LaserScript.cs

using UnityEngine;
using System.Collections;

public class LaserScript : Projectile {
    public GameObject laserStart;
    public GameObject laserMiddle;
    public GameObject laserEnd;
    public float maxLaserDistance;

    private GameObject start;
    private GameObject middle;
    private GameObject end;

    private float timer = 0f;
    private float timerMax = 10f;
    private float startSpriteWidth;

    void InstantiateLaserPart(ref GameObject part, GameObject laserPart) {
        if (part == null) {
            part = Instantiate<GameObject>(laserPart);
            part.transform.parent = gameObject.transform;
            part.transform.localPosition = Vector2.zero;
            part.transform.localEulerAngles = Vector2.zero;
        }
    }

    RaycastHit2D RaycastDirection(Vector2 direction) {
        return Physics2D.Raycast(
            this.transform.position,
            direction,
            maxLaserDistance
        );
    }

    void FadeLaser() {
        timer -= Time.deltaTime;
        if (timer <= 5) {
            transform.localScale -= new Vector3(0f, transform.localScale.y) * Time.deltaTime;
            if (transform.localScale.y <= 0.05) {
                Destroy(gameObject);
            }
        }
    }

    void Start() {
        timer = timerMax;
        startSpriteWidth = laserStart.GetComponent<Renderer>().bounds.size.x;

        InstantiateLaserPart(ref start, laserStart);
        InstantiateLaserPart(ref middle, laserMiddle);
    }

    // Update is called once per frame
    void Update() {
        FadeLaser();

        float currentLaserDistance = maxLaserDistance;
        RaycastHit2D hit = RaycastDirection(this.transform.right);

        if (hit.collider != null) {
            currentLaserDistance = Vector2.Distance(hit.point, this.transform.position);
            InstantiateLaserPart(ref end, laserEnd);
        } else if (end != null) {
            Destroy(end);
        }


        middle.transform.localScale = new Vector3(
            currentLaserDistance - startSpriteWidth + 0.1f,
            middle.transform.localScale.y,
            middle.transform.localScale.z
        );
        middle.transform.localPosition = new Vector3(currentLaserDistance / 2f, 0f);

        if (end != null) {
            end.transform.localPosition = new Vector2(currentLaserDistance, 0f);
        }
    }
}