MaterialX errors

[pablode]

Hey, this may be an exporter problem, but there are a few errors when it comes to MaterialX nodes in the standalone USD files (respective mat.usdc, viewed with usdview 24.05):

clamshell
Node interface error: Input 'in' doesn't match declaration: <convert name="mtlxconvert1" type="float" nodedef="ND_convert_boolean_float">

countertop
Node interface error: Input 'base_color' doesn't match declaration: <standard_surface name="mtlxstandard_surface_grout" type="surfaceshader" nodedef="ND_standard_surface_surfaceshader">
Node interface error: Input 'in2' doesn't match declaration: <add name="mtlxadd23" type="vector3" nodedef="ND_add_vector3FA">
Node interface error: Input 'in2' doesn't match declaration: <add name="mtlxadd24" type="vector3" nodedef="ND_add_vector3FA">
Node interface error: Input 'in2' doesn't match declaration: <add name="mtlxadd19" type="vector3" nodedef="ND_add_vector3FA">
Node interface error: Input 'in2' doesn't match declaration: <add name="mtlxadd20" type="vector3" nodedef="ND_add_vector3FA">

cyc_wall
NodeDef not found for Node 'ND_hmtlxcircles2d_float'
Node interface error: Input 'mix' doesn't match declaration: <mix name="mtlxmix2" type="color3" nodedef="ND_mix_color3">
Node interface error: Input 'in1' doesn't match declaration: <multiply name="mtlxmultiply14" type="float" nodedef="ND_multiply_float">
Node interface error: Input 'in1' doesn't match declaration: <multiply name="mtlxmultiply15" type="float" nodedef="ND_multiply_float">

egg_amber
NodeDef not found for Node 'standard_surface'
Node interface error: Input 'opacity' doesn't match declaration: <standard_surface name="Surface" type="surfaceshader">
Invalid value: <input name="clampoutput" type="boolean" value="0"> (5x)

egg_damascus
Node interface error: Input 'in' doesn't match declaration: <separate3 name="mtlxseparate3c1" type="multioutput" nodedef="ND_separate3_color3">

egg_geode
Node interface error: Input 'in' doesn't match declaration: <separate3 name="mtlxseparate3c1" type="multioutput" nodedef="ND_separate3_color3">

egg_lava_stone
Invalid value: <input name="clampoutput" type="boolean" value="0"> (5x)

egg_normals
Node interface error: Input 'in' doesn't match declaration: <hsvadjust name="mtlxhsvadjust1" type="color3" nodedef="ND_hsvadjust_color3">

egg_ore_swirl
Node interface error: Input 'in' doesn't match declaration: <hsvadjust name="mtlxhsvadjust1" type="color3" nodedef="ND_hsvadjust_color3">
Node interface error: Input 'in2' doesn't match declaration: <add name="mtlxadd9" type="vector3" nodedef="ND_add_vector3">

egg_patterns
Warning: in _AddMaterialXNode at line 241 of F:\USD-24.05\pxr\imaging\hdMtlx\hdMtlx.cpp -- NodeDef not found for Node 'ND_hmtlxcircles2d_float'
(many times, crashes Storm)

egg_pickle
Invalid value: <input name="clampoutput" type="boolean" value="0"> (6x)

For reference, here is the 1.38 specification: https://github.com/AcademySoftwareFoundation/MaterialX/tree/v1.38.10/documents/Specification

Implementation (e.g. standard surface): https://github.com/AcademySoftwareFoundation/MaterialX/tree/main/libraries

[pablode]

I've made some efforts to fix the issues, most of them are trivial. Unfortunately, there is no equivalent for the ND_hmtlxcircles2d_float node in MaterialX 1.38 (and only partially in 1.39).

The asset can only render the same outside of Houdini if this node is replaced with logic that only uses the MaterialX standard nodes

Some other observations:

• the Invalid value: <input name="clampoutput" type="boolean" value="0"> usually come from unifiednoise2d/unifiednoise3d nodes. Here, the inputs are exported as type int. I checked my local Houdini 20.0.563 files, and the input is declared as boolean. So either the export is wrong, or perhaps the type can be changed in the UI
• all the other issues above stem from implicit type conversions, most prominently vector3 -> color3. These work fine with some backends (e.g. GLSL), but are technically not valid and cause errors with other MaterialX backends (MDL). I would expect some warnings/errors shown to the user here

[stehrani3d]

Thanks very much again Pablo, that's very helpful. For starters I have updated the "cyc_wall" asset to use the native MtlX Tiled Circles node. I'll need to do the same for the "egg_patterns" asset.

[stehrani3d]

@pablode Whenever you find some time, would you mind taking another look and seeing what errors remain after the recent commits? Thank you.

[pablode]

Sure! Most has indeed been resolved 🙂 some minor ones left:

egg_ore_swirl
Node interface error: Input 'position' doesn't match declaration: <noise3d name="mtlxnoise3d1" type="float" nodedef="ND_noise3d_float"
Node interface error: Input 'in1' doesn't match declaration: <add name="mtlxadd9" type="float" nodedef="ND_add_float">

egg_damascus (6x), egg_lava_stone (5x), egg_patterns (3x), egg_pickle (6x)
Invalid value: <input name="clampoutput" type="boolean" value="0">

egg_patterns
Node interface error: Input 'in' doesn't match declaration: <convert name="mtlxconvert1" type="float" nodedef="ND_convert_boolean_float">
Node interface error: Input 'in' doesn't match declaration: <convert name="mtlxconvert2" type="float" nodedef="ND_convert_boolean_float">
Node interface error: Input 'in' doesn't match declaration: <convert name="mtlxconvert3" type="float" nodedef="ND_convert_boolean_float">

[stehrani3d]

Fantastic, thanks very much Pablo. It's not apparent to me what I can do on the Houdini side to fix "ore_swirl" and "damascus". For "patterns" I can revert the mtlx convert nodes to the previous Signature.

[pablode]

egg_patterns looks good now 👍

regarding egg_ore_swirl:

• I think you need a <convert> node which converts the float type from mtlxadd9 to vector3 consumed by the mtlxnoise3d1:position input

regarding the unifiednoiseXd:clampoutput issues:

• maybe you can update to Houdini 20.5 where MaterialX 1.38.10 is used?
• perhaps you can author an explicit false boolean for the input? (instead of 0). Or if it's incorrectly type-restricted to an int, connect a <constant> node?