Developer Notes

Only one or the other is supported

// Calculate the fog needed for translucency
Output.BasePassInterpolants.VertexFog = CalculateVertexAtmosphericFog(, ResolvedView.TranslatedWorldCameraOrigin);
Output.BasePassInterpolants.VertexFog = CalculateVertexHeightFog( - ResolvedView.TranslatedWorldCameraOrigin);


Using both an Atmospheric and Exponential Height Fog will cause an issue rendering Translucency-based Materials.  (See Screenshots below)

Cannot use both Atmospheric Fog and an Exponential Height Fog together  

Steps to Reproduce


  1. Open attached project (fog Test)
  2. Once the scene is loaded enable visibility on the Atmospheric Fog

The cube will render on top of the fog.

The red cube gets partially occluded by the dense Exponential Height Fog.

1.  Create a New Blank Project with Starter Content
2.  In the Minimal_Default map, Delete the Table and 2 Chairs
3.  Increase the scale of the Glass Statue to (3,3,3)
4.  Add an Exponential Height Fog into level.
5.  In the Exponential Height Fog, Change the Fog Density to .25
6.  Pull the camera back a far distance from the Floor and Statue Assets
7.  Turn the Atmospheric Fog off and back on again
The Glass Statue's translucency changes depending on whether the Atmospheric Fog effect is on or off with the Exponential Height Fog.
The Translucency should render the same even if both effects are on.  

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Won't Fix
ComponentUE - Graphics Features
Affects Versions4.
Target Fix4.16
CreatedJul 10, 2014
ResolvedJan 26, 2017
UpdatedApr 27, 2018
View Jira Issue