unity3d: shoot where mouse clicks on sceen - mouse

Question

Looking at various bulletin boards, this is a common problem, yet I could not find any good answers online.
My project has a first-person car that moves via the arrow keys. I want a gun mounted on the car to be able to shoot via crosshair that can aim anywhere on the current screen. Right now the bullets just shoot right through the middle all the time, except for the times when I click on the screen and nothing happens (which is about 50%). Here is the code which I got via various scripts on the web:
var speed = 20;
var bullet: GameObject;
function Update () {
var hit : RaycastHit;
if(Input.GetButtonDown("Fire1")){
var ray = Camera.main.ScreenPointToRay (Input.mousePosition); //ray from
// through the mousePosition.
if(Physics.Raycast(ray, hit, 1000)) { //does the ray collide with
// anything.
//add stuff here for finding type of object and such.
Debug.Log("Hit Something at mouse position");
Debug.DrawRay (ray.origin, ray.direction * 10, Color.yellow);
//Display the ray.
var projectile:GameObject = Instantiate(bullet,transform.position,transform.rotation);
projectile.rigidbody.velocity = transform.forward * speed;
}
}
}
If anyone could help, it would be very much appreciated.

Answer 1

Your ray is correct (pointing to middle of screen), but it has nothing to do with the way your making the bullet travel. The bullet travels based on a transform.forward * speed. What you need to do is get the hit point of your ray, then get a direction from your bullets origin to that point.
Vector3 direction = hit.point - projectile.transform.position;
projectile.rigidbody.velocity = direction * speed;
1000 is pretty low for a screenPointToRay, so you might want to up that by a lot if you want to avoid future problems.
Also rigidbody has been deprecated, im not sure if you should be doing a (GameObject).rigidbody directly like that
http://docs.unity3d.com/ScriptReference/GameObject-rigidbody.html

Answer 2

Without actually posting you any code, I can tell you that what you should probably be looking into is why your projectile is setting its rotation from the transform's rotation instead of the rotation of your ray if I understand your attempt.
The projectile is clearly gaining all of it's properties (including those which are supposed to be detached from the origination) from the vehicle and just following along accordingly.
Try setting your projectile's rotation to that of your ray.
Also, your ray is more than likely only ever hitting half of the time because of your amount of distance to test. Try upping that number, or creating walls for it to collide with at shorter range.