The duration, in seconds, for which particles are spawned before the system is first rendered. Animatable.
- iOS 8.0+
- macOS 10.10+
- Mac Catalyst 13.0+
- tvOS 9.0+
- watchOS 3.0+
The default value is
0 seconds, specifying that the system begins emitting particles on the first frame SceneKit renders it in. Change this value to “fast forward” the particle system so that it appears to have been running for some amount of time when it is first rendered.
For example, consider a particle system that simulates falling snow. With the default behavior, the scene is initially clear of snowflakes, which only begin to fall as the scene appears. If you set a
warmup duration of several seconds, the scene will be already filled with falling snow when it first appears.
You can animate changes to this property’s value. See Animating SceneKit Content.