MonoBehaviour.OnPreCull()

Description

Event function that Unity calls before a Camera culls the scene.

In the Built-in Render Pipeline, Unity calls OnPreCull on MonoBehaviours that are attached to the same GameObject as an enabled Camera component, just before that Camera performs the culling operation that determines what it can see. Use OnPreCull to execute your own code at this point in the render loop; for example, you can change the Camera's settings before performing the culling operation, to affect what the Camera sees. OnPreCull can be a coroutine.

For similar functionality that does not require the script to be on the same GameObject as a Camera component, see Camera.onPreCull. For similar functionality in the Scriptable Render Pipeline, see RenderPipelineManager.

// Attach this to the same GameObject as a Camera component.
// This script inverts the view of the Camera, so that everything rendered by it is flipped

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour
{
    Camera cam;

    void Start()
    {
        cam = GetComponent<Camera>();
    }

    void OnPreCull()
    {
        cam.ResetWorldToCameraMatrix();
        cam.ResetProjectionMatrix();
        cam.projectionMatrix = cam.projectionMatrix * Matrix4x4.Scale(new Vector3(1, -1, 1));
    }

    void OnPreRender()
    {
        GL.invertCulling = true;
    }

    void OnPostRender()
    {
        GL.invertCulling = false;
    }
}

Additional resources: Camera.onPreCull, MonoBehaviour.OnPreRender, MonoBehaviour.OnPostRender, CommandBuffer, Extending the Built-in Render Pipeline using CommandBuffers.