How about glfw.window_hint(glfw.VISIBLE, 1) explicitly in the constructor?

[Qualot]

Thank you for the helpful software!

Our team uses mujoco.renderer and this MujocoViewer at the same time.
mujoco.renderer is for segmentation/depth rendering.

After the initialization of a renderer,
The viewer window does not appear.

I think that the constructor of renderer executes the following code
https://github.com/google-deepmind/mujoco/blob/2.3.7/python/mujoco/renderer.py#L80
https://github.com/google-deepmind/mujoco/blob/2.3.7/python/mujoco/glfw/__init__.py#L25

This is the MWE.

import mujoco
import mujoco_viewer
import glfw


model = mujoco.MjModel.from_xml_path('humanoid.xml')
data = mujoco.MjData(model)

renderer = mujoco.Renderer(model)

#Commenting out this line hides the viewer window
glfw.window_hint(glfw.VISIBLE, 1)

# create the viewer object
viewer = mujoco_viewer.MujocoViewer(model, data)

# simulate and render
for _ in range(10000):
    if viewer.is_alive:
        mujoco.mj_step(model, data)
        viewer.render()
    else:
        break

# close
viewer.close()

I think adding the line of glfw.window_hint(glfw.VISIBLE, 1) like
https://github.com/rohanpsingh/mujoco-python-viewer/blob/main/mujoco_viewer/mujoco_viewer.py#L46-L47
would solve this problem of unexpected hidden window.

It should be noted that using renderer and viewer.render() in the loop would require the context switching as the following issue.
#35

On the other hand, I guess that the frame buffer part does not need modifications because
https://github.com/rohanpsingh/mujoco-python-viewer/blob/main/mujoco_viewer/mujoco_viewer.py#L49-L50
automatically sets the active buffer to the default window.

What do you think of these?
If these sound reasonable, I would send a PR.