## glTF (PBR) shader

### Material Panel > Property > Parameter

Alpha
  It adjusts how the object opaque. 0 stands for perfect transparent (nothing can be seen), and 1 stands for perfect opacity. It can be specified when the [Alpha mode] is [Mask] or [Blend].
  In path tracing, Changing the opacity value causes a lot of noise, so it is recommended to set [Transmission]/[Volume] or use the [Transparency] shader to represent translucent objects.
Metallic
  Set the metallic luster on the surface of the material.
Roughness
  Specify the roughness of the surface of the material.
Emissive
  Specifies how much light will be emitted as an area light source. The standard range is 0 to 1, but you can make the light source stronger by directly entering a number greater than 1.
Alpha mode
  Specifies the representation of the [Alpha] value (including an alpha channel in [Texture] mapping).
  - Opaque - The alpha value is ignored. It is all opaque. This is the default for Alpha mode.
  - Mask - The part whose alpha value is lower than the specified [Alpha cutoff] is expressed as transparent. The part with high alpha value is expressed as opaque.
  - Blend - Make transparent the background according to the alpha value.
Alpha cutoff
  When [Alpha mode] is [Mask], it determines transparency / opacity according to this cutoff value.
  *In [Alpha mode] other than Mask, this value is ignored.

#### Specular-Glossiness

It enables Specular-Glossiness extension. When it is enabled, the Specular-Glossiness calculation model without Metallic/Roughness is applied. It cannot be combined with other extensions.

Diffuse
  Specifies how much brighter the light hits the area.
Specular
  Specifies how bright the incoming light is.
Glossiness
  Specifies how widely or narrowly the reflected light is reflected.

#### Extensions

It is possible to configure settings that correspond to the extended glTF specifications defined by Khronos.

Clearcoat
  It highlights reflections caused by thin films on the surface, such as on the body of an automobile. This is especially useful when using environmental maps.
Clearcoat factor
  Specifies how much the clear paint is emphasized.
Clearcoat roughness
  Specifies whether to blur reflections caused by the clear coating.
Refraction
  Enables specification of the refractive index of the medium. It is used in combination with [Clearcoat], [Transmission] or [Volume]. If not specified, a refractive index of 1.5 is applied.
Index of refraction
  Specifies the refractive index.
Sheen
  Light is superimposed on the point of shallow angle of incidence. Effective for expressing shiny fabrics such as satin fabrics.
Sheen factor
  Specifies the intensity or color of the gloss.
Sheen roughness
  Specifies the degree of diffusion of reflections due to gloss.
Specular
  More detailed settings can be made for the reflected light component produced by [Metallic] and [Roughness].
Specular factor
  Specifies the intensity of reflected light.
Specular color
  Specifies the color of the reflected light.
  The edge of the highlight will appear in the specified color, but the diffuse component outside of it will lose its color and the opposite color will be emphasized.
Anisotropy
  Sets the intensity of specular highlight to differ vertically and horizontally relative to the tangential direction. Currently, this only applies to the real-time 3D display and is not reflected in Render.
  For anisotropic reflections to be displayed correctly, UVs must be properly assigned for tangential calculations.
Anisotropy strength
  Specifies the strength of the anisotropic reflection.
Anisotropy rotation
  Specifies the rotation angle of the anisotropic reflection.
Iridescence
  Rainbow-colored stripes are appeared on the surface by the thin-film interference.
Iridescence factor
  Specifies the intensity or the iridescence.
Iridescence ior
  Specifies the refractive index of the thin film layer of the iridescence.
Iridescence thick-min (thickness minimum)
  Specifies the minimum thickness of the thin film layer of the iridescence in nanometers. Affects when an [Iridescence thickness] mapping image is specified, and the thickness varies within the minimum and maximum thickness range depending on the pixel value of the image.
Iridescence thick-max (thickness maximum)
  Specifies the maximum thickness of the thin film layer of the iridescence in nanometers.
Transmission
  Surface can be made transparent. Unlike when setting [Alpha mode], the background can be blurred by [Roughness].
  If the base color is white, the image will be completely transparent, but colors will be absorbed if the base color is not white. In addition, a high value for [Metallic] cancels the effect of [Transmission].
Transmission factor
  Specifies how much transparency should be applied.
Volume
  Used in combination with [Transmission]. It can express a substance such as glass, where light passes through the interior with refraction and attenuation.
Thickness
  Specifies the thickness of the medium in real dimensions. It is treated as a thin film if 0, and light is refracted and advanced inside the film by that amount if non-zero value is specified.
  Combined with [Thickness] mapping, it can be used to effectively express thickness on objects that are not flat.
  This value is applied to the preview display only. The path tracing rendering does not use it.
Attenuation distance
  Specifies the distance in real dimensions to which light must reach before maximum attenuation occurs.
Attenuation color
  Specifies the color to which the light will be attenuated when it reaches the [Attenuation distance].
Dispersion
  Used in combination with [Transmission] and [Volume]. The refractive index changes for each wavelength inside the glass, dispersing colors, recreating the rainbow-like appearance of the color boundaries of objects seen through the glass.
Dispersion strength
  Specify the strength of the dispersion.
Unlit
  The base color is directly displayed as it is, without any illumination calculation by each parameter. Cannot be combined with other extensions.

### Material Panel > Property > Mapping

Texture
  It specifies the color pattern of the material. If the texture image contains an alpha channel, it is used as a semi-transparency or mask in combination with the [Alpha mode] setting.
Normal
  It specifies the irregularities of the material.
  The depth of irregularities is adjusted by [Normal map scale].
Metal/Rough
  Adjust the intensity of [Metallic] and [Roughness] locally in the image.
  Of the RGB images, the R channel is used for metallic and the G channel is used for roughness.
Emissive
  It specifies the part where the material emits light.
  The intensity of the emission is adjusted by [Emission].
Occlusion
  It specifies the part where the shades of the material are.
  The intensity of the shade is adjusted by [Occlusion map strength].
  The R channel of the RGB image is used.
Clearcoat
  Adjust the intensity of [Clearcoat factor] locally in the grayscale image.
  The R channel of the RGB image is used.
Clearcoat roughness
  Adjust the intensity of [Clearcoat roughness] locally in the grayscale image.
  The G channel of the RGB image is used.
Clearcoat normal
  It specifies the irregularities of the [Clearcoat] of the material.
  The depth of irregularities is adjusted by [Clearcoat normal scale].
Sheen color
  Adjust the intensity of [Sheen color] locally in the color image.
Sheen roughness
  Adjust the intensity of [Sheen roughness] locally in the grayscale image.
  The A channel of the RGB image is used.
Specular
  Adjust the intensity of [Specular factor] locally in the grayscale image.
  The A channel of the RGB image is used.
Specular color
  Adjust the intensity of [Specular color] locally in the color image.
Anisotropy
  Adjust the [Anisotropy rotation] and [Anisotropy strength] locally in the color image.
  The R channel of the RGB image is used for rotation (tangent), G channel for rotation (bi-tangent), and B channel for strength.
Iridescence
  Adjust the intensity of [Iridescence factor] locally in the grayscale image.
  The R channel of the RGB image is used.
Iridescence thickness
  Adjust the thickness of thin film layer for [Iridescence] locally in the grayscale image.
  The G channel of the RGB image is used.
Transmission
  Adjust the intensity of [Transmission factor] locally in the grayscale image.
  The R channel of the RGB image is used.
Thickness
  Adjust the intensity of [Thickness] locally in the grayscale image.
  The G channel of the RGB image is used.