If "UVFlipping Mode" under Rendering on the Required node of an emitter is set to anything other than "None," the particles can become stretched and distorted. As a workaround, I have discovered that if you change the Mirror Flags under Initial Size module 0 (X-Axis) from "different" to "same" it will fix the stretching even if UVFlipping Mode is enabled.

Steps to Reproduce
  1. Open attached sample project
  2. Open ThinLineBug particle system in editor
  3. Under the "Required" module of the emitter, note that under Rendering "UVFlipping Mode" is set to "RandomFlip UVIndependent."
    Result: Sometimes the particles spawn very stretched out and thin
    Expected: Shape and size of the particles would not be affected by Flipping UVs, only the horizontal and vertical axes of the texture.

When you change "UVFlipping Mode" to "None" the stretching issue is fixed.

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Won't Fix
ComponentUE - Rendering - Niagara
Affects Versions4.18.1
CreatedNov 17, 2017
ResolvedAug 18, 2021
UpdatedSep 19, 2021