Forums Houdini Learning Materials Copy Stamp, Reference particle by ID rather than PT?

Copy Stamp, Reference particle by ID rather than PT?

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timot.mo
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Hi, so I have copy sop on a pop network referencing the sphere. So I put a stamp “Resize” rand($PT)/4 on the uniform scale of the transform node to give variable sizes of the particle sphere.

This works up until the particles die, then there's a random resize popping thing that happens. I know why this is happening, the PT numbers are changing. So is there a way to reference by ID or is there a better way to do this?
Edited by timot.mo - Feb. 9, 2017 12:17:07

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sepu
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The popnet if you middle click give you an an attribute id by default, so you can use the syntax @id.
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timot.mo
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sepu
The popnet if you middle click give you an an attribute id by default, so you can use the syntax @id.

Thanks so here's the info on my Popnetwork.. what am I looking for?

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timot.mo
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sepu
The popnet if you middle click give you an an attribute id by default, so you can use the syntax @id.

Also @ID is a vex code right? I haven't got onboard with VEX yet. not sure how my expression should be.
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tamte
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don't use stamping for that
just append Attribute Randomize SOP after your dopnet
Attrib Name: pscale
Dimensions: 1
tweak distribution and values as you wish
and most importantly in Options tab check Seed Attribute
Copy SOP will pick pscale up and automatically scale each copy, much faster than stamping
Edited by tamte - Feb. 9, 2017 17:23:08
Tomas Slancik
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sepu
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on your point attributes where it says "id"
when you use attributes usually are lowercase, so it will be @id. You can create your own and name as you wish but I will recommend just staying how they are by defaults.

take a look at this

https://www.sidefx.com/docs/houdini15.5/vex/snippets [sidefx.com]

the expression will look like 
rand(@id)/4
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timot.mo
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tamte
1

Thank you! Added the Attribute Randomize SOP after the dop network but Im not sure what do from here..

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sepu
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is not pScale is pscale.
Not sure what you want to do exactly
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timot.mo
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sepu
pscale


I would like to have random sizes on the spheres emitting from the pop network. It was working with the stamp until the particles died, obviously that can't work because the point number changes.

Thanks you for helping me on this.
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A-OC
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Like this ?

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timot.mo
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A-OC
Like this ?
Yes! Thank for this! Something I can study! BTW Where is the force pushing your particles up?

EDIT: never mind, I can see that in the “source_first_input” inside the pop network, you set the “set initial velocity” Dropdown. Very cool, I didn't know that you could do this too.

Learning stuff.. this is fun
Edited by timot.mo - Feb. 10, 2017 10:29:42
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