What causes a SmoothDamp velocity ref shared between values in Unity?

SmoothDamp stores its working state in the velocity ref parameter, so sharing one velocity across several independent SmoothDamp calls corrupts each call's internal state.

How do I catch this when it only happens for some players?

Capture it automatically from the player's device with the full stack trace, the device and OS, the build, and a breadcrumb trail of what they did. That turns a vague complaint into a specific, reproducible issue you can fix without owning the hardware it happens on.

How to Fix SmoothDamp Velocity Ref Shared Between Axes in Unity

Quick answer: Give every SmoothDamp call its own persistent velocity variable, and never pass a fresh local each frame, which would reset the smoothing and cause stutter.

If a value smoothed with SmoothDamp jitters, overshoots, or never settles, the velocity ref is being shared or reset. Each smoothed quantity needs its own stable velocity field. Here is how to fix it.

How to fix it

1. One velocity per value

Declare a separate Vector3 velocity (or float) field for each thing you SmoothDamp. A camera position and an FOV value must not share the same ref.

2. Keep the velocity persistent

The velocity must be a member field that survives across frames, not a local declared inside Update. A local resets to zero every frame and breaks the smoothing.

3. Reset velocity on teleport

When you snap the value instantly (a respawn or cut), zero the velocity ref so the next SmoothDamp does not lurch from stale momentum.

Catching the ones you can't reproduce

The hardest version of this to fix is the one you can't reproduce — it only happens on a player's hardware, OS, driver, or save state, under conditions that simply aren't present on your machine. A report that says “it crashed” or “it froze” gives you nothing to act on, so the bug survives release after release while quietly costing you players.

Automatic error capture closes that gap. Each failure arrives with its full stack trace, the device and OS, the build number, and a breadcrumb trail of what the player did right before it broke, so even a failure you have never seen becomes a specific, reproducible issue. Fold identical failures into one signature ranked by how many players each hits, and your worklist sorts itself worst-first instead of arriving as a stream of vague complaints.

This is where a tool like Bugnet earns its place. Its SDK captures every Unity error automatically with the full stack trace plus device, OS, memory, build, and game-state context, folds duplicates into one grouped issue with an occurrence count, and ties each to the build it first appeared on — so you fix the problem that hurts the most players first and confirm it is gone when its signature disappears from the next release.

Most of the time the fix is small. Seeing the failure clearly is the part that actually costs you.