Limit rigidbody movement in X direction

Unity Engine
1

Hi guys,

I’m using the rigidbody character controller from the Unity wiki to move an AI character. I’ve replaced the inputs with Vector 3 (0,0,1) so that movement is only in the Z axis. and am controlling the movement with a pathfinding script. I’m getting a lot of “skating” in the X direction. I want to limit the movement to the character’s Z axis only. In other words, I want to prevent it from sliding sideways on the terrain. This is an insect type character so to be realistic, it has to move only in the forward direction. Here’s the script I’m using. Just wondering if any of you amazing coders out there can make a suggestion as to how to fix it. Thanks in advance. Here’s the code:

using UnityEngine;
using System.Collections;
 
[RequireComponent (typeof (Rigidbody))]
[RequireComponent (typeof (CapsuleCollider))]
 
public class CharacterControls : MonoBehaviour {
 
	public float speed = 10.0f;
	public float gravity = 10.0f;
	public float maxVelocityChange = 10.0f;
	public bool canJump = true;
	public float jumpHeight = 2.0f;
	private bool grounded = false;
 
 
 
	void Awake () {
	    rigidbody.freezeRotation = true;
	    rigidbody.useGravity = false;
	}
 
	void FixedUpdate () {
	    if (grounded) {
	        // Calculate how fast we should be moving
	        Vector3 targetVelocity = new Vector3 (0,0,1);
	        targetVelocity = transform.TransformDirection(targetVelocity);
	        targetVelocity *= speed;
 
	        // Apply a force that attempts to reach our target velocity
	        Vector3 velocity = rigidbody.velocity;
	        Vector3 velocityChange = (targetVelocity - velocity);
	        velocityChange.x = Mathf.Clamp(velocityChange.x, -maxVelocityChange, maxVelocityChange);
	        velocityChange.z = Mathf.Clamp(velocityChange.z, -maxVelocityChange, maxVelocityChange);
	        velocityChange.y = 0;
	        rigidbody.AddForce(velocityChange, ForceMode.VelocityChange);
 
	        // Jump
	        if (canJump  Input.GetButton("Jump")) {
	            rigidbody.velocity = new Vector3(velocity.x, CalculateJumpVerticalSpeed(), velocity.z);
	        }
	    }
 
	    // We apply gravity manually for more tuning control
	    rigidbody.AddForce(new Vector3 (0, -gravity * rigidbody.mass, 0));
 
	    grounded = false;
	}
 
	void OnCollisionStay () {
	    grounded = true;    
	}
 
	float CalculateJumpVerticalSpeed () {
	    // From the jump height and gravity we deduce the upwards speed 
	    // for the character to reach at the apex.
	    return Mathf.Sqrt(2 * jumpHeight * gravity);
	}
}
2

In Update or LateUpdate

rigidbody.position = Vector3(rigidbody.position.x, rigidbody.position.y, 0); //limit z

Also add constrain z in the rigidbody (but this is no guarantee I’ve noticed)