Question

I’m working on a game where the player controls a space ship that circles clock/counterclockwise around a center point while shooting projectiles coming from said point. I have everything written, although actual placement is slightly off and rotation isn’t working.

For movement, I have:

if (code==KeyEvent.VK_LEFT) {
            trans.setToIdentity();
            trans.translate(player.x-10, player.y-10);
            player.moveLeft();
                            //trans.rotate(?)
            System.out.println(player.x + " " + 
                               player.y + " " + player.dX + " " + player.dY);
}

Where trans is an AffineTransform, player.moveLeft() changes the player’s coordinates to a point on the circle (working as expected, uses sin/cos/theta, simple trig). When I draw an object with Graphics2D it follows the coordinates, but when I use an imported image it trails by several (~25) pixels. Since I have an angle, x, y, and radius, what can I use with AffineTransform to rotate the image around its center point and have it constantly face the center point?

Answer 1

        if (code==KeyEvent.VK_LEFT) {
            trans.setToIdentity();
            player.moveLeft();
            trans.translate(player.x-shipImg.getWidth()/2,player.y-shipImg.getHeight()/2);
            trans.rotate(player.angle-1.57, shipImg.getWidth()/2, shipImg.getHeight()/2);
        }

Figured it out. First move the ship’s center point to the player’s x,y coordinates, and then rotate (with a slight angle tweak) around the center point.