MaterialX: Sdr can not provide node information for ND_convert_float_color3

[JGamache-autodesk]

Description of Issue

The usdMtlx Sdr parser goes thru one level of indirection to get the mx::NodeDef by asking the mx::NodeGraph or mx::Implementation for a mx::NodeDef, and sometimes the indirect call fails.

Steps to Reproduce

1. With a MaterialX enabled build of USD, open UsdView and do the following in the interpreter window:

>>> from pxr import Sdr
>>> r = Sdr.Registry()
>>> [i for i in r.GetNodeNames() if not r.GetNodeByName(i)]
['LightFilter', 'PluginLightFilter', 'ND_disney_brdf_2012_surface', 'ND_disney_bsdf_2015_surface', 'ND_add_displacementshader', 'ND_add_volumeshader', 'ND_arrayappend_integer_integerarray', 'ND_arrayappend_integerarray_integerarray', 'ND_arrayappend_float_floatarray', 'ND_arrayappend_floatarray_floatarray', 'ND_arrayappend_color3_color3array', 'ND_arrayappend_color3array_color3array', 'ND_arrayappend_color4_color4array', 'ND_arrayappend_color4array_color4array', 'ND_arrayappend_vector2_vector2array', 'ND_arrayappend_vector2array_vector2array', 'ND_arrayappend_vector3_vector3array', 'ND_arrayappend_vector3array_vector3array', 'ND_arrayappend_vector4_vector4array', 'ND_arrayappend_vector4array_vector4array', 'ND_arrayappend_string_stringarray', 'ND_arrayappend_stringarray_stringarray', 'ND_curveadjust_float', 'ND_curveadjust_color3', 'ND_curveadjust_color4', 'ND_curveadjust_vector2', 'ND_curveadjust_vector3', 'ND_curveadjust_vector4', 'ND_mix_displacementshader', 'ND_mix_volumeshader', 'ND_convert_float_color3', 'ND_convert_float_color4', 'ND_convert_float_vector2', 'ND_convert_float_vector3', 'ND_convert_float_vector4', 'ND_convert_vector3_color3', 'ND_convert_vector4_color4', 'ND_convert_color3_vector3', 'ND_convert_color4_vector4', 'ND_convert_color3_color4', 'ND_convert_color4_color3', '11753386459202641452']

All the buggy MaterialX nodes have in common that the NodeGraph/Implementation they use is missing a link back to the NodeDef they represent.

To fix:

Go directly from Document to NodeDef in UsdMtlxParserPlugin::Parse(const NdrNodeDiscoveryResult&) using:

    auto nodeDef = document->getNodeDef(discoveryResult.identifier.GetString());
    if (!nodeDef) {
        TF_WARN("Invalid MaterialX NodeDef; unknown node name ' %s '",
            discoveryResult.identifier.GetText());
        return GetInvalidNode(discoveryResult);
    }

    ShaderBuilder builder(discoveryResult);
    ParseElement(&builder, nodeDef);

and remove the two ParseElement functions that uses const mx::ConstNodeGraphPtr& and const mx::ConstImplementationPtr& impl in parser.cpp.

System Information (OS, Hardware)

Package Versions

Build Flags

[spiffmon]

Thanks for reporting, @JGamache-autodesk - would you like to submit a PR for the fix?

[JGamache-autodesk]

Hi @spiffmon, I will start the process to get a PR submitted. First one from me, so will require some time to get all the details right.

[spiffmon]

No worries - we'll wait for it, and thank you!

[jilliene]

Filed as internal issue #USD-6913

[pmolodo]

I assume this issue can be closed now?

[spiffmon]

Indeed - the fix made it into 22.03 . Sorry, our automation will close the PR but not, I think the Issue, when there are both.