Rhino 6.8 and 6.9 bug - texture on mesh backface

I made two flat mesh objects - they are inside the following Rhino model file.
mesh backface bug.3dm (2.0 MB)

I have configured Rhino to display backfaces as texture:

The texture is shown below:

The back face of the left mesh does not display correct texture. The back face of the right mesh displays correct texture, but its scale is sometimes wrong. The scale changes when I flip the mesh and when I flip the other mesh.

By the way, the problems with backface texture are as old as Rhino 6.

The same bug is in Rhino 6.9.

Hello - this seems OK here with your texture re-applied.

mesh backface.3dm (1.4 MB)


I opened your file (mesh backface.3dm) in read-only mode. Rhino ran about 100 times slower than normal speed, and backface meshes had different scales (shown in the following screenshot).

I saved your file and opened it again. This time Rhino ran at normal speed, but the backface meshes still had different scales.