.vrmat export and brdf_useRoughness property

[phill_moris]

When exporting VRayMtl to .vrmat, the brdf_useRoughness property is ignored. Is this a bug or is it supposed to be like this?

[hermit.crab]

Seems to work as expected. You can open the .vrmat in Notepad and check for yourself. Look for the "roughness_model" and "option_use_roughness" parameters, both values of which should either be 0 for Use Glossiness or 1 for Use Roughness.

[phill_moris]

Seems to work as expected. You can open the .vrmat in Notepad and check for yourself. Look for the "roughness_model" and "option_use_roughness" parameters, both values of which should either be 0 for Use Glossiness or 1 for Use Roughness.

It's weird, but mine is actually different from what you described.
I'll describe the order of my actions.
1. I created a material with "Use roughness" enabled, set the "reflect_glossiness" value to 0.0, named it "Gold_Roughness" and saved it to the file vrmat_gold-roughness.vrmat



2. Then opened the file vrmat_gold-roughness.vrmat in a text editor. Below is a screenshot of the parameters and values:



3. Now I created another material, but this time I enabled "Use glossiness", set the "reflect_glossiness" value to 1.0, named the material "Gold_Glossiness" and saved it to the file vrmat_gold-glossiness.vrmat



4. Then opened the file vrmat_gold-glossiness.vrmat in a text editor. Below is a screenshot of the parameters and values:



As you can see from the screenshots, all the values of the second material saved in the vrmat file remain the same as those of the first material. Also, in both .vrmat files, the "roughness_model" property is always equal to 1, regardless of whether "Use roughness" or "Use glossiness" is enabled.

PS: Before exporting to .vrmat, I assigned materials to an object, selected this object and exported as "Materials from selected objects -> to a single .vrmat file".

[hermit.crab]

I tested this with the latest official and it is exporting "Use Glossiness" as option_use_roughness = 0 and "Use Roughness" as option_use_roughness = 1. Which V-Ray and 3ds Max versions do you have installed?

Regarding the "roughness_model" parameter, you are right it does export 1 in both cases. I thought it had to follow the other option, but I guess it has a different purpose. I'll talk to the devs about it.

[phill_moris]

Which V-Ray and 3ds Max versions do you have installed?

I use V-Ray 6, update 2.1 (6.20.07 build 32557) + 3dsMax 2024.
Strange situation.. Sometimes materials are saved correctly, but sometimes not. I can't understand what the reason is and in what cases this happens.
Also, I wanted to clarify one more question about vrmat - when I save materials with bitmap textures rotated by 90 degrees in "W" (without changing the offset, tiling and mirror), then in vrmat in the "uvw_transform" parameter of this texture I see the following values:

<vector>
<x>0</x>
<y>1</y>
<z>0</z>
</vector>
<vector>
<x>-1</x>
<y>-2.980232e-08</y>
<z>0</z>
</vector>
<vector>
<x>0</x>
<y>0</y>
<z>1</z>
</vector>
<vector>
<x>1</x>
<y>2.980232e-08</y>
<z>0</z>
</vector>

How can I understand which of these vector values correspond to the texmap coord properties "offset", "tiling", "rotate" and "mirror"? Why are some strange numbers displayed instead of 90 degrees? What numbers should I enter to get 45 or 60 degrees (for example)?
I'm probably asking strange questions, but sometimes it becomes necessary to make changes to the material if there is only a vrmat file and the original from which it was saved is missing. In general, it's a pity that there is no tool for editing materials from vrmat files, so sometimes you have to do it manually in a text editor. But in any case, I will be very grateful for any help with this.

[hermit.crab]

How can I understand which of these vector values correspond to the texmap coord properties "offset", "tiling", "rotate" and "mirror"?

Trial and error.

Why are some strange numbers displayed instead of 90 degrees? What numbers should I enter to get 45 or 60 degrees (for example)?

Vector data.

it's a pity that there is no tool for editing materials from vrmat files, so sometimes you have to do it manually in a text editor.

There used to be, but it got depricated. I think V-Ray for Sketchup or Revit still has it.

Otherwise, I suggest taking a look at other options for transferring scenes and shaders such as USD.