# size The initial size of the particle as a 2D vector representing width and height. ``` var size: SIMD2 { get set } ``` ## Discussion For most particle systems, this represents the billboard size in world space units. - `x` component: width of the particle - `y` component: height of the particle Equal values create square particles, while different values create rectangular particles. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)