Buggy motion blur effect on UI when moving the camera

[monsieurbab]

Hello!

I am testing the free version of Nova UI to see if it would suit our project. We are on Unity version 2022.3.4f1 with HDRP. The Root UI has the ScreenSpace component attached. However, when I move the position or rotation of our main camera (like when our player moves), a kind of buggy motion blur appears on the UI.

I tested on a blank HDRP project, same problem. I also tested on a blank project in Built-In RP and this problem does not appear. So it seems that this problem only occurs in HDRP (and maybe in URP?)

Here is a video of your Demo scene (slightly edited) so you can see the problem: https://www.youtube.com/watch?v=nANvvFuhrME
Please note that no motion blur or other post process effect is enabled.

Do you have a solution to this problem? We would really like to use the full version of your plugin for our future game!

Thank you in advance for your help! :)

[adgray1]

Just to confirm, motion blur is disabled in your HDRP Volume Profile asset?

I ask because it's enabled by default and will still apply, even if there isn't an explicit post-processing volume attached to the scene camera.

[monsieurbab]

Thank you for the quick reply!

Indeed, on the blank test project, the motion blur in the global settings was not disabled.

However, on our real Unity project, even disabling motion blur in the global settings, the problem was still present. In fact to solve this problem, I had to deactivate the anti aliasing (TAA mode) on the main camera or switch it to FXAA or SMAA mode.

It seems that this problem requires disabling motion blur + disabling TAA anti aliasing on the camera. For the moment it solves the problem as long as we don't need this type of anti aliasing.

Thanks for your help :)

[fjnoyp]

I have the same issue... I bought your package on the sale and whenever the camera rotates quickly, the ui blurs/glitches just as shown in the the demo youtube video above.

Why is this closed if it's an active issue?

[monsieurbab]

Hello, I closed it because by disabling motion blur and anti-aliasing, the problem disappears. But yes it will be better if this bug is fixable by the developpers because in case our project need anti-aliasing (it will for sure) or motion blur, this problem will be really annoying.

[dkonik]

This issue is not specific to Nova and by default will occur with any transparent content that renders in front of moving opaque content, as you can see in the following video with a transparent quad in front of the moving cube:

HDRPTransparentArtifact.mp4

The root cause is a result of transparent objects (such as Nova content) not rendering motion vectors, which you can read more about (including additional potential work arounds) here, but the simplest workaround for screen space UI would probably be to render the UI after post-processing takes place. This can be accomplished by:

1. Putting the Nova UI on a separate layer (e.g., the UI layer). You can do this by changing the layer of the root UIBlock, and selecting the "Yes, change children" option when prompted.
2. Set the culling mask of your camera to not render the UI layer
3. Add a Custom Pass Volume to your camera, with the following configuration:
   • Set the Mode to Camera
   • Set the camera to be your target camera
   • Set Injection Point to After Post Process
   • Add a new Draw Renderers Custom Pass and then:
     • Under filters, set the Queue to All and the LayerMask to only render the UI layer
     • Under Overrides, ensure Back to Front is checked in the Sorting dropdown

Here is an image of the final configuration (with the markup indicating things you'll need to change):

[monsieurbab]

Thank you a lot for this solution! That completely solves the problem with HDRP camera post-processing! Again, thank you very much!