Thin film with Specular and Transmission

Hello,

We have noticed an unexpected behavior about the thin film when using it with a specular and transmission. It seems that when the thin film is enabled the transmission is not handling the TIR anymore. Is this the expected behavior ?

Here some images from Maya Arnold (MtoA 4.0.2 - 46d4a92e (master) - Feb 13 2020 03:01:44) that shows the issue :

Here we can see that increasing the depth transmission change nothing when the thin film is enabled :


And if we are visualizing this LPE : CTT+TL which correspond to internal reflection we have the TIR for the case when there is no thin film for the depth 3 and 4 but there is nothing when the thin film is enabled.


Thanks,

Kevin

Reproduce the thin-film behavior described in the issue using the Maya Arnold/MtoA context and compare transmission at depths 3 and 4 with thin film enabled and disabled. Check the CTT+TL light path expression for internal reflection and establish whether total internal reflection is expected; done means the behavior is understood and the issue has a documented resolution.

Written by the indexing model from the issue text.