# Detonating projectile at mouse point

--------I have a system set up where a central turret spawns a projectile aimed at the mouse cursor whenever the player presses a button. I’m trying to make it so that the projectiles detonate where the cursor was when they were launched. I have tried a few different approaches, but can’t get them to work right. ATM I have a it working for exactly the screen scale of the game preview window, but resizing it distorts the detonation distance and de-syncs it with the mouse point (Also it’s pretty hacky IMO). Does anyone know what the best way to do this is? My current projectile code is here:

``````public int speed;
public GameObject shockwave;
Vector3 object_pos;
Vector3 mouse_pos;
float lifespan;
public GameObject shipExplosion;
public GameObject energyDrop;

int timer = 0;
void Start () {
mouse_pos = Input.mousePosition;
object_pos = Camera.main.WorldToScreenPoint(rigidbody2D.transform.position);
mouse_pos.x = mouse_pos.x - object_pos.x;
mouse_pos.y = mouse_pos.y - object_pos.y;

//Calculates the distance from the spawn point to cursor
lifespan = Mathf.Sqrt(Mathf.Abs(mouse_pos.x) * Mathf.Abs(mouse_pos.x) + Mathf.Abs(mouse_pos.y) * Mathf.Abs(mouse_pos.y));

//Calculates time for the projectile to reach the cursor point based on the projectile speed,
//then multiplies by 1.5 because that scale works with the window :/
lifespan = lifespan / speed * 1.5F;

//Calculates the angle and velocities to launch at
float angle = Mathf.Atan2(mouse_pos.y, mouse_pos.x);

float xVel = speed * Mathf.Cos(angle);
float yVel = speed * Mathf.Sin(angle);

rigidbody2D.velocity = new Vector2(xVel, yVel);

}

void Update () {
timer++;

//If the time it's been alive is greater then the lifespan set above, detonate
if (timer > lifespan)
{
Instantiate(shockwave, new Vector3(transform.position.x, transform.position.y, 0), new Quaternion(0, 0, 0, 1));
Destroy(this.gameObject);
}
}
``````

If you don’t mind a bit of math, I think its slightly faster to calculate the distance and time, then countdown the time and detonate. But if you wanna keep it simple you can check it every frame with Vector3.Distance, But isn’t it better to just detect a collision/trigger and then detonate? I didn’t play around in 2D with that yet, but I’m making a tower defense game and I use collision detection for relatively slow projectiles, and raycast for “bullets”.

Also, its not good to manually edit a Quaternion,