MSL : Translated shader texture bake fails with binding error

[kwokcb]

Issue

If you use try to back with a shader translation node with the MSL backend then it will fail with

 MSL bind attribute error.

Steps:

1. Input file Aluminum.mtlx (from PhysicallyBased)

<?xml version="1.0"?>
<materialx version="1.38" colorspace="lin_rec709">
  <standard_surface name="SR_Aluminum" type="surfaceshader">
    <input name="base_color" type="color3" value="0.912, 0.914, 0.92" />
    <input name="specular_color" type="color3" value="0.97, 0.979, 0.988" />
    <input name="specular_roughness" type="float" value="0" />
    <input name="metalness" type="float" value="1" />
  </standard_surface>
  <surfacematerial name="Aluminum" type="material">
    <input name="surfaceshader" type="surfaceshader" nodename="SR_Aluminum" />
  </surfacematerial>
</materialx>

2. Passes with GLSL backend

python translateshader.py --glsl 1 Aluminum.mtlx x.mtlx gltf_pbr
Processing material: Aluminum
Wrote baked document: x.mtlx

3. Fails with MSL backend (no --glsl flag set)

python translateshader.py Aluminum.mtlx x.mtlx gltf_pbr             
Processing material: Aluminum
Traceback (most recent call last):
  File "/Users/bernardkwok/work/bernard_MaterialX_2/python/Scripts/translateshader.py", line 101, in <module>
    main()
  File "/Users/bernardkwok/work/bernard_MaterialX_2/python/Scripts/translateshader.py", line 98, in main
    baker.bakeAllMaterials(doc, searchPath, opts.outputFilename)
LookupError: MSL bind attribute error.

