[MTOA] primvars:arnold:matte not taken into account

[raphaelj4T6XS]

Hello Arnold team,

We are testing arnold in Maya via USD files. We noticed that prims with the primvar arnold:matte=True are not correctly evaluated.

Steps to reproduce:
Create a sphere and a dome light in Maya. Check the Arnold matte property of the sphere. In the render view, the sphere will be black. Export the scene to a usd file and import back that usd file in a new maya scene ( "Stage from file..." option). If render, the sphere wont be black (gray if default lambert).The matte attribute seems ignored.

The thing is the usd file is rendered correctly if we use kick directly on that usd file.

Is it a missing feature from mtoa ? from maya ufe ? Can we fix it on our side ?

Thank you
Raphael

[Stephen.Blair]

Is it just some prims with matte on, or all? If all, you can enable matte on the mayaUsdProxyShape

[raphaelj4T6XS]

Hello,
No it is only given prims. In my example I could create multiple spheres and turn only one to matter=True. With is it not working ?

[sebastien.blaineau.ortegaHRM3U]

Hi Raphael, thanks for reporting it. It's indeed a bug that we're fixing right now (reference is MTOA-1036).

I don't think there's a workaround unfortunately (apart from using a aiStandin instead of a mayaUSD proxy shape). The problem is that the proxy shape extension forces matte to its default value in the usd procedural node. This will override the value from the child nodes inside of the usd file.

Thanks again for reporting it, sorry for the inconvenience.

[raphaelj4T6XS]

Thank you Sebastien. Good to ear that you are working on it !
Raphael

[sebastien.blaineau.ortegaHRM3U]

ah no, there's actually a workaround in case you need it.

Select the proxyShape ( the shape node, not it transform), and do Modify->Add Attribute, to create a boolean extra attribute called "overrideMatte". This attribute will be disabled by default and it should solve the issue until we release a fix for it.

[raphaelj4T6XS]

Indeed it worked. Thank you.
I take this opportunity to ask you why, in the attribute editor of the USD sphere, if I uncheck the 'Primvars: Arnold: Matte' attribute, the sphere stay matte (with your workaround applied). Is it related to the same fix ?