VrayTwoSided material causes render/attribute issues

[racoonart]

I found a rather strange bug with VrayTwoSided materials. I have a setup where different flowers get assigned different colors. That works fine with a simple VrayMtl but as soon as I add a Vray2Sided material behind that it breaks the color assignment. I need to restart Houdini for it to work again. I attached a scene for reproducing the problem below. The important nodes are colored pink.

Steps to reproduce:
1) open the scene and hit render, flowers should have different colors.
2) go into obj/grass/ , deactivate the "petalsbase" material node and activate "petals2sided" directly below. Hit render again, the flower petals are now all white.
3) deactivate "petals2sided" and activate "petalsbase" again, hit render. The flowers stay white.

[Gosho.Genchev]

That's so bizzarre ... not only is the export correct in both cases (where the flowers are correctly randomzied, or always white) but toggling the "Bypass" flag (yellow) on and off the Copy to Points SOP seems to do some internal force-refresh and the scene starts rendering correctly again with both "petalsbase" and "petals2Sided".

I'll ping the devs - since the export is correct, maybe there's something we can do here.

Best regards!

[bdancer]

This seems to be some Houdini issue and probably has to be reported to SideFX - in this particular setup attribute values got reset for some reason.
Open point properties in geometry spreadsheet and do step "2" - notice that all point attributes ("clr", "density", "range", "variant") become 0.0.

[racoonart]

Indeed it does, interesting. I'll try to reproduce the problem without vray in the scene and report it to sidefx. Thanks for the input!

[edit] sidenote: also only happens if I have "pack and instance" on in the copytopoints sop.