The XML schema for the .mats file format is available in Src/Samples/Libraries/GeoEn2Support/common_mats.xsd.

There are two types of material: Blinn-Phong and PBR. Some elements and attributes are common to both types.

Blinn-Phong Materials

`<materials>`

Your materials must be enclosed within a single <materials> element, with the following attributes. Your <materials> element may contain any number of <material> elements describing the IDs/GUIDs and behaviour of individual materials.

Attribute	Usage	Description	Values
`version`	Required	The version of the `.mats` file format.	Integer

`<material>`

The <material> element is used to assign material IDs/GUIDs and describe the behaviour of individual materials. Any number of <material> elements may appear within your <materials> element.

The <diffuse> element is used to specify the diffuse channel as a single colour or a texture.

Attribute	Usage	Description	Values
`colour`	Optional	Specifies the colour of the diffuse channel.	4-element vector as string (RGBA)
`scale`	Optional	The scale to apply to the diffuse channel.	Float
`uvScale`	Optional	The scale to apply to the mesh's UVs before looking up in the diffuse texture.	2-element vector as string (XY scale)
`uvOffset`	Optional	The offset to apply to the mesh's UVs before looking up in the diffuse texture (applied after the above `uvScale`).	2-element vector as string (XY scale)

The <diffuse> element can optionally contain a child <texture> element, containing the filename of the texture to use.

`<opacity>`

The <opacity> element is used to specify the opacity channel as a single colour or a texture.

Attribute	Usage	Description	Values
`colour`	Optional	Specifies the colour of the opacity channel.	4-element vector as string (RGBA)
`scale`	Optional	The scale to apply to the opacity channel.	Float
`uvScale`	Optional	The scale to apply to the mesh's UVs before looking up in the opacity texture.	2-element vector as string (XY scale)
`uvOffset`	Optional	The offset to apply to the mesh's UVs before looking up in the opacity texture (applied after the above `uvScale`).	2-element vector as string (XY scale)

`<specular>`

The <specular> element is used to specify the specular channel as a single colour or a texture, along with a power.

Attribute	Usage	Description	Values
`colour`	Optional	Specifies the colour of the opacity channel.	4-element vector as string (RGBA)
`scale`	Optional	The scale to apply to the opacity channel.	Float
`power`	Required	A power to apply to the specular channel.	Float
`uvScale`	Optional	The scale to apply to the mesh's UVs before looking up in the specular texture.	2-element vector as string (XY scale)
`uvOffset`	Optional	The offset to apply to the mesh's UVs before looking up in the specular texture (applied after the above `uvScale`).	2-element vector as string (XY scale)

The <specular> element can optionally contain a child <texture> element, containing the filename of the texture to use.

PBR Materials

`<pbrMaterials>`

Your materials must be enclosed within a single <pbrMaterials> element, with the following attributes. Your <pbrMaterials> element may contain any number of <pbrMaterial> elements describing the IDs/GUIDs and behaviour of individual materials.

Attribute	Usage	Description	Values
`version`	Required	The version of the `.mats` file format.	Integer

`<pbrMaterial>`

The <pbrMaterial> element is used to assign material IDs/GUIDs and describe the behaviour of individual materials. Any number of <pbrMaterial> elements may appear within your <pbrMaterials> element.

`<baseColour>`

The <baseColour> element is used to specify the baseColour channel as a colour and/or a texture.

Attribute	Usage	Description	Values
`colour`	Optional	Specifies the colour of the baseColour channel.	4-element vector as string (RGBA)
`scale`	Optional	The scale to apply to the baseColour channel.	Float
`uvScale`	Optional	The scale to apply to the mesh's UVs before looking up in the baseColour texture.	2-element vector as string (XY scale)
`uvOffset`	Optional	The offset to apply to the mesh's UVs before looking up in the baseColour texture (applied after the above `uvScale`).	2-element vector as string (XY scale)

The <baseColour> element can optionally contain a child <texture> element, containing the filename of the texture to use.

`<metallic>`

The <metallic> element is used to specify the metallic channel as a single channel texture.

Attribute	Usage	Description	Values
`scale`	Optional	The scale to apply to the metallic channel.	Float
`uvScale`	Optional	The scale to apply to the mesh's UVs before looking up in the metallic texture.	2-element vector as string (XY scale)
`uvOffset`	Optional	The offset to apply to the mesh's UVs before looking up in the metallic texture (applied after the above `uvScale`).	2-element vector as string (XY scale)

The <metallic> element must contain a child <texture> element, containing the filename of the texture to use.

`<roughness>`

The <roughness> element is used to specify the roughness channel as a single channel texture.

