Description

Deactivating and then reactivating the same GPU system will cause existing particles to die.

Steps to Reproduce
  1. Create a Niagara system using the Omnidirectional Burst template emitter
  2. Change the emitter's Sim Target to GPUCompute Sim
  3. Disable the Gravity Force module 
  4. Increase the Drag value to 2 in the Drag module
  5. Change the lifetime to 5.0 in the Initialize Particle module
  6. Compile and Save the system
  7. Add the system to a level
  8. In the level blueprint bind events to the 1 and 2 keys
  9. Have 1 call deactivate on the system and have 2 call activate
  10. PIE and press 1 before the particles die then press 2 soon after

RESULT

The existing particles will be killed, and new ones will spawn. On CPU systems the existing particles will remain and live until their lifetime runs out.

Have Comments or More Details?

There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-101696 in the post.

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Fixed
ComponentUE - Niagara
Affects Versions4.254.26
Target Fix4.26
Fix Commit14600256
Release Commit14600256
CreatedOct 22, 2020
ResolvedOct 28, 2020
UpdatedApr 27, 2021