this glasses model seems to work fine with opaque or alpha hash selected but i need this custom alpha value with it that those other modes cant seem to deliver. it works fine until you pan a certain distance for the body to basically act like a mask for whatever reason.
blend file and glasses textures
tell me if the skin textures are needed as well
Alpha blend requires that meshes get sorted in the right order-- if a deeper face gets drawn after a shallower face, then the deeper face will never get drawn because the depth buffer is already written with a shallower value. That's why alpha blend is so tricky, and gets trickier the more layers of alpha blend that you have.
In this case, it is usually the two sides, front and back, of the glasses that are confusing the sorting. For alpha blend materials, Blender gives the "show backface" option in material settings. By telling blender not to consider the backfaces in any sorting algorithms, the sorting will work more often:
Here, I'm comparing the glasses with "show backface" disabled, with the original glasses above.
Note that in this file, the glasses are not the only alpha blend material. You also have at least two thin eye layers that are alpha blend. The more layers of alpha blend you have, the more likely you are to get sorting issues. These sorting issues are only going to come out at specific angles and deformations, and it's impossible to check them all. If you can use alpha hash or clip on any layers, you will get better results. I know that there are some things that just don't work right without alpha blend, but you should pick just one, most important, layer to get the alpha blend.
