VAT - Niagara triggering twice

Hi everyone,

I recently worked through the new version of the Vertex Animation Textures tutorial from SideFX for Unreal (link to tutorial), and I came across an undocumented issue that was hard to pin down. After much troubleshooting, my colleague Michael Hall and I discovered a workaround, which I hope will save others time and frustration.

The Issue: The problem we encountered was a double-triggered animation effect when running the Vertex Animation Textures in Unreal Engine Through Niagara. Here’s how we solved it.

Solution Steps:

  1. In Your Base Material:
  • Place a RemapValueRange node.
  • Add four Constant variables to the node.
  • Convert one of the constants to a Parameter and name it something descriptive. I used NumberofFramesFromHoudini, representing the number of frames in your vertex animation set up in Houdini or another software.
  1. Add a Dynamic Parameter Node:
  • Drop in a Dynamic Parameter node and give it a name to track.
  1. Set Up in Niagara:
  • Within your Niagara System, place a Dynamic Material Parameters module.
  • Switch from a Float Interface to Float From Curve.
  • Make sure to flip the curve from (0.0, 0.0) to (1.0, 1.0)
  • Finally, set your Niagara System and emitter to Once to avoid double-triggered animations.

We wanted to share our findings here to help anyone encountering the same issue,

I hope this helps. Let us know if you’ve found additional workarounds!

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