Skip to content

Exporter Reference

Material Authoring

Custom Maya attributes, alpha mode setup, and shader-specific behaviours that affect how materials are written on export.

Open Exporter Overview Material Texture Maps Technical Details

Custom Material Attributes

The plug-in automatically adds glTF-specific custom attributes to every supported material node when the plug-in loads and whenever a new material is created. The attributes appear in the Extra Attributes section of the Attribute Editor.

gltfDoubleSided

A boolean attribute that forces the exported material's doubleSided flag to true, regardless of mesh backface-culling state. Toggle glTF Double Sided to On in the Extra Attributes section.

When left Off (the default), the exporter falls back to the per-shape backface culling setting in Maya. Enable this attribute to override that automatic detection — particularly useful when one material is shared across shapes with inconsistent culling settings.

This attribute is present on all supported shader types: standardSurface, aiStandardSurface, openPBRSurface, and StingrayPBS.

gltfAO

A float attribute that explicitly routes a texture into the glTF occlusion channel, bypassing the automatic packed-ORM detection logic. Connect an occlusion texture's output to glTF AO in the Extra Attributes section.

This is useful when your occlusion map is stored separately from your metallic-roughness texture.

Alpha Mode Authoring

The exporter supports three glTF alpha modes: OPAQUE, BLEND, and MASK.

BLEND Mode

Connect a texture or value to the material's opacity/transmission attribute to get alphaMode=BLEND in the exported output.

MASK Mode with alphaCutoff

To export alphaMode=MASK with a precise cutoff threshold, wire an Arnold aiCompare node between your opacity texture and the shader's opacity input:

  1. Connect the opacity texture's outAlpha to aiCompare.input2.
  2. Set the Test operation on aiCompare to less than (<). Any comparison test mode (less than, less than or equal, greater than, greater than or equal) triggers MASK detection — less than is the recommended choice.
  3. Set aiCompare.input1 to the cutoff threshold (for example 0.5). This value is exported as alphaCutoff.
  4. Connect aiCompare.outValue to the shader's opacity input:
  5. standardSurface, aiStandardSurface: connect to opacity.
  6. openPBRSurface: connect to geometryOpacity.

Without this aiCompare node pattern, the exporter cannot determine a cutoff threshold and will not write alphaMode=MASK.

Shader-Specific Notes

StingrayPBS — mask_threshold and Alpha Cutoff

For StingrayPBS materials, the exporter reads the mask_threshold attribute to populate the glTF alphaCutoff value when the material is in MASK alpha mode. Set this attribute in Maya to control the cutoff threshold on export.

OpenPBR — Emission Luminance Scale

When exporting an openPBRSurface shader, the exporter divides the emissionLuminance value by 1000 before writing it as KHR_materials_emissive_strength. This compensates for the importer's corresponding multiply-by-1000 applied on import, preserving the round-trip value.

If you set emissionLuminance directly on an openPBRSurface in a scene that was not imported through this plug-in, the exported emissive strength will be 1/1000th of the Maya value. In that case, multiply your intended glTF emissive strength by 1000 when setting emissionLuminance in Maya.