feat: VR camera fly mode (RC Mode 2 twin-stick controls)

[towneh]

Summary

Adds a VR "fly mode" to the handheld capture camera in to provide a much greater degree of freedom for film-making, streaming and taking photos, using RC "Mode 2" twin-stick controls.

Fly Mode activate and recall is on the B/Y button, replacing the old thumbstick-click toggle. The thumbstick toggle was one motivation: repeated stick-clicks wears the thumbstick over time and presents a negative user association.

Proposal: Hold the camera, quick press B/Y → it detaches to world space and both hands pilot. quick press B/Y again → it returns to hand.

Twin-stick mapping (RC Mode 2):

Axis	Stick	Effect
Throttle	pilot Y	Altitude — straight world-up/down, heading-independent
Yaw	pilot X	Rate-based turn; heading holds when the stick re-centres
Pitch	free Y	Forward / back, relative to heading
Roll	free X	Strafe, relative to heading

While flying, the avatar is pinned in place via look / movement / crouch locks.

Built on the existing fly infrastructure (CameraPinSpace.WorldSpace, the pin constraint, and the existing fly-speed / acceleration / momentum fields) rather than new scaffolding — only a yawRate tunable is added.

Desktop fly mode is unchanged.

Two commits

• fix: gate VR turn on the LookRotation lock — the snap/smooth-turn block applied controller turn input unconditionally, so a held LookRotation lock suppressed desktop look but not VR stick-turn. Added a lock guard mirroring the existing MovementLock guard. Without this, the pilot stick's yaw would also rotate the avatar while flying. This is a small change to a shared control path (BasisLocalCharacterDriver), so it is called out separately.
• feat: VR camera fly mode with RC Mode 2 twin-stick controls — the fly mode itself, entirely within BasisHandHeldCameraInteractable.

Required checks

All boxes below must be ticked before this PR can merge. If a check is genuinely N/A, tick it anyway and explain under Notes.

