//TriangleApplet.java

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

public class TriangleApplet extends JApplet {

    int x1, y1, x2, y2, x3, y3;
    
    public void init() {
        String input;

        input = JOptionPane.showInputDialog( "Enter x of point 1" );
        x1 = Integer.parseInt( input );
        input = JOptionPane.showInputDialog( "Enter y of point 1" );
        y1 = Integer.parseInt( input );
        input = JOptionPane.showInputDialog( "Enter x of point 2" );
        x2 = Integer.parseInt( input );
        input = JOptionPane.showInputDialog( "Enter y of point 2" );
        y2 = Integer.parseInt( input );
        input = JOptionPane.showInputDialog( "Enter x of point 3" );
        x3 = Integer.parseInt( input );
        input = JOptionPane.showInputDialog( "Enter y of point 3" );
        y3 = Integer.parseInt( input );
    }
    
    public void paint (Graphics g) {

        g.setFont( new Font( "Serif", Font.BOLD, 16 ) );

	//the 3 lines
        g.drawLine( x1, y1, x2, y2 );
        g.drawLine( x1, y1, x3, y3 );
        g.drawLine( x3, y3, x2, y2 );

	//label the vertices
        g.setColor( Color.RED );
        g.drawString("("+x1+","+y1+")",x1,y1);
        g.drawString("("+x2+","+y2+")",x2,y2);
        g.drawString("("+x3+","+y3+")",x3,y3);

        //midpoints of the 3 lines
        int x12mid = (x1+x2) / 2;
        int y12mid = (y1+y2) / 2;
        int x13mid = (x1+x3) / 2;
        int y13mid = (y1+y3) / 2;
        int x23mid = (x2+x3) / 2;
        int y23mid = (y2+y3) / 2;

        //lengths of the lines (Pythagorean formula)
        int len12 = (int)Math.sqrt((x1-x2)*(x1-x2) + (y1-y2)*(y1-y2));
        int len13 = (int)Math.sqrt((x1-x3)*(x1-x3) + (y1-y3)*(y1-y3));
        int len23 = (int)Math.sqrt((x2-x3)*(x2-x3) + (y2-y3)*(y2-y3));

	//display the length at the midpoint
        g.setColor( Color.CYAN );
        g.fillOval(x12mid-1,y12mid-1,2,2);
        g.drawString(""+len12,x12mid,y12mid);
        g.fillOval(x13mid-1,y13mid-1,2,2);
        g.drawString(""+len13,x13mid,y13mid);
        g.fillOval(x23mid-1,y23mid-1,2,2);
        g.drawString(""+len23,x23mid,y23mid);

	//centroid of triangle: (average of x's, average of y's).
	//center of mass, center of gravity, balance point.
	//average of all points in the triangle.
        int xc, yc;    
        xc = (x1+x2+x3) / 3;
        yc = (y1+y2+y3) / 3;

	//display the centroid
        g.setColor( Color.BLUE );
        g.fillOval(xc-1,yc-1,2,2);
        g.drawString("("+xc+","+yc+")",xc,yc);

	//line from vertex to centroid
        g.drawLine( x1, y1, xc, yc );
        g.drawLine( x2, y2, xc, yc );
        g.drawLine( x3, y3, xc, yc );

	//line from midpoint to centroid
        g.setColor( Color.YELLOW );
        g.drawLine( x12mid,y12mid, xc, yc );
        g.drawLine( x13mid,y13mid, xc, yc );
        g.drawLine( x23mid,y23mid, xc, yc );

	//circle centered at vertex, of radius to centroid
        g.setColor( Color.MAGENTA );
        int len1c = (int)Math.sqrt((x1-xc)*(x1-xc) + (y1-yc)*(y1-yc));
 	g.drawOval(x1-len1c, y1-len1c, 2*len1c, 2*len1c);
        int len2c = (int)Math.sqrt((x2-xc)*(x2-xc) + (y2-yc)*(y2-yc));
 	g.drawOval(x2-len2c, y2-len2c, 2*len2c, 2*len2c);
        int len3c = (int)Math.sqrt((x3-xc)*(x3-xc) + (y3-yc)*(y3-yc));
 	g.drawOval(x3-len3c, y3-len3c, 2*len3c, 2*len3c);
    }
}