Refraction problems

[ensar_huskovic]

Hi,
I am just going to quickly describe the problem that I encountered and I would appreciate it if it could be fixed. (I cannot upload the scene)
I have a glass bottle 3d model that is supposed to have a label on it. Glass is fairly thick.
I use simple glass material with no graphics (IOR 1.45) for the whole bottle (including inside) except for the section on the outside that needs to have a label. There I use Vray blend material with the mentioned glass and a simple vray material that has the graphics label in diffuse slot. There is an object behind the bottle. Refraction breaks down and that object is shown wrong in comparison when just a simple glass is applied to the whole bottle.
Also, there is a problem with the edges which is also shown on gpu rendering.
Tested it on CPU - works fine!
Refraction needs much attention on GPU and that is a shame because with cpu it's very slow.
I hope this gets fixed asap.
Thanks

[hermit.crab]

Could you simplify the scene (or reproduce the issue on a fresh one) and send it to support@chaosgroup.com so we can take a look? Mention this thread in the e-mail.

[ensar_huskovic]

Ok so I recreated the problem in a simple scene. Turns out it is not a huge deal, I think my original file had some other issues that I am not sure where they are coming from yet. Mainly borders of the glass look fine now both on cpu and gpu. However, the problem is in the part of the mesh that has a decal. Anyway you can see it in the file. CPU and GPU give me different results in that area.

[hermit.crab]

Thanks for the report. It seems like a bug, I've logged it (internal bug-tracker system id: VGPU-4519) for our developers to look into. As a workaround, rather than using material ids, unwrap the label polygons on a separate map channel and use a single VRayBlend material with a Blend mask on that specific channel.