Unity3D AI system

using UnityEngine;
using System.Collections;

/*
 * AI system for Unity3D, NavMesh powered
 * © Robin van Ee 2012
 * Use with permission per project unless otherwise licensed
 * Contact [email protected] for licensing options
*/

public class Enemy : MonoBehaviour {
    private string[] routines = {"Idle","Patrol","Search","Attack"};
    public int routelength;
    public Transform[] route;
    public int startroutine = 0;
    //Our current routine
    private int curro;
    private int cur = 0;
    public GameObject player;
    NavMeshAgent navma;
    int importance = 1;
    //Estimated position of target
    Vector3 estpos;
    //First position we are at
    Vector3 fipo;

    void Start(){
        fipo = transform.position;
        navma = this.GetComponent<NavMeshAgent>();
        curro = startroutine;
        for(int i = 0; i< routelength;i++){
            route[i].gameObject.GetComponent<MeshRenderer>().enabled = false;
        }
    }
    void Update(){
        if(routines[curro]=="Idle"){
            idle();
        }
        else if(routines[curro]=="Patrol"){
            patrol();
        }
        else if(routines[curro]=="Search"){
            search();
        }
        else if(routines[curro]=="Attack"){
            attack();
        }
        hear();
        see();
    }

    void idle(){
        navma.destination = fipo;
    }

    //In this routine, we patrol a given area.
    void patrol(){
        importance = 2;
        if(cur<routelength){
            Vector3 dest = route[cur].position;
            navma.destination = dest;
            if(targetDistance(route[cur].position)<2){
                cur++;
            }
        }
        else{
            cur = 0;
        }
    }

    //In this routine, we're investigating a sound.
    void search(){
        importance = 2;
        navma.destination = estpos;
        //We're at the estimated position
        if(targetDistance(estpos)<1){
            //We continue where we left of before seeing or hearing the player
            curro = startroutine;
            //Hear and See will change estpos, so if we're hearing or seeing the player right now, we won't do this.
        }
    }

    void attack(){
        importance = 4;
        navma.destination = player.transform.position;
        if(targetDistance(player.transform.position)<2){
            navma.destination = transform.position;
        }
    }



    //Our senses
    void hear(){
        //We hear the player (he is close), but not hard enough to drop everything we're doing
        //We're also not doing anything important
        if(targetDistance(player.transform.position)<15 && importance<2){
            //Chance of 1% (per frame) we're going to investigate
            //This actually determines the accuraccy of our estimated position
            if(Random.value<0.01){
                estpos = player.transform.position;
                curro = 2;
            }
        }
        //Player is quite close, we definitely heard him now.
        if(targetDistance(player.transform.position)<10 && importance<4){
            //Chance of 50% (per frame) that we update our estimated position
            if(Random.value<0.5){
                estpos = player.transform.position;
            }
            curro = 2;
        }
    }

    void see(){
        RaycastHit hit;
        if(Physics.Raycast(transform.position, Vector3.forward, out hit)){
            //We saw the player
            if(hit.collider.gameObject.name == player.name){
                print("saw player");
                //If close to the player, attack
                if(targetDistance(player.transform.position)<10){
                    curro = 3;
                }
                else{
                    //We remember where we last saw the player and investigate at that position
                    estpos = player.transform.position;
                    curro = 2;
                }
            }
        }
    }

    //Simple 3D Pythagoras
    float targetDistance(Vector3 target){
        float distance = 0;
        Vector3 distancev;
        distancev.x = target.x - transform.position.x;
        distancev.y = target.y - transform.position.y;
        distancev.z = target.z - transform.position.z;
        distance = Mathf.Sqrt(distancev.x*distancev.x + distancev.y*distancev.y);
        distance = Mathf.Sqrt(distance*distance + distancev.z*distancev.z);
        return distance;
    }
}