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Changing a property of a particle overtime based on age?

Message 1 of 8
925 Views, 7 Replies

Changing a property of a particle overtime based on age?

Hello, all. 🙂


I'm just begging to get a grasp of Bifrost, and I'm trying to do things I could easily do in nPArticles, like map a particles color, and transparency  based on a particle's age.  Something like the pic I attached.  That was with nParticles and Arnold.  I'm sure there's a way but I just haven't figured it out.  Also, how would I get a sort of color accumulation effect with the render of the particles?


Thanks 🙂



Message 2 of 8
in reply to: ajsiytangcoE9EW6



Try this node:


Message 3 of 8
in reply to: mspeer


Thanks for the reply.  I tried that, and I do think that is what I need but I when I tried I couldn't get it to work.  I was able to get the point size to vary from birth till death, but for some reason I couldn't get it working with color.  Would you know what property name I should be using?  is it just color?  or point_color?  or something else?

Message 4 of 8
in reply to: ajsiytangcoE9EW6


You need to add the "color" Attribute first by using the node


( Property: color )

Message 5 of 8
in reply to: mspeer

Hi again 🙂


Thanks for sending me off in the right directions! 🙂  I got it working, sort of.  I used the set_property node, the set_Geo_property node kept turning red and giving errors.  So the set_property node has a value node plugged into it and is also piping into the source_particles node.    I also figured out that I needed an aiUserColor node to get the color into the aiStandard material.


Now to figure out how to plug a ramp in and I'll be all set!



Message 6 of 8

happy new year 


im working on an art project  and I just can't get this to work !  could you please post your scene file if that's not too much hassle or screen shot that explains how you got it to work 


would be greatly appreciated !



Message 7 of 8
in reply to: thomaslisle1309

Yeah, this is not the most user friendly thing to set up.

You need the following as far as I know:


- an arnold material assigned to your particles with an aiUserDataColor node in the color input (under Base section)

- there the Attribute needs to be named "color"

- set_geo_property node (with the property named "color")

- set_particle_property_from_age node (property "color")

- make sure your data type on these nodes is math float3 (for RGB values)


This works as you can see in the graph below, but it will not show up in the viewport, onlythe renders.graph.png


Message 8 of 8
in reply to: sklauss

hi. many many thanks !  oh. i just didnt set the ports to float 3 ! makes sense as colour is rgb-  i have been wondering for weeks how arnold knows that a property set my bifrost is aiuserdata color data - but read yesterday that arnold treats any userset property as aiuserdata !  which answers that ! 


well i will give it a go this afternoon. many thanks again and happy new year

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