open_pbr_surface.mtlx

<?xml version="1.0"?>
<materialx version="1.39">
  <!-- An alternate graph implementation for target languages with limited layering capabilities. -->

  <nodegraph name="NG_open_pbr_surface_surfaceshader_limited_layers" nodedef="ND_open_pbr_surface_surfaceshader" target="genmdl">

    <!-- Roughening due to coat-->
    <power name="coat_roughness_to_power_4" type="float">
      <input name="in1" type="float" interfacename="coat_roughness" />
      <input name="in2" type="float" value="4.0" />
    </power>
    <multiply name="two_times_coat_roughness_to_power_4" type="float">
      <input name="in1" type="float" nodename="coat_roughness_to_power_4" />
      <input name="in2" type="float" value="2.0" />
    </multiply>
    <power name="specular_roughness_to_power_4" type="float">
      <input name="in1" type="float" interfacename="specular_roughness" />
      <input name="in2" type="float" value="4.0" />
    </power>
    <add name="add_coat_and_spec_roughnesses_to_power_4" type="float">
      <input name="in1" type="float" nodename="two_times_coat_roughness_to_power_4" />
      <input name="in2" type="float" nodename="specular_roughness_to_power_4" />
    </add>
    <min name="min_1_add_coat_and_spec_roughnesses_to_power_4" type="float">
      <input name="in1" type="float" value="1.0" />
      <input name="in2" type="float" nodename="add_coat_and_spec_roughnesses_to_power_4" />
    </min>
    <power name="coat_affected_specular_roughness" type="float">
      <input name="in1" type="float" nodename="min_1_add_coat_and_spec_roughnesses_to_power_4" />
      <input name="in2" type="float" value="0.25" />
    </power>
    <mix name="effective_specular_roughness" type="float">
      <input name="fg" type="float" nodename="coat_affected_specular_roughness" />
      <input name="bg" type="float" interfacename="specular_roughness" />
      <input name="mix" type="float" interfacename="coat_weight" />
    </mix>

    <!-- Calculate main specular roughness -->
    <open_pbr_anisotropy name="main_roughness" type="vector2">
      <input name="roughness" type="float" nodename="effective_specular_roughness" />
      <input name="anisotropy" type="float" interfacename="specular_roughness_anisotropy" />
    </open_pbr_anisotropy>

    <!-- Subsurface (thin-walled) -->
    <max name="subsurface_color_nonnegative" type="color3">
      <input name="in1" type="color3" interfacename="subsurface_color" />
      <input name="in2" type="float" value="0.0" />
    </max>
    <oren_nayar_diffuse_bsdf name="subsurface_thin_walled_reflection_bsdf" type="BSDF">
      <input name="color" type="color3" nodename="subsurface_color_nonnegative" />
      <input name="roughness" type="float" interfacename="base_diffuse_roughness" />
      <input name="normal" type="vector3" interfacename="geometry_normal" />
    </oren_nayar_diffuse_bsdf>
    <subtract name="one_minus_subsurface_scatter_anisotropy" type="float">
      <input name="in1" type="float" value="1.0" />
      <input name="in2" type="float" interfacename="subsurface_scatter_anisotropy" />
    </subtract>
    <multiply name="subsurface_thin_walled_brdf_factor" type="color3">
      <input name="in1" type="color3" interfacename="subsurface_color" />
      <input name="in2" type="float" nodename="one_minus_subsurface_scatter_anisotropy" />
    </multiply>
    <multiply name="subsurface_thin_walled_reflection" type="BSDF">
      <input name="in1" type="BSDF" nodename="subsurface_thin_walled_reflection_bsdf" />
      <input name="in2" type="color3" nodename="subsurface_thin_walled_brdf_factor" />
    </multiply>
    <translucent_bsdf name="subsurface_thin_walled_transmission_bsdf" type="BSDF">
      <input name="color" type="color3" nodename="subsurface_color_nonnegative" />
      <input name="normal" type="vector3" interfacename="geometry_normal" />
    </translucent_bsdf>
    <add name="one_plus_subsurface_scatter_anisotropy" type="float">
      <input name="in1" type="float" value="1.0" />
      <input name="in2" type="float" interfacename="subsurface_scatter_anisotropy" />
    </add>
    <multiply name="subsurface_thin_walled_btdf_factor" type="color3">
      <input name="in1" type="color3" interfacename="subsurface_color" />
      <input name="in2" type="float" nodename="one_plus_subsurface_scatter_anisotropy" />
    </multiply>
    <multiply name="subsurface_thin_walled_transmission" type="BSDF">
      <input name="in1" type="BSDF" nodename="subsurface_thin_walled_transmission_bsdf" />
      <input name="in2" type="color3" nodename="subsurface_thin_walled_btdf_factor" />
    </multiply>
    <mix name="subsurface_thin_walled" type="BSDF">
      <input name="fg" type="BSDF" nodename="subsurface_thin_walled_reflection" />
      <input name="bg" type="BSDF" nodename="subsurface_thin_walled_transmission" />
      <input name="mix" type="float" value="0.5" />
    </mix>

