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[Feature Request] - Transparent Materials with Specular Highlights

I have another feature request that I did not see on the Unreal Roadmap that I have seen similar posts on the unreal forums about.

This feature request would be to add specular lighting support to transparent materials (i.e. Water, Windows).

Is this capability going to be making a release any time soon? If not, can this be added to the Roadmap for users to vote on?

Thanks,
Mike C.

We already have that!

you have to change the surface type of a translucent material to TLM surface
see the grab for exact location
3b563ff8d7c06fcbe51d8ddc4749f26410690105.jpeg

My materials are already configured using the TLM Surface lighting mode.

I can create my material as an Opaque with a Specular map applied and it looks correct, as soon as I change it to transparent (TLM Surface) and use the same Specular light reflection value as the opaque materials and even set the opacity to 1.0 I get no specular light reflection out of the materials.

While I agree that the TLM Surface ‘should’ be the correct way to do this, it currently does not work as expected.

-I’m not the only one seeing this issue btw -
https://forums.unrealengine.com/showthread.php?1873-Transparent-materials-don-t-look-that-good&highlight=transparent+specular

You can give it a bit of metallic value if you want to boost the reflections.

Hi Jacky,
My material has Metallic and Specular set to values of 1+ and the material still shows up with barely any highlights.

Admittedly, transparent materials look better than they did in the original 4.0 release, but far behind the quality of specular reflections on transparent materials i’ve worked with in other engines (example: CryEngine default water material)

I’ve included screenshots from a very basic material below to illustrate my example.

If the engine truly supports specular highlighting on transparent materials then feel free to move this to the support section of the forums, but I’ve yet to see ANY example anywhere of a transparent material that has specular highlights. If you know of a way to get a specular reflection on a transparent materials (like a glass window, or water surface) then please let me know how that can be achieved through the currently available engine material editor. I’d ask that you provide an example of how this is done if you do move it to a different forum.

The picture below is a high specular with a 50% metallic surface - This looks great and is what I expect (for an Opaque)

Mat_Opaque_SpecHalfMetal.jpg

The picture below is a high specular with a 50% metallic surface - This looks terrible, as the metallic component simply washes away the color and provides no specular reflections at all. Moving the opacity value from 1 to 0 does nothing to the specular reflections, but does slowly fade out the object until it is fully transparent.

4bc1ff39386f8a200237ea61470f27684508c500.png

Ideally, a fully opaque transparent material would look identical to an opaque material with the same color,spec,normals,etc… I know thats not the engines rendering pipeline works, however most other engines do this far better than UE4 does at the current time.

Epic is aware of the issues with translucent materials and they’ll get fixed in time eventually. Until then we’ll have to do with what we have, and it isnt horrible really. Something to keep in mind while preparing a translucent material, dont rely on material editor’s previewer. Place a sphere(or any other mesh) in your level and apply your material to it and you’ll see that it actually has reflections.

As Jacky mentioned, make sure you are looking at the results in the viewport, I put together a quick translucent material (TLM_Surface) with a basic light orange color, and you can se from the images the difference specular 0 and 1 makes.

Image #1 - Material

Image #2 - Specular value of 0

Image #3 - Specular value of 1

There are other ways of improving this as well, using a fresnel or custom reflection nodes (with a cubemap). The rendering guys at epic did mention they are working on forward rendering, planar reflections for translucent materials (water), and translucent reflection fixes on the previous Twitch support stream (2 weeks ago), so improvements will be coming soon as well. :slight_smile:

Wow, I feel like a dumb*$$ - :slight_smile: I was doing most of my material testing in the material editor, not bothering to apply the changes unless it looked right in the preview window. Running in the UE4 game editor the material does have good specular reflections. Thanks for clearing this up.

BTW, DotCam, your Ocean Wave Simulation looks Amazing! Can’t wait to see the final version of it. Great Job!