Setting the Emitter Time module with an emitter that is not set to loop will result in an incorrect render of the particles past the emitter duration.

Emitter Duration set to 3 seconds:
[Image Removed]

Also Reproduced in Dev-Rendering CL-2817080 and 4.11 Preview 1

Steps to Reproduce

*Quick Repro: Open Attached Project*

  1. Create a Blank Project with No Starter Content
  2. Create a Translucent Unlit Material called M_Test with the Particle Color Node's RGB output pin attached to the Emissive Input and the Alpha Pin attached to the Opacity Input
  3. Create a New Particle System
  4. In the Required Module, assign M_Test as the Material
  5. In the Required Module, set the Emitter Duration to 3 and Loops to 1
  6. In the Initial Velocity Module, set Min to 0,0,400 and Max to 0,0,400
  7. Delete the Color Over Life Module
  8. Add an Initial Color Module
  9. Add a Scale Color Over Life Module
  10. In the Scale Color Over Life Module, set Use Emitter Life to true.
  11. In the Scale Color Over Life Module, set Alpha Over Life as follows:
  • Constant Curve
  • Point 1 In Value 0, Out Value 1
  • Point 2 In Value 2, Out Value 0
  1. In Cascade Viewport, turn on Particle Time View Option

RESULTS: In Cascade Viewport, notice the Particles fade out correctly from 0 to 2 seconds, stay invisible for 1 second and then pop back into existence for an additional second.

EXPECTED: The particles should not pop back in after 3 seconds.

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Won't Fix
ComponentUE - Rendering
Affects Versions4.
CreatedJan 7, 2016
ResolvedOct 30, 2018
UpdatedMar 26, 2020