    <!-- Subsurface (non-thin-walled) -->
    <multiply name="subsurface_radius_scaled" type="color3">
      <input name="in1" type="color3" interfacename="subsurface_radius_scale" />
      <input name="in2" type="float" interfacename="subsurface_radius" />
    </multiply>
    <subsurface_bsdf name="subsurface_bsdf" type="BSDF">
      <input name="color" type="color3" nodename="subsurface_color_nonnegative" />
      <input name="radius" type="color3" nodename="subsurface_radius_scaled" />
      <input name="anisotropy" type="float" interfacename="subsurface_scatter_anisotropy" />
      <input name="normal" type="vector3" interfacename="geometry_normal" />
    </subsurface_bsdf>

    <!-- Opaque Dielectric Base -->
    <max name="base_color_nonnegative" type="color3">
      <input name="in1" type="color3" interfacename="base_color" />
      <input name="in2" type="float" value="0.0" />
    </max>
    <oren_nayar_diffuse_bsdf name="diffuse_bsdf" type="BSDF">
      <input name="weight" type="float" interfacename="base_weight" />
      <input name="color" type="color3" nodename="base_color_nonnegative" />
      <input name="roughness" type="float" interfacename="base_diffuse_roughness" />
      <input name="normal" type="vector3" interfacename="geometry_normal" />
      <input name="energy_compensation" type="boolean" value="true" />
    </oren_nayar_diffuse_bsdf>
    <convert name="subsurface_selector" type="float">
      <input name="in" type="boolean" interfacename="geometry_thin_walled" />
    </convert>
    <mix name="selected_subsurface" type="BSDF">
      <input name="fg" type="BSDF" nodename="subsurface_thin_walled" />
      <input name="bg" type="BSDF" nodename="subsurface_bsdf" />
      <input name="mix" type="float" nodename="subsurface_selector" />
    </mix>
    <mix name="opaque_base" type="BSDF">
      <input name="fg" type="BSDF" nodename="selected_subsurface" />
      <input name="bg" type="BSDF" nodename="diffuse_bsdf" />
      <input name="mix" type="float" interfacename="subsurface_weight" />
    </mix>