Alternative is

1. Translate first to get (translated.mtlx)

<?xml version="1.0"?>
<materialx version="1.39" colorspace="lin_rec709">
  <gltf_pbr name="SR_Aluminum" type="surfaceshader">
    <input name="base_color" type="color3" output="base_color_out" nodegraph="nodegraph1" />
    <input name="metallic" type="float" output="metallic_out" nodegraph="nodegraph1" />
    <input name="roughness" type="float" output="roughness_out" nodegraph="nodegraph1" />
    <input name="specular" type="float" output="specular_out" nodegraph="nodegraph1" />
    <input name="specular_color" type="color3" output="specular_color_out" nodegraph="nodegraph1" />
    <input name="ior" type="float" output="ior_out" nodegraph="nodegraph1" />
    <input name="anisotropy_strength" type="float" output="anisotropy_strength_out" nodegraph="nodegraph1" />
    <input name="anisotropy_rotation" type="float" output="anisotropy_rotation_out" nodegraph="nodegraph1" />
    <input name="transmission" type="float" output="transmission_out" nodegraph="nodegraph1" />
    <input name="thickness" type="float" output="thickness_out" nodegraph="nodegraph1" />
    <input name="attenuation_color" type="color3" output="attenuation_color_out" nodegraph="nodegraph1" />
    <input name="attenuation_distance" type="float" output="attenuation_distance_out" nodegraph="nodegraph1" />
    <input name="sheen_color" type="color3" output="sheen_color_out" nodegraph="nodegraph1" />
    <input name="sheen_roughness" type="float" output="sheen_roughness_out" nodegraph="nodegraph1" />
    <input name="clearcoat" type="float" output="clearcoat_out" nodegraph="nodegraph1" />
    <input name="clearcoat_roughness" type="float" output="clearcoat_roughness_out" nodegraph="nodegraph1" />
    <input name="dispersion" type="float" output="dispersion_out" nodegraph="nodegraph1" />
    <input name="emissive" type="color3" output="emissive_out" nodegraph="nodegraph1" />
    <input name="emissive_strength" type="float" output="emissive_strength_out" nodegraph="nodegraph1" />
    <input name="normal" type="vector3" output="normal_out" nodegraph="nodegraph1" />
    <input name="tangent" type="vector3" output="tangent_out" nodegraph="nodegraph1" />
    <input name="alpha" type="float" output="alpha_out" nodegraph="nodegraph1" />
    <input name="alpha_mode" type="integer" output="alpha_mode_out" nodegraph="nodegraph1" />
  </gltf_pbr>
  <surfacematerial name="Aluminum" type="material">
    <input name="surfaceshader" type="surfaceshader" nodename="SR_Aluminum" />
  </surfacematerial>
  <nodegraph name="nodegraph1">
    <standard_surface_to_gltf_pbr name="node1" type="multioutput" nodedef="ND_standard_surface_to_gltf_pbr">
      <input name="base_color" type="color3" value="0.912, 0.914, 0.92" colorspace="lin_rec709" />
      <input name="specular_color" type="color3" value="0.97, 0.979, 0.988" colorspace="lin_rec709" />
      <input name="specular_roughness" type="float" value="0" colorspace="lin_rec709" />
      <input name="metalness" type="float" value="1" colorspace="lin_rec709" />
    </standard_surface_to_gltf_pbr>
    <output name="base_color_out" type="color3" nodename="node1" output="base_color_out" />
    <output name="metallic_out" type="float" nodename="node1" output="metallic_out" />
    <output name="roughness_out" type="float" nodename="node1" output="roughness_out" />
    <output name="specular_out" type="float" nodename="node1" output="specular_out" />
    <output name="specular_color_out" type="color3" nodename="node1" output="specular_color_out" />
    <output name="ior_out" type="float" nodename="node1" output="ior_out" />
    <output name="anisotropy_strength_out" type="float" nodename="node1" output="anisotropy_strength_out" />
    <output name="anisotropy_rotation_out" type="float" nodename="node1" output="anisotropy_rotation_out" />
    <output name="transmission_out" type="float" nodename="node1" output="transmission_out" />
    <output name="thickness_out" type="float" nodename="node1" output="thickness_out" />
    <output name="attenuation_color_out" type="color3" nodename="node1" output="attenuation_color_out" />
    <output name="attenuation_distance_out" type="float" nodename="node1" output="attenuation_distance_out" />
    <output name="sheen_color_out" type="color3" nodename="node1" output="sheen_color_out" />
    <output name="sheen_roughness_out" type="float" nodename="node1" output="sheen_roughness_out" />
    <output name="clearcoat_out" type="float" nodename="node1" output="clearcoat_out" />
    <output name="clearcoat_roughness_out" type="float" nodename="node1" output="clearcoat_roughness_out" />
    <output name="dispersion_out" type="float" nodename="node1" output="dispersion_out" />
    <output name="emissive_out" type="color3" nodename="node1" output="emissive_out" />
    <output name="emissive_strength_out" type="float" nodename="node1" output="emissive_strength_out" />
    <output name="normal_out" type="vector3" nodename="node1" output="normal_out" />
    <output name="tangent_out" type="vector3" nodename="node1" output="tangent_out" />
    <output name="alpha_out" type="float" nodename="node1" output="alpha_out" />
    <output name="alpha_mode_out" type="integer" nodename="node1" output="alpha_mode_out" />
  </nodegraph>
</materialx>

2. Run bake:

python baketextures.py ./translated.mtlx x.mtlx          
Processing material: Aluminum
Traceback (most recent call last):
  File "/Users/bernardkwok/work/bernard_MaterialX_2/python/Scripts/baketextures.py", line 73, in <module>
    main()
  File "/Users/bernardkwok/work/bernard_MaterialX_2/python/Scripts/baketextures.py", line 70, in main
    baker.bakeAllMaterials(doc, searchPath, opts.outputFilename)
LookupError: MSL bind attribute error.

(You can also load this into MaterialXViewer and interactively translate to gltf_pbr then bake, but this will crash the program:

Processing material: Aluminum
Error in texture baking: MSL bind attribute error.
-[_MTLCommandEncoder dealloc]:134: failed assertion `Command encoder released without endEncoding'
zsh: abort      ./bin/MaterialXView

This is with head of main at SHA: e9cefcc