I’m developing a 2D Unity project and implementing an AI pathfinding solution. The navigation system works well overall - my AI characters find paths correctly and avoid obstacles as intended. However, I’m facing a strange issue with the z-coordinate values. Even though I’m working in 2D space where everything should stay at z=0, my AI agents keep changing their z position while moving along their calculated routes. The starting location has z=0 and the destination also has z=0. When I check the waypoints along the path, they all show z=0 as well. But somehow the AI agent itself ends up with z values ranging from -8 to -2 during movement. I followed the standard 2D setup instructions and didn’t change any core pathfinding code. The AI prefab starts with transform position (0,0,0) but gets modified during runtime. Has anyone encountered similar z-axis problems with AI navigation in 2D projects? What might cause the pathfinding system to alter the z position when it should remain constant?
Yeah, this z-axis drift is way more common with Unity’s pathfinding than it should be. Hit this exact issue on my last 2D project - turns out NavMeshAgent was the problem. Even in 2D games, it runs in 3D space internally and applies gravity-like forces that mess with your z position over time. If you’re stuck with NavMeshAgent, set baseOffset to zero and handle updatePosition manually. Honestly though, I just ditched it completely and built a custom pathfinding system using only Vector2 coordinates. Better performance and zero z-axis headaches. Also check if you’ve got animation components on your AI prefab - they can mess with transforms indirectly. Look for position keyframes in your Animator controller that might be touching the z coordinate at runtime.
Had the exact same issue six months ago - drove me nuts for weeks. The problem isn’t your pathfinding, it’s how Unity handles transform updates during movement. You’re probably using Vector3.Lerp or similar interpolation that’s causing floating point errors on the z-axis. Check your camera following scripts or any interpolation between the agent’s position and target waypoint. Here’s what fixed it for me: lock the z position in your movement update loop. Just add transform.position = new Vector3(transform.position.x, transform.position.y, 0f) right after position updates. Also make sure your camera isn’t messing with agent positions through parent-child relationships in the hierarchy. This z-lock completely stopped the drifting without breaking pathfinding accuracy.
Check your Rigidbody2D settings if you’re using physics for movement. Hit this exact issue last year on a tower defense project.
Problem was using regular Rigidbody instead of Rigidbody2D on my AI agents. Even with position constraints, the 3D physics kept nudging z values during collisions and movement updates.
Switch to Rigidbody2D and freeze the Z position constraint in the inspector. Already using Rigidbody2D? Double check you’re calling MovePosition with Vector2 coordinates, not Vector3.
Another gotcha - make sure your NavMesh or pathfinding grid is actually flat at z=0. Sometimes the navigation surface gets warped during generation, especially if you’ve got 3D colliders in the scene that shouldn’t be there.
Quick debug: log the waypoint positions right before your agent moves to them. If those show non-zero z values, your pathfinding surface is the problem.