MonoBehaviour.OnRenderObject()

Description

OnRenderObject is called after camera has rendered the Scene.

This can be used to render your own objects using Graphics.DrawMeshNow or other functions. This function is similar to OnPostRender, except OnRenderObject is called on any object that has a script with the function; no matter if it's attached to a Camera or not.

using System.Collections;
using UnityEngine;

public class ExampleClass : MonoBehaviour
{
    public Mesh mainMesh;
    public Mesh miniMapMesh;

    void OnRenderObject()
    {
        // Render different meshes for the object depending on whether
        // the main camera or minimap camera is viewing.
        if (Camera.current.name == "MiniMapcam")
        {
            Graphics.DrawMeshNow(miniMapMesh, transform.position, transform.rotation);
        }
        else
        {
            Graphics.DrawMeshNow(mainMesh, transform.position, transform.rotation);
        }
    }
}