user_scn and update_hfield() equivalents in Renderer class

Hi,

Is it possible to have the user_scn and update_hfield() from passive_viewer in Renderer? I want the screens of my viewer and render synchronized so I can record what I see. As in the video below, the above two features of the viewer help me visualize my results well. Due to these custom artifacts, I can only record them from an external screen recorder, which is a hassle.

https://github.com/google-deepmind/mujoco/assets/54435909/5b526f39-19f6-4a60-a026-9cfb5eba4741