Help needed: PBR and Opacity map wop't work together

I tried to set up my PBR material with an Opacity-map (exported from Substance Painter 2) but the two won’t work together.
If I choose the only Blend Mode which does support Opacity (Translucent) it greys out most of my PBR channels, as the picture shows:


This obviously does not work but I saw a tutorial where the material was set up like this:


This looks exactly like what I need but I cant get my Material to behave that way and since the object in question is a bottle, it looks really wrong.
Has somebody encountered this ever and/or knows how to fix it?

Change lighting mode to surface or per pixel.

Thank you for the quick reply but I obviously am a newcomer to unreal so where exactly do I change the lighting mode? Of course I searched for that too but I could not find it (maybe I don’t know what to look for?). Maybe you could help me again, which would maybe benefit other people looking for solutions.

It’s right here :


Okay I found that now. I actually found that earlier but I thought it was not right because I get this:

Wrong Translucency.png
Wrong Translucency_2.jpg

This is not right since the container in the front is supposed to be solid metal.
I then tried inverting the opacity map with a OneMinus node but and this happened:


This looks like the map works correct, only inverted. For example, the label on the bottles are fully invisible.
If I remove the node again, it’s just as bad as before.

to me it Looks like the Basic sorting Problem.
translucent faces cannot be sorted properly with deferred shading like UE does.

You either have to stick with the “bottle in the back is rendered in front” or you can use Forward shading in 4.13

if your bottle in the front is completely opaque, use the Default lit shading model instead of translucent. this gets rid of the sorting issue.
renounce translucent shading model whenever possible!

Yeah then maybe I should arrange my models differently because all these bottles are on a single UV to save space. It’s annoying that there does not seem to be an easy solution to this.

Looking at your opacity map, it looks like its actually not 100% white where that metal box is. If its not 100% white it will show through even if it happens to render those polygons last.

What exactly do you want to show inside of this? If this is just supposed to show some liquid inside I would probably try to render the liquid and refraction as part of the actual surface and just make the entire thing opaque.

I actually just want the bottle to be empty and you shouldn’t be able to look through the label or the dirt on it.
Even if I just create a Constant3Vector within unreal and put it into the Opacity, the problem persists. where I can see the bottles in the back through the metal container in the front.

I don’t actually see any alpha differences where that label on the glass is. Looks like the whole opacity texture is white there. You’d want to glass to be some partial value and the label to be white to get that effect. Looks like your opacity map is just setup up wrong?

Is it important to actually see other moving objects behind the glass? If not, you could capture a static cube and simply blend to it in the material

The Opacity map has some differences:


I exported the Opacity-channel from Substance Painter. Maybe I am overlooking something really basic but I can’t help it. I don’t know what to do except deleting the Opacity altogether.

Ya but the area right outside of the label in the center of that last image is grey, and you said it was supposed to be a metal box. That means it will be partially transparent. And the whole left side of the image has a white opacity, which seems to be the part of the mesh you want to be translucent. If anything the left area should be grey, minus the triangle shaped label on it.

If you painted this opacity in substance, why did you paint anything other than solid white for the metal box?

Okay I think there is a misunderstanding about what I want to be transparent and what not :smiley:
Those two green bottles should be partially transparent and the metal cylinder should not.
Here is the Albedo where you can clearly see how the UV is layed out:


As you can see, the parts in grey are supposed to be on the green bottles and therefore partially transparent

Always split that kind of mesh to two elements.(opaque and transparent) Transparent shading just wont look solid shading even when opaque is 1.

You made my day! Spent two days doing juggling and I got it at just one click! Thanks you so much!