reseting the depth buffer mid frame

You can do this.

Panda’s rendering loop has quite a few clears in it:

for all windows by window sort order do:
  if win.clear_depth then clear depth buffer of entire window
  if win.clear_color then clear color buffer of entire window
  for all displayregion by displayregion sort order do:
    cam = displayregion.camera
    if cam.clear_depth then clear depth buffer of displayregion
    if cam.clear_color then clear color buffer of displayregion
    render camera into specified region of window

So basically, all you need to do is create a new displayregion in the window with a new camera, and set the camera to clear the depth buffer of its region.

Here’s a recent thread that shows how:

discourse.panda3d.org/viewtopic.php?t=3335