Attribute	Usage	Description	Values
`scale`	Optional	The scale to apply to the roughness channel.	Float
`uvScale`	Optional	The scale to apply to the mesh's UVs before looking up in the roughness texture.	2-element vector as string (XY scale)
`uvOffset`	Optional	The offset to apply to the mesh's UVs before looking up in the roughness texture (applied after the above `uvScale`).	2-element vector as string (XY scale)

The <roughness> element must contain a child <texture> element, containing the filename of the texture to use.

`<ao>`

The <ao> element is used to specify the ao channel as a single channel texture.

Attribute	Usage	Description	Values
`diffuseScale`	Optional	The scale to apply to the ao channel when applied to indirect diffuse lighting.	Float
`specularScale`	Optional	The scale to apply to the ao channel when applied to indirect specular lighting.	Float
`uvScale`	Optional	The scale to apply to the mesh's UVs before looking up in the ao texture.	2-element vector as string (XY scale)
`uvOffset`	Optional	The offset to apply to the mesh's UVs before looking up in the ao texture (applied after the above `uvScale`).	2-element vector as string (XY scale)

The <ao> element must contain a child <texture> element, containing the filename of the texture to use.

`<cavity>`

The <cavity> element is used to specify the cavity channel as a single channel texture.

Attribute	Usage	Description	Values
`scale`	Optional	The scale to apply to the cavity channel.	Float
`uvScale`	Optional	The scale to apply to the mesh's UVs before looking up in the cavity texture.	2-element vector as string (XY scale)
`uvOffset`	Optional	The offset to apply to the mesh's UVs before looking up in the cavity texture (applied after the above `uvScale`).	2-element vector as string (XY scale)

The <cavity> element must contain a child <texture> element, containing the filename of the texture to use.

Common

The atttributes and child elements listed below are common to both <material> and <pbrMaterial> elements:

Attribute	Usage	Description	Values
id	Required	The identifier of this material.	String
guid	Optional	The GUID of this material.	GUID string
`backfaceBehaviourType`	Optional	The backface ray hit behaviour type of this material.	String: `invalid` `black` `transparent` `doubleSided`
`shadowfaceBehaviourType`	Optional	Defines the triangle faces which cast direct lighting shadows. Used in precomputed directional visibility and baking. Note that the precompute treats `bothWithInvalidBack`as `back`.	String: `front` `back` `both` `bothWithInvalidBack`
`indirectTransparency`	Optional	Fraction of incident rays which pass through the material.	Positive float (default `0.0`)
`indirectReflectivity`	Optional	The fraction of incident rays which are reflected by the material.	Positive float (default `1.0`)
`isEmissive`	Optional	Setting to true will enable special treatment appropriate for emissive materials.	Boolean (default `false`)

`<normal>`

The <normal> element is used to specify the normal channel as a texture.

Attribute	Usage	Description	Values
`scale`	Optional	The scale to apply to the normal channel.	Float
`useForBaking`	Optional	Whether the normal channel should be used when baking.	Boolean
`uvScale`	Optional	The scale to apply to the mesh's UVs before looking up in the normal texture.	2-element vector as string (XY scale)
`uvOffset`	Optional	The offset to apply to the mesh's UVs before looking up in the normal texture (applied after the above `uvScale`).	2-element vector as string (XY scale)

The <normal> element must contain a child <texture> element, containing the filename of the texture to use.

`<emissive>`

The <emissive> element is used to specify the emissive channel as a single colour or a texture.

Attribute	Usage	Description	Values
`colour`	Optional	Specifies the colour of the emissive channel.	4-element vector as string (RGBA)
`scale`	Optional	The scale to apply to the emissive channel.	Float
`uvScale`	Optional	The scale to apply to the mesh's UVs before looking up in the emissive texture.	2-element vector as string (XY scale)
`uvOffset`	Optional	The offset to apply to the mesh's UVs before looking up in the emissive texture (applied after the above `uvScale`).	2-element vector as string (XY scale)

The <emissive> element can optionally contain a child <texture> element, containing the filename of the texture to use.

`<transparency>`

The <transparency> element is used to specify the transparency channel as a single colour or a texture.

Attribute	Usage	Description	Values
`colour`	Optional	Specifies the colour of the transparency channel.	4-element vector as string (RGBA)
`scale`	Optional	The scale to apply to the transparency channel.	Float
`uvScale`	Optional	The scale to apply to the mesh's UVs before looking up in the transparency texture.	2-element vector as string (XY scale)
`uvOffset`	Optional	The offset to apply to the mesh's UVs before looking up in the transparency texture (applied after the above `uvScale`).	2-element vector as string (XY scale)

The <transparency> element can optionally contain a child <texture> element, containing the filename of the texture to use.