RotationNegativeAboutOrigin13.java

package hw;

import java.awt.*;
import javax.swing.*;
import javax.swing.JFrame;

public class RotationNegativeAboutOrigin13 extends JFrame{
	int xPoly[]= {30,65,86,100,145,95,60};
	int yPoly[]= {30,20,36,56,75,105,60};
	int i; 
	
	RotationNegativeAboutOrigin13(){
		setTitle("Rotation On Negative");
		setSize(1200,1200);
		setVisible(true);
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	}
	
	public void paint(Graphics g) {
		g.translate(400,400);
		g.drawPolygon(xPoly, yPoly, xPoly.length);
		
		rotateAt(-45);
	} 
	
	public void rotateAt(double deg) {
		double angleInRadian=Math.toRadians(deg);
		for(i=0;i<xPoly.length;i++) {
			xPoly[i]=(int)Math.round(xPoly[i]*Math.cos(angleInRadian)-yPoly[i]*Math.sin(angleInRadian));
			yPoly[i]=(int)Math.round(xPoly[i]*Math.sin(angleInRadian)+yPoly[i]*Math.cos(angleInRadian));
		}
		Graphics g=this.getGraphics();
		g.translate(400, 400);
		g.drawPolygon(xPoly, yPoly, xPoly.length);
	}
	
	public static void main(String[] args) {
		javax.swing.SwingUtilities.invokeLater(new Runnable() 
		{
			public void run() {
				new RotationNegativeAboutOrigin13();
			}
		});
	}
}