[4.14] particles in VR rotate when rotating HMD side to side

Development Platform & Builds XR Development
, , , , ,
1

When working in VR particles that are set to facing modes other than ‘PSA Facing Camera Position’ will rotate with the HMD when you rotate your head from side to side. This would be the setting to use, but then we are limited to square particles when we need rectangular. Is there any way around this limitation?

I’ve read on the forum that a fix is to turn off ‘Use Pawn Control Rotation’ on the camera, but this is already unchecked and the problem still occurs.

Thanks.
~Mike D.

2

The 4.14.3 particle editor Emitter tab has a Remove HMD Roll checkbox that worked well enough for me today, testing with the Starter Content P_Steam, no other changes required

124581-hmdrollcapture.png

][1]

2 Likes
3

I know this is an oldish thread, but thanks for saving my life :)!!
Do we know if there are any improvement or hit on performance?

4

Probably no significant performance change is my non-authoritative answer - i.e. I’m not an expert in this area but I did look into the 5.0 source a bit re how “Remove HMD Roll” is used:

  1. The engine uses the flag whether its checked or not in ParticleGPUSimulation.cpp:

    Resources->UniformParameters.RemoveHMDRoll = InResourceData.bRemoveHMDRoll ? 1.f : 0.f;

ie that line has the same performance regardless of what you pick in the editor.

  1. Calculating how the particle will be rendered in VR already involves a variety of low level calculations, so this one setting probably just slightly modifies an already complex set of math that’s (hopefully) GPU accelerated
5

Sorry to update an old topic, but what about pitch rotation? How did you fix it?