HW1

Homework 1, due Thursday, Sept 16.

You should make a separate folder on your Website for your assignments for this class. Send an email to the grader ( kk776@cs.nyu.edu ), with the subject line "UNDERGRADUATE GRAPHICS", telling him the URL of that folder.

When you have finished the assignment below, post the working applet onto the web. Post the source code too.

I've provided a very simple Applet which conforms to the Java 1.1 spec, below, for the benefit of those of you who've never written a Java applet before. If you don't have a Java development environment already, you can fetch the Java 2 Standard Edition (J2SE) from Sun at http://java.sun.com/downloads/. If you already had an earlier version installed, you can use that instead. Everything we'll do this semester will be compatible all the way back to Java 1.1, and therefore will run in all browsers and with any development environment you're likely to have.

All that VerySimpleApplet does right now is display an 'X' shape. It extends class BufferedApplet, which just takes care of double buffering. Once you have installed the J2SE development environment, you can compile it by typing: "javac VerySimpleApplet.java" in a command line window, and then you can run it by loading file VerySimpleExample.html in your Web browser.

Your assignment for this week:

Make a web folder for your assignments for this class.
Modify VerySimpleApplet to draw something exciting, interesting, aesthetically pleasing, silly, politically informative, deeply comic in an ironically profound way, or just plain cool. This assignment is largely for fun, so the only real requirement is that you have fun with it (hint: it would be very bad if by amazing coincidence you and somebody else made exactly the same exciting/cool picture). Try out various features in java.awt.graphics, such as filling polygons (method fillPolygon), drawing text strings (method drawString), creating 3D-looking rectangles (method fill3DRect), and so on.
Post your working assignment up on your web folder.
Remember to send an email to the grader at kk776@cs.nyu.edu telling him what URL you'll be posting your assignments to. The subject line of that email should be "UNDERGRADUATE GRAPHICS".


VerySimpleExample.html 

<html>
<head>
<title>Very Simple Example of a Java Applet</title>
</head>
<body bgcolor=#ffe0e0>
<center>
<applet code=VerySimpleApplet.class width=400 height=400>
</applet>
</center>
</body>
</html>


VerySimpleApplet.java 

/*
   THIS IS A VERY SIMPLE JAVA APPLET THAT JUST DRAWS AN X SHAPE.
*/

import java.awt.*;

public class VerySimpleApplet extends BufferedApplet
{
   int x = 100, y = 100; // COORDINATES OF THE CENTER OF THE X

   public void render(Graphics g) {

      // WHENEVER THERE IS "DAMAGE", WE NEED TO REDRAW

      if (damage) {

         // SET COLOR TO WHITE AND CLEAR THE APPLET WINDOW

         g.setColor(Color.white);
         g.fillRect(0, 0, bounds().width, bounds().height);

	 // SET COLOR TO BLACK AND DRAW AN X SHAPE

         g.setColor(Color.black);
         g.drawLine(x - 20, y + 20, x + 20, y - 20);
         g.drawLine(x - 20, y - 20, x + 20, y + 20);
      }
   }
}

class BufferedApplet extends java.applet.Applet implements Runnable
{
/*
   THIS CLASS HANDLES DOUBLE BUFFERING FOR YOU, SO THAT THE IMAGE
   DOESN'T FLICKER WHILE YOU'RE RENDERING IT.  YOU DON'T REALLY
   NEED TO WORRY ABOUT THIS SUPPORT CODE, AND YOU'LL PROBABLY NEVER
   NEED TO CHANGE IT.  IT IS JUST USEFUL LOW LEVEL PLUMBING.
*/

   public void render(Graphics g) { }   // *you* define how to render
   public boolean damage = true;        // you can force a render

   private Image image = null;
   private Graphics buffer = null;
   private Thread t;
   private Rectangle r = new Rectangle(0, 0, 0, 0);

   // A BACKGROUND THREAD CHECKS FOR CHANGES ABOUT 30 TIMES PER SECOND

   public void start() { if (t == null) { t = new Thread(this); t.start(); } }
   public void stop()  { if (t != null) { t.stop(); t = null; } }
   public void run()   { try { while (true) { repaint(); t.sleep(30); } }
                             catch(InterruptedException e){}; }
/*
   UPDATE GETS CALLED BY THE SYSTEM.
   IT CALLS YOUR RENDER METHOD, WHICH DRAWS INTO AN OFF-SCREEN IMAGE.
   THEN UPDATE COPIES THE IMAGE YOU'VE RENDERED ONTO THE APPLET WINDOW.
*/

   public void update(Graphics g) {
      if (r.width != bounds().width || r.height != bounds().height) {
         image = createImage(bounds().width, bounds().height);
         buffer = image.getGraphics();
         r = bounds();
         damage = true;
      }
      render(buffer);
      damage = false;
      if (image != null)
         g.drawImage(image,0,0,this);
   }
}