Just upgraded to 4.14, and have an issue I think is problem specific.
Developing for VR, I seem to get 1-2 frame hitches every once in a while in seemingly random directions so I’m having a hard time finding the culprit. When I profile the CPU, I find that the hitches are because the render thread is creating a texture under:
RenderThread::FDrawSceneCommand::RenderViewFamily::Translucency drawing::FSceneRenderer_RenderDistortion::(FSceneRenderer_RenderDistortion_Render and FSceneRenderer_RenderDistortion_Post)
So my questions are thus:
What textures are being created at runtime for the translucency? Almost everything is static in the scene and I don’t use any procedural textures.
What’s the best way to start narrowing this down further?
I’ve already used showflag.translucency 0 to turn it off which fixes the problem. I’m not sure if this issue existed before 4.14, but if it did I never found it. I’ve tested and it occurs in both the forward and deferred renderers. I’ve been selectively changing out translucent materials and hiding translucent objects but haven’t found the issue yet.
just finding this question made me happy.
Realizing it does not have a solution (or input from Epic Staff) made me only a little less happy.
I have the exact (exact !) same issue as you have: VERY slight 1-frame glitch when I move my head left to right in some locations (the glitch is most apparent when looking at the stat numbers while wearing the CV1 → they “tear” a little bit).
The only difference with me is that my spike is showing up in the “FSceneRenderer_RenderDistortion_Post” (I have a 12ms spike).
Let’s hunt this thing down to find a solution.
Before finding this question I also slapped a thread up on the forum: Forum Thread here
also : showflag.translucency 0 completely works for removing the hitch, but it is of course not a workable permanent solution as it not only disables all regular translucent materials but consequently also all particle effects since they relay highly on translucency
edit: I think/hope I found a solution for you. I’m cautiously optimistic in saying that, for now at least, I think I no longer have this glitch.
What I did was switch off the “Separate Translucency” checkbox in Project Settings > Rendering > Translucency
Hopefully that checkbox is “checked” on your end so you can at least uncheck it to see if it makes the same difference as it did here.
very strange.
In fact - I downloaded the Showdown demo from the marketplace and duplicated all “Rendering” project settings from there into my project and the hitch just went away, in my case the “separate translucency” checkbox being the culprit (when I re-enabled it the hitch was back). Very strange that this does not work on your end
This has nothing to really do with the CreateTexture call shown in the CPU profile, but we found that making sure that the compositor (vrcompositor.exe for steamVR) is set to at lease high priority in task manager (we normally just set it to realtime) alleviates these hitches. Maybe the CreateTexture time increase isn’t the cause, but a symptom?
Making sure that that process is set to high priority gets rid of all our random hitches using the Vive.
