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# SpotLightComponent.SurroundingsLight

A component that specifies that the spot light illuminates the physical and immersive environment.

```
struct SurroundingsLight
```

## Performance Considerations

Set [`attenuationRadius`](/documentation/RealityKit/SpotLightComponent/attenuationRadius) deliberately on lights that use this component.
Its default is often larger than needed, and the resulting
on-screen footprint is the dominant driver of this effect’s cost.

The cost depends on how many pixels receive this effect, which is why attenuation radius and outer
angle are important.  There is also a cost for each light that is in each pixel.

Excessive use of this effect may contribute to user-noticeable frame drops
and can cause the device to heat up in graphically demanding situations.
Monitor the thermal state and reduce usage as a mitigation, if necessary.
Apps can monitor thermal state changes by subscribing
to the <doc://com.apple.documentation/documentation/Foundation/NotificationCenter/MessageIdentifier/thermalStateDidChange>
notification.

To stay responsive to the device’s available thermal headroom, read
<doc://com.apple.documentation/documentation/Foundation/ProcessInfo/thermalState-swift.property>
and observe <doc://com.apple.documentation/documentation/Foundation/NotificationCenter/MessageIdentifier/thermalStateDidChange>
to react when it changes. As the reported state moves from `.fair` toward `.serious` and `.critical`,
reduce the attenuation radius or outer angle, or remove this component from lights where the effect
is not essential.

## Relationships

### Conforms To

[`Equatable`](/documentation/Swift/Equatable)

[`Component`](/documentation/RealityKit/Component)

---

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