I’m building a 2D Unity game and implementing pathfinding using the A* navigation system. The pathfinding works great - my characters find routes correctly and dodge obstacles perfectly. However, I’m running into a weird issue with the Z coordinate.
My character spawns at Z position 0 and the destination also has Z position 0. But while moving along the calculated path, the character’s Z value keeps changing randomly between -1 and -9. When I check the waypoints on the path, they all show Z position 0 like they should.
I followed the 2D setup guide exactly and didn’t change any of the package code. The character prefab has transform position set to (0,0,0) by default.
Has anyone encountered this Z-axis drift problem before? What might be causing the pathfinding to modify the Z coordinate during movement?
Yeah, this is a floating point precision issue with your movement interpolation. I’ve hit this exact problem before - it’s usually the movement script causing drift, not the pathfinding.
What are you using for movement? Vector3.MoveTowards or Vector3.Lerp? If you’re not locking the Z position during movement, Unity adds tiny floating point errors that build up over time.
Quick fix: add transform.position = new Vector3(transform.position.x, transform.position.y, 0f); right after your movement update. Better solution is to work with Vector2 and convert back to Vector3 with Z locked at 0.
I had this same issue on a mobile project last year. Pathfinding was perfect but movement script was the problem. Also check your camera - make sure it’s orthographic, not perspective. Perspective cameras cause weird Z behavior in 2D games.
This video covers A* implementation really well and shows proper 2D setup. The movement examples should help you avoid Z drift completely.
