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Question by Jansen · Jun 16, 2010 at 11:16 PM · physicsraycastlinecast

Linecast and target visibility

Hello,

I am attempting to use the AI script to create simple behaviors. When using the 'First Person Controller' as the target for the AI script to hunt down and attack, it works fine. When I use the AI characters themselves as the transform target for each other, they follow their Waypoint paths normally and do not attempt to attack each other or move toward each other. Has anyone attempted this or knows if their are sections in the AI script that require the First Person Controller as the target? Or are there inherent elements in the Character Controller that the AI script is communicating with?

I'm out of solutions :(

Thank you for reading my essay length question, Jansen

The code is from Unity's FPS tutorial:

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;

public var atDesk : boolean = false;

var useWaypointSet = 0;

private var lastShot = -10.0;

var pastroll : boolean = true;

// 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;

 if(useWaypointSet == 0)
 {
     Patrol();
 }
 else if(useWaypointSet == 1)
 {
     Patrolone();
 }

}

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 Patrolone () { var curWayPoint = AutoWayPoint1.FindClosest(transform.position); while (pastroll) { var waypointPosition = curWayPoint.transform.position; // Are we close to a waypoint? -> pick the next one! if (Vector3.Distance(waypointPosition, transform.position) < pickNextWaypointDistance && atDesk == false) curWayPoint = PickNextWaypoint1 (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 &gt; shootRange * 3)
             return;

         lastVisiblePlayerPosition = target.position;
         if (distance &gt; 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 player is in sight
         if (distance &lt; shootRange &amp;&amp; angle &lt; 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 &lt; 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 &gt; bestDot &amp;&amp; cur != currentWaypoint) {
         bestDot = dot;
         best = cur;
     }
 }

 return best;

}

function PickNextWaypoint1 (currentWaypoint : AutoWayPoint1) { // 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 : AutoWayPoint1 in currentWaypoint.connected) {
     var direction = Vector3.Normalize(cur.transform.position - transform.position);
     var dot = Vector3.Dot(direction, forward);
     if (dot &gt; bestDot &amp;&amp; cur != currentWaypoint) {
         bestDot = dot;
         best = cur;
     }
 }

 return best;

}

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avatar image e-bonneville · Jun 17, 2010 at 12:47 AM 0
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Could you perhaps post your script? Thanks.

avatar image Jansen · Jun 17, 2010 at 05:46 PM 0
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I posted the entire AI script for reference. You'll find the 'target' variable used in CanSeeTarget() and AttackPlayer().

avatar image Jason_DB · Jun 17, 2010 at 11:26 PM 0
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Try putting a Debug in CanSeeTarget() to check whether they detect their targets.

avatar image Jansen · Jun 18, 2010 at 12:18 AM 0
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So after a series of Debugs in CanSeeTarget(), when the two characters get within 'attackRange' it breaks out of that if statement, but does not get passed the next if statement doing the Linecast between the two positions...
What would cause the Linecast to fail between the two characters?

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Answer by Ricardo · Jun 28, 2010 at 07:19 AM

Hello Jansen,

If your trouble is with the Linecast as you mention on the comments, try doing a Debug.DrawRay like I suggested here, as your linecast might be undershooting the mark or hitting another collider on the way.

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