updated title to solved.
Link to comment
Share on other sites

Hi James

I had a look at your scene. That is right some the particle get ejected outside the sphere instantly.. and the more you res up the collision VDB. the worse it gets..

It is very lucky that I had the same issue once with a flip sim as the answer is the least you expect and is almost impossible to find in books.

The container needs to be open somewhere. Apparently particle based simulations don't work in a sealed container. You can cap it but it need to have an opening. So I punched a hole in the sphere and it works fine.

Let me know if that works on your end




  • Thanks 1
Link to comment
Share on other sites

Thank you both! I definitely wouldn't have figured that out and my google fu wasn't turning anything up, but both of those work! Wouldn't have guessed the boolean option, and I knew there was a check box I was missing and totally would've blanked on the Invert Sign - the tool tip talk of laser scanning which I found odd as I have no experience with that. 

Link to comment
Share on other sites

I must say that the invert sign is a cleaner option :) as you don't need to render this one and create one with thickness just for render.

James, turn off display flag on your collider sphere and create a new geo node for the rendered sphere with thickness.. if yo intend to render..

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...