    <!-- Dielectric Base VDF -->
    <convert name="transmission_color_vector" type="vector3">
      <input name="in" type="color3" interfacename="transmission_color" />
    </convert>
    <ln name="transmission_color_ln" type="vector3">
      <input name="in" type="vector3" nodename="transmission_color_vector" />
    </ln>
    <multiply name="extinction_coeff_denom" type="vector3">
      <input name="in1" type="vector3" nodename="transmission_color_ln" />
      <input name="in2" type="float" value="-1.0" />
    </multiply>
    <convert name="transmission_depth_vector" type="vector3">
      <input name="in" type="float" interfacename="transmission_depth" />
    </convert>
    <divide name="extinction_coeff" type="vector3">
      <input name="in1" type="vector3" nodename="extinction_coeff_denom" />
      <input name="in2" type="vector3" nodename="transmission_depth_vector" />
    </divide>
    <convert name="transmission_scatter_vector" type="vector3">
      <input name="in" type="color3" interfacename="transmission_scatter" />
    </convert>
    <divide name="scattering_coeff" type="vector3">
      <input name="in1" type="vector3" nodename="transmission_scatter_vector" />
      <input name="in2" type="vector3" nodename="transmission_depth_vector" />
    </divide>
    <subtract name="absorption_coeff" type="vector3">
      <input name="in1" type="vector3" nodename="extinction_coeff" />
      <input name="in2" type="vector3" nodename="scattering_coeff" />
    </subtract>
    <extract name="absorption_coeff_x" type="float">
      <input name="in" type="vector3" nodename="absorption_coeff" />
      <input name="index" type="integer" value="0" />
    </extract>
    <extract name="absorption_coeff_y" type="float">
      <input name="in" type="vector3" nodename="absorption_coeff" />
      <input name="index" type="integer" value="1" />
    </extract>
    <extract name="absorption_coeff_z" type="float">
      <input name="in" type="vector3" nodename="absorption_coeff" />
      <input name="index" type="integer" value="2" />
    </extract>
    <min name="absorption_coeff_min_x_y" type="float">
      <input name="in1" type="float" nodename="absorption_coeff_x" />
      <input name="in2" type="float" nodename="absorption_coeff_y" />
    </min>
    <min name="absorption_coeff_min" type="float">
      <input name="in1" type="float" nodename="absorption_coeff_min_x_y" />
      <input name="in2" type="float" nodename="absorption_coeff_z" />
    </min>
    <convert name="absorption_coeff_min_vector" type="vector3">
      <input name="in" type="float" nodename="absorption_coeff_min" />
    </convert>
    <subtract name="absorption_coeff_shifted" type="vector3">
      <input name="in1" type="vector3" nodename="absorption_coeff" />
      <input name="in2" type="vector3" nodename="absorption_coeff_min_vector" />
    </subtract>
    <ifgreater name="if_absorption_coeff_shifted" type="vector3">
      <input name="value1" type="float" value="0.0" />
      <input name="value2" type="float" nodename="absorption_coeff_min" />
      <input name="in1" type="vector3" nodename="absorption_coeff_shifted" />
      <input name="in2" type="vector3" nodename="absorption_coeff" />
    </ifgreater>
    <ifgreater name="if_volume_absorption" type="vector3">
      <input name="value1" type="float" interfacename="transmission_depth" />
      <input name="value2" type="float" value="0.0" />
      <input name="in1" type="vector3" nodename="if_absorption_coeff_shifted" />
      <input name="in2" type="vector3" value="0.0,0.0,0.0" />
    </ifgreater>
    <ifgreater name="if_volume_scattering" type="vector3">
      <input name="value1" type="float" interfacename="transmission_depth" />
      <input name="value2" type="float" value="0.0" />
      <input name="in1" type="vector3" nodename="scattering_coeff" />
      <input name="in2" type="vector3" value="0.0,0.0,0.0" />
    </ifgreater>
    <anisotropic_vdf name="dielectric_volume" type="VDF">
      <input name="absorption" type="vector3" nodename="if_volume_absorption" />
      <input name="scattering" type="vector3" nodename="if_volume_scattering" />
      <input name="anisotropy" type="float" interfacename="transmission_scatter_anisotropy" />
    </anisotropic_vdf>

    <!-- Thin-film Thickness -->
    <multiply name="thin_film_thickness_nm" type="float">
      <input name="in1" type="float" interfacename="thin_film_thickness" />
      <input name="in2" type="float" value="1000.0" />
    </multiply>

