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  "title" : "faceCulling"
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# faceCulling

A process in which the system specifies polygons to remove before
rendering a mesh using this material.

```
var faceCulling: PortalMaterial.FaceCulling { get set }
```

## Discussion

To improve performance, RealityKit culls polygons, or faces, that it
determines won’t be visible. Discarding faces that aren’t part of the
final render eliminates the need to do any calculations for those
faces.

RealityKit recognizes when a face aims toward the camera (a front face)
or away from the camera (a back face). This value controls the type of
faces RealityKit culls.

This value defaults to [`MaterialParameterTypes.FaceCulling.back`](/documentation/RealityKit/MaterialParameterTypes/FaceCulling/back),
which means RealityKit removes faces that point away from the camera.
Most of the time, this is the correct behavior, because back faces are
usually obscured by other front-facing polygons.

You can change the culling behavior to cull front faces instead or to
turn off face culling altogether, but be aware that turning off face
culling results in less efficient rendering and may negatively impact
your app’s frame rate.

---

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