gistfile1.cs

using UnityEngine;
using System.Collections;

[RequireComponent(typeof(CharacterScript))]

public class EnemyAI : MonoBehaviour {
	
	public enum EnemyState
	{
		searching,
		following
	}
	
	//time in seconds till the character determines a new heading.
	public float timeToChangeDirection=5.0f;
	
	//amount of damage to do to the player
	public int damage=5;
	
	//how fast this can deal damage
	public float damageFrequency=1.0f;
	
	//internal timer to track last time dealt damage.
	private float damageTimer;
	
	//reference to the character script.
	private CharacterScript character;
	
	//internal timer to keep track of elapsed time.
	private float internalTimer=0.0f;
	
	//direction relative to the character to head.
	private Vector2 heading;
	
	private EnemyState currentState;
	private GameObject target;
	
	/// <summary>
	/// Used for initializing your script component
	/// </summary>
	
	private void Awake () {
		
		//cache the character script
		this.character=this.GetComponent<CharacterScript>();
		
		//set an initial heading.
		this.createNewHeading();
		
		//set internal timer for damagefrequency
		this.damageTimer=this.damageFrequency;
		
		this.currentState=EnemyState.searching;
		
	}
	
	/// <summary>
	/// called after all awakes are called.
	/// </summary>
	
	private void Start()
	{
/*		
		this.character.SetDeathFunction( () => {
			//destroy the game object.
			Destroy(this.gameObject);
		});
*/
		
	}
	
	/// <summary>
	/// Update that is called once per frame.
	/// </summary>
	
	private void Update () {
		
		//increment our damage timer by the time it took to complete the last frame.
		this.damageTimer += Time.deltaTime;
		
	}
	
	/// <summary>
	/// Update that is kept in sync with physics.
	/// </summary>
	
	private void FixedUpdate()
	{
		
		//if we are searching, call the search function
		if(this.currentState == EnemyState.searching)
		{
			this.Search();
		} else if(this.currentState==EnemyState.following)
		{
			//if we are following, call the follow function
			this.Follow();
		}
		
	}
	
	/// <summary>
	/// The enemy follows the player.
	/// </summary>
	
	private void Follow()
	{
		
		//vector math says position to go minus current position = vector we should head in.
		Vector3 nTransform = this.target.transform.position - this.transform.position;
		
		//make sure its of magnitude 1.
		nTransform.Normalize();
		
		//move that direction
		character.Move(nTransform);
		
	}
	
	/// <summary>
	/// The enemy searches for the player.
	/// </summary>
	
	private void Search()
	{
		
		//increase the internal timer by
		//the amount of time that has passed.
		this.internalTimer+=Time.deltaTime;
		
		//determine if we need to create a new heading.
		if (this.internalTimer > this.timeToChangeDirection)
		{
			//create a new heading
			this.createNewHeading();
			
			//reset the timer.
			this.internalTimer=0.0f;
		}
		
		//move the character in the direction of its heading
		character.Move(heading);
		
	}
	
	/// <summary>
	/// Generates a new random heading for the character
	/// and applies that heading immediately.
	/// </summary>
	
	private void createNewHeading()
	{
		//I used -100 to 100 to give an equal chance for any direction
		float xCoord=Random.Range(-100.0f, 100.0f);
		float yCoord=Random.Range(-100.0f, 100.0f);
		
		//set our heading to the random headings.
		heading = new Vector2(xCoord, yCoord);
		
		//make sure the magnitude of our heading is 1
		heading.Normalize();
		
	}
	
	/// <summary>
	/// Called when a collision happens between the character
	/// and something else.
	/// </summary>	
	/// <param name=“other”>What you collided with.</param>
	
	private void OnCollisionEnter2D(Collision2D other)
	{
		//make sure we don’t do too much damage to the player
		if (other.gameObject.tag=="Player" && this.damageTimer > this.damageFrequency)
		{
			//deal some damage!
//			other.gameObject.GetComponent<CharacterScript>().AdjustHealth(-1*this.damage);
			//reset the timer so we don’t damage too much again.
			this.damageTimer=0.0f;
		}
		
		//create a new heading, you ran into something.
		this.createNewHeading();
		
	}
	
	public void SetSpawnedBy(GameObject o)
	{
//		this.spawnedBy=o;
		
	}
	
	public GameObject GetSpawnedBy()
	{
//		return this.spawnedBy;
		return null;
	}
	
	/// <summary>
	/// Occurs when something enters its trigger zone.
	/// </summary>
	/// <param name=“other”></param>
	
	private void OnTriggerEnter2D(Collider2D other)
	{
		//check to see what this thing is
		if (other.gameObject.tag=="Player")
		{
			//Its the player! FOLLOW IT!
			this.currentState=EnemyState.following;
			
			//set the target.
			this.target=other.gameObject;
		}
		
	}
	
	/// <summary>
	/// Occurs when something exits its trigger zone.
	/// </summary>
	/// <param name=“other”></param>
	
	private void OnTriggerExit2D(Collider2D other)
	{
		//Check to see what it is
		if (other.gameObject.tag=="Player")
		{
			//Its the player, I can’t see it anymore, stop following.
			this.currentState=EnemyState.searching;
		}
		
	}
	
}