如何使播放器始终指向鼠标

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.

Answer 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());