Search Issue Tracker

Won't Fix



Found in



Issue ID




Particle System Burst Emission timing is not consistent

Visual Effects - Legacy


Reproduction steps:
1. Open Project in ""
2. Notice Particle System's settings
3. Enter Play Mode

Expected result: there will always be only one Particle active
Actual result: sometimes 2 Particles are active at the same time creating a flashing effect

Reproducible in: 2017.4.35f1, 2018.4.14f1, 2019.2.16f1, 2019.3.0f2, 2020.1.0a15

1. Visible both in Scene and Game view
2. Settings to notice: Start Lifetime = Duration = 1 & Burst Time = 0, Count = Cycles = 1

  1. Resolution Note:

    I've looked into this, and I think any changes to this code are very high risk.
    Floating point accuracy limitations mean that it's going to be very difficult to make this behave robustly. Particle ages are updated in discrete steps as frames advance, and whilst doing this, error accumulates. Eg after 0.8 seconds, the stored lifetimes might be 0.7999999. These kinds of inaccuracies mean that simulations relying on precise and exact numbers may fail in the ways you are seeing.

Add comment

Log in to post comment