    <!-- Dielectric Base -->
    <!-- apply IOR ratio inversion method to avoid TIR artifact (as in Coat TIR section of spec) -->
    <divide name="specular_to_coat_ior_ratio" type="float">
      <input name="in1" type="float" interfacename="specular_ior" />
      <input name="in2" type="float" interfacename="coat_ior" />
    </divide>
    <divide name="coat_to_specular_ior_ratio" type="float">
      <input name="in1" type="float" interfacename="coat_ior" />
      <input name="in2" type="float" interfacename="specular_ior" />
    </divide>
    <ifgreater name="specular_to_coat_ior_ratio_tir_fix" type="float">
      <input name="value1" type="float" nodename="specular_to_coat_ior_ratio" />
      <input name="value2" type="float" value="1.0" />
      <input name="in1" type="float" nodename="specular_to_coat_ior_ratio" />
      <input name="in2" type="float" nodename="coat_to_specular_ior_ratio" />
    </ifgreater>
    <mix name="eta_s" type="float">
      <input name="fg" type="float" nodename="specular_to_coat_ior_ratio_tir_fix" />
      <input name="bg" type="float" interfacename="specular_ior" />
      <input name="mix" type="float" interfacename="coat_weight" />
    </mix>
    <subtract name="eta_s_minus_one" type="float">
      <input name="in1" type="float" nodename="eta_s" />
      <input name="in2" type="float" value="1.0" />
    </subtract>
    <add name="eta_s_plus_one" type="float">
      <input name="in1" type="float" nodename="eta_s" />
      <input name="in2" type="float" value="1.0" />
    </add>
    <divide name="specular_F0_sqrt" type="float">
      <input name="in1" type="float" nodename="eta_s_minus_one" />
      <input name="in2" type="float" nodename="eta_s_plus_one" />
    </divide>
    <multiply name="specular_F0" type="float">
      <input name="in1" type="float" nodename="specular_F0_sqrt" />
      <input name="in2" type="float" nodename="specular_F0_sqrt" />
    </multiply>
    <multiply name="scaled_specular_F0" type="float">
      <input name="in1" type="float" interfacename="specular_weight" />
      <input name="in2" type="float" nodename="specular_F0" />
    </multiply>
    <clamp name="scaled_specular_F0_clamped" type="float">
      <input name="in" type="float" nodename="scaled_specular_F0" />
      <input name="low" type="float" value="0.0" />
      <input name="high" type="float" value="0.99999" />
    </clamp>
    <sqrt name="sqrt_scaled_specular_F0" type="float">
      <input name="in" type="float" nodename="scaled_specular_F0_clamped" />
    </sqrt>
    <sign name="sign_eta_s_minus_one" type="float">
      <input name="in" type="float" nodename="eta_s_minus_one" />
    </sign>
    <multiply name="modulated_eta_s_epsilon" type="float">
      <input name="in1" type="float" nodename="sign_eta_s_minus_one" />
      <input name="in2" type="float" nodename="sqrt_scaled_specular_F0" />
    </multiply>
    <subtract name="one_minus_modulated_eta_s_epsilon" type="float">
      <input name="in1" type="float" value="1.0" />
      <input name="in2" type="float" nodename="modulated_eta_s_epsilon" />
    </subtract>
    <add name="one_plus_modulated_eta_s_epsilon" type="float">
      <input name="in1" type="float" value="1.0" />
      <input name="in2" type="float" nodename="modulated_eta_s_epsilon" />
    </add>
    <divide name="modulated_eta_s" type="float">
      <input name="in1" type="float" nodename="one_plus_modulated_eta_s_epsilon" />
      <input name="in2" type="float" nodename="one_minus_modulated_eta_s_epsilon" />
    </divide>
    <ifgreater name="if_transmission_tint" type="color3">
      <input name="value1" type="float" interfacename="transmission_depth" />
      <input name="value2" type="float" value="0.0" />
      <input name="in1" type="color3" value="1.0, 1.0, 1.0" />
      <input name="in2" type="color3" interfacename="transmission_color" />
    </ifgreater>
    <dielectric_bsdf name="dielectric_transmission" type="BSDF">
      <input name="tint" type="color3" nodename="if_transmission_tint" />
      <input name="ior" type="float" nodename="modulated_eta_s" />
      <input name="roughness" type="vector2" nodename="main_roughness" />
      <input name="normal" type="vector3" interfacename="geometry_normal" />
      <input name="tangent" type="vector3" interfacename="geometry_tangent" />
      <input name="scatter_mode" type="string" value="T" />
    </dielectric_bsdf>
    <layer name="dielectric_volume_transmission" type="BSDF">
      <input name="top" type="BSDF" nodename="dielectric_transmission" />
      <input name="base" type="VDF" nodename="dielectric_volume" />
    </layer>
    <mix name="dielectric_substrate" type="BSDF">
      <input name="fg" type="BSDF" nodename="dielectric_volume_transmission" />
      <input name="bg" type="BSDF" nodename="opaque_base" />
      <input name="mix" type="float" interfacename="transmission_weight" />
    </mix>
    <dielectric_bsdf name="dielectric_reflection" type="BSDF">
      <input name="tint" type="color3" interfacename="specular_color" />
      <input name="ior" type="float" nodename="modulated_eta_s" />
      <input name="roughness" type="vector2" nodename="main_roughness" />
      <input name="normal" type="vector3" interfacename="geometry_normal" />
      <input name="tangent" type="vector3" interfacename="geometry_tangent" />
      <input name="scatter_mode" type="string" value="R" />
    </dielectric_bsdf>
    <dielectric_bsdf name="dielectric_reflection_tf" type="BSDF">
      <input name="tint" type="color3" interfacename="specular_color" />
      <input name="ior" type="float" nodename="modulated_eta_s" />
      <input name="roughness" type="vector2" nodename="main_roughness" />
      <input name="normal" type="vector3" interfacename="geometry_normal" />
      <input name="tangent" type="vector3" interfacename="geometry_tangent" />
      <input name="scatter_mode" type="string" value="R" />
      <input name="thinfilm_thickness" type="float" nodename="thin_film_thickness_nm" />
      <input name="thinfilm_ior" type="float" interfacename="thin_film_ior" />
    </dielectric_bsdf>

