How to determine if an Enemy is moving left or right?

Question

First, here's the code

 using UnityEngine;
 using System.Collections;
 
 public class BMoveAI : MonoBehaviour
 {
     public Vector2 pos1;
     public Vector2 pos2;
     public float speed;
 
     void Update()
     {
         transform.position = Vector3.Lerp (pos1, pos2, Mathf.PingPong (Time.time * speed, 1.0f));
     }
 }

So what I'm trying to do is make my Enemy's sprite flip depending on whether he is moving left or right. So my question is how I would detect moving left or right?

Answer 1

Best Answer

Answer by Zee-Play · Feb 22, 2017 at 04:07 AM

You could store your character's Y position in a variable, and then in the next frame check whether the new position is smaller or greater than the last one. (Assuming Y axis is your horizontal, and it's that way ->) You might need to swap left and right depending on what your sprite looks like.

 using UnityEngine;
 using System.Collections;
  
 private float oldPosition = 0.0f
 
 public class BMoveAI : MonoBehaviour
 {
     public Vector2 pos1;
     public Vector2 pos2;
     public float speed;
 
     void Start()
     {
         oldPosition = transform.position.y;
     }
 
      void Update()
     {
         transform.position = Vector3.Lerp (pos1, pos2, Mathf.PingPong (Time.time * speed, 1.0f));
 
         if (transform.position.y > oldPosition) // he's looking right
         {
             transform.localRotation = Quaternion.Euler(0, 0, 0);
         }
 
         if (transform.position.y < oldPosition) // he's looking left
         {
             transform.localRotation = Quaternion.Euler(0, 180, 0);
         }
         oldPosition = transform.position.y; // update the variable with the new position so we can chack against it next frame
     }
 }

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APERSONWHOISAPERSON · Feb 22, 2017 at 05:45 AM 0

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Thank you for the answer! However now when I start the game: The sprite just flips and then doesn't change... Any help is appreciated. :)

Zee-Play APERSONWHOISAPERSON · Feb 22, 2017 at 11:53 AM 0

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Try this, tested and it works

 using UnityEngine;
 using System.Collections;
 
  public class BMoveAI : MonoBehaviour
 {
     public Vector2 pos1;
     public Vector2 pos2;
     public float speed;
     private float oldPosition = 0.0f;
 
     
     void Start()
     {
         oldPosition = transform.position.x;
     }
 
     void Update()
     {
         transform.position = Vector3.Lerp(pos1, pos2, Mathf.PingPong(Time.time * speed, 1.0f));
 
         if (transform.position.x > oldPosition) // he's looking right
         {
             transform.localRotation = Quaternion.Euler(0, 0, 0);
         }
 
         if (transform.position.x < oldPosition) // he's looking left
         {
             transform.localRotation = Quaternion.Euler(0, 180, 0);
         }
         oldPosition = transform.position.x; // update the variable with the new position so we can chack against it next frame
     }
 }

APERSONWHOISAPERSON Zee-Play · Feb 22, 2017 at 07:04 PM 0

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Yes! It works! Thank you for your help Zee-Play. :)

How to determine if an Enemy is moving left or right?

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