Using VDB SDF's distance value, how do I make particles lying on some range of surface?

[aesthete]

Hi guys.

 

I've been trying to make particles snap onto surface using vdb sdf.(volume sample and gradient)

Specifically, I am trying to emit the particles from sdf volume and let them lie on some range of a surface.

  

I know how to snap particles on a surface but what I really want to make is exactly not that all particles stick on the surface.

I want some particles to lie down a short distance away from the surface outside or inside.(randomly)

It may be softball question but I can't get easily figured out…

Any suggestions would be appreciated!

 

lee

prac_sdf_distance.hip

[mestela]

Here's one way. I give each particle a random sdf target,  subtract the current sdf value from that, and use that to scale each particle's velocity.

To make it easier to tweak I've run the sdf_target value through a ramp, then a fit range, so you can determine the min+max sdf values you want, and the distribution of those values.

 

 

prac_sdf_distance_mestela.hipnc

[aesthete]

Thank you so much for your replying and the hip file. I did not even know that using particle's velocity can make them lied on what I determined!

 

If you don't mind, I have another question.

 

After trying out the way you suggested, I also wanted to make the particles move around on each particle's surface where they lie on.

 

It's like P + ((normalized gradient * negate) * (signed distance))

gives the result that particles are snapped onto the surface and slightly move around the surface.  How can I do this?

[mestela]

pretty much what you said.

I added a colour transfer from the base shape to the particles to make it easier to visualise.

 

 

prac_sdf_distance_and_noise.hipnc

[Atom]

Thanks for the example file Matt, you can certainly have a lot of fun with that setup.

Here is the letter T.

 

[aesthete]

Thanks a lot for your help again and Atom's image! Really helpful! I'll give it a try.