    <!-- 
      Explicitly using 'mix(layer(bsdf1, bsdf3), layer(bsdf2, bsdf3), weight)' instead of 'layer(mix(bsdf1, bsdf2, weight), bsdf3)' to overcome code gen limitations.
      Both expressions are semantically equivalent.
    -->
    <layer name="dielectric_base_tf" type="BSDF">
      <input name="top" type="BSDF" nodename="dielectric_reflection_tf" />
      <input name="base" type="BSDF" nodename="dielectric_substrate" />
    </layer>
    <layer name="dielectric_base_notf" type="BSDF">
      <input name="top" type="BSDF" nodename="dielectric_reflection" />
      <input name="base" type="BSDF" nodename="dielectric_substrate" />
    </layer>
    <mix name="dielectric_base" type="BSDF">
      <input name="fg" type="BSDF" nodename="dielectric_base_tf" />
      <input name="bg" type="BSDF" nodename="dielectric_base_notf" />
      <input name="mix" type="float" interfacename="thin_film_weight" />
    </mix>

    <!-- Metal Layer -->
    <multiply name="metal_reflectivity" type="color3">
      <input name="in1" type="color3" interfacename="base_color" />
      <input name="in2" type="float" interfacename="base_weight" />
    </multiply>
    <multiply name="metal_edgecolor" type="color3">
      <input name="in1" type="color3" interfacename="specular_color" />
      <input name="in2" type="float" interfacename="specular_weight" />
    </multiply>
    <generalized_schlick_bsdf name="metal_bsdf" type="BSDF">
      <input name="weight" type="float" interfacename="specular_weight" />
      <input name="color0" type="color3" nodename="metal_reflectivity" />
      <input name="color82" type="color3" nodename="metal_edgecolor" />
      <input name="roughness" type="vector2" nodename="main_roughness" />
      <input name="normal" type="vector3" interfacename="geometry_normal" />
      <input name="tangent" type="vector3" interfacename="geometry_tangent" />
    </generalized_schlick_bsdf>
    <generalized_schlick_bsdf name="metal_bsdf_tf" type="BSDF">
      <input name="weight" type="float" interfacename="specular_weight" />
      <input name="color0" type="color3" nodename="metal_reflectivity" />
      <input name="color82" type="color3" nodename="metal_edgecolor" />
      <input name="roughness" type="vector2" nodename="main_roughness" />
      <input name="normal" type="vector3" interfacename="geometry_normal" />
      <input name="tangent" type="vector3" interfacename="geometry_tangent" />
      <input name="thinfilm_thickness" type="float" nodename="thin_film_thickness_nm" />
      <input name="thinfilm_ior" type="float" interfacename="thin_film_ior" />
    </generalized_schlick_bsdf>
    <mix name="metal_bsdf_tf_mix" type="BSDF">
      <input name="fg" type="BSDF" nodename="metal_bsdf_tf" />
      <input name="bg" type="BSDF" nodename="metal_bsdf" />
      <input name="mix" type="float" interfacename="thin_film_weight" />
    </mix>
    <mix name="base_substrate" type="BSDF">
      <input name="fg" type="BSDF" nodename="metal_bsdf_tf_mix" />
      <input name="bg" type="BSDF" nodename="dielectric_base" />
      <input name="mix" type="float" interfacename="base_metalness" />
    </mix>

