Edge trimming with GPU : errors with multi subobject material

[francomanko]

So it seems that if I have some grass scattered with vrayscatter, and the grass has a multisub material, it renders incorrectly. Renders fine with CPU. If I assign a single material to the grass object, trim works as expected.


I've attached a scene.

This is with max 2023, vray release (6.1.2) , Nvidia 528.49 on 3090 card.



GPU : With multi/sub object material



GPU : Single vraymtl assigned

[dimitar_panayotov]

Hi francomanko, we were able to reproduce the issue when Override mtl from V-Ray render settings is used. From what I saw in your scene, you also have a material loaded there. However, the provided scene didn't have a multi-sub mtl in it, and the Override mtl setting was turned Off. Could you please confirm that the issue happens only when Override mtl is checked?

[francomanko]

Hi, sorry the material must have been stripped out when i archived. Ive attached another scene.

For me it happens regardless of a material being in the override setting, and eitherway the overide option was turned off.

[dimitar_panayotov]

Hi francomanko, we were able to reproduce the issue by having a multi-sub mtl. applied to each of the grass sources. It looks like the multi-sub mtl. of the first one is transferred to the area where Edge trim was applied on the second one. The issue is now logged into our system under VMAX-13285.

[francomanko]

hi, thanks for the reply.

I'm not sure what you said is correct, unless im misunderstanding. The scene contained 2 grass source objects, one with multi/sub material, the other with a single material only. This was just to show them side by side etc, one working, the other not. They arent connected, or at least shouldnt be. If i delete the one that works (i.e a single material assigned) the error still occurs.

apologies if ive misunderstood.

[dimitar_panayotov]

Hi, the only way I was able to get a similar result to what you described was to add another multi-sub mtl. to the grass source that had just a simple V-Ray material. It was not possible to get that error directly from your saved scene. Several team members tried with that second scene and they couldn't get the results as shown in the images above.
In the image here, you could see what we got directly from the provided scene (V2). So maybe something else is missing in this scene, which could lead to that behavior. Did you pack all the materials? Is "edgetrimming_gpu_V2" a "Save selected" version of your actual file? Is there anything that could be changed during the saving of your file?

[francomanko]

hmm so weird Its not a save selected, just regular save.

Heres a link to a folder, containing a video, a 3dsmax project folder with a new scene, and an 3dsmax archive of it...not sure what else i can do

Eitherway you have repo'd it in some fashion so thats good.

https://drive.google.com/drive/folde...usp=share_link

Cheers

[dimitar_panayotov]

Hi, francomanko. I've checked your last scene. Override Mtl. was checked in the V-Ray Render settings, which will produce an issue. This is logged into our system under VMAX-13283. Once it's off, it renders as expected on my machine. Is it working properly if you disable the Override Mtl. option?
Thank you for sharing the video and the files.

[francomanko]

error still happens if i disable the override mtl.

I've added another scene in that folder on my drive (same link as before)... edgetrimming_V4.max, which is a fresh scene so shouldnt be any chance of any legacy data in there...issue still occurs. (See image)

Again, works fine on cpu.

I'm presuming ive set it up correctly?

[dimitar_panayotov]

Hi, several people tested the last scene and unfortunately we were not able to reproduce the problem. The fact that it works on CPU is fine. For CPU, Edge trimming is implemented differently. Keep in mind that V-Ray and V-Ray GPU are different render engines.
As a last step, you could try to rename the ENU folder. This will create a new one on the next start of 3ds Max that will not include all the additional scripts you have. You could try to reset the V-Ray Settings as well. If that doesn't change anything, you could submit a ticket to our support team where you can arrange a remote debugging session on your machine. When you submit the ticket, please add a link of this topic in it.
I will keep you posted when the other 2 registered issues are fixed, which could lead somehow to a fix for your specific case.

[francomanko]

will do, thx for your help.

[francomanko]

hi, just for the record, i renamed the ENU folder and reset vray settings. problem still occurred. Just found another issue that might be related to multi/sub material too...but i'll save that bundle of fun for another post

[francomanko]

Ive submitted a new ticket regarding another multi/sub material related error, this time to do with object properties.

ticket no. #117658