// Copyright © 2011 Mark F. Russo
// Bryn Mawr College, Department of Computer Science
// Permission is granted to copy and distribute provided 
// this entire copyright notice is reproduced in all copies.

int positionX = 250;
int positionY = 250;
int deltaX = 0;
int deltaY = 0;

void setup() {
  size(500, 500);
  smooth();
}

void draw() {
  background(255);
  
  // Increment position and clip value
  positionX = positionX + deltaX;
  positionY = positionY + deltaY;
  
  // Clip values
  if (positionX < 0)      positionX = 0;
  if (positionX > width)  positionX = