2d shooter pistol raycast phan4

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

public class pistol : MonoBehaviour {
    public float shootdelay = 0, damage = 20;
    public LayerMask whattohit;
    public Transform firepoint;

    // Use this for initialization
    void Start () {
        firepoint = transform.Find("shootpoint");
    }

    // Update is called once per frame
    void Update () {
        shootdelay += Time.deltaTime;

        if (shootdelay >= 0.5f)
        {
            if (Input.GetKeyDown(KeyCode.Mouse0))
            {
                shootdelay = 0;
                shot();
            }
        }
    }

    public void shot()
    {
        Vector2 mousepos = new Vector2
            (Camera.main.ScreenToWorldPoint(Input.mousePosition).x,
             Camera.main.ScreenToWorldPoint(Input.mousePosition).y);

        Vector2 firepointpos = new Vector2(firepoint.position.x, firepoint.position.y);

        RaycastHit2D hit = Physics2D.Raycast
            (firepointpos, (mousepos - firepointpos), 10f, whattohit);
        Debug.DrawLine(firepointpos, (mousepos - firepointpos) * 100, Color.cyan);

        if (hit.collider != null)
        {
            Debug.DrawLine(firepointpos, hit.point, Color.red);
            Debug.Log("We hit " + hit.collider.name);
            hit.collider.SendMessageUpwards("Damage", damage);
        }


    }
}