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use SOP attribute to drive POP source parameter


WLVL

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Hi All! 

1_ 
I'd like to import an attribute created in SOP in the POPNET. 
I want to drive the particle emission rate based on this attribute. 
I've tried to use the point function in the constantrate parameter of the pop source. 

like: 

point( my sop node path, $PT, "myatt", 0) 
or 
point( my sop node path, $CUSTOM_ID, "myatt", 0) 
where custum_id is just a variable created in sop based on pt. 


there's something i am missing icon_confused.gif 

2_how do i make the SOP attribute update every frame 


3_ 
also i see in POPSource/Source Emission Attribute. 
The help doc says 
"When in surface mode, this point attribute will be used to vary the chance of any polygon from emitting polygons. Higher values will increase the relative chance of that polygon getting an emission." 

but it doesnt specify the values range. I supposed 0-1 (0-100% chance of emission). I did some test but seems to have no effect. 


thanks for helping!

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Hi, 

 

To import an attribute from SOPs to POPs, you can use a SopSOLVER in Dops. Inside the sop solver put an object merge calling your sop geometry and then with an attribute transfer you can import the attributes to pops.

 

Hope this helps!

Edited by argilop
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Hi argilop and merlino!

thanks for your replies!

 

so, i used the emission attribute in the pop source and it actually works (in the scene i was working with, it was just hard to visualize).

 

 

what i'd like to know is how to use an attribute to drive a parameter in DOP. In SOP i would use a point expression, in DOP i don't know.

in the attached file i created an emit_var attribute, i'd like to use it to drive the velocity variance in the POP Source. What syntax should i use to call it?

 

thank you!

SOP_att_drive_parm_in_DOP.hipnc

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you can use the same expressions in dop parms as in sop parms, but just be aware of the "set initial" vs "set always" operation status.  many/most dops are designed to only evaluate parms on the first frame ("set initial").  if you have something animate, you need to make sure it's set to "set always".  you may have to dive into dop tool nodes to find the underlying base dop with the operation flag.

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  • 3 months later...

well, not in UI directly

but if you know that any VOP network's parameter (Parameter VOP) can be overriden by attribute with the same name and type

then just by looking inside of the Source POP you can see which values can be directly controlled from attributes, not many, but in case of velocity you are in luck

 

so to control velocity variance, you can just create v@var attribute on your source (quite dangerous if you think about it as many parameters inside use very simple names, easy to override by accident)

 

so similarly to override Velocity slider you can hunt down and find out that you can just create v@parmvel attribute on your source which will automatically override that, etc .

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  • 3 years later...
1 hour ago, dyei nightmare said:

this doesnt work in H17

do you have an example?

as far as I know attribute overrides for VOP Parameters/Binds is basis of a lot of tools, I'd be  surprised if it suddenly didn't work in H17, so maybe you are trying to override something that's not a VOP Parameter?

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1 hour ago, anim said:

do you have an example?

as far as I know attribute overrides for VOP Parameters/Binds is basis of a lot of tools, I'd be  surprised if it suddenly didn't work in H17, so maybe you are trying to override something that's not a VOP Parameter?

 nop, but what works is doing everything in sop solver,  ignoring $SF and simulation stuff vars,  just doing things with $F,  

Edited by dyei nightmare
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  • 3 years later...

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