Translucent Blend Mode Issue

[Raycord_de1]

Hallo,

I’m new in Unreal and new in this forum. So please be indulgent if my Questions silly, or I’m on the wrong place to Ask.

I created a model with Blender and wanted to make a little promo video. In Blender I had the problem that due to the denoising the video is flickering. I couldn’t find a workaround witch fixes this satisfying.

So I loaded my complete Scene in UE5 and it looks good. Except the 3D-Text with the Translucent Blend mode. I wanted to make a simple effect, that my text fade in and out. So I imported my text as fbx to UE5, made a simple PBR Material, with base color, metalness, roughness an normal map, and I controlled the opacity with a MaterialParameterCollection setup with keyframes in the sequencer.

First Issue:

As You can see, while the Material opacity is set to 1, a few triangles from the letter behind, shines trough the letter in front. And this while all normals facing outside, as You can see in the following screenshot:

Because days of troubleshooting, searching the net, and asking chatGPT were unsuccessful I created the text new, with the 3D Text plugin of UE. The triangle-issue is gone - BUT - in the next screenshot You can see, that there’s a strange “shine-through” effect, while the opacity is still set to 1.

So I changed my way another time, and set my Blender_imported text to a place, where the camera comes straight to the text, so that the effect that faces of the backside shine through the letter in front, can’t appear.

BUT, another problem appears! The next screenshot shows, how it looks in the UE5 viewport. This is ok for me:

Then I rendered the short video and as You see in the following rendered image, the text looks different.

Probably because reflections with GI, but I don’t now, and honestly I have no patience and desire left. I really hope You can help me at at least one problem, so that I can finish my short video.

Sorry for the long post, but I think it was a kind of self-therapie

Many Thanks,
raycord

[ClockworkOcean]

I think you’re causing yourself problems with the translucency.

What about revealing text with a world position sphere mask?

How to...Sphere Mask

[ClockworkOcean]

This sort of concept ( no translucency, that’s the point )

( masked material )

[Raycord_de1]

Hello ClockworkOcean,

thank You for Your feedback. With this I made interesting text effects. But what I can’t figure out is, how to fade the whole text in and out. This is what I wanted to do with the Translucent Blend Mode. The opacity of the Text should fade smoothly in from 0 to 1 and out from 1 to 0.

Is this possible with the masked blend mode?

Thank You,
ray

[ClockworkOcean]

No, it’s not

Well it is with a dither node, but then it’s a bit pixely, and you have a strange shadow.

You’re trying to promote the PBR nature of the engine, and yet, this is what’s tripping you up

If you have translucent letters, you can see the back from the inside, because it’s PBR

[Raycord_de1]

Thank You. That is exactly what I don’t understand.

If I use the translucent blend mode the text will be transparent as long I use an opacity value less than 1. But if the value of the opacity is 1, the object should have no transparency and is fully opaque. Why is this not the case? And what is the solution?

In blender I also use PBR Materials and a fading translucency is no problem. You can change it until the object is fully opaque.

[ClockworkOcean]

Yes, at 1, it should not be see-though

[Raycord_de1]

Puh, I’m pleased to read this. But what’s going on with my text. The pictures shown above are all with opacity 1.

[ClockworkOcean]

Is the material just a color and opacity?

[Raycord_de1]

No, there are maps for metalness, roughness, normal map and the opacity will be influenced with a Material Parameter Collection:

But I tried it with just a color and a constant node for the opacity. The result is just the same.

[ClockworkOcean]

See my pic, are you using surface translucency volume?

[Raycord_de1]

Yes I do:

[ClockworkOcean]

Sorry, out of ideas

[Raycord_de1]

Welcome to the club

[Raycord_de1]

For me it is very hard to believe, that UE5 is not able to generate a simple Material fade in and out effect without issues. The following screenshot shows a Text made with the 3D Text Plugin of Unreal, and a few cubes and a cylinder. All with the same Material, with Translucent Blend Mode and the opacity set to 1.

The Text got the issues, and the cubes with the cylinder not.

Is there no way to solve this?

[BananableOffense]

The reason for your issues are sorting issues. Translucent materials don’t draw into the depth buffer for technical reasons so sorting triangles can be difficult. There are a few ways you can potentially fix it.
One is to check the box (I think in the mesh instance settings) to sort triangles. Another is to enable Order Independent Transparency in project settings, which adds to the cost of transparent materials but makes layered translucent materials look more correct.

[Raycord_de1]

Hello BananableOffense,

Enable Order Independent Transparency (Experimental) in the project settings was still checked. But after checking the Sort Triangles checkbox in the Mesh instances somethings happens. The triangles of the imported Text become flickering. Then I tried it with the 3D Text Plugin Text and some of the backfacing Issues are gone others still there.

I checked the Sort Triangles checkbox in every Mesh Instance of the text.

[Raycord_de1]

Noone an Idea? Unreal Engine 5 isn‘t able to create a simple Material fade in and out effect without Issues? Really?

[ClockworkOcean]

I think it’s the text. As you saw, the basic shapes work fine.

[Raycord_de1]

Yes, I think that too. But I can‘t believe that there isn‘t a solution. Lastly it‘s the Unreal Engine with presets for film making. What is a film without 3D Text effects. And the letters from the 3D plugin text are nothing else than meshes. Simple meshes. What if You want to fade another mesh in and out? This should be a standard effect, out of the box.

If there isn‘t a solution would mean, that you can‘t use the Material blend mode „Translucent“ anymore, except for very basic static meshes. You can‘t let objects appear smoothly at all. Really crazy!

But I think, the issue now is clear. It‘s the order of the objects triangles. I read a view things about the sort order, and it seams that the unreal engine can‘t really sort the triangles safely. The only solution probably is, to split the mesh into different objects, so that the engine can sort them with the different pivot points.

But what I don‘t understand is, why the issues still exist. In the whole thread we talking about the Translucent Blend Mode with the opacity set to 1. This should mean, that the Blend Mode „Translucent“ should become at the end to the „Opaque“ Blend mode. But this is not the case.

If I use the 3D Text with the „Opaque“ Blend Mode, there are no issues with the sorting order. But if I use the same Object with the „Translucent“ Blend Mode with the opacity set to 1, the issue is there, even though the object isn‘t transparent anymore.

With this in mind, I tried to fix it, with changing the material, so that in the moment when the materials opacity becomes 1, the material change to the same materiel but with the blend mode „Opaque“. This solves the sorting order issue, but due to a different shadow or reflection interpretation the object looks different. So the fade in is smoothly, but when the material changes You realize the change significantly.

It is really crazy to invest so much time and power in a very basic effect, due to unreal engines inability.