Navmesh Ai Upgrade

Hi there! I have been developing a game using the FPS tutorial as a base. I like the patrol AI but half the time my enemies get stuck. Also when detecting an enemy they run striate at the player’s last know position, making them very dumb and easy to outsmart. I was wondering if anyone out there knew enough about Navmesh (I myself do not understand it) to upgrade the ai to where they will track the player, and yet have few mishaps with animation.

Thanks in advance!

Sincerely, The Noob of Noobs.

AI script.

var speed = 3.0;
var rotationSpeed = 5.0;
var shootRange = 15.0;
var attackRange = 30.0;
var shootAngle = 4.0;
var dontComeCloserRange = 5.0;
var delayShootTime = 0.35;
var pickNextWaypointDistance = 2.0;
var target : Transform;

private var lastShot = -10.0;

// Make sure there is always a character controller
@script RequireComponent (CharacterController)

function Start () {
	// Auto setup player as target through tags
	if (target == null && GameObject.FindWithTag("Player"))
		target = GameObject.FindWithTag("Player").transform;

	Patrol();
}

function Patrol () {
	var curWayPoint = AutoWayPoint.FindClosest(transform.position);
	while (true) {
		var waypointPosition = curWayPoint.transform.position;
		// Are we close to a waypoint? -> pick the next one!
		if (Vector3.Distance(waypointPosition, transform.position) < pickNextWaypointDistance)
			curWayPoint = PickNextWaypoint (curWayPoint);

		// Attack the player and wait until
		// - player is killed
		// - player is out of sight		
		if (CanSeeTarget ())
			yield StartCoroutine("AttackPlayer");
		
		// Move towards our target
		MoveTowards(waypointPosition);
		
		yield;
	}
}


function CanSeeTarget () : boolean {
	if (Vector3.Distance(transform.position, target.position) > attackRange)
		return false;
		
	var hit : RaycastHit;
	if (Physics.Linecast (transform.position, target.position, hit))
		return hit.transform == target;

	return false;
}

function Shoot () {
	// Start shoot animation
	animation.CrossFade("shoot", 0.3);

	// Wait until half the animation has played
	yield WaitForSeconds(delayShootTime);
	
	// Fire gun
	BroadcastMessage("Fire");
	
	// Wait for the rest of the animation to finish
	yield WaitForSeconds(animation["shoot"].length - delayShootTime);
}

function AttackPlayer () {
	var lastVisiblePlayerPosition = target.position;
	while (true) {
		if (CanSeeTarget ()) {
			// Target is dead - stop hunting
			if (target == null)
				return;

			// Target is too far away - give up	
			var distance = Vector3.Distance(transform.position, target.position);
			if (distance > shootRange * 3)
				return;
			
			lastVisiblePlayerPosition = target.position;
			if (distance > dontComeCloserRange)
				MoveTowards (lastVisiblePlayerPosition);
			else
				RotateTowards(lastVisiblePlayerPosition);

			var forward = transform.TransformDirection(Vector3.forward);
			var targetDirection = lastVisiblePlayerPosition - transform.position;
			targetDirection.y = 0;

			var angle = Vector3.Angle(targetDirection, forward);

			// Start shooting if close and play is in sight
			if (distance < shootRange && angle < shootAngle)
				yield StartCoroutine("Shoot");
		} else {
			yield StartCoroutine("SearchPlayer", lastVisiblePlayerPosition);
			// Player not visible anymore - stop attacking
			if (!CanSeeTarget ())
				return;
		}

		yield;
	}
}

function SearchPlayer (position : Vector3) {
	// Run towards the player but after 3 seconds timeout and go back to Patroling
	var timeout = 3.0;
	while (timeout > 0.0) {
		MoveTowards(position);

		// We found the player
		if (CanSeeTarget ())
			return;

		timeout -= Time.deltaTime;
		yield;
	}
}

function RotateTowards (position : Vector3) {
	SendMessage("SetSpeed", 0.0);
	
	var direction = position - transform.position;
	direction.y = 0;
	if (direction.magnitude < 0.1)
		return;
	
	// Rotate towards the target
	transform.rotation = Quaternion.Slerp (transform.rotation, Quaternion.LookRotation(direction), rotationSpeed * Time.deltaTime);
	transform.eulerAngles = Vector3(0, transform.eulerAngles.y, 0);
}

function MoveTowards (position : Vector3) {
	var direction = position - transform.position;
	direction.y = 0;
	if (direction.magnitude < 0.5) {
		SendMessage("SetSpeed", 0.0);
		return;
	}
	
	// Rotate towards the target
	transform.rotation = Quaternion.Slerp (transform.rotation, Quaternion.LookRotation(direction), rotationSpeed * Time.deltaTime);
	transform.eulerAngles = Vector3(0, transform.eulerAngles.y, 0);

	// Modify speed so we slow down when we are not facing the target
	var forward = transform.TransformDirection(Vector3.forward);
	var speedModifier = Vector3.Dot(forward, direction.normalized);
	speedModifier = Mathf.Clamp01(speedModifier);

	// Move the character
	direction = forward * speed * speedModifier;
	GetComponent (CharacterController).SimpleMove(direction);
	
	SendMessage("SetSpeed", speed * speedModifier, SendMessageOptions.DontRequireReceiver);
}

function PickNextWaypoint (currentWaypoint : AutoWayPoint) {
	// We want to find the waypoint where the character has to turn the least

	// The direction in which we are walking
	var forward = transform.TransformDirection(Vector3.forward);

	// The closer two vectors, the larger the dot product will be.
	var best = currentWaypoint;
	var bestDot = -10.0;
	for (var cur : AutoWayPoint in currentWaypoint.connected) {
		var direction = Vector3.Normalize(cur.transform.position - transform.position);
		var dot = Vector3.Dot(direction, forward);
		if (dot > bestDot && cur != currentWaypoint) {
			bestDot = dot;
			best = cur;
		}
	}
	
	return best;
}

Sounds like you need some pathfinding. Running in a straight line will often cause the problems you describe, as the AI are basically just running blindly, without regard to their actual environment. In general, AI should pick a goal position, compute a path to that position, and then follow the path. Also check out NavMeshAgent which can make moving along the NavMesh a lot easier.