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Particle goals possible

Anyone know if there is anyway to setup particle goals in Cascade. Like, I want a particle system to travel to a goal object and then back again. I see there are attractors but that is just a single point in space. Any ideas?

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asked Dec 05 '14 at 02:40 PM in Using UE4

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Hey Walkinginspace -

You can use the Direct Location module with a Constant Curve Distribution In Val 0 would be 0 for Time 0 Out Val 0 would be the origin or initial location you want the particles to spawn at, In Val 1 would be 1 for Lifetime of your Particle System Out Val 1 would be the vector location of your goal. You can manually enter these locations or through the Vector Particle Parameter drop down you can use blueprints to pull the information from your objects and actors in the level. (If your goal is moving I would absolutely pull from the Blueprint).

Thank You

Eric Ketchum

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answered Dec 05 '14 at 05:17 PM

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Lovecraft_K ♦♦ STAFF
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avatar image walkinginspace Dec 06 '14 at 01:57 AM

Awesome! Thanks for that information. I'm still very new to Blueprints and UE 4, can you explain the process of using the VPP dropdown and pulling that information through Blueprints. I'll give it a go, but would love some more details on that. I see a lot of people with questions about the Particle Parameters and doesn't seem to be much documentation on it. Thanks again for your help!


avatar image Lovecraft_K ♦♦ STAFF Dec 08 '14 at 03:46 PM

Hey -

Sure here is a visual for you: alt text

In whatever module you want to use the BP controlled Parameter set the Distribution to VectorParticle Parameter this will open the Min Input, Max Input, Min Output, Max Output and Constant sections. The Min and Max Values in Input and Output set what Cascade and the emitter sees as the values so if you set a min input of 2 and a min output of 1 and your BP set the value to 1 then the output would be 2. Those areas essentially act as clamps. The Constant is more for testing but can be set to have the emitter always execute a certain value, think about a water fountain that is constantly running then occasionally spitting higher. I usually don't use the constant and leave it at 0. In the example above, I actually have it set to constantly give a random value between a range which is the equivalent of a Vector Uniform Distribution in Cascade.

Finally make sure your Parameter Name matches. I almost always check this first if I have a problem.

Hopefully that helps you get started, if you have further questions please let me know -

Eric Ketchum

vectorparameter.jpg (239.7 kB)
avatar image walkinginspace Dec 09 '14 at 04:12 AM

Thanks a ton for this. I'll get cracking on it now! I'll let you know how it goes. I'm sure a working version will be something a lot of people will be interested in.

Thanks again!

avatar image walkinginspace Dec 09 '14 at 07:01 AM

alt text

So here's the basic idea...now, I just need the vector particle params right? Still not sure how to do that. I see in your example i see the size vector. I'm not sure how to make the vector change...like is it one parameter that gets set? I get confused when I read the above....thanks again for your help, I think i'm almost there!

moveparticles.jpg (109.1 kB)
avatar image walkinginspace Dec 09 '14 at 07:12 AM

Also does direct Location just effect the particle or the emitter. To make the emitter move do I use something else. If it's a school of fish, makes sense the emitter will move to keep the fish movement going...maybe? I'm admittedly in over my head:)

avatar image walkinginspace Dec 09 '14 at 07:25 AM

alt text

So this does what I need. But one problem. The particle system jumps from one point to the other really fast. Is there some way to make them move in a fluid fashion, animated to the other point?

Thanks again!

avatar image walkinginspace Dec 09 '14 at 09:39 AM

alt text

So this has the emitter moving issues solved! Now, next step is to increase the drag on the particles, so they can have a school of fish type movement....any hints? I'm thinking I can just take the output of the lerp and run it into a vector param...

avatar image Lovecraft_K ♦♦ STAFF Dec 09 '14 at 03:05 PM

Hey -

Yes that exactly how I would do it in this setup. Excellent problem solving,

Eric Ketchum

avatar image walkinginspace Dec 09 '14 at 09:51 PM

One issue i'm running into. If I want to adjust one parameter input say drag amount...the vector output from the Lerp has 3 values...how do i break out just one value to be input-ed into the other one value...or does it just do it automatically?

avatar image Lovecraft_K ♦♦ STAFF Dec 09 '14 at 10:01 PM

Pull off the vector and Break Vector (Node's name) then you can choose from the XYZ float values.

avatar image walkinginspace Dec 09 '14 at 10:02 PM

Do I need to do that both for the lerp output and the particle param input?

avatar image Lovecraft_K ♦♦ STAFF Dec 09 '14 at 10:07 PM

You are trying to plug in a Float Value into your Parameter so just off of the Output of the Lerp.

avatar image walkinginspace Dec 09 '14 at 10:14 PM

alt text

what's confusing is the parameter looks like it's taking 3 values in...so i'm not sure how i can correspond to just one value on a parameter in cascade...

cap.jpg (49.8 kB)
avatar image Lovecraft_K ♦♦ STAFF Dec 09 '14 at 10:24 PM

If you are using a Vector Parameter from Cascade then the Parameter needs a Vector input (which is made of 3 float values representing the XYZ axis values). Most parameters in Cascade are vector so taking a value from your Lerp (assuming its a Vector Lerp) you can input into the parameter directly without breaking anything.

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