    <!-- Coat darkening calculation  -->
    <!-- approximate Kcoat, "internal diffuse reflection coefficient" of coat  -->
    <subtract name="one_minus_coat_F0" type="float">
      <input name="in1" type="float" value="1.0" />
      <input name="in2" type="float" nodename="coat_ior_to_F0" />
    </subtract>
    <multiply name="coat_ior_sqr" type="float">
      <input name="in1" type="float" interfacename="coat_ior" />
      <input name="in2" type="float" interfacename="coat_ior" />
    </multiply>
    <divide name="one_minus_coat_F0_over_eta2" type="float">
      <input name="in1" type="float" nodename="one_minus_coat_F0" />
      <input name="in2" type="float" nodename="coat_ior_sqr" />
    </divide>
    <subtract name="Kcoat" type="float">
      <input name="in1" type="float" value="1.0" />
      <input name="in2" type="float" nodename="one_minus_coat_F0_over_eta2" />
    </subtract>
    <!-- approximate base metal albedo estimate, Emetal  -->
    <multiply name="Emetal" type="color3">
      <input name="in1" type="color3" interfacename="base_color" />
      <input name="in2" type="float" interfacename="specular_weight" />
    </multiply>
    <!-- approximate base dielectric albedo estimate, Edielectric  -->
    <mix name="Edielectric" type="color3">
      <input name="fg" type="color3" interfacename="subsurface_color" />
      <input name="bg" type="color3" interfacename="base_color" />
      <input name="mix" type="float" interfacename="subsurface_weight" />
    </mix>
    <!-- thus calculate overall base albedo estimate approximation, Ebase  -->
    <mix name="Ebase" type="color3">
      <input name="fg" type="color3" nodename="Emetal" />
      <input name="bg" type="color3" nodename="Edielectric" />
      <input name="mix" type="float" interfacename="base_metalness" />
    </mix>
    <!-- final base darkening factor due to coat:  base_darkening = (1 - Kcoat) / (1 - Ebase*Kcoat)  -->
    <multiply name="Ebase_Kcoat" type="color3">
      <input name="in1" type="color3" nodename="Ebase" />
      <input name="in2" type="float" nodename="Kcoat" />
    </multiply>
    <subtract name="one_minus_Kcoat" type="float">
      <input name="in1" type="float" value="1.0" />
      <input name="in2" type="float" nodename="Kcoat" />
    </subtract>
    <subtract name="one_minus_Ebase_Kcoat" type="color3">
      <input name="in1" type="color3" value="1.0, 1.0, 1.0" />
      <input name="in2" type="color3" nodename="Ebase_Kcoat" />
    </subtract>
    <convert name="one_minus_Kcoat_color" type="color3">
      <input name="in" type="float" nodename="one_minus_Kcoat" />
    </convert>
    <divide name="base_darkening" type="color3">
      <input name="in1" type="color3" nodename="one_minus_Kcoat_color" />
      <input name="in2" type="color3" nodename="one_minus_Ebase_Kcoat" />
    </divide>
    <multiply name="coat_weight_times_coat_darkening" type="float">
      <input name="in1" type="float" interfacename="coat_weight" />
      <input name="in2" type="float" interfacename="coat_darkening" />
    </multiply>
    <mix name="modulated_base_darkening" type="color3">
      <input name="fg" type="color3" nodename="base_darkening" />
      <input name="bg" type="color3" value="1.0, 1.0, 1.0" />
      <input name="mix" type="float" nodename="coat_weight_times_coat_darkening" />
    </mix>
    <multiply name="darkened_base_substrate" type="BSDF">
      <input name="in1" type="BSDF" nodename="base_substrate" />
      <input name="in2" type="color3" nodename="modulated_base_darkening" />
    </multiply>

