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Optimizations to glTF PBR graph #2467

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Merged
jstone-lucasfilm merged 3 commits into from
Jul 8, 2025
Merged

Optimizations to glTF PBR graph #2467

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Optimizations to glTF PBR graph
jstone-lucasfilm Jul 1, 2025
49e3f44
Merge branch 'main' into main
jstone-lucasfilm Jul 7, 2025
bf0cec7
Merge branch 'main' into main
jstone-lucasfilm Jul 8, 2025
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70 changes: 26 additions & 44 deletions libraries/bxdf/gltf_pbr.mtlx
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Original file line number Diff line number Diff line change
Expand Up @@ -135,12 +135,10 @@
</mix>

<!-- Dielectric -->

<oren_nayar_diffuse_bsdf name="diffuse_bsdf" type="BSDF">
<input name="color" type="color3" interfacename="base_color" />
<input name="normal" type="vector3" interfacename="normal" />
</oren_nayar_diffuse_bsdf>

<dielectric_bsdf name="transmission_bsdf" type="BSDF">
<input name="weight" type="float" value="1" />
<input name="tint" type="color3" interfacename="base_color" />
Expand All @@ -150,31 +148,25 @@
<input name="tangent" type="vector3" nodename="selected_tangent" />
<input name="scatter_mode" type="string" value="T" />
</dielectric_bsdf>

<mix name="transmission_mix" type="BSDF">
<input name="bg" type="BSDF" nodename="diffuse_bsdf" />
<input name="fg" type="BSDF" nodename="transmission_bsdf" />
<input name="mix" type="float" interfacename="transmission" />
</mix>
<invert name="iridescence_inv" type="float">
<input name="in" type="float" interfacename="iridescence" />
</invert>
<generalized_schlick_bsdf name="reflection_bsdf" type="BSDF">
<input name="weight" type="float" nodename="iridescence_inv" />
<input name="color0" type="color3" nodename="dielectric_f0" />
<input name="color90" type="color3" nodename="dielectric_f90" />
<input name="roughness" type="vector2" nodename="roughness_uv" />
<input name="normal" type="vector3" interfacename="normal" />
<input name="tangent" type="vector3" nodename="selected_tangent" />
<input name="scatter_mode" type="string" value="R" />
</generalized_schlick_bsdf>

<mix name="transmission_mix" type="BSDF">
<input name="bg" type="BSDF" nodename="diffuse_bsdf" />
<input name="fg" type="BSDF" nodename="transmission_bsdf" />
<input name="mix" type="float" interfacename="transmission" />
</mix>

<layer name="dielectric_bsdf" type="BSDF">
<input name="top" type="BSDF" nodename="reflection_bsdf" />
<input name="base" type="BSDF" nodename="transmission_mix" />
</layer>

<!-- Thin-film + Dielectric
Note: Due to limitations in codegen, the base layer BSDF is duplicated (#1035). -->

<generalized_schlick_bsdf name="tf_reflection_bsdf" type="BSDF">
<generalized_schlick_bsdf name="reflection_bsdf_tf" type="BSDF">
<input name="weight" type="float" interfacename="iridescence" />
<input name="color0" type="color3" nodename="dielectric_f0" />
<input name="color90" type="color3" nodename="dielectric_f90" />
<input name="roughness" type="vector2" nodename="roughness_uv" />
Expand All @@ -184,33 +176,26 @@
<input name="thinfilm_thickness" type="float" interfacename="iridescence_thickness" />
<input name="thinfilm_ior" type="float" interfacename="iridescence_ior" />
</generalized_schlick_bsdf>


<layer name="tf_dielectric_bsdf" type="BSDF">
<input name="top" type="BSDF" nodename="tf_reflection_bsdf" />
<add name="reflection_bsdf_blend" type="BSDF">
<input name="in1" type="BSDF" nodename="reflection_bsdf" />
<input name="in2" type="BSDF" nodename="reflection_bsdf_tf" />
</add>
<layer name="dielectric_layer" type="BSDF">
<input name="top" type="BSDF" nodename="reflection_bsdf_blend" />
<input name="base" type="BSDF" nodename="transmission_mix" />
</layer>

<mix name="mix_iridescent_dielectric_bsdf" type="BSDF">
<input name="bg" type="BSDF" nodename="dielectric_bsdf" />
<input name="fg" type="BSDF" nodename="tf_dielectric_bsdf" />
<input name="mix" type="float" interfacename="iridescence" />
</mix>

<!-- Metal -->

<generalized_schlick_bsdf name="metal_bsdf" type="BSDF">
<input name="weight" type="float" nodename="iridescence_inv" />
<input name="color0" type="color3" interfacename="base_color" />
<input name="color90" type="color3" value="1, 1, 1" />
<input name="roughness" type="vector2" nodename="roughness_uv" />
<input name="normal" type="vector3" interfacename="normal" />
<input name="tangent" type="vector3" nodename="selected_tangent" />
</generalized_schlick_bsdf>

<!-- Thin-film + Metal
Note: Due to limitations in codegen, the base layer BSDF is duplicated (#1035). -->

<generalized_schlick_bsdf name="tf_metal_bsdf" type="BSDF">
<generalized_schlick_bsdf name="metal_bsdf_tf" type="BSDF">
<input name="weight" type="float" interfacename="iridescence" />
<input name="color0" type="color3" interfacename="base_color" />
<input name="color90" type="color3" value="1, 1, 1" />
<input name="roughness" type="vector2" nodename="roughness_uv" />
Expand All @@ -219,18 +204,15 @@
<input name="thinfilm_thickness" type="float" interfacename="iridescence_thickness" />
<input name="thinfilm_ior" type="float" interfacename="iridescence_ior" />
</generalized_schlick_bsdf>

<mix name="mix_iridescent_metal_bsdf" type="BSDF">
<input name="bg" type="BSDF" nodename="metal_bsdf" />
<input name="fg" type="BSDF" nodename="tf_metal_bsdf" />
<input name="mix" type="float" interfacename="iridescence" />
</mix>
<add name="metal_blend" type="BSDF">
<input name="in1" type="BSDF" nodename="metal_bsdf" />
<input name="in2" type="BSDF" nodename="metal_bsdf_tf" />
</add>

<!-- Dielectric/metal mix -->

<mix name="base_mix" type="BSDF">
<input name="bg" type="BSDF" nodename="mix_iridescent_dielectric_bsdf" />
<input name="fg" type="BSDF" nodename="mix_iridescent_metal_bsdf" />
<input name="bg" type="BSDF" nodename="dielectric_layer" />
<input name="fg" type="BSDF" nodename="metal_blend" />
<input name="mix" type="float" interfacename="metallic" />
</mix>

Expand Down