6.837 - Project #1 (Sept 11, 2001)

Checkpoint due: September 19, Project due: September 26

Ground Rules:

Feel free to discuss assignments and your approach with others.
Don't use code from previous semesters.
The design and code must be your own.
Cite any models, images, ideas, or algorithms that you do not develop yourself.
The assignment and the checkpoint are due before 8pm of the days indicated.
A working version of your applet and source code must be linked to your course home page.
All source code must also be submitted via Athena's turnin procedure.
1. Develop your projects in directories named project1, project2, etc. (depending on the project number)
2. Before turning in, put your project in a tar archive using tar command on athena:
```
      tar -cvf projectX.tar projectX
```
  - here projectX.tar is the archive name, and projectX is your project directory.
  - X is the project number.
  - make sure you are in the parent directory of projectX
3. Use turnin command to turn in the tar file
```
      turnin -c 6.837 X projectX.tar
```
  Make sure you include the course number (-c 6.837) and the project number (X).
4. For example, to turn in project 1:
  - make sure your project is in the directory named 'project1'
  - go to the parent directory of project1
  - type 'tar -cvf project1.tar project1' to create the tar archive
  - type 'turnin -c 6.837 1 project1.tar' to turn in the archive
Check this page frequently for updates and clarifications.

Summary of Project:

Files you will need
Checkpoint 1 is due on Sept 19, by 8pm. You should (at least) complete Checkpoint.java, AnimatedSprite.java, and Playfield.java based on the outlines that we have given you. You will need to use the Raster.java that we have given you. We have given you an HTML file (Checkpoint.html) to test your applet.
The finalized project 1 is due on Sept 26, by 8pm. You should (at least) complete Invaders.java based on the outline we have give you. You will need to use the Raster.java that we have given you plus your completed AnimatedSprite.java and Playfield.java.
Extra Credit: Create an applet for the 6.837 Web page.

Objective:

Raster object

Checkpoint: Sprites

You should not modify the given Raster object, but extend it.
Your sprites should be properly clipped against the edges of the play field.
Your Playfield class must be a initialized with an image and provide methods for scrolling the image (the background) about the play field. Your applet must demonstrate the scrolling capability of your Playfield.
Your sprites must implement transparent pixel regions. You are not require to implement alpha blending, just opaque and transparent pixels. The idea is that you are loading rectangular images, and your sprites will not be rectangular, hence some of the pixels in your rectangular image will be transparent. As a side note, certain images (some GIFS) set the alpha channel of its pixels for you (i.e. support transparency in the file format). We're fine with you using only these GIFs. There are other image formats that don't, namely JPEG. If you want to use them, you will have to devise your own way to determine which pixels of the image (for example: the white pixels) will be transparent and which will not.
Your sprites should be animated, that is, they should cycle through a predefined sequence of images and displacements. In the Resources section below, we give you a couple of sample image sequences that you may want to use. Feel free to get others or make your own. In the code we provide you, we have a mechanism for parsing simple specs of animation sequences (image frame number, number of ticks for that frame, x offset, y offset). For example, the code used on this page for the missile animation in the Checkpoint applet above is:
```
<APPLET codebase="Checkpoint" code="Checkpoint.class" width=400 height=300>
<param name="background" value="Checkpoint/clouds.jpg">
<param name="backgroundScrollX" value="5">
<param name="backgroundScrollY" value="-1">
<param name="defender" value="Checkpoint/missile.gif, 3, 0,1,0,0, 1,1,0,0, 2,1,0,-1"> 
</APPLET>
```
The "background" parameter is the file name for the background image of the playfield. The "backgroundScrollX" and "backgroundScrollY" values indicate the displacement that creates the motion effect. In our implementation, these scroll offsets refer to a displacement of the screen relative to the background image, thus, the background image appears to be moving in the opposite direction, i.e. with the negative of the specified offsets. The "defender" sprite is specified by specifying an image file name, the number of frames in the animation (see below), and then a sequence of four-tuples (image frame, ticks, dx, dy) that specify the animation. In your game, you will need to specify several animated sprites by adding additional parameters. Here's the input to the Invaders game at the top of this page:
```
<APPLET codebase="Invaders" code="Invaders.class" width=400 height=300>
<param name="background" value="Invaders/clouds.jpg">
<param name="backgroundScrollX" value="5">
<param name="backgroundScrollY" value="-1">
<param name="invader" value="Invaders/invader.gif, 7"> 
<param name="defender" value="Invaders/defender.gif, 1"> 
<param name="missile" value="Invaders/missile.gif, 3"> 
<param name="bomb" value="Invaders/bomb.gif, 1"> 
</APPLET>
```
You must include your applet on a web page that is linked to your course web page. This page should include instructions on using your applet, and any other information or observations that you believe will be useful to the graders of your project.
Here is some code to get you started: Outline of Playfield class and Outline of AnimatedSprite class and an Outline of Checkpoint.java (which is nearly complete).

Project 1: The Game

Outline of Invaders.java

You need to keep track of the different kinds of sprites: invaders, missiles, bombs and the defender. When sprites go off the screen, you should get rid of them.
You will need to detect interactions among the sprites: bombs hitting the defender, missiles hitting the invaders or the bombs.
You might want to do explosions, which is cool but will require some work to make them disappear.

Project 1: Extra Credit (and Glory)

We are looking for a Java applet that could appear as a banner on our class page. Once you complete the Invaders game, try extending the applet you wrote for the Checkpoint to create a compelling and visually interesting banner with animated sprites. After the due date, we will have the class vote to select the best applet, which will be added to the class page. The only requirement is that the banner window should be 800 pixels wide x 200 pixels high. Here's your chance for those 15 minutes of fame...

Resources:

Here are some example sprites that you may find useful for this assignment. You can also use anything else that you find. To make copies of these using Internet Explorer or Netscape simply right-click on the images to specify a filename and directory.

Below are a few examples of animated sprites that you can use. You can download them in exactly the same way as described above. You might feel tempted to use an animated GIF files as source images for your AnimatedSprite class. Doing this is much harder than you might imagine. I have found it much easier to include all of the frames of the animation (concatenated side-by-side) into a single image file. There are several image editors that allow you to do this cutting and pasting operations easily. The number of frames in the animation can be communicated as a parameter to the applet (see examples above). If all frames are the same size the images can be diced up easily.

5 frames of a walking ant (750 x 120). One possible animation of a walking sequence is 0-1-2-1-0-3-4-3.

7 frames of a monkey (897 x 180). Frames 0-1-2-3-4-3-2-1 are his gait, and the sequence 2-5-6-5-2 is a turn of his head.

12 frames of a rotating world (768 x 64). Obvious animations are 0-1-2-...-11.

7 frames of an "invader" (found on the Web) (188 x 28). Obvious animation is 0-1-2-...-6.

3 frames of a wobbly missile (found on the Web) (36 x 22). Obvious animation is 0-1-2.

Last Updated: 9/9/01