Developer Notes

This was marked as by design because SSAO doesn't work correctly on hair and was making blonde hair too dark to look realistic. If you want to work around this AO needs to be applied via material.

Description

The Hair shader no longer allows ScreenSpace AO on areas of the screen it occupies. While in the Ambient Occlusion Visualizer it appears that the material draws on top of the SSAO.

REGRESSION?
Yes

Worked in Binary 4.14.3 CL 3249277
Broken in Binary 4.15 preview 3 CL 3278667

Steps to Reproduce
  1. Open a blank project
  2. Add an unbounded post process volume
  3. Make the Ambient Occlusion intensity 1 and the Power 8 to make the effect very obvious
  4. Add a basic sphere to the scene
  5. Create a new material and set the shading model to hair then apply to sphere
  6. Change the view mode to ambient occlusion located under Buffer Visualization

RESULT
The sphere draws on top of the SSAO

EXPECTED
The SSAO is unaffected by the sphere and draws on top.

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By Design
ComponentUE - Graphics Features
Affects Versions4.15
Target Fix4.16
CreatedFeb 6, 2017
ResolvedFeb 10, 2017
UpdatedApr 27, 2018