Upgrading from 4.7.6 to 4.8.0 breaks emitters, about 1/4 particles spawned (reproduction included)

Development Asset Creation FX
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EDIT: I’ve done a little more research and you may want to skip this initial post and jump down to my comment below.

Since upgrading my project from 4.7.6 to 4.8.0 I’m having some trouble with particle emitters. They are only emitting about 1/4 the normal amount of particles. This happens in PIE, standalone game, etc. To reproduce:

*Create a first person shooter example project in 4.7.6

*Go to FirstPersonBp/Blueprints/ and open FirstPersonHud

*Add a EventBeginPlay event and link it with a Execute Console Command node with the command sg.EffectsQuality 1, compile/save

*Create a new particle emitter, open it and save it to apply the defaults

*Place the particle emitter in the level somewhere you can see it easily

*Start the game in PIE to apply the console command added to FirstPersonHud

*Observe that the particle emitter is emitting about 20 particles

*Close project and upgrade it to 4.8.0, open upgraded project

*Start game in PIE, observe that the particle emitter is emitting about 5 particles

I’ve found a partial workaround, but it is not adequate in my situation. The particle emitter still malfunctions on lower Engine Scalability Settings.

*Go to your unreal projects folder, open up the recently created 4.8.0 example shooter project folder and delete the saved folder(This is so you can change Engine Scalability Settings, using the sg.TextureQualitySettings seems to make Engine Scalabilty Settings permanently unchangeable.)

*Open 4.8.0 example shooter project in Unreal Editor, go back to FirstPersonBP/Blueprints and open FirstPersonHud

*Delete the EventBeginPlay and the console command

*Go to Settings, Change your Engine Scalability Settings to Epic

*Start game in PIE, observe that the particle emitter is emitting about 20 particles and seems to be fixed

*Go to Settings, Change your Engine Scalability Settings to Low

*Start game in PIE, observe that the particle emitter is malfunctioning again and only emitting about 5 particles

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I have the same problem. I would really love to see a staff member’s opinion about this.

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I’ve dug up some more info. This looks like it could be an intended change but I don’t see it in the patch notes. Go to UnrealProjects/Intermediate/Config/CoalescedSourceConfigs and open the Scalability file. Towards the bottom you will find r.EmitterSpawnRateScale. These are set to 0.125, 0.25, 0.5, and 1.0 for EffectsQuality levels 0-3 in 4.8.0, but in 4.7.6 the r.EmitterSpawnRateScale is set to 1.0 for all effects quality levels.

Unfortunately when I try to change and save these values in notepad they don’t stick.

However, issuing the following console command adequately resolves the issue:
r.EmitterSpawnRateScale 1

Alternatively “apply global spawn rate scale” can be turned off on each particle emitter in cascade.

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Good to know. Thanks man!

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Hi Xylo -

Yes, this was a fix to the bug where the Emitter Quality was not scaling as originally intended, because the console variable was incorrectly set in code.

You should be able to set the console variable in the Engine\Config\ConsoleVariables.ini file and it will stick in your projects on next running.

Thank You -

Eric Ketchum

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Thank you for pointing me to the engine folder Eric. I was trying to change the BaseScalability in my project folder but I should have been changing BaseScalability in the engine folder. Now I am able to revert BaseScalability in 4.8.0 to the desired 4.7.6 settings.