How to Fix the Dot Product Sign Wrong for a Facing Check in Unity

An enemy that shoots at things behind it, or a stealth check that triggers from the wrong side, usually has its dot product set up wrong. Getting the operands and sign right fixes the facing logic. Here is how.

How to fix it

1. Use forward and direction-to-target

The correct test is Vector3.Dot(transform.forward, dirToTarget) where dirToTarget = (target.position - transform.position).normalized. A positive dot means the target is ahead.

2. Threshold with a cosine for a cone

For a field-of-view cone, compare the dot against Mathf.Cos(halfAngle * Mathf.Deg2Rad) rather than zero, so only targets inside the cone count as seen.

3. Normalize both operands

If either vector is unnormalized the dot is scaled by its length and your threshold no longer corresponds to an angle. Normalize before comparing.

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.