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pan.mentolka

popdrag - slower particle in selected radius

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Hello houdini masters!

I have small issue, in popnet. Im trying to create moving particles on plane, but with different "speed" U can see my intention on scheme down here. Can u guys please help me?

I will be very grateful for any advices. Thank u very much!!

 

particles_issue.hip

scheme.png

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You can use length of P to control the speed.

Something like this: v@v *= fit(length(v@P), radius_min, radius_max, max_drag, 1);

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Hey Drughi

OMG! How u guys are doing that?!  works.... thank u so much!!!!

But how to make it with multiple "center points". I mean more centers with slower motion of particles. I tried something in popnet/ pop vop, but unsuccesfully....

particles_issue.hip

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Hi Michal,

the LYNX_force from the LYNX VFX Toolset can also do this, but more user friendly/interactively with customizable falloffs, see this video for more info. You can grab it for free here: https://github.com/LucaScheller/VFX-LYNX

 

Cheers,

Luca

Edited by LucaScheller

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On 10/20/2019 at 2:26 PM, pan.mentolka said:

Hey Drughi

OMG! How u guys are doing that?!  works.... thank u so much!!!!

But how to make it with multiple "center points". I mean more centers with slower motion of particles. I tried something in popnet/ pop vop, but unsuccesfully....

particles_issue.hip

Hi, your issue is in the pop drag node. You have "@falloff" in the activation slider, which is deactivating the whole node, because that expression isn't valid for that parameter. Think of activation as like a "global" parameter for the node. It can't be changed per particle, it's either on or off. Instead, you should leave Activation to 1 and use "VEXpressions" to multiply the drag (airresist) by your custom attribute. Also, you have "0.798" as the point number for your distance lookup in the VOP where you set the f@falloff attribute. You should be careful that it is set to the correct point number.

Nodes changed are in red.

 

particles_issue_jamesr.hip

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On 22. 10. 2019 at 12:02 AM, jamesr said:

Hi, your issue is in the pop drag node. You have "@falloff" in the activation slider, which is deactivating the whole node, because that expression isn't valid for that parameter. Think of activation as like a "global" parameter for the node. It can't be changed per particle, it's either on or off. Instead, you should leave Activation to 1 and use "VEXpressions" to multiply the drag (airresist) by your custom attribute. Also, you have "0.798" as the point number for your distance lookup in the VOP where you set the f@falloff attribute. You should be careful that it is set to the correct point number.

Nodes changed are in red.

 

particles_issue_jamesr.hip

Thank u so much James, now it works! I added more "falloffs" and it works perfectly!!!

Can I ask U one more time? I have problem to put particles just inside of the object (i mean not sliding on the surface, but flowing just inside of the geometry). I tried poplimit node, but this works just like BoundingBox, and I need to defined it by my specific geometry... maybe u can help me fix this too...

 

And Thank u again for your previous explanation and help.

 

cheers

pop_inside_issue.hip

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Sure. In your note you say 

Quote

I need to let flow particles  just inside the testing geo. But keep them all inside, by bouncing from the surface.

"by bouncing from the surface" you mean act like a normal collider, just inside right? Like have the particles bounce around the inside? That's how I read it. Added/changed nodes are in gold.

pop_inside_issue_jamesr.hip

 

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