// Author: Kelvin Sung
// Date: October 25, 2012
// Base code for Homework 9a

void setup()
{
  size(400, 350);  // size of window
  frameRate(10);   // 10 updates per second
}


void draw()
{
  background(128);                // gray background
  trappedBall(25, 50);
}

void trappedBall(int x, int y)
{
  // the white box that trap the balls
  fill(255);
  rect(x-25, y-50, 50, 50);  // box that trap the balls
  
  // trapped ball
  fill(color(255, 0, 0));       // color of the ball
  ellipse(x+random(-20,20), y-random(5,45), 3, 3); // the ball
}