[Sidefx-houdini-list] using $AGE for size.

Ben Schrijvers ben.schrijvers at guerrilla-games.com
Thu Feb 18 12:30:48 EST 2010

This is indeed the way to do it.
$AGE is an absolute value so particles that live 5 seconds will have a 
size of 5 at the end of their life.
This is probably different for each particle. The final metaball shape 
will also ne very different if you change the life expectancy of the 

You can also use $LIFE instead of $AGE to get a value that scales from 0 
to one during the lifetime of each particle.
In this way the shape will stay the more the same if you play with the 


Spencer Lueders wrote:
> After your popnet, before your copy SOP, put a point SOP down. Put $AGE in the Particles Tab > Pscale parameter.
> You could do it inside your particle sim using a Property POP > Misc Tab > Pscale, but that would require you to re-sim your particles each time you need change your scale.
> ----- Original Message -----
> From: "jacob fisher" <jacobfshr at gmail.com>
> To: sidefx-houdini-list at sidefx.com
> Sent: Thursday, 18 February, 2010 12:18:08 PM
> Subject: [Sidefx-houdini-list] using $AGE for size.
> Sorry I don't currently have Houdini available in front of me, but I
> want to create a simple scene where I have spheres copied onto a
> particle network.
> As the particles age, want the spheres to increase in size.
> My initial thought was I could just use $AGE for metaball radxyz.
> However, because of the set up, metaball popnet copy, I can't use $AGE, can I?
> Should I set up a Null in my particle network and pull that $AGE
> attribute with ch("../popnet/null/$AGE") or something like that?
> Hopefully this is a real basic problem I'm over/under thinking.
> -jake
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