Side Scrolling Shooter. How to aim my bullet trajectory at the mouse cursor?

Questions & Answers
1

I know this question may sound familiar but I cannot find any answers for this nor can, in my limited experience with unity, wrap my head around how to make this calculation.

Take a look at this project. How do I get the bullets to shoot toward the cursor all the time? Keep in mind that the character isnt necessarily in the middle of the screen.

http://caleb-stamper.com/downloads/2DGameplayTutorial.zip

THANK YOU so much for helping.

For those who'd like a taste of my trouble before downloading:

var projectile: Rigidbody;
var speed = 20;
function Update () 
{
if(Input.GetMouseButton (0) )
    {
        var instantiatedProjectile : Rigidbody = Instantiate(projectile,transform.position, transform.rotation); 

        var mousex = Input.mousePosition.x;
        var mousey = Input.mousePosition.y;

        instantiatedProjectile.velocity = transform.TransformDirection(Vector3 (0,mousey - .5 * Screen.width,speed));
    }
}
2

I have to say, I didn't download the project. But from the code you posted, something along these lines should do the job. The trick is - to read the current distance from the camera (to the player's ship, or whatever is launching the projectile). Then convert the mouse position to a world position at the same distance away from the camera.

You can then use the normalized difference between these two points as the velocity - multiplied by whatever speed you like.

(untested code - for illustrative purposes, may contain errors, etc!)

var projectile: Rigidbody;
var projectileSpeed = 20;
function Update () 
{
    if(Input.GetMouseButton (0) )
{
        var instantiatedProjectile : Rigidbody = Instantiate(projectile,transform.position, transform.rotation); 

        // get current distance from camera
        var distFromCam = Camera.main.transform.InverseTransformPosition(transform).z;

        // get target in world space, at same distance from camera:
        var targetScreenPos = Input.mousePosition;
        targetScreenPos.z = distFromCam;
        var targetPosition = Camera.main.ScreenToWorldPoint(targetScreenPos);

        // calculate direction & velocity:
        var targetDelta = (transform.position - targetPosition);
        var launchVelocity = targetDelta.normalized * projectileSpeed;

        instantiatedProjectile.velocity = launchVelocity;
    }
}

(If all your objects are always at the same fixed distance away from the camera, you could optimise this code by having that as a constant value rather than looked-up using InverseTransformPosition)

3

I was poking around at the Camera class documentation the other day, and I believe it has built-in functions for turning a screen or viewport coordinate (e.g. a mouse x/y) into a world-space coordinate at a specified depth from camera, or better yet, a ray that works with the collision system.