Interactive viewer mouse controls crash with MuJoCo >= 3.11 (gymnasium mjv_moveCamera incompatibility)

[ratheron]

Summary

Mouse interaction (drag to rotate/pan, scroll to zoom) in the interactive sim.render(mode="human") window crashes with a TypeError when using MuJoCo >= 3.11.0 together with gymnasium 1.3.0. Offscreen rendering (rgb_array, depth_array, rgbd_tuple) is unaffected.

This is not a bug in Crazyflow itself, but it affects every user on our current lockfiles (mujoco 3.12.0 + gymnasium 1.3.0), so we should decide how to handle it.

Reproduction

pixi run -e tests python examples/plugins/disturbance.py

Then drag the camera with the mouse in the viewer window.

Traceback

  File "crazyflow/sim/sim.py", line 248, in render
    return self.viewer.render(mode)
  File ".../gymnasium/envs/mujoco/mujoco_rendering.py", line 600, in _cursor_pos_callback
    mujoco.mjv_moveCamera(
        self.model, action, dx / width, dy / height, self.scn, self.cam
    )
TypeError: mjv_moveCamera(): incompatible function arguments. The following argument types are supported:
    1. (m: MjModel, action: int, reldx: float, reldy: float, cam: MjvCamera) -> None

Root cause

• MuJoCo 3.11.0 (2026-07-28) made a breaking API change: "Removed unneeded mjvScene argument from mjv_moveCamera" (changelog). The function now takes 5 arguments instead of 6.
• gymnasium 1.3.0 (2026-04-22, latest release on PyPI) predates that change and still passes self.scn in WindowViewer._cursor_pos_callback and _scroll_callback.
• Crazyflow only uses gymnasium.envs.mujoco.mujoco_rendering.MujocoRenderer (crazyflow/sim/sim.py) and never calls mjv_moveCamera directly.

Gymnasium has already fixed this on main in Farama-Foundation/Gymnasium#1678 (merged 2026-08-29) via a _MUJOCO_CAMERA_LEGACY_MODE version check, but no release containing the fix exists yet.

Options

1. Do nothing and wait for the next gymnasium release. Simplest; the GUI stays broken for everyone on a fresh install until then.
2. Constrain MuJoCo in pyproject.toml: "mujoco>=3.3.0,<3.11" and "mujoco-mjx>=3.3.0,<3.11", re-lock, and lift the bound once gymnasium ships the fix. Note that a !=3.11.*,!=3.12.* exclusion (like the existing jax!=0.10.2) doesn't really fit: the incompatibility is between a pair of packages, and every future MuJoCo release would be broken too until gymnasium releases.
3. Add a temporary compatibility shim in sim.py for mode="human": if mujoco.__version__ >= 3.11 and gymnasium's mujoco_rendering has no _MUJOCO_CAMERA_LEGACY_MODE, wrap the viewer's cursor/scroll callbacks to call mjv_moveCamera without scn. ~15 lines, keeps MuJoCo 3.12 available, removable when gymnasium releases.
4. Drop the gymnasium renderer and move to mujoco.viewer (passive viewer) for human mode. Larger change, but removes a dependency on gymnasium internals that has now bitten us. Would need to replace add_marker usage in crazyflow/sim/visualize.py.

I would go for 2. Is there a reason we have bumped Python to 3.14 @amacati and thus allowed for newer mujoco versions?

[amacati]

Let's wait for the gym fix and then pin the new version