Jump to content
Vertex

How to detect/ID particles colliding with static object in FLIP simulation?

Recommended Posts

Hi all - basic FLIP question around detecting particles that collide.

I have a simple setup (see screenshot) and I need to detect and group particles that collide with the static object in order to assign a new Cd to these collision particles - hopefully determined by either a ramp OR a texture color from the collision geo.

I'm having trouble finding good references for detecting colliding particles in a flip tank / flip solver setup. I found several tutorials covering setting up a pop collision detect node for a pop solver, but I'm unsure how to translate that to a flip solver - or even if a pop collision detect would work with a flip solver. Any help or pointers would be much appreciated. Thank you!

 

Screenshot 2022-01-04 215324.jpg

Share this post


Link to post
Share on other sites

You can merge in your collision mesh and colorize it. Then use an attribute transfer to copy the collision color onto the flip particles.

ap_flip_colorize_collision.hiplc

Untitled-1.jpg

  • Like 2

Share this post


Link to post
Share on other sites

Thank you! Diving into your project now...

Share this post


Link to post
Share on other sites

@atom If I can trouble you with a one more question - your example file was incredibly clear and thank you for sharing it.

My follow-up is - can the attribute transfer persist? In other words, once a blue particle collides with the box and turns red, can it STAY red, even once it rolls off the box and is no longer touching it?

I saw a few examples using a solver, but once I move the attribute transfer node into the solver the particle simulation either disappears or begins to act erratically. If you have any additional thoughts would much appreciate them.

Thank you!

Share this post


Link to post
Share on other sites

You do not need to use an attrib transfer btw.  You can use a pop collision inside DOPs and you can output a grp for the hit the collision for you to color post sim. Flip is just pts so you can use any of the pop nodes.

Here is the scene fixed. 

houdini_kzX43chOii.gif

ap_flip_colorize_collision.hiplc

  • Like 3

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×