Did you fix this lipline issue? I am also facing the same thing and trying to fix this for months now.

@Bill3D I am trying to draw lipstick texture on ARKitFaceMesh. I have already received very good results when I am just using ARKit. But to meet a certain criteria, I need the option to modify the ARKit Face Mesh vertices. For that reason I took the vertices from ARFaceAnchor and derived normals and textureCoordinates correctly. Now using SCNode and SCNmaterial, I am trying to render the texture on my face. While colors are getting applied but I am not able to get the exact lipstick texture on my face. It is taking any random color from the texture and plotting it. I have already checked whether my UV coordinates are right or not. Turns out the UV coordinates are perfectly aligned with the ARKit Face mesh UV coordinates. Now I am really lost regarding how can I apply texture on my custom face mesh. Any idea on this?