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  "title" : "Emitter Render Order"
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# Emitter Render Order

These constants specify the order that emitter cells are composited. They are used by the [`renderMode`](/documentation/QuartzCore/CAEmitterLayer/renderMode) property.

## Topics

### Constants

[`static let unordered: CAEmitterLayerRenderMode`](/documentation/QuartzCore/CAEmitterLayerRenderMode/unordered)

Particles are rendered unordered. This mode uses source-over compositing.

[`static let oldestFirst: CAEmitterLayerRenderMode`](/documentation/QuartzCore/CAEmitterLayerRenderMode/oldestFirst)

Particles are rendered oldest first. This mode uses source-over compositing.

[`static let oldestLast: CAEmitterLayerRenderMode`](/documentation/QuartzCore/CAEmitterLayerRenderMode/oldestLast)

Particles are rendered oldest last. This mode uses source-over compositing.

[`static let backToFront: CAEmitterLayerRenderMode`](/documentation/QuartzCore/CAEmitterLayerRenderMode/backToFront)

Particles are rendered from back to front, sorted by z-position. This mode uses source-over compositing.

[`static let additive: CAEmitterLayerRenderMode`](/documentation/QuartzCore/CAEmitterLayerRenderMode/additive)

The particles are rendered using source-additive compositing.


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