Static Mesh planes and Landscape do not properly implement "Shadow Two Sided"

Development Rendering
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1

Found bug in 4.9.2, confirmed to persist in 4.10.1

To Recreate:

Create blank project, delete SkySphere_bp, clear everything except for:

  1. a blank post process (just make sure to set indirect illumination intensity to 0 so there is no ambient lighting)
  2. A default, dynamic Directional light
  3. A static mesh plane, or a landscape, set to material that does not have a flat normal map. Make sure to check the “Shadow Two Sided” boolean is set to true on both.
  4. Make sure to re-build the lighting to clear any old lightmaps
  5. Set directional lighting to an upward angle, but not completely perpendicular to the plane and landscape. My picture uses a 50 degree upward angle.

Note that the normals of both the landscape, and the plane surface are being lit when they definitely should not be.

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2

Bump. Very easy to reproduce. Can’t see this being intended behavior.

3

Bump. The same results are produced even if the material is “two sided”

4

Hey HuntaKiller,

Thank you for taking the time to report this issue. I was able to reproduce this issue on my end and entered a bug report for this issue, UE-24656. One this issue has been fixed, it will be integrated in an upcoming full release or hotfix.

If you have further questions, please let me know.

Thanks,

5

Just wondering if this has been looked at at all by the team or if its just on the to-do list, I haven’t been able to find a workaround that solves the problem without removing the sunrise/set.

6

It is still on the to do list. I will add community interest to the bug to help give it a higher priority.

7

The issue has been set as “Won’t Fix” can we re-open it? I would really want to get it fixed, for this issue is bothering me so much and I don’t want to end up placing planes under the map to keep the light from leaking.

8

Hey Kristjanmn,

I just updated the ticket internally to reflect your concerns. If we are able to review the issue again and get a fix, it will be reflected on our public JIRA once the fix has been made.

Thank you,

9

Bug tracker was closed again

10

How dumb “no one has complained about this bug in a while so we won’t be fixing it”.
I’ll make sure to complain about this more. Epic this is a ridiculous bug, why are surfaces lit from the wrong side? Reopen and address this!

11

bump… they just did reworked the landscape rendering pipeline… seriously…
I get that this isn’t a part of the LOD / Tessellation but its also a shadowing issue…

12

This is still an issue, years later.

14

Bump. Still not fixed