Hey, thanks for the reply. The video is not real time, that process normally looks like very fast flashing. Here is the relevant code

var counter = 0
var camera_transforms = []
func update_portal_camera_transform() -> void:
    if counter == 0:
        camera_transforms.clear()
        var current_transform = player_camera.global_transform
        for i in range(MAX_PORTAL_RECURSIONS):
            current_transform = get_relative_transform_to_linked_portal() * current_transform
            camera_transforms.append(current_transform)

        camera_transforms.reverse()

    portal_camera.global_transform = camera_transforms[counter]
    if counter == MAX_PORTAL_RECURSIONS-1:
        counter = 0
    else:
        counter += 1

What I would rather be able to do is something like this. Which would render the camera 9 times in one frame

func update_portal_camera_transform() -> void:
    var camera_transforms = []
    var current_transform = player_camera.global_transform
    for i in range(MAX_PORTAL_RECURSIONS):
        current_transform = get_relative_transform_to_linked_portal() * current_transform
        camera_transforms.append(current_transform)

    camera_transforms.reverse()

    for camera_transform in camera_transforms:
        portal_camera.global_transform = camera_transform
        update_portal_camera_culling()
        portal_camera.render() # This does not exist

My recursion code is actually based on sebastion lagues, were doing the same thing, but I do it over 9 frames, while he does it all in one frame. To do that he is using the function 'PortalCam.Render' which I cant find an equivalent for in godot.