• Author: Graham Mitchell
• Filename: PolygonDemo.java

Polygon Demo

Here are some more examples of the various functions at your disposal in Java's graphics library. Download the following code and get it to compile.

Files Needed

• PolygonDemo.java

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

public class PolygonDemo extends Canvas
{
    public void paint( Graphics g )
    {
        g.setColor(Color.black);
        g.drawString("Hey, a triangle!", 50, 50);
        
        Polygon tri = new Polygon();
        tri.addPoint(100, 100);
        tri.addPoint(100, 300);
        tri.addPoint(200, 300);
        
        g.setColor(Color.blue);
        g.fillPolygon(tri);
        
        Polygon pent = new Polygon();
        pent.addPoint(450, 200);
        pent.addPoint(500, 250);
        pent.addPoint(475, 350);
        pent.addPoint(425, 350);
        pent.addPoint(400, 250);
        
        g.setColor(Color.green);
        g.fillPolygon(pent);

        Polygon hex = new Polygon();
                
        // use trig to make a regular hexagon
        int radius = 100; // pixels
        int xCenter = 200;
        int yCenter = 500;
        for ( double ang = 0; ang<2*Math.PI; ang=ang+(2*Math.PI)/6.0)
        {
            double xDelta = radius * Math.cos(ang);
            double yDelta = -radius * Math.sin(ang);
            hex.addPoint(xCenter+(int)xDelta, yCenter+(int)yDelta);
        }

        g.setColor(Color.black);
        g.fillPolygon(hex);
    }

    public static void main(String[] args)
    {
        JFrame win = new JFrame("Polygon Demo");
        win.setSize(1024,768);
        win.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        win.add( new PolygonDemo() );
        win.setVisible(true);
    }

}

What You Should Do on Your Own

Assignments turned in without these things will receive half credit or less.

1. There is a green pentagon being drawn on the screen. What happens if you change the order of the points being added? Answer in a comment.
2. Make a trapezoid somewhere on the screen. The color doesn't matter, and it doesn't matter if it's filled-in or an outline.

©2013 Graham Mitchell

This assignment is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.