I’m currently working on a large environment scene that includes a church. I’m using trim sheets for the architectural elements, and one of the trim sheets includes a packed alpha map for opacity—intended for a stained glass material with metal ornaments.
I’ve tried different blend modes in the material setup, but I can’t get it to work properly. When I use the Translucent blend mode, the entire trim sheet becomes translucent. But if I use the Opaque mode, the stained glass appears solid and loses the transparency.
I’m exporting from Substance Painter using the Packed UE5 pre-set, so the alpha channel should contain the correct opacity information.
I will add a pictures of the texture itself for more information:
If anyone has encountered a similar issue, setting up a material that combines both solid and translucent areas,
any help would be greatly appreciated. If I can’t figure this out, my only option would be to separate everything into different meshes and materials, which I’d really prefer to avoid.
This is your only reasonable option. You don’t need to split up the texture, but translucent surfaces pretty much always need to be split off into their own material.
UE’s new material system, Substrate, exists in part to fix the exact problem you are experiencing. You can’t have a translucent material next to an opaque material and have them use different shading models.
Maybe I’m not understanding but I don’t see how Strata improves on this?
His problem isn’t that he has two different shading models, it’s that he needs two different blend modes (opaque and translucent) and as far as I can tell Strata still only allows for a single blend mode per material.
For what it’s worth, “premultiplied alpha” blending can emulate all other blend modes – translucent, opaque, additive.
It still has the problem of ordering, though, so, in general, you always want all opaque and cutout materials to be in one material group, and all actually-blended-pixels to be in another material group.
(I’m saying “material group” because that’s what it’s called in some DCC tools – that maps to “material slots” in Unreal.)
This is really not a big deal, it takes a couple of minutes max, all you need to do is assign a different material to the glass polygons in your modeling software and re-export the mesh. The texture and UVs can stay the same.
