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FLIP Particles sticking on a animated surface (And staying there!)


HappehLemons

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Using a deforming collisions, has anyone had success with getting flip particles to stick to the surface and stay there? 

I'd like flip particles that make contact with an animated deforming collider to stick on contact with some way to determine if they stay stuck on the collision object in that position where they collide, or they are loosened off the surface to begin acting as normal flip particles / begin sliding down the surface. 

It seems anytime I add animation and particles into the mix they either fall off because of the animation, or they get pulled off the collision surface by the flip particles themselves in the case of more viscus fluids.

I've tried:

Stick on collision... no luck. While it helps the particles hold on there for a bit, and guide them on the surface, maxing out everything, the particles still seem to slide down the surface and fall off even with the most viscus fluids. Enabling slip on collision and zeroing it out doesn't seem to help much either. Friction didn't do much either. 

Is there any tricky non-expensive (hopefully simple) way of doing this? It'll be used in animation so I can't have the sims taking too long.

I'd like it to be done inside the autodop network and not post sim so it can be interacted with by other flip particles / the collider. I've found solutions to do this post-sim but it doesn't give me the result I'm looking for. 

Edited by HappehLemons
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Just to continue updating this while I try to find a solution here's what I come across for resources:

Been on the hunt for something that something sticks to an animated surface with velocity and doesn't full off unless it's set to. It'll also need to resolve quickly, because it will be used for animation.

(The below all include .hip files that work on H18)

 

1)

This method uses a popdrag for air resistance plus some other methods that work well to keep particles smoothly flowing across a surface. Suffers from animation really throwing it out of wack. 

When particles fell off the surface because of rotation in animation from the collision object it caused them to have very strange behavior (They kind of just flated in the air in a strange pattern).

I didn't dig too much into this, but didn't seem very CPU taxing and did do a good job of smoothly flowing surfaces.

https://www.sidefx.com/forum/topic/24897/

(Hip File)

https://www.sidefx.com/forum/attachment/2540103a248b6325ae9c84345748756cbb800e33/

 

2)

Not really applicable. It's using a fog map to make a stick on collision mask based on Houdini built in stick on collision setup that doesn't give a great stick result for me.. So not adding any stick, just making it per object level.

Overall a method that converts your geo to a fog density, uses a volume wrangle to control the density of the fog and uses that as a stick mask. Seems to be a bit more of a taxing method as the default sims example are simple, yet take a while per frame then other methods listed. May of just been the scene setup.
Works well, but a simple rotation caused all particles fall off. Had great sticking effects with good control, but I wasn't able to easily find a method to get these to stick to an animated surface during a 180 rotation on the sphere.  

https://www.sidefx.com/forum/topic/33954/

(Hip file)

https://www.sidefx.com/forum/attachment/dc1b85ffd5ead04d635ddb117ec8eff5e3d81399/

 

3)

Not really applicable again as it's also using the stick on collision tools within houdini. It's using a fog map to make a stick on collision mask but using a different node setup with a part of geo versus the whole thing.

It converts an area to a gas field and uses that as a stick mask. Goes about it a bit different way - blasts off the section and uses a pryo node to turn it into density, but like the first method, a rotation caused particles to fall out. Scene simmed pretty fast, maybe due to the areas of selection being converted to a fog being smaller..

(Hip file)

https://forums.odforce.net/applications/core/interface/file/attachment.php?id=44804

4)

Particles really *stick" right where they hit, and the sim was very quick. Doing a rotation did cause them to come off, it didn't make all of them. I'll have to mess around some more with the settings on this. Uses a Geometry VOP DOP and sample collision field for every particle . Might start digging into this method.

(Hip File)

https://forums.odforce.net/applications/core/interface/file/attachment.php?id=17044

5)

Have not tested this yet because it's not free. Considering picking this up but not sure if it would work for me.

It's a scene for $33.

It's more about surface adhesion versus *sticking* though so it may not have what I need. Can't speak to much becasue I haven't used it. Benchmarks show it to resolve pretty quickly though and add very little onto total sim times.

https://gumroad.com/l/Oejcb

Edited by HappehLemons
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