Hey everyone, Unreal noob here. I’m using Unreal for a work project, and I’m having trouble creating a material that contains some colored glass surfaces of different colors. We are rendering everything using Path Tracing, which is important to note.
The Substance Painter-textured objects are a couple thick, colored glass perfume bottles with dirt/grime/smudges on top, as well as torn stickers. The dirt and stickers cover the transmissive surfaces partially, so I exported a transmission map that determines the areas where the semi-transparent bits of dirt and sticker residue cover the glass.
In Maya, which is my main 3D app, simply plugging that map into the transmission input of an Arnold standard shader and then plugging the separate transmission color map into the transmission color input would work right away, and the shader would transition from translucent glass to opaque dirt/sticker smoothly. But, in Unreal, following the few guides on glass I can find, the glass seems to dislike the transmission map, and weird colors appear in the transition areas of dirt and sticker, like pink, green, yellow splotches. And I also haven’t gotten a firm grip on how I’m supposed to handle the glass colors.
My current setup is as follows:
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substrate slab BSDF connected to the Font Material input of the main material node
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Blend mode is TranslucentColoredTransmittance
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Translucency Lighting Mode is Surface ForwardShading
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Refraction method is IOR, and I’ve set it to 1.5
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Diffuse Albedo has a map where the non-glass surfaces are colored, and glass is black
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Glass color map connected to Substrate Transmittance-To-MeanFreePath node’s transmittanceColor input, and its MFP output connected to the slab’s SSS MTF input
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Transmission map (grayscale map determining what’s glass and what’s not) connected to SSS MFP Scale input.
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Other maps, like normals, roughness, metalness, etc., are connected to respective inputs as well.
I have also tried creating a slab for the glass and another for the non-glass, and then using a horizontal blend node with the transmission map ackness or the brightness of the transmittance color, it’s as though the color of the glass travelting as the mix mask, but I get the same result.
If I set the glass transmittance color too dark or the Transmittance-to-MFP thickness value too low, where the glass appears almost black, the dirt and stickers look correct. But as soon as I start making that colored translucency show by increasing the thics through the color wheel as the transmission value goes from 1 to 0 in that map.
Am I doing something wrong? What am I missing?