Hi.
I am making a really simple program to refresh my knowledge in java (which is obviously needed). When I click the screen, I want a bullet to appear in the center and move towards the point I clicked. Right now, when I click on the left half the bullet will go either straight up or directly left, and if I click the right half then it just stays in the center of the screen.
I have two classes (plus a third main class):
ShooterPanel class

package shooter;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.*;

public class ShooterPanel extends JPanel implements Runnable, MouseListener {

    boolean gameOver;
    int aimFPS = 60;

    int mouseX;
    int mouseY;
    boolean hasShot;
    Thread t = new Thread(this);

    Bullet[] bullets = new Bullet[100];

    public ShooterPanel(){

        addMouseListener(this);
        t.start();

    }

    public void fireShots(){

        if(hasShot){

            for(int i = 0; i < bullets.length; i++){

                if(bullets[i] == null){

                    bullets[i] = new Bullet(200, 200, mouseX, mouseY);
                    double angle = Math.atan2(bullets[i].targetY - bullets[i].posY, bullets[i].targetX - bullets[i].posX);
                    if(angle < 0){
                        angle += 360;
                    }
                    bullets[i].setAim(angle);
                    System.out.println("Created a new bullet object");
                    break;

                }

            }
            hasShot = false;

        }

    }

    public void moveBullets(){

        for(Bullet bullet : bullets){

            if(bullet != null){

                bullet.move();
                System.out.println("New bullet position is [" + bullet.posX + ", " + bullet.posY + "]");

            }

        }

    }

    @Override
    public void paintComponent(Graphics gc){

        super.paintComponent(gc);

        for(Bullet bullet : bullets){

            if(bullet != null){
                gc.setColor(Color.BLACK);
                gc.fillOval(bullet.posX, bullet.posY, 7, 7);
                System.out.println("Drew a bullet");
            }

        }
        gc.setColor(Color.BLACK);
        gc.fillOval(50, 50, 20, 20);
        gc.drawString("Hiya", 80, 80);

    }

    @Override
    public void run(){

        while(!gameOver){

            fireShots();

            moveBullets();

            repaint();

            try{
                Thread.sleep(1000 / aimFPS);
            }catch(InterruptedException ie){
                t.interrupt();
                System.out.println("Couldn't pause thread");
            }

        }

    }

    @Override
    public void mouseClicked(MouseEvent e) {

    }

    @Override
    public void mousePressed(MouseEvent e) {

    }

    @Override
    public void mouseReleased(MouseEvent e) {
        mouseX = e.getX();
        mouseY = e.getY();
        hasShot = true;
        System.out.println("Heard mouse realease at [" + mouseX + ", " + mouseY + "]");
    }

    @Override
    public void mouseEntered(MouseEvent e) {

    }

    @Override
    public void mouseExited(MouseEvent e) {

    }

}

Bullet class

package shooter;

public class Bullet {

    int posX;
    int posY;
    int targetX;
    int targetY;
    double aim;

    public Bullet(int posX, int posY, int targetX, int targetY){

        this.posX = posX;
        this.posY = posY;
        this.targetX = targetX;
        this.targetY = targetY;

    }

    public double getAim(){

        return aim;

    }

    public void setAim(double angle){

        this.aim = angle % (2 * Math.PI);

    }

    public void move(){

        double stepX = Math.cos(getAim());
        double stepY = Math.sin(getAim());
        posX += stepX;
        posY += stepY;

    }

}

28eab7aac59212799405257a808b9fcb
this is a picture of what happens. The bullets are either going straight up or directly left, not even diagonal.

The code does angle calcs using 360 in one place and 2pi in another, so maybe you are mixing or confusing degrees and radians?

Be a part of the DaniWeb community

We're a friendly, industry-focused community of developers, IT pros, digital marketers, and technology enthusiasts meeting, networking, learning, and sharing knowledge.