Vulkan: TAA causes snapping effect when a camera and a light source are moving together

[victfv]

Godot version

4.0 beta 4

System information

Windows 10, Vulkan Clustered, GTX 650 Ti 2GB

Issue description

When parenting a camera and a light source (spot or omni) to a character and moving, having TAA on causes a sort of snapping effect on the light. Also, any other moving lights will have the same happen to them to a lesser extent. It doesn't happen to stationary lights.

2022-11-06.16-44-51.mp4

Steps to reproduce

• Create a dark scene with a low roughness material on the floor, preferably with a normal map.
• Add a moving light and camera to the scene and turn TAA on.

Minimal reproduction project

LightTAA.zip

[Calinou]

This is likely expected, as the light itself (and its resulting reflection) doesn't have motion vectors. Does any other engine handle this situation correctly?

[victfv]

I installed Unreal 4.27.2 to test it out.
Here's the result.

2022-11-06.19-49-22.mp4

I turned off auto exposure and motion blur in the post process volume.

It seems to still happen, but instead of snapping it slowly fades in. Also, the specular highlights don't seem lose as much brightness as in Godot.

[victfv]

Turning off specular shows that only the specular lags behind in UE4, while both diffuse and specular lag behind in Godot.

Godot:

2022-11-06.19-58-49.mp4

UE4:

2022-11-06.20-01-01.mp4

[Calinou]

cc @clayjohn