    <!-- Coat Layer -->
    <mix name="coat_attenuation" type="color3">
      <input name="fg" type="color3" interfacename="coat_color" />
      <input name="bg" type="color3" value="1.0, 1.0, 1.0" />
      <input name="mix" type="float" interfacename="coat_weight" />
    </mix>
    <multiply name="coat_substrate_attenuated" type="BSDF">
      <input name="in1" type="BSDF" nodename="darkened_base_substrate" />
      <input name="in2" type="color3" nodename="coat_attenuation" />
    </multiply>

    <open_pbr_anisotropy name="coat_roughness_vector" type="vector2">
      <input name="roughness" type="float" interfacename="coat_roughness" />
      <input name="anisotropy" type="float" interfacename="coat_roughness_anisotropy" />
    </open_pbr_anisotropy>
    <dielectric_bsdf name="coat_bsdf" type="BSDF">
      <input name="weight" type="float" interfacename="coat_weight" />
      <input name="ior" type="float" interfacename="coat_ior" />
      <input name="roughness" type="vector2" nodename="coat_roughness_vector" />
      <input name="normal" type="vector3" interfacename="geometry_coat_normal" />
      <input name="tangent" type="vector3" interfacename="geometry_coat_tangent" />
      <input name="scatter_mode" type="string" value="R" />
    </dielectric_bsdf>
    <layer name="coat_layer" type="BSDF">
      <input name="top" type="BSDF" nodename="coat_bsdf" />
      <input name="base" type="BSDF" nodename="coat_substrate_attenuated" />
    </layer>

    <!-- Fuzz Layer -->
    <sheen_bsdf name="fuzz_bsdf" type="BSDF">
      <input name="weight" type="float" interfacename="fuzz_weight" />
      <input name="color" type="color3" interfacename="fuzz_color" />
      <input name="roughness" type="float" interfacename="fuzz_roughness" />
      <input name="normal" type="vector3" interfacename="geometry_normal" />
      <input name="mode" type="string" value="zeltner" />
    </sheen_bsdf>
    <layer name="fuzz_layer" type="BSDF">
      <input name="top" type="BSDF" nodename="fuzz_bsdf" />
      <input name="base" type="BSDF" nodename="coat_layer" />
    </layer>

