How to make the player always point to the mouse

Question

Just for fun I thought I would create the game Asteroids. I'm a little bit stuck on the the fact I can't get the player to always look where the mouse is. Here is the player class below.

public class Player extends GameObject {

    private int size;

    public Player(float x, float y, int width, int height) {
        super(x, y, width, height);
        size = width / 2 + height / 2;
    }

    public void update() {

    }

    public void render(Graphics g) {
        Point mouse = MouseInfo.getPointerInfo().getLocation();
        int centerX = (int) (mouse.getX() - getX());
        int centerY = (int) (mouse.getY() - getY());
        double angle = Math.toDegrees(Math.atan2(centerY, centerX));

        Graphics2D g2d = (Graphics2D) g;
        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

        g2d.setColor(Color.white);
        g2d.rotate(angle, (int) getX() + getWidth() / 2, (int) getY() + getHeight() / 2);
        g2d.drawLine((int) getX() + getWidth() /  2, (int) getY(), (int) getX(), (int) getY() + getHeight());
        g2d.drawLine((int) getX() + getWidth() /  2, (int) getY(), (int) getX() + getWidth(), (int) getY() + getHeight());
        g2d.drawLine((int) getX(), (int) getY() + getHeight(), (int) getX() + getWidth() / 2, (int) getY() + getHeight() - size / 6);
        g2d.drawLine((int) getX() + getWidth(), (int) getY() + getHeight(), (int) getX() + getWidth() / 2, (int) getY() + getHeight() - size / 6); 
    }

    public Rectangle getBounds() {
        return new Rectangle((int) getX(), (int) getY(), getWidth(), getHeight());
    }

    public void setSize(int size) {
        this.size = size;
    }

    public int getSize() {
        return size;
    }

}

I guess it sort of works in the fact that if I move my mouse the player does rotate but it rotate pretty fast. So I ask am I doing anything wrong? Before you ask, I have looked it up on Google and found some question like this one but none have helped me.

score 1 · Accepted Answer · edited May 23 '17 at 12:21

1

The argument to Graphics2D.rotate is in radians, not degrees. Try removing Math.toDegrees from the computation of angle. Reference here.

Updated: Per this comment, getLocation gives the mouse position in screen coordinates, not in the user coordinates of your Graphics2D. You need to convert the coordinates, but how to do that will be specific to your game library.

Updated 2: Assuming GameObject extends java.awt.Component somehow, try getLocationOnScreen (reference here, from the comment noted above):

Point me_absolute = getLocationOnScreen()
int centerX = (int) (mouse.getX() - me_absolute.getX());
int centerY = (int) (mouse.getY() - me_absolute.getY());

edited May 23 '17 at 12:21

Community

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1

answered Dec 09 '14 at 14:51

cxw

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Thanks for the fast reply. I went ahead and removed the "Math.toDegrees" and it now is rotating at a much slower speed but it is still not pointing to the mouse. All the player is doing is it is rotating the the same direaction as my mouse but not pointing at my mouse. – RealINandOUT Dec 09 '14 at 15:01
@Real, which game framework are you using? That is, what library is `GameObject in? – cxw Dec 09 '14 at 16:28
I'm using the default Java libraries and the class "GameObject" is a abstract class I made. All objects in the game extends the "GameObject" class. – RealINandOUT Dec 09 '14 at 16:58

How to make the player always point to the mouse

1 Answers1