Niagara Invisible Collision

Development Asset Creation
1

Can Niagara particles collide with invisible objects?

I’ve tried both CPU(Ray March) and GPU collision (Distance field/Depth Buffer), but nothing works. Can anyone give me a hint on how to solve invisible collisions? Thank you so much！

2

I had the same problem before, but I now know how to do it.

Here are the steps:

  1. Create a new material.
  2. Name the material “Invisible Force”.
  3. Edit the material by double-clicking on it.
  4. Go to “Details” and change the blend mode to “Masked”.
  5. Create a constant node and connect it to the material node under “Opacity Mask”.
  6. Set the constant node’s value to “0”.
  7. Drag and drop the “Invisible Force” material to the object you’re using to collide with the Niagara simulation.

If you followed these steps correctly, it should work. Trust me. :wink:

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3

For me Invisible Collision works only when I changed Niagara particles to CPU

4

Not true. If Unreal cannot see it, then its considered non existent apparently.

5

The only thing that actually works is to select the Static Mesh Object you want to be an invisible collider and then check the box for: “Visible In Scene Capture Only”

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6

Dont work for me
As well as “Invisible Force” material.

7

Thanks! It works with motion design cloner.

8

WORKAROUND:

None of these suggestions worked for me in my case. What I have created is a glass dome style overhang bedroom with glass ceilings and I wanted Niagara particles to bounce off of my translucent glass material. Wasn’t working. Tried everything I could find suggestion wise and nothing worked. I found a work around in the event someone else comes across this:

UNREAL Version 5.5.4

What I did was, I made sure that my imported objects that I made in blender had their collision complexity inside the objects details set to “USE COMPLEX COLLISION AS SIMPLE” just to make sure, I created a material as suggested above by @anonymous_user_0965ff94 and applied it to a duplicated object in the same location as my glass (probably not necessary to duplicate the object, but I did it anyways to make sure the invisible force didn’t take away my reflective glass).

Then after applying the material to the object, in the objects material details scroll down to RENDERING, then select RENDER MAIN PASS, VISIBLE RAY TRACING, VISIBLE IN REAL TIME SKY CAPTURES. (I dont think real time sky capture was necessary, but I cant remember why it was relevant that I had that ticked, so i included it here just encase)

Inside my hanging particle Niagara system in the Collision Settings I changed GPU COLLISION TYPE to: GPU RAY TRACE (EXPERIMENTAL), then below in RAY TRACE QUERY PROPERTIES I changed TRACE PROVIDER to: HW RAY TRACING

I had an issue where it wasn’t working at first, not sure if there has to be a correct order to make it work out of the gate or what, but after getting frustrated with it I sat there starring at my screen for a few minutes wondering what I could do to make it work and noticed one of the glass panels was actually colliding as intended, but the rest weren’t. So I further investigated and the only thing I did to make the rest of them start working was I change the duplicated objects material from INVISIBLE FORCE that was already applied prior to making the changes inside of Niagara, to something solid, then switched it back to the Invisible force material, then double checked to make sure that RENDER MAIN PASS & VISIBLE RAY TRACING were still ticked and it started working on all the panels one by one after changing them. Sorry for the long explanation.

Hope this helps keep someone from banging their head against the wall for hours/days like I did.