steeplechase/unity/Assets/Pterodactyl.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Pterodactyl : MonoBehaviour
{
    const float horizontalSpeed = 300f;
    const float verticalSpeed = 200f;

    DragonMovement[] _dragons;
    // Start is called before the first frame update
    void Start()
    {
        _dragons = FindObjectsOfType<DragonMovement>();
    }

    // Update is called once per frame
    void Update()
    {
        DragonMovement closestPlayerToMyLeft = null;
        float closestDistance = float.MaxValue;

        foreach (DragonMovement dragon in _dragons)
        {
            float distance = Vector3.Distance(gameObject.transform.position, dragon.transform.transform.position);
            if (distance < closestDistance && dragon.transform.position.x < this.transform.position.x)
            {
                closestDistance = distance;
                closestPlayerToMyLeft = dragon;
            }
        }

        float verticalDirection = 1f;

        if (closestPlayerToMyLeft != null && closestPlayerToMyLeft.transform.position.y < this.transform.position.y)
            verticalDirection = -1f;

        if (closestPlayerToMyLeft == null)
            verticalDirection = 0;

        transform.position = new Vector3(transform.position.x - Time.deltaTime * horizontalSpeed, transform.position.y + (Time.deltaTime * verticalSpeed * verticalDirection), transform.position.z);

        if (transform.position.x < -100f)
        {
            GameObject.Destroy(this.gameObject);
        }
    }

    private void OnTriggerEnter2D(Collider2D collision)
    {
        if (collision.CompareTag("Fireball"))
        {
            GameObject.Destroy(this.gameObject);
        }
    }
}