Moving an object back and forth on a single axis automatically

Hi All,

As you will probably tell by my following question I'm very new to Scripting and C#.
What I'm trying to do is make a gameobject (so for example in this case an enemy), move automatically on a particular axis (in this case the x), back and forth. So for example, it will move 3 along the x axis then back to its starting position and continually do that.
I have found the following script for a similar idea using Coroutines:

Code (csharp):

1. public Vector3 pointB;
2.    
3.     IEnumerator Start () {
4.         Vector3 pointA = transform.position;
5.         while (true) {
6.             yield return StartCoroutine(MoveObject(transform, pointA, pointB, 3));
7.             yield return StartCoroutine(MoveObject(transform, pointB, pointA, 3));
8.         }
9.     }
10.    
11.     IEnumerator MoveObject (Transform thisTransform, Vector3 startPos, Vector3 endPos, float time) {
12.         float i = 0.0f;
13.         float rate = 1.0f / time;
14.         while (i < 1.0f) {
15.             i += Time.deltaTime * rate;
16.             thisTransform.position = Vector3.Lerp(startPos, endPos, i);
17.             yield return null;
18.         }
19.     }
20.  

while this works, the problem is that it needs to have a Vector3 set in the Inspector for each gameobject. I want to be able to save a prefab of the enemy then spawn it anywhere and it keeps the same logic without putting in a new vector for each one.

What I have tried is giving pointB a set value, such as:
pointB = new Vector3 (transform.position.x + 3, transform.position.y, transform.position.z)

however, that just threw up a lot of errors.

Any help will be appreciated, thank you very much.

 

What sort of errors did that give you?

 

try this

Code (csharp):

1. public float min=2f;
2.     public float max=3f;
3.     // Use this for initialization
4.     void Start () {
5.        
6.         min=transform.position.x;
7.         max=transform.position.x+3;
8.    
9.     }
10.    
11.     // Update is called once per frame
12.     void Update () {
13.        
14.        
15.         transform.position =new Vector3(Mathf.PingPong(Time.time*2,max-min)+min, transform.position.y, transform.position.z);
16.        
17.     }

 

You could do something like (Using C#):

Code (csharp):

1.  
2. using UnityEngine;
3. using System.Collections;
4.  
5. public class MoveTest : MonoBehaviour
6. {
7.     public Vector3 pointB;
8.    
9.     IEnumerator Start()
10.     {
11.         var pointA = transform.position;
12.         while(true)
13.         {
14.             yield return StartCoroutine(MoveObject(transform, pointA, pointB, 3.0f));
15.             yield return StartCoroutine(MoveObject(transform, pointB, pointA, 3.0f));
16.         }
17.     }
18.    
19.     IEnumerator MoveObject(Transform thisTransform, Vector3 startPos, Vector3 endPos, float time)
20.     {
21.         var i= 0.0f;
22.         var rate= 1.0f/time;
23.         while(i < 1.0f)
24.         {
25.             i += Time.deltaTime * rate;
26.             thisTransform.position = Vector3.Lerp(startPos, endPos, i);
27.             yield return null;
28.         }
29.     }
30. }
31.  

Sourced from some unity answers thread, then tested in Unity. Works well.

EDIT: for more complex movement, and examples, and lots more, check out "tweening" and some of the packages available, like hotween, iTween, or leanTween to mention a few. They provide lots of good info in this area of simple movement of gameobjects with little to no interaction. Good luck!

 

Var isn't C#

 

Have you tested it yet?

I didn't write the script like I said it came from some page I googled, but I had thought it worked...

if you need to you can make floats be float, ints be int, and so on.

EDIT: just to make sure it worked, I tested it again:

 

Yes it is.

--Eric

 

var is C#'s Implicit Type. Basically, the compiler will try to automatically assign it a type.

It's convenient for quick coding, but strong typing is a better paradigm.

https://msdn.microsoft.com/en-us/library/bb383973.aspx?f=255&MSPPError=-2147217396

 

How to make this not looping?

 

Why do people always overlook the naturally oscillating mathematical functions?

