Not sure how to implement a bullet system in Java Slick game?

Question

So, I have been following tutorials on a Slick API 2D Game Java tutorial, and I got the basics of how to use the API. But then, when I was playing around and trying to make a game. I tried to implement a bullet/firing system into my 2D space shooter game. And I can't seem to find a way to do it!

I've tried looking around on Google and YouTube, but it's not helping at all...! All my game does right now is move a ship right to left. I want to be able to make it so that the a bullet-like object is fired every time the space bar is pressed. I am just not sure how to go about it... I'm hoping someone can explain it simply to a new programmer !

Answer 1

Assuming you're using polling for input, you'll need to add a check to your update method for the spacebar. If the spacebar is pressed, then add a new instance of Bullet to an array of bullets and pass the initial x, y, and velocity in the constructor.

Your Bullet class may look something like:

public class Bullet
{
    public static float VELOCITY;
    private Vector2f position;

    public Bullet(float x, float y, float velocity)
    {
        position = new Vector2f(x, y);

        VELOCITY = velocity;
    }

    public void update(float delta, boolean vertical)
    {
        if(vertical)
        {
            y += VELOCITY * delta;
        }
        else
        {
            x += VELOCITY * delta;
        }
    }
}

You'll also want to call the update method for the bulelts in your update method. Do this with something like:

for(Bullet bullet : bullets)
{
    bullet.update(delta, true);
}