Description

Stationary Spot Lights in Forward Rendering cause artifacts when lighting transluceny set to Volumetric PerVertex NonDirectional. When the camera is moved around the object, the lit vertices flicker. Stationary Point Lights however function as expected and do not flicker.

Found in 4.21 CL# 4753647, 4.22 CL# 6574378, 4.23 CL# 6925347

Steps to Reproduce
  1. Open the Editor and Enable Forward Shading
  2. Create a translucent material with .5 opacity and base color
  3. Set the Translucency lighting mode to Volumetric PerVertex NonDirectional Translucency
  4. Place a sphere into the scene and scale it up a bit
  5. Aim the spot light at the sphere, bake lighting, and rotate the camera around

Result:
The Sphere will flicker and artifact

Expected:
The sphere would be lit appropriately as it is with other light sources

Have Comments or More Details?

There's no existing public thread on this issue, so head over toAnswerHub just mention UE-76293 in the post.

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Unresolved
ComponentRendering - Features Teams
Affects Versions4.214.224.23
Target Fix4.24
CreatedJun 14, 2019
UpdatedJul 19, 2019