• Tested — I built and ran this locally. The change works in the editor and (where relevant) in a built player.
• Transform access is combined and limited — In hot paths, transform reads/writes go through TransformAccessArray or are otherwise batched. I have not added per-frame transform.position / transform.rotation / transform.localPosition calls inside loops. Whenever I need both position and rotation, I use the combined APIs — SetPositionAndRotation / SetLocalPositionAndRotation for writes, GetPositionAndRotation / GetLocalPositionAndRotation for reads — instead of two separate property accesses; the combined call does one local-to-world matrix traversal instead of two.
• Addressables used for asset/memory loading — Any new asset loads go through Addressables. No new Resources.Load, no direct asset references that pull large content into memory on scene load.
• No new GetComponent / AddComponent where avoidable — Where unavoidable, the result is cached on a field, and any GetComponent<T> is replaced with TryGetComponent<T>(out var x) — bare GetComponent will be denied. TryGetComponent is the modern API (Unity 2019.2+) and skips the Editor-only GC allocation GetComponent causes when a component is missing: Unity wraps the null return in a managed "fake null" object so its overloaded == operator can still detect destroyed C++ objects, and constructing that wrapper allocates; TryGetComponent returns a bool plus out parameter and never builds the wrapper. None of these calls run inside Update, LateUpdate, FixedUpdate, jobs, or other per-frame code paths.
• Per-frame work is scheduled through BasisEventDriver — Any new per-frame work hooks into BasisEventDriver rather than adding standalone Update / LateUpdate / FixedUpdate callbacks on a MonoBehaviour.
• Anything added to BasisEventDriver is bulletproof, or guarded by try/catch — BasisEventDriver runs the single per-frame tick that drives the whole framework (network apply, local player sim, blendshapes, JigglePhysics, nameplates, and more) as one sequential chain. An unhandled exception anywhere in that chain aborts the rest of the tick, so every step after the throwing one is silently skipped for that frame. New work added to the driver must either be guaranteed not to throw, or be wrapped in a try/catch that contains the failure and surfaces it through BasisDebug — logged once / rate-limited, never every frame (see the existing HVRBasisBuiltInAddresses.Simulate() guard for the pattern). Expect this to be scrutinized closely in review.
• Considered jobification — I asked whether this work can be moved to a Unity Job (Burst-compiled where possible). If it can, it is. If it cannot, the reason is in Notes.
• No needless { get; set; } properties or access lockdowns — Public fields are fine; Basis is meant to be read and modified freely, so don't wall things off private/internal without a real reason. Don't wrap a field in { get; set; } when the accessors do nothing — property accessors have a real performance cost vs direct field access, and the lead maintainer prefers plain fields (or a method / setter-only property when only the setter needs logic) over a noop-getter pair. For .Instance singletons, callers reassigning Type.Instance is allowed; if that would break your code, log a warning or throw — don't block the assignment. Locking down access is not your call.
• Camera access goes through BasisLocalCameraDriver — Code that needs the local camera (transform, projection, rig data, etc.) pulls it from BasisLocalCameraDriver rather than looking one up itself. Don't roll a separate camera discovery path.
• Logging uses BasisDebug — All new logging calls go through BasisDebug.Log / BasisDebug.LogWarning / BasisDebug.LogError (with an appropriate LogTag) instead of UnityEngine.Debug.Log / Debug.LogWarning / Debug.LogError. BasisDebug routes through Basis's tagged, color-coded logger and respects the project-wide LoggingDisabled toggle so logging can be killed at runtime; bare Debug.Log calls bypass that and will be denied.
• No scene-wide discovery for dependencies — New code is architected so it does not need FindObjectOfType / FindObjectsOfType / GameObject.Find / FindGameObjectsWithTag to locate what it depends on. References are wired in — registered through an existing manager/driver, injected at init, or passed in by the caller — rather than discovered by scanning the scene at runtime. If a scene scan is genuinely unavoidable, justify it under Notes.
• No allocations in hot paths — Per-frame code (Update / LateUpdate / FixedUpdate, simulation loops, jobs, anything called once per frame or more) does not allocate. No new on reference types, no LINQ, no string concatenation/interpolation, no boxing, no foreach over interface-typed collections. Allocate once at init and reuse the buffer.
• No debugging in hot paths — No log calls of any kind on per-frame paths, including BasisDebug. Hot-path logging floods the console and incurs cost on every frame regardless of whether the message is filtered out downstream. If a hot-path log is needed while iterating, gate it behind #if UNITY_EDITOR and remove (or leave gated) before merge.
• Hot-path collection access is optimized — Cache .Count (lists) / .Length (arrays) into a local int before the loop instead of re-reading the property each iteration. Prefer T[] (with a separate length int when the array is over-sized) over List<T> where the data is hot — Unity's mono BCL doesn't expose CollectionsMarshal.AsSpan(List<T>), so a list can't be fed into Span<T> / unsafe paths cleanly. Where the perf justifies it, drop into Span<T> / ref locals / Unsafe.As / unsafe pointer code to skip bounds checks and copies, and call out the invariants you're relying on under Notes so reviewers can sanity-check them.

Testing details

Tick the platforms you actually tested on. Leave the rest unticked — these are informational and do not block merge.

• Windows
• Linux
• Android
• iOS
• macOS

Input / control mode coverage:

• Tested in VR (note headset under Notes)
• Tested in desktop / non-VR mode
• Tested with phone controls (mobile touch input)
• N/A — change does not touch player/XR/input code

Where applicable, confirm these flows still work after your changes:

• Hot-switching (desktop ↔ VR mode swap at runtime)
• Avatar swapping
• Server swapping (joining / leaving / changing servers)
• N/A — change does not touch any of the above

Notes

Draft — not merge-ready yet. open items:

1. Not yet built locally

2. Known interaction: left-hand B/Y also opens the hamburger menu. The hamburger menu is bound to the left-hand secondary button (BasisActionDriver), so launching/recalling with the left hand as pilot also toggles the menu. Right-hand piloting is clean. This is intentionally not fixed here — the fix is tracked in feat: gate hamburger/quick menu behind a brief delayed hold gesture #838

Checklist context:

• Jobification — N/A. Single-camera flight integration on the local player only; a handful of vector ops per frame, not job-worthy.
• Camera access — operates on the handheld camera's own captureCamera (the prop's capture camera), not the local player camera, so BasisLocalCameraDriver discovery does not apply.
• BasisEventDriver — per-frame work runs via the existing BasisLocalPlayer.AfterSimulateOnLate registration; no new Update/standalone tick added.
• Hot path — MoveVRFlying runs per frame; it allocates nothing (Vector3/Quaternion are value types) and logs nothing. The only BasisDebug calls are on the launch/recall edges.