HW 2: Paddle Ball Game

PAT 204/504: Creative Coding (Fall 2025)

Due at 11:59pm ET on September 17

Instructions

• Please submit both your code and your final rendering. You will receive zero credit if the code is missing.
• All assignments must be completed on your own. You are welcome to exchange ideas with your peers, but this should be in the form of concepts and discussion, not in the form of writing and code.
• Provide proper citations/references for any external resources you use in your writing and code.
• Submit your work to Gradescope.
• Late submissions will be accepted for up to a week with 1 point deducted per day.

Q1: Paddle Ball Game (3 points)

Implement a simple paddle ball game in Processing.

• When the game starts, the ball starts from the center of the paddle and moves towards a random upward direction at a preset speed (ballSpeed, which defaults to 10).
• The player controls the paddle’s movement using the mouse. The center of the paddle should be at the same x-position as the mouse.
• The ball bounces back when it hits the top/left/right wall.
• The ball bounces back if it hits the paddle at the bottom.
• The game is over if the player doesn’t catch the ball with the paddle. Show “GAME OVER!” and freeze everything.
• The game restarts when the player clicks the mouse. The ball will be reinitialized to the center of the paddle, moving towards another random upward direction.

Please submit your code as a PDE file and the final rendering as an animated GIF file.

Q2: Sticky & Shrinking Paddle Ball Game (2 points)

Now, let’s make this game more fun and challenging:

• Shrink the paddle bar size after each successful catch until the bar reaches a reasonable minimum width.
• Apply stickiness between the paddle and the ball. That is, a fixed ratio of the paddle velocity will be transferred to the ball when they touch.

Please submit your code as a PDE file and the final rendering as an animated GIF file. Try your best to demonstrate the stickiness by moving the paddle when catching the ball.

Template Sketch

Here is a template sketch for you to get started with:

boolean isGameOver = false; // whether the game is over
boolean saveFrames = false; // whether to save the frames
float barWidth = 60; // width of the paddle bar
float barHeight = 10; // height of the paddle bar
float ballSpeed = 10; // speed of the ball
float ballWidth = 10; // width of the ball

// DEFINE OTHER GLOBAL VARIABLES YOU NEED HERE

// Initialize the game
void init() {
  // YOUR CODE HERE
}

void setup() {
  // Create a 400x400 canvas
  size(400, 400);

  // Set the frame rate to 30 fps
  frameRate(30);

  // YOUR CODE HERE

  // Initialize the game
  init();
}

void draw() {
  // Check if the game is over
  if (isGameOver) {
    // Save the frame for making an animated GIF
    if (saveFrames) {
      saveFrame("frames/###.png");
    }

    // Return immediately if the game is over
    return;
  }

  // YOUR CODE HERE

  // Save the frame for making an animated GIF
  if (saveFrames) {
    saveFrame("frames/###.png");
  }
}

// Reset the game when the mouse is clicked
void mouseClicked() {
  init();
}

Note that the template includes a boolean switch saveFrames that controls if the saveFrame() function at the end of the draw() function will be executed. When saveFrames is set to true, each frame generated by a call of the draw() function will be saved to the folder frames/ in the project directory. You can then use the built-in movie maker (“Tools > Movie Maker”) to create an animated GIF. Also, the GIF standard does not support 60 fps, so we need to add frameRate(30) to the setup() function to set the frame rate to 30 fps.

Hints

• To install Movie Maker,
  1. Click “Tools > Manage Tools”
  2. Click “Movie Maker II | Movie Maker for Processing 4”
  3. Click “Install”
• There’s a bug in the latest release of Movie Maker for Windows. To fix it,
  1. Download the ffmpeg executable
  2. Copy “ffmpeg.exe” (in the bin/ folder) to “C:\Users\[USERNAME]\Documents\Processing\tools\MovieMaker\tool”
• You might want to search in the documentation to find the functions that you need.
• You might want to limit the initial direction of the ball to a smaller range than [0, π] so that it won’t take too long for the ball to reach to the top and back to the paddle.
• You can calculate the paddle velocity using pmouseX and mouseX, where pmouseX stores the value of mouseX in the previous frame.