There's a visual glitch when using more than one BOM texture layer on a Universal Aux channel if there's partial transparency in the texture using Blinn-Phong textures. I've made BOM textures with partial transparency for rigged fairy wings, so that customers could layer a stripey texture on top of the main wing texture. However, it's as if there's an outline of 100% transparency around the edges of the upper stripey texture that punches a hole straight through the underlying wing texture as well.

It shows up the most when in front of a bright background.

I tried making the stripe texture completely black with a 100% transparent background by converting it to a vector and then converting it back into a raster image in Photoshop, and this minimizes the issue so that it's only visible if you're very zoomed in, but this means there can't be layered BOM textures with blended edges at all on the Aux channels.

I had envisioned being able to make add-ons like colorful peacock 'eye' spots, faded edges, etc so people could really customize their wings' look, but this doesn't seem to be possible right now.It happens whether the files are PNG or TGA, with or without an alpha channel.Since the main wing textures have partial transparency, changing the blend mode to alpha mask would not solve the issue.

Hopefully you can see the problem in the screenshots. You might at first think it's the white outline 'halo' issue but no, it's actually that the edges have an outline that are completely clear so the background shows through.