---
title: MDLMaterialSemantic.emission
framework: modelio
role: symbol
role_heading: Case
path: modelio/mdlmaterialsemantic/emission
---

# MDLMaterialSemantic.emission

The color emitted as radiance from a material’s surface.

## Declaration

```swift
case emission
```

## Discussion

Discussion A renderer (or other software component processing the material) might not treat the emission channel of a material as a light source illuminating the scene. Instead, an emission channel prevents affected areas of a surface from being darkened by other aspects of lighting and shading. Model I/O uses this semantic for the Ka and map_Ka attributes when importing from the MTL file format (for assets in the OBJ file format).

## See Also

### Constants

- [MDLMaterialSemantic.baseColor](modelio/mdlmaterialsemantic/basecolor.md)
- [MDLMaterialSemantic.subsurface](modelio/mdlmaterialsemantic/subsurface.md)
- [MDLMaterialSemantic.metallic](modelio/mdlmaterialsemantic/metallic.md)
- [MDLMaterialSemantic.specular](modelio/mdlmaterialsemantic/specular.md)
- [MDLMaterialSemantic.specularExponent](modelio/mdlmaterialsemantic/specularexponent.md)
- [MDLMaterialSemantic.specularTint](modelio/mdlmaterialsemantic/speculartint.md)
- [MDLMaterialSemantic.roughness](modelio/mdlmaterialsemantic/roughness.md)
- [MDLMaterialSemantic.anisotropic](modelio/mdlmaterialsemantic/anisotropic.md)
- [MDLMaterialSemantic.anisotropicRotation](modelio/mdlmaterialsemantic/anisotropicrotation.md)
- [MDLMaterialSemantic.sheen](modelio/mdlmaterialsemantic/sheen.md)
- [MDLMaterialSemantic.sheenTint](modelio/mdlmaterialsemantic/sheentint.md)
- [MDLMaterialSemantic.clearcoat](modelio/mdlmaterialsemantic/clearcoat.md)
- [MDLMaterialSemantic.clearcoatGloss](modelio/mdlmaterialsemantic/clearcoatgloss.md)
- [MDLMaterialSemantic.bump](modelio/mdlmaterialsemantic/bump.md)
- [MDLMaterialSemantic.opacity](modelio/mdlmaterialsemantic/opacity.md)