VRayMtlWrapper not supported?

[JonasNöll]

Hi,

according to this list (https://docs.chaos.com/display/VMAX/...orted+Features) the VRayMtlWrapper material should be supported in GPU mode. However it seems that the Matte properties have no effect. In CPU mode it works without issues.
Is that a bug?

[hermit.crab]

Mind if you attach a sample scene so we can have a look?

[JonasNöll]

Hi,

there are 2 issues:

1. The Matte doesn't work unless the AlphaContribution is between -0.9 and -1. Anything apart from those values will make matte properties to not work.
2. If the AlphaContribution is between -0,9 and -1 AND in the BaseMtl is anything else than a VRayMtl (for example a VRayBlendMtl) it will make it matte BUT the shadow options don't work.

So the only way to have the VRayMtlWrapper work in GPU mode is to have an AlphaContribution between -0,9 and -1 AND use a VRayMtl as the BaseMtl.
CPU doesn't have any of those issues.

I attached you a sample scene.

Best,
Jonas

[hermit.crab]

1. In GPU, only Alpha Contribution -1 (Matte must be active) ̶a̶n̶d̶ ̶1̶ ̶a̶r̶e̶ ̶s̶u̶p̶p̶o̶r̶t̶e̶d̶. Decimal values, one and zero, are not. This is already logged (internal tracker ID: VGPU-2828 ).
2. I can reproduce this and will log it (logged as internal tracker ID: VGPU-6815). Is there a specific reason to use a VRayBlendMtl for the shadow catcher?

[JonasNöll]

HI:

1. Actually +1 also doesn't work. Only values between -0.9 and -1 as I mentioned. You can try it out. If only -1 is supported you might want to set this value internally regardless of what value is chosen in the menu as a workaround. Otherwise it will cause confusion. I only found this out after extensive testing.
2. I have a usecase here as I'm working on a tool/script where you can easily switch between the matte and an standard option for the floorplane and the basematerial HAS to be a VRayBlendMtl. So that's how I noticed that.
Is it a very common usecase? Probably not, but as said in CPU it works without issues. It might cause confusion you just want to create a matte shadow pass on your existing scene by putting a Wrapper in front of your existing material and no shadows show up.

[hermit.crab]

1. Actually +1 also doesn't work. Only values between -0.9 and -1 as I mentioned. You can try it out. If only -1 is supported you might want to set this value internally regardless of what value is chosen in the menu as a workaround. Otherwise it will cause confusion. I only found this out after extensive testing.

I stand corrected, it disables the Matte. It's better we support the whole parameter fully, rather than settings temporary defaults.

2. I have a usecase here as I'm working on a tool/script where you can easily switch between the matte and an standard option for the floorplane and the basematerial HAS to be a VRayBlendMtl. So that's how I noticed that.
Is it a very common usecase? Probably not, but as said in CPU it works without issues. It might cause confusion you just want to create a matte shadow pass on your existing scene by putting a Wrapper in front of your existing material and no shadows show up.[/QUOTE]

Okay. Already logged the issue (edited my previous post with the ID).

[JonasNöll]

I stand corrected, it disables the Matte. It's better we support the whole parameter fully, rather than settings temporary defaults.

Hi, in this case I would remove the VRayMtlWrapper from the supported materials in the GPU page alltogether in the meantime. As you default the AlphaContribution to 1 (which doesn't work) it will just register as not supported to the average user. Since it shows as supported on the feature page I just wasted quite a bit of time to find out that it actually is not suported. Or make a note on the page itself.