    <!-- Emission Layer -->
    <subtract name="coat_ior_minus_one" type="float">
      <input name="in1" type="float" interfacename="coat_ior" />
      <input name="in2" type="float" value="1.0" />
    </subtract>
    <add name="coat_ior_plus_one" type="float">
      <input name="in1" type="float" value="1.0" />
      <input name="in2" type="float" interfacename="coat_ior" />
    </add>
    <divide name="coat_ior_to_F0_sqrt" type="float">
      <input name="in1" type="float" nodename="coat_ior_minus_one" />
      <input name="in2" type="float" nodename="coat_ior_plus_one" />
    </divide>
    <multiply name="coat_ior_to_F0" type="float">
      <input name="in1" type="float" nodename="coat_ior_to_F0_sqrt" />
      <input name="in2" type="float" nodename="coat_ior_to_F0_sqrt" />
    </multiply>
    <multiply name="emission_weight" type="color3">
      <input name="in1" type="color3" interfacename="emission_color" />
      <input name="in2" type="float" interfacename="emission_luminance" />
    </multiply>
    <uniform_edf name="uncoated_emission_edf" type="EDF">
      <input name="color" type="color3" nodename="emission_weight" />
    </uniform_edf>
    <multiply name="coat_tinted_emission_edf" type="EDF">
      <input name="in1" type="EDF" nodename="uncoated_emission_edf" />
      <input name="in2" type="color3" interfacename="coat_color" />
    </multiply>
    <convert name="one_minus_coat_F0_color" type="color3">
      <input name="in" type="float" nodename="one_minus_coat_F0" />
    </convert>
    <generalized_schlick_edf name="coated_emission_edf" type="EDF">
      <input name="color0" type="color3" nodename="one_minus_coat_F0_color" />
      <input name="color90" type="color3" value="0.0, 0.0, 0.0" />
      <input name="exponent" type="float" value="5.0" />
      <input name="base" type="EDF" nodename="coat_tinted_emission_edf" />
    </generalized_schlick_edf>
    <mix name="emission_edf" type="EDF">
      <input name="fg" type="EDF" nodename="coated_emission_edf" />
      <input name="bg" type="EDF" nodename="uncoated_emission_edf" />
      <input name="mix" type="float" interfacename="coat_weight" />
    </mix>

    <!-- Surface Construction -->
    <surface name="shader_constructor" type="surfaceshader">
      <input name="bsdf" type="BSDF" nodename="fuzz_layer" />
      <input name="edf" type="EDF" nodename="emission_edf" />
      <input name="opacity" type="float" interfacename="geometry_opacity" />
      <input name="thin_walled" type="boolean" interfacename="geometry_thin_walled" />
    </surface>

    <!-- Output -->
    <output name="out" type="surfaceshader" nodename="shader_constructor" />

  </nodegraph>

  <!--
    OpenPBR Anisotropy node definition
  -->
  <nodedef name="ND_open_pbr_anisotropy" node="open_pbr_anisotropy" nodegroup="pbr" doc="Computes anisotropic surface roughness as defined in the OpenPBR specification.">
    <input name="roughness" type="float" value="0.0" />
    <input name="anisotropy" type="float" value="0.0" />
    <output name="out" type="vector2" />
  </nodedef>

  <!--
    OpenPBR Anisotropy graph definition
  -->
  <nodegraph name="NG_open_pbr_anisotropy" nodedef="ND_open_pbr_anisotropy">
    <invert name="aniso_invert" type="float">
      <input name="in" type="float" interfacename="anisotropy" />
    </invert>
    <multiply name="aniso_invert_sq" type="float">
      <input name="in1" type="float" nodename="aniso_invert" />
      <input name="in2" type="float" nodename="aniso_invert" />
    </multiply>
    <add name="denom" type="float">
      <input name="in1" type="float" nodename="aniso_invert_sq" />
      <input name="in2" type="float" value="1.0" />
    </add>
    <divide name="fraction" type="float">
      <input name="in1" type="float" value="2.0" />
      <input name="in2" type="float" nodename="denom" />
    </divide>
    <sqrt name="sqrt" type="float">
      <input name="in" type="float" nodename="fraction" />
    </sqrt>
    <multiply name="rough_sq" type="float">
      <input name="in1" type="float" interfacename="roughness" />
      <input name="in2" type="float" interfacename="roughness" />
    </multiply>
    <multiply name="alpha_x" type="float">
      <input name="in1" type="float" nodename="rough_sq" />
      <input name="in2" type="float" nodename="sqrt" />
    </multiply>
    <multiply name="alpha_y" type="float">
      <input name="in1" type="float" nodename="aniso_invert" />
      <input name="in2" type="float" nodename="alpha_x" />
    </multiply>
    <combine2 name="result" type="vector2">
      <input name="in1" type="float" nodename="alpha_x" />
      <input name="in2" type="float" nodename="alpha_y" />
    </combine2>
    <output name="out" type="vector2" nodename="result" />
  </nodegraph>

</materialx>