Transparency Reflections in 4.12?

Hi, I’m searching for a way to replicate the official Unreal documentation to see reflection on glass:

I setup the material in the same way:
But in 4.12 there is no TLM Surface vale for the parameter “Traslucency lighting mode”, so I used “Surface per pixel”.
This is my result:
Left - classic reflective opaque material / Center - double sided bottle mesh (to simulate the glass thickness) / Right - Single side bottle mesh
2016-06-17 00_33_47-Refraction00 - Unreal Editor.png

As you can see, there are no reflections, and the final result is quite odd.

Where I am wrong? Any kind of help is appreciated, thank you!

Anyone? :confused:

Up! Having the same problem.

It looks like you have no object to reflect in the scene and did you add an cubemap?

Hey guys,

There is a bug in 4.12 related to transparency which is being investigated by Epic currently (bug report ID UE-31589), here is the bug report:

[MENTION=4894]Tim Hobson[/MENTION] actually just replied an hour ago saying the issue appears to be resolved in version 4.12.4, so update your engine and see if that fixes it.

If any of you are already on 4.12.4 and still have this issue, please reply to the AnswerHub thread I linked above with an image and description so they can investigate further.


To add to this, looking at your material setup for the lighting mode you have the experimental Surface PerPixel selected. This requires that you set r.ForwardLighting 1 to work (You can read this in the ToolTip if you hover over the selection as well). If you do not you will not have the specular reflection from lights for the glass. That’s not the same issue as reported with the post I responded to a little bit ago.

Try using Lighting Mode Surface Translucency Volume.

There was a sphere reflection capture in the scene, but also two errors from me:

  • the sphere reflection capture didn’t work because there was no SkyLight object.
  • the opaque material had a black base color.

I updated to 4.12.4 and added a SkyLight object in the scene. This is the result:
2016-07-02 18_23_25-Refraction00 - Unreal Editor.png

As you can see, the sphere reflection capture object + the SkyLight object allows the opaque object to have reflections, but still no reflection on the basic glass material configured as the official Unreal tutorial (see my first post).
Then, I tried to add the fantastic “advanced glass material pack” bought from the marketplace, and then… here there are the reflections!
2016-07-02 18_29_50-Refraction00 - Unreal Editor.png

So my question now is: why reflections didn’t work with the “basic glass material with reflection” suggested by the Unreal official guide? Need to update that help page? What is the minimum material configuration to achive reflections on the glass?

I tried to type r.ForwardLighting=0 or r.ForwardLighting=1 into the console while in Play mode, but nothing happen. Am I doing something wrong to follow your suggestion?

Hi, same question (2018-02-12) Anyone knows ? Thanks

You material needs to have Translucency set to “SurfaceVolume”

I got a video around about this and I will upload it for you to see the setup, tells also somethings useful for this kind of application, just hints.

PS: got it uploaded, made it for some folks some time ago about almost same material setup you did, hope it helps too.