Don't clear anything.
This will leave colors and depth buffer from the previous frame or whatever was displayed before. See Also: Camera.clearFlags property, camera component.
// Don't clear anything
camera.clearFlags = CameraClearFlags.Nothing;
using UnityEngine;
using System.Collections;
public class example : MonoBehaviour {
void Example() {
camera.clearFlags = CameraClearFlags.Nothing;
}
}
import UnityEngine
import System.Collections
class example(MonoBehaviour):
def Example():
camera.clearFlags = CameraClearFlags.Nothing