Draft: The content on this page is complete, but it has not been reviewed yet.

Experimental: This feature is currently experimental and is subject to change in later major versions. To use this feature, enable Experimental Operators/Blocks in the Visual Effects tab of your Project's Preferences.

# Spawner Callbacks Spawner Callbacks is a C# API that enables defining custom runtime behavior and create new Blocks for use in Spawn Contexts. Spawner Callbacks enable you do the following: * Control the Spawn Context state (Playing, Stopped, Delayed) * Read/Write the Output Spawn Count * Read/Write SpawnEvent Attributes ## Writing Spawner Callbacks The full reference of the API is available [here](https://docs.unity3d.com/2019.3/Documentation/ScriptReference/VFX.VFXSpawnerCallbacks.html).