fix(webclient): fix XR panel snapping to face away from user when dragged to the side

[yanziz-nvidia]

Closes #546

Summary

• Bug 1 (snap fix): The face-camera damp() call had no angle wrapping. The target yaw from setFromQuaternion lives in [-π, +π], so when the camera crosses near the side/behind the panel the target jumps from +π-ε to -π+ε — geometrically ~0° but numerically ~2π. damp() is a plain lerp so it took the ~2π wrong-way path, spinning the panel to face backward. Fix normalizes the diff to [-π, π] before calling damp().
• Bug 2 (yaw accuracy): The old code used setFromUnitVectors(zAxis, dir3D) + setFromQuaternion('YXZ') to get the horizontal yaw. Because dir3D included the camera's height offset, the 3D shortest-path quaternion's Euler Y was not the true horizontal yaw. Replaced with Math.atan2(dx, dz) on the XZ plane — simpler and correct.

Test plan

• Enter XR session and drag the panel to the far left or right of your FOV
• Walk close to the side of the panel so the camera is nearly level with its edge — panel should continue facing you, not snap away
• Walk behind the panel — it should smoothly rotate to re-face you
• Verify normal forward-facing behaviour is unchanged

🤖 Generated with Claude Code

[coderabbitai]

📝 Walkthrough

Walkthrough

CloudXRUI.tsx refactors the face-camera rotation implementation to remove quaternion and Euler conversions. The module now imports only essential Three.js types, retains position-vector helpers for computing projected coordinates on the XZ plane, and directly computes target yaw using atan2 from those projections. Angular deltas are normalized to the range [-π, π] for shortest-path interpolation, and the group rotation is dampened toward the computed target, replacing the prior quaternion-to-Euler (YXZ) extraction logic.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title directly describes the main bug fix: correcting XR panel snapping behavior when dragged to the side, which matches the core objective of fixing face-camera rotation logic.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/webclient-panel-face-away-snap

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[yanziz-nvidia]

See https://nvidia.github.io/IsaacTeleop/preview/pr-629/client/#/sim

[gareth-morgan-nv]

LGTM. Maybe add a test?