Is there a way to turn on anti aliasing MSAA for GearVR in Unreal Engine 4.14?

Could it be that 4.14 is broken for Gear VR ?

4.14.1 is out btw

rpalandri said:

Hello!
The forward rendering path for VR is really for PC only, the mobile side has always been forward only.

By default, MSAA should be on when you start GearVR, but issues in the config files might have messed that up. How it works is, if gearvr.EnableMSAA is 1 when the plugin starts, then whatever the value of r.MobileOnChipMSAA is, it will be set as 1 (activated). r.MobileOnChipMSAA is the CVar that actually controls the rendertarget being set as an MSAA rendertarget, which activates the feature.

How we can debug this:
when gearvr.EnableMSAA is set, it will log :

UE_LOG(LogHMD, Log, TEXT("Enabling r.MobileOnChipMSAA, previous value %d"), CVarMobileOnChipMSAA->GetInt());

Can you see this "Enabling r.MobileOnChipMSAA, previous value..." log in your run? 

If yes, and you still don't see MSAA, where the magic really happens is in OpenGLRenderTarget.cpp, line 201, where this is called:
glFramebufferTexture2DMultisampleEXT
instead of this
FOpenGL::FramebufferTexture2D.
Could you verify in which path your renderer goes?

Thanks a lot

Thanks a lot for the info. in the meantime I had to switch to another task (saving mp4 files even if on  separate thread freezes the UE game thread and the gearVR IMU stays on, allowing you to see a frozen quad...). But I will try out your test as soon as I can, which will be in a couple days probably. Ill report back when I do.

Hey!
Sorry you're running into issues with UE4.

So 1), we're seeing that  "[2016.12.09-10.18.12:048][-8607492]LogHMD: Enabling r.MobileOnChipMSAA, previous value 0" is being called, so good! the value should be 1.

To check in which part of the code the engine goes in OpenGLRenderTarget.cpp, you could add a logging line, like :  UE_LOG(LogTemp, Log, TEXT("Going through MSAA codepath")) in the multisample FBO case, and UE_LOG(LogTemp, Log, TEXT("Going through non-MSAA codepath")) in the other,so that we're sure which path we're going on.

One reason why it would switch off the MSAA codepath is if your driver/device doesn't support the MSAA extension (GLES doesn't support MSAA by default, it's a per-vendor extension that does). When VRAPI starts, it prints out all the supported extensions. Can you verify it contains GL_EXT_multisampled_render_to_texture? Can you also send us your exact model of device, and OS build version? A log of the execution of a UE4 program would also be helpful (containing the VRAPI start, vrmodes, everything :) )

Can you also send us a screenshot of your aliased scene? Although on-device MSAA is definitively helpful, it doesn't remove all the edges.

Thanks a lot

@rpalandri

The device is:
. Samsung Galaxy S6.
. Software and Baseband version: G920PVPS4CPJ1
. Hardware version: G920P.02
. Model number: SM-G920P
. Android version: 6.0.1
. Kernel version: 3.10.61-8847946

I'm also attaching logs (all, ue output only, vrapi output only).

I see that the UE log is the one that seems to list all device gl extensions. And I do see:
12-09 21:42:27.481  8399  8423 D UE4     : [2016.12.10-02.42.27:488][-8606092]LogRHI:   GL_EXT_multisampled_render_to_texture

Interestingly too, I see that the gles version seems to be 3. I was expecting GLES2 since I do not have v3 checked in the project settings under platform android.

About putting logs in OpenGLRenderTarget.cpp, I guess I need the source code version of the engine right? And recompiling the engine itself?

I am currently running the 4.14.1 version from the Epic launcher.
I tried modifying the file, adding:

UE_LOG(LogTemp, Log, TEXT("------------------------ !!@# : MSAA | 1"));

at line 200. And a similar log for the else branch:

UE_LOG(LogTemp, Log, TEXT("------------------------ !!@# : NO MSAA | 1"));

and hitting compile in the editor but it did not print anything when running on the device.
Also, when I modified the cpp it warned me that it was under version control and had to be made read/write.

About sending you an image of the aliasing I am wondering how could I do this, since the aliasing becomes obvious only when putting on the headset and staring thru the lenses.

This is gonna sound weird, but are you sure you're not running MSAA? Everything here seems to be pointing towards MSAA being on (which I also replicate on an S6 on 4.14.1). If you send us a screenshot (pressing the home and lock button at the same time), I'll put it in the headset to repro :)

MSAA 2x is good, but far form magic, especially if the aliasing doesn't come from the geometry but from the textures (which something like FXAA/SMAA/TAA would solve, but not MSAA)

@rpalandri

I'll try to get you a screenshot soon.

And yeah, honestly it might just be on. The reason why I think it might not is cause in Unity, a similar scene with MSAA at 4 or 8 definitely makes a difference. My scene is actually made up so far exclusively of an UMG widget. A sort of flat 'card' with some text and an image.

. I see a lot of shimmering in the image, which as you say, would be related to texture filtering and mipmaps. 

. I also see the text shimmering, this I'm not sure how it could be addressed; not sure about Unreal settings related to text since I am new to it. The only thing I've seen so far is the UMG DPI setting but I'm not sure if it is just for metrics when designing the widget or if it has an effect on rendering.

. Finally, the widget's (a square) borders are very jagged. This is what made me think MSAA might be off. I assume the widget is rendered over a quad. If so, the quad is geometry and I would expect MSAA to affect its edges.

Makes sense?

Afaik MSAA antialiases only edges of geometry. Since UMG widgets aren't geometry per se, the images and text on them won't be AA'ed. You should probably use stereo layers instead (render your UMG into stereo layers).