Event function that Unity calls before a Camera renders the scene.
In the Built-in Render Pipeline, Unity calls OnPreRender on MonoBehaviours that are attached to the same GameObject as an enabled Camera component, just before that Camera renders the scene. For a full description and code example, see MonoBehaviour.OnPreRender.
For similar functionality that does not require the script to be on the same GameObject as a Camera component, see Camera.onPreRender. For similar functionality in the Scriptable Render Pipeline, see RenderPipelineManager.