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3. public class OccilatingPosition : MonoBehaviour
4.     {
5.      public enum OccilationFuntion { Sine, Cosine }
6.      public void Start ()
7.      {
8.          //to start at zero
9.          StartCoroutine (Oscillate (OccilationFuntion.Sine, 1f));
10.          //to start at scalar value
11.          //StartCoroutine (Oscillate (OccilationFuntion.Cosine, 1f));
12.      }
13.  
14.      private IEnumerator Oscillate (OccilationFuntion method, float scalar)
15.      {
16.          while (true)
17.          {
18.              if (method == OccilationFuntion.Sine)
19.              {
20.                  transform.position = new Vector3 (Mathf.Sin (Time.time) * scalar, 0, 0);
21.              }
22.              else if (method == OccilationFuntion.Cosine)
23.              {
24.                  transform.position = new Vector3(Mathf.Cos(Time.time) * scalar, 0, 0);
25.              }
26.              yield return new WaitForEndOfFrame ();
27.          }
28.      }
29. }
30.  

@nbg_yalta simply stop the coroutine whenever you'd like using:

Code (CSharp):

1. StopCoroutine(Oscillate());

.

 

Use yield return null instead of yield return new WaitForEndOfFrame. (So you don't create new objects.) Anyway it's possible people just want stuff to pingpong without the slowdown/speedup that you get with sine.

--Eric

 

That's true, but it is often desired. I usually create those objects in an outer scope, but use this for simplicity as its what is seen in Unity's tutorials.

 

is there a way to update the Point A and B so that the enemies are ping ponging to different locations all the time?

 

I think perhaps you should open a new thread or even a unity answers post, because its difficult to tell what you mean without a detailed explanation, and also this thread is pretty old.

 

I'm sure no one is still looking at this, but just in case:

Here is code for a Saw (circle) that I have going back and forth.
It exposes a speed and distance for your GameObject as well.
I also have it spinning because it was for a saw.
I used Rigidbody2D since I have it using a collider as well.

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class saw : MonoBehaviour
6. {
7.  
8.     public float distance;
9.     public float spinSpeed;
10.     public float linearSpeed;
11.     private Rigidbody2D rgb2d;
12.     private float startPosition;
13.  
14.     // Start is called before the first frame update
15.     void Start()
16.     {
17.         rgb2d = GetComponent<Rigidbody2D>();
18.         startPosition = rgb2d.position.x;
19.     }
20.  
21.     private void FixedUpdate()
22.     {
23.         rgb2d.SetRotation(rgb2d.rotation + spinSpeed * Time.fixedDeltaTime);
24.         rgb2d.MovePosition(new Vector2((Mathf.Sin((2 * Mathf.PI * (Time.time*linearSpeed/distance)) - (Mathf.PI / 2)) * (distance/2) + (distance/2))+startPosition,rgb2d.position.y));
25.     }
26. }

 

I looked at it

 

yup I looked at it too

 

Code (csharp):

1.  
2. public class BlockMoveUni : MonoBehaviour
3. {
4.     [SerializeField]
5.     public Vector3 targetPos1;
6.     [SerializeField]
7.     public Vector3 targetPos2;
8.     [SerializeField]
9.     public float speed = 1f;
10.     public bool canMove;
11.     public bool firstMove;
12.     void Start()
13.     {
14.        
15.         firstMove = true;
16.        
17.     }
18.     void Update()
19.     {
20.         if(transform.position == targetPos1)
21.         {
22.             firstMove = false;
23.         }
24.         if (transform.position == targetPos2)
25.         {
26.             firstMove = true;
27.         }
28.         if (canMove)
29.         {
30.             if (firstMove)
31.             {
32.                 transform.position = Vector3.MoveTowards(transform.position, targetPos1, speed* Time.deltaTime);
33.             }
34.             else
35.             {
36.                 transform.position = Vector3.MoveTowards(transform.position, targetPos2, speed* Time.deltaTime);
37.             }
38.         }
39.        
40.     }
41. }
42.  

Hi Guys, I know the question is old but being as a beginner I have made an extremely easy to follow code that can be plugged into any OBJ and adjust purely through Unity. Probably not very optimised but found it easy to implement. Please follow instruction under to apply. If you are more experienced or can see any glaring mistake or ways to optimise it a lot more, please let me know
1. Add script to Object you want to move.
2.Set Target1 as first destination
3. Set Target2 as second destination/starting point if you want to move back where it started.
4. select canMove as true if want to move straight away or leave false if you want to activate by a trigger.
5. change speed via Unity.
This should allow you to use on all moving Objects in scene or game without having to adjust code.

 

you can use animator to move back forth without single line of coding

 

how do you do this on the z axis

 

transform.position =new Vector3(Mathf.PingPong(Time.time*2,max-min)+min, transform.position.y, transform.position.z)

new Vector3(position.x, position.y, position.z) ...... Look at where the PingPong is in the original code. The position.x

Simply put the Mathf.PingPong in the transform.position.z ... Or whichever position on the x,y,z Vector3 you so desire.

 

Thank you so much