How to make an object follow on 1 axis??

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Howdy:

I'm taking a scripting class this semester and I need some help. I've been researching now for about half an hour and I can find a lot of questions that are sort of what I need, but not exactly, and I can't seem to successfully adapt any of the answers to what I'm working on.

I'm making a side scrolling "endless runner". It scrolls right to left and you control a character in the center that can move forward & backward 3 spaces and left & right 5 spaces (relative to the character). You are being chased by an enemy (both the enemy & the character are simple cubes at this point) that follows behind you and follows your movement along the Z coordinate.

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I've kinda sorta got it working but I think there's a better solution out there and would like so suggestions. I've tried understanding Vector3.Lerp & Vector3.MoveTowards, but I can't make them do what I need them to do.

Let me preface all of this by saying that I just started working with Unity this semester so I'm a complete newbie at all this, and have limited programming skills (took an introductory C++ class last semester), so please bear that in mind when replying.

Here's the following cube's code that "sorta works":

 #pragma strict
 
 function Start () 
 {
 
 }
 
 var IceKingSpeed = 20; // IceKing's movement speed
 //var IceKingDelay = 0.5; // The amount of time (in seconds) the IceKing delays before following Finn
 var zIceKing : float;
 var IceKingzPosMoveLimit = 15;
 var IceKingzNegMoveLimit = 3;
 var IceKingKnockBack = 0.01;
 var target : Transform;
 var smooth = 5.0;
 
 function Update () 
 {
 //  Debug.Log("IceKing's z Position => [" + zIceKing + "] & IceKing's x Position => [" + xIceKing + "]"); // Shows the z position of Finn
 //  Basic Tracing Movement
  zIceKing = transform.position.z;
  var z = Input.GetAxis("Vertical") * Time.deltaTime * IceKingSpeed;
  if (zIceKing <= IceKingzPosMoveLimit && zIceKing >= IceKingzNegMoveLimit)
      {
 // yield WaitForSeconds(IceKingDelay); ==> Never could this damn delay thing to work right, so I took it out.     
  transform.Translate(0, 0, z);
 // transform.position.z = Vector3.Lerp (transform.position, target.position, Time.deltaTime * smooth); ==> I tried this but ERROR
  }
     else if (zIceKing > IceKingzPosMoveLimit)
         transform.position.z -= IceKingKnockBack;
     else
      transform.position.z += IceKingKnockBack;         
 }

I'm open to suggestions, but please save the criticism if you have nothing constructive to offer, I'm trying to learn.

Answer 1

So you could do this:

Define the target position of the ice king as a script level variable
Change that position based on your input
Clamp the position

Lerp to that position for smooth movement

   var iceKingTargetPosition : Vector3;
     var smoothingFactor : float = 4; //Smaller is more smooth
     var IceKingSpeed = 20; // IceKing's movement speed
     var IceKingzPosMoveLimit = 15;
     var IceKingzNegMoveLimit = 3;

     function Start() {
         iceKingTargetPosition = transform.position;
     }

     function Update() {
          iceKingTargetPosition.z = Mathf.Clamp(iceKingTargetPosition.z + Input.GetAxis("Vertical") * Time.deltaTime * IceKingSpeed,
                  IceKingzNegMoveLimit, IceKingzPosMoveLimit);
          transform.position = Vector3.Lerp(transform.position, iceKingTargetPosition, Time.deltaTime * smoothingFactor);
     }

The only problem with this is that it will take a long time for the character to actually reach the target z (although it will close in quickly) as you are always moving towards it by a fraction.

You could also do a SmoothDamp - which will be more rapid to get there. The key to this technique is that the iceKingTargetPosition is a real world position.

     var iceKingTargetPosition : Vector3;
     var smoothingFactor : float = 0.5; //Smaller is less smooth
     var IceKingSpeed = 20; // IceKing's movement speed
     var IceKingzPosMoveLimit = 15;
     var IceKingzNegMoveLimit = 3;
     var IceKingVelocity : Vector3;

     function Start() {
         iceKingTargetPosition = transform.position;
     }

     function Update() {
          iceKingTargetPosition.z = Mathf.Clamp(iceKingTargetPosition.z + Input.GetAxis("Vertical") * Time.deltaTime * IceKingSpeed,
                  IceKingzNegMoveLimit, IceKingzPosMoveLimit);
          transform.position = Vector3.SmoothDamp(transform.position, iceKingTargetPosition, iceKingVelocity, smoothingFactor);
     }

How to make an object follow on 1 axis??

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