Texture which displays the content of a Viewport.
To create a ViewportTexture in code, use the Viewport.get_texture method on the target viewport.
Note: When local to scene, this texture uses Resource.setup_local_to_scene to set the proxy texture and flags in the local viewport.
NodePath viewport_path =
The path to the Viewport node to display. This is relative to the scene root, not to the node which uses the texture.