Black flicker in viewport and PIE (Mac OS 10.12)

We are about to (tomorrow) start a class using UE4.15 installed in a lab setup with no launcher.

The computers are iMacs with Intel Iris Pro 6200 cards, 8GB RAM, OS 10.12.

We are getting bad black flickering artefacts on a new FPS project with nothing added or adjusted and on a blank project (but only when close to surface).
We are also getting the highlight error mentioned in other posts (the selection highlight appears even when transparency is set to zero).

Lastly the game icons (e.g. player start) appear chequer-boarded as if selected even when not.

Does anyone have any suggested solutions? I have found threads that say Intel Iris cards are not supported. Can we go back to a version that works better and if so which version would that be?

Any help much appreciated.



There’s already a bug somewhere about the selection highlighting on Intel and I’ve reported that to Apple. The 2D icons rendering in the viewport are a long-standing issue that again Apple should be aware of already.

The black rendering is news to me and I’ve reported that as well. Right now I don’t know what the cause is so it is impossible to provide solution or ETA.

Okay. Thanks. BTW the Black Flicker doesn’t happen in 4.14.3 but does in 4.15.0 and 4.15.1. The highlight transparency issue and selected game icons happens in all three.

I have the same problem. If it’s a GPU issue, why in 4.14 it didn’t happen?

This isn’t known to occur on AMD or Nvidia GPUs so the current position is that we’ve found a GPU specific problem.

One potential cause is that the Metal shader standard & compiler takes a very different tack in what optimisations are permitted on floating-point code, which means subtle changes in shaders can expose new and exciting bugs like this. It isn’t always obvious what causes such problems at first glance and as a practical matter there are too many changes between releases to simply compare and expect to find the problem.

It will require deeper investigation to find the underlying problem whatever it may be, which could be something else entirely.

This is Apple device so you don’t have many various models to test. Only MacBook. This bug causes UE4 useless. This is critical bug. Please fix this as soon as possible.

The matrix of Unreal Engine rendering features versus unique GPUs used in Macs is actually very large and complex. Consequently it is impractical to manually test every single feature on every possible Mac GPU for every build.

I understand and appreciate the frustration when a bug slips through and we don’t want that to happen but it is inevitable that sometimes they do. Especially considering that the whole Metal graphics stack on Mac from GPU drivers, OS frameworks, shader compilers and UE4 MetalRHI code has had less than 2 years of development vs. most of a decade for Direct3D 10/11. We will work to identify and resolve this issue with Apple as soon as we can but until we have we can’t provide any ETA.

FYI for anyone also having the annoying highlight issue: Under Preferences > Viewports > Look and Feel you can Turn off Selection Outline and turn on Highlight Brackets. That creates an easier to handle look (see pic).

Also, can confirm that issues described above don’t happen on Macs with other cards just Intel Iris Pro.

Hi, I bought the Katanami Character from the Asset Store and get black rendered triangle artefacts on my Mac Book 2012 using UE 4.15. GPU: NVIDIA GeForce GT 650M 1024 MB Intel HD Graphics 4000 1536 MB.

The grey/black artefacts are in the viewport, or mesh preview window when going close to the mesh. The mesh itself seems fine to me. Other Materials have the same effect.
“Optimization Viewports → Light Complexity” shows the same triangles black. All other blue checked meshes are rendered correctly.

I will test with 4.14.

This doesn’t occur in 4.14 and works fine.

Changing the antialiasing filter (TemoralAA) had no effect on 4.15.
Seems to be related to the update of Metal? Have OS 10.12.

Have not changed the TemporalAA quality from 4 to 3 as found on another post.

There were a lot more than Metal changes between 4.14 and 4.15 so it would be unwise to jump to any conclusions as to what caused this problem. As I’ve stated above, even subtle changes to shaders can cause such problems in Metal due to different floating point optimisations changing depth/position precision. Or it may be something else entirely - until we’ve investigated fully it is impossible to know for sure.

Hi! I got this issue on opening project on our new 2017 iMac 21,5 for iOS development and deployment. Radeon with 4gb vram.
The old 2012 iMac does not have the problem. Both Run High Sierra and engine 4.16.3
A new 4.16 fps vanilla project I just created on the same iMac shows no flicker!

Converting the project to 4.17 makes phenomenon go away. (at least upon first try) Not a practical solution right now, but may indicate that it has to do with Metal since 4.17 turn metal off, am I right? Also the machine without problem is Xcode 9.0 and new machine is 9.0.1. (I will try to revert to Xcode 8.3 on this machine, but am not looking forward to it) Curious that problem is not persistent. BMC95 gets flickering on new project. Is the project created on Mac or win? Next curiosity. My college tells me that on the first day of testing the machine, when we first saw the flickering, we restarted the project and the problem was gone only to return next time.

Same issue on MacBook Pro 13 2017 Intel Iris Plus Graphics 640 and UE 4.17.2
Blinking black areas