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How do I edit a Constant within a Particle Parameter from Blueprint?

I'm trying to link the radius of the sphere of one of the particle emitters with how much the trigger of a controller is pushed in. The more pushed in, the bigger the sphere. As far as I know, this has to be done by changing the constant in the Particle Parameter, but how do I link this constant to a value I can edit in Blueprint?

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asked Mar 13 '15 at 02:24 PM in Using UE4

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avatar image Kbrom3d Apr 28 '15 at 04:57 PM

Bumping this as I have the same question...can change many things but a constant seems to not be one of them? Thoughts anyone? Thanks

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Hey Roach,

For that particular constant, you need to use a "Set Float Parameter" node in your blueprint. I am attaching a project that will help explain what I mean, but I'll also break it down for you here in case the link becomes broken in the future.

Example Project

In the example project, I've linked Numpad 8 and Numpad 2 up to manipulate the Parameter.

So what I did was make a fresh particle system and simply add a Sphere (Seed) module to the Emitter(and enabled surface only). Then I changed the Start Radius distribution type to DistributionFloatParticleParameter. Make the Parameter Name something unique ("TestParticleParameter" for me). Make the Param Mode "DPM Direct". As you know, the Constant is what we will be manipulating here, so I set mine to 50 by default.

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So, I created two inputs in my project settigns called "Increase"(Numpad 8) and "Decrease"(Numpad 2).

In the following screenshot, the important node is Set Float Parameter. You must use the exact parameter name that you set in Cascade. Then hook in your particle system component.

The rest of the node network is used to increase and decrease the size as well as cap it between 0 and 250 units.

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Let me know if that makes sense.

-Matt W.

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answered May 05 '15 at 03:59 PM

avatar image Kbrom3d May 05 '15 at 04:05 PM

Working great on my end, thanks Matt!

avatar image -Roach- May 07 '15 at 06:00 AM

Thank you very much

avatar image hyawatha15 Aug 09 '17 at 10:59 PM

This doesn't seem to work on 4.15. If I set the parameter with Event Begin Play, it works, but after that, updating the value doesn't seem to do anything.

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