Translucency not showing on reflections

[garciabores]

A have a new issue related to translucency. I don't know if it is related to material, post-process volume or mesh. I'll explain below:
Once I have the glass reflecting and letting the light pass through, I realised that translucency is not showing in the reflective shapes. I have a mirror in front of a glass and if i look to the mirror the reflcted glass appears opaque (but shows reflections). Find attached the examples.

A: Note that the lamp glass balls are reflecting black in the glass doors
B: The reflected doors don't show the translucency

PS: Include Translucent Objects in Raytracing Reflections is already enabled, and Max. refraction Rays is 3. Enabling and disabling Refraction doesn't affect.
Any help would be appreciated, and thanks again for the previous answers.
Thanks in advance

[presto423]

In all the textures involved (glass, mirror, door frames, etc), is sRGB enabled (in texture editor for those textures, not material editor)? Also in texture editor for those, is MipGen Settings set to NoMipMaps? For RT, it may need to be set so sRGB is disabled and NoMipMaps.

[S-Dot]

It may just be a limitation of the current implementation of ray tracing. I spent quite a bit of time to find a solution but nothing seems to enable it. Even in the demo project from Scion that is available to download in the 'Learn' tab of the launcher all glass has been removed from the windows and the picture frames. If you find a way to make that visible let me know, please.

[garciabores]

In all the textures involved (glass, mirror, door frames, etc), is sRGB enabled (in texture editor for those textures, not material editor)? Also in texture editor for those, is MipGen Settings set to NoMipMaps? For RT, it may need to be set so sRGB is disabled and NoMipMaps.

Glass and Mirror materials don't have any texture within (they are plain pure materials), so i cannot disable mipmaps nor sRGB. Let me know if i'm wrong, I'm still a rookie.

It may just be a limitation of the current implementation of ray tracing. I spent quite a bit of time to find a solution but nothing seems to enable it. Even in the demo project from Scion that is available to download in the 'Learn' tab of the launcher all glass has been removed from the windows and the picture frames. If you find a way to make that visible let me know, please.

Wow, I hope is not a limitation, but as far as you have tried to find a solution and you couldn't, I'm a bit worried. There's no way UE4 can be used for archviz without this feature. If i find a way to solve it of course I'll let you know. Keep on trying different options but quite dissapointed about it.

Thanks both for your fast response.

[Suthriel]

Wow, I hope is not a limitation, but as far as you have tried to find a solution and you couldn't, I'm a bit worried. There's no way UE4 can be used for archviz without this feature. If i find a way to solve it of course I'll let you know. Keep on trying different options but quite dissapointed about it.

Unfortunately, it IS a limitation, it´s not only glass, it´s almost any transparent material, that gets not reflected by raytracing. Ever wondered, why most if not all raytracing demos contain almost no glass or ice or water, or clouds or fog and smoke? Cuz until now, all of this won´t be reflected and therefore be missing in all raytraced reflections. Even the most recent showcase for volumetric clouds in 4.26 did not use raytracing to reflect the clouds in the water. Until now, a material is handled as eiter opaque (and will be reflected as such) or it´s transparent and completely invisible for the raytracer.

Either that, or all of us are missing out on some important infos cuz i am waiting since rtx introduction for a raytraced solution for glass and fog/nebula/clouds.

[S-Dot]

Unfortunately, it IS a limitation, it´s not only glass, it´s almost any transparent material, that gets not reflected by raytracing. Ever wondered, why most if not all raytracing demos contain almost no glass or ice or water, or clouds or fog and smoke? Cuz until now, all of this won´t be reflected and therefore be missing in all raytraced reflections. Even the most recent showcase for volumetric clouds in 4.26 did not use raytracing to reflect the clouds in the water. Until now, a material is handled as eiter opaque (and will be reflected as such) or it´s transparent and completely invisible for the raytracer.

Whatever I do it is always 100% opaque. I would be happy to have it not show up at all in a mirror if that is possible. Would be better than a grey ugly object. The best I could do is tweak the colour of the glass so it somehow blends with the rest of the scene in the mirror.

[Suthriel]

Whatever I do it is always 100% opaque. I would be happy to have it not show up at all in a mirror if that is possible. Would be better than a grey ugly object. The best I could do is tweak the colour of the glass so it somehow blends with the rest of the scene in the mirror.

if you really want to make it invisible for the raytraced reflections, then i might have a solution four you (found a neat trick here in the forum). Change the materials blend mode to "masked" then add a RaytracingQualitySwitch to the Opacity Mask input, and for the switch inputs use a constant or parameter with 1 for the normal input and a constant/parameter with zero to the raytraced input.

With parameters you can decide during play and test, which variant is best for you. With parameters set to 1 for the normal, it becomes visible for the camera, with 1 for raytrace input, it becomes visible for the reflection. Zero makes it invisible for the camera (normal) or the reflection (raytraced).

Looks like this:

[S-Dot]

if you really want to make it invisible for the raytraced reflections, then i might have a solution four you (found a neat trick here in the forum). Change the materials blend mode to "masked" then add a RaytracingQualitySwitch to the Opacity Mask input, and for the switch inputs use a constant or parameter with 1 for the normal input and a constant/parameter with zero to the raytraced input.

With parameters you can decide during play and test, which variant is best for you. With parameters set to 1 for the normal, it becomes visible for the camera, with 1 for raytrace input, it becomes visible for the reflection. Zero makes it invisible for the camera (normal) or the reflection (raytraced).

Thanks. That will help a lot.

[Suthriel]

Thanks. That will help a lot.

Shoot, i forgot, that we are still talking about transparent objects, and that solution is mainly about completely opaque objects, that you don´t want to be reflected. But maybe with the correct blendmode, you can still use this solution and boost it´s transparency for raytraced, (linked to the Opacity node, instead of opacity mask), so that it gets threated as fully transparent. But not sure, what else is then affected.

But this RaytracingQualitySwtich is worth some experiments

[S-Dot]

But this RaytracingQualitySwtich is worth some experiments

I'm using that all the time now to remove detail normals from the materials when raytracing is enabled. Helps quite a bit with the performance if you have detail normals on walls or floor.