4.5 Particle Collision resets on project change

Minor (but annoying) bug:

Particle collision channels do not seem to properly store their value when changed, and evidently default to colliding with all channels unless manually specified in a given session.

Spawn a particle emitter from a location on a static mesh with some particles (mesh, sprite, it doesn’t matter) set to collide. I use “Freeze Movement” as the collision option but whatever. Make sure that the emitter spawns the particles within the character’s collision capsule or some other component which is NOT WorldStatic.

Set the collision channel to world static, and save. PIE should show these particles colliding only with WorldStatic objects, as expected.

Now, close the project and reopen it; the particles should collide with the player collisio capsule, the mesh, and everything else.

Open the particle emitter, change the collision channel to, say, WorldDynamic and then BACK to WorldStatic. Suddenly collision works again… But only until the next time you close and reopen the editor.

Hey RhythmScript -

Thank you for your report. I was able to reproduce this internal and have submitted a report to our enginnering team to investigate.

Eric Ketchum

So, this still isn’t fixed as of 4.6… is there any sort of ETA on this? Or a workaround I can use instead?

Hello -

It is currently being worked on, but I still do not have an ETA for you, for reference it is UE-4466.

Eric Ketchum

This has had me scratching my head for weeks!
Even more annoying is that the problem persists when packaging the project :frowning:

Everyone -

This particular issue has been fixed in our Master Branch of the engine. If you are running a github compiled version and would like to get the fix now it is available as this commit. It should be coming soon in a Launcher version as well

Thank You

Eric Ketchum