Issues with light path expressions

[simon_lundberg]

I've been using LPEs with V-Ray GPU a lot recently. But I have a few issues.

It seems that you cannot mix object tags and material tags in a single light path expression. In the attached scene, I have the following expressions:

1. The sphere on the left (tagged 'Left'), followed by any number of interactions of anything other than the objects tagged 'Right' or 'Ground'. Oddly enough, this also includes direct visibility of the background. That seems like a bug.

C.'Left'+.[^'Right''Ground']*

2. The sphere on the left via its material name, followed by any number of interactions of anything other than the materials named 'RightMat' and 'GroundMat'. This does not include direct visibility of the background, but is other than that identical to the first LPE.

C.'mLeftMat'+.[^'mRightMat''mGroundMat']*

3. This *should* look identical to LPE 1 & 2: one or more interactions with the material named 'LeftMat', followed by any number of interactions of anything other than the objects tagged 'Right' or 'Ground'. However, this LPE is completely black.

C.'mLeftMat'+.[^'Right''Ground']*

4. Both spheres via their materials.

C.['mLeftMat''mRightMat']+.*

5. Both spheres via their object LPE tags (and the background???).

C.['Left''Right']+.*

6. Should include both spheres; is black instead.

C.['Left''mRightMat']+.*

[hermit.crab]

1. It seems LPEs with object labels include the Background. Logged (internal bug-tracker id: VGPU-6455). You can easily remove it in post through a Background RE.
2. The results are identical on my end (except the Background of course)
3. Most likely not supported. Will have to ask the devs. Otherwise, using boolean operations with mixed object/material labels do work. For example:

(C.'Left'.*)|(C.'mRightMat'.*)

4. Same as 2.
5. Same as 1.
6. Same as 3.