VelocityPerpendicular particle orientation doesn't work with 0 speed

Bug Reports Engine Bugs
1

System Information:
Intel (R) Core™ i7-6700K CPU @ 4.00GHz, 32 GB, NVIDIA GeForce RTX 2080 SUPER
Reproduction File:
particleorientationbug.rbxl (55.2 KB)

If you create a ParticleEmitter with the Orientation property set to VelocityPerpendicular, setting the speed to 0 will cause nothing to ever render, even with acceleration.

In this picture, there are 3 ParticleEmitters all with VelocityPerpendicular orientation, so the particles should face upwards

particleglitch
particleglitch1085×597 404 KB

The left has only speed, the middle has only upward acceleration, and the right has both. Notice how no particles are visible on the middle emitter.

Expected behavior

When a particle emitter has acceleration but no speed, the particles should still be visible.

12 Likes
2

You can set the speed to 0.01 as a work around

3

That’s what I usually do, but it’s important for acceleration to have the same effect since it can be in world space while speed is always relative to the ParticleEmitter’s parent.

4

I’m hoping this gets fixed, a tad-bit tedious to always set the speed to 0.01 instead of just not having it move at all. Still won’t render when I set it to zero.

5

This should be fixed now. Let me know if you have any further questions.

2 Likes
6

This created a new issue where VelocityPerpendicular particles no longer have their orientation synced with their parent’s orientation, but rather always being the same rotation synced with the world.
I’ve detailed it more here, VelocityPerpendicular is buggy
and there’s another post discussing it here Particle emitters with "VelocityPerpendicular" setting dont seem to face direction of the Emitter's perpendicular axis anymore?

22 Likes
7

The issue still persists with VelocityParallel & VelocityPerpendicular.
Even with a Rate of 100 for a particle with inf lifetime, it’ll never emit anything with a Speed of 0 regardless of the value of any other property.
Changing only the Speed to 0.001 will instantly start emitting the particle as intended.

Please also refer to the reply above mine for the new issue, it’s a major inconvenience for combat systems using vfx like sword slashes.

4 Likes
8

The issue still persists. If the speed is 0 and the orientation is VelocityPerpendicular the particles don’t render