Shooting bullets in mouse direction for 2D game

Questions & Answers
1

I am working on a top down game where the player can shoot bullets by aiming with his mouse. However, I am quite new to programming and am having a bit of trouble figuring out how to do so. My bullet prefab has this code on it:

    public float speed;

public PlayerController player;

public GameObject enemyDeathEffect;

public GameObject impactEffect;

// Use this for initialization
void Start () {
	player = FindObjectOfType<PlayerController> ();

	if (player.transform.localScale.x < 0)
		speed = -speed;
}

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

	GetComponent<Rigidbody2D> ().velocity = new Vector2 (GetComponent<Rigidbody2D> ().velocity.x, speed);

}

void OnTriggerEnter2D(Collider2D other) {

	if (other.tag == "Enemy") {
		Destroy (other.gameObject);
		//Instantiate (enemyDeathEffect, other.transform.position, other.transform.rotation);


	}

	//Instantiate(impactEffect, other.transform.position, other.transform.rotation);

	if (other.name == "player") {
		return;
	}

	Destroy (gameObject);

	}

}

I instantiate the bullet using my player controller script. On it, I have a GameObject variable called firePoint, which is an empty GameObject situated at the center of my player sprite. I also have a GameObject variable in which I drag the prefab of my bullet for the player to access.

For now, the bullet goes upwards.

public Transform firePoint;
public GameObject friendlyBullet;

public bool hasGun;

public bool savedAnn;

public int memoriesCollected;

public bool nextToAnn;
public bool nextToMemory;

public bool memoryExists;

// Use this for initialization
void Start () {
	
	playerBody = this.gameObject.GetComponent<Rigidbody2D> ();

}


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

	//go right
	if (Input.GetKey (KeyCode.D)) {
		playerBody.AddForce(new Vector2 (speed, 0));
		//transform.position += new Vector3 (speed * Time.deltaTime, 0.0f, 0.0f);
	}

	//go left
	if (Input.GetKey (KeyCode.A)){
		playerBody.AddForce(new Vector2 (-speed, 0));
		//transform.position -= new Vector3 (speed * Time.deltaTime, 0.0f, 0.0f);
	}

	//go up
	if (Input.GetKey (KeyCode.W)){
		playerBody.AddForce(new Vector2 (0, speed));
	
		//transform.position += new Vector3 (0.0f,speed * Time.deltaTime, 0.0f);
	}

	//go up
	if (Input.GetKey (KeyCode.S)){
		playerBody.AddForce(new Vector2 (0, -speed));
	
		//transform.position -= new Vector3 (0.0f,speed * Time.deltaTime, 0.0f);

}
if (Input.GetKeyDown (KeyCode.Space) && (hasGun) ) {

		Instantiate (friendlyBullet, firePoint.position, firePoint.rotation);

	} 
	
	
}

Any pointers as to where to integrate the mouse position would be greatly appreciated!

2

var Rotation : Quaternion = Quaternion.LookRotation (transform.position - Camera.main.ScreenToWorldPoint (Input.mousePosition), Vector3.forward);

transform.rotation = Rotation;
transform.eulerAngles = Vector3 (0, 0, transform.eulerAngles.z);

This works perfectly for aiming by mouse. Insert it in FixedUpdate function at start.

Additionally let me share you some another tips. Firstly, NEVER use GetComponent in Update function! Update function do instructions 60 frames per second, so you are getting access to the same component 60 times per second. Much better is to insert component to variable as reference and then access it in Awake or Start (Awake do instructions once even when script is disabled, but Start do instructions once when script IS enabled). Secondly you can define movement by AddForce much simpler. Look at this:

PlayerRigidbody2D.AddForce (Vector2 (Input.GetAxis ("Horizontal") * MovementSpeed, Input.GetAxis ("Vertical") * MovementSpeed));

And the last advice. All code defining physics insert in FixedUpdate function. It works as normal Update, but it is counted by “fixed rate”. See documentation for further details.