CODEWITHSUNDEEP
javaawtjava-2dgraphics2d
user2378547
user2378547

Reputation: 1

Rotating graphics

I am trying to make a bullet class. When it is called it will get a direction and an initial position. The problem is the direction is not working it only goes up no matter what I set as the direction.

Please Help.

Thanks in advance

public class Bullet extends JComponent implements ActionListener{

private int bx,by;
private double theta;
private double BvelX, BvelY;
private Timer timer = new Timer(8,this);

public Bullet(int bx, int by, double theta)
{
    this.bx = bx;
    this.by = by;
    this.theta = theta;

    BvelX = 0;
    BvelY = -1;

    timer.start();
    revalidate();
}


public void paintComponent(Graphics g)
{
    super.paintComponent(g);
    Graphics2D graphicsS = (Graphics2D) g;

    graphicsS.rotate(theta, bx, by);
    graphicsS.setColor(Color.RED);
    graphicsS.fillOval(bx, by,  8, 8);
}

public void actionPerformed(ActionEvent e) 
{
    bx += BvelX;
    by += BvelY;

    /*by += 5*(Math.sin(theta));
    bx += 5*(Math.cos(theta));*/

    revalidate();
    repaint();
}

}

Upvotes: 0

Views: 98

Answers (2)

cmd
cmd

Reputation: 5830

your direction is right here:

BvelX = 0;
BvelY = -1;

this says go strait up

you probably want something like what is commented out

BvelY = 5*(Math.sin(theta));
BvelX = 5*(Math.cos(theta));

Since your positions are integer, you will not be able to go exactly the direction you are pointing. Maybe you should store doubles, but draw integers. Then you could get the bullet to travel closer to theta.

Upvotes: 1

Majid Laissi
Majid Laissi

Reputation: 19778

Well it goes up because:

BvelX = 0;
BvelY = -1;

And when you update:

bx += BvelX;
by += BvelY;

So y is decremented (so it goes up) but x always stays the same (so it doesn't go left or right)

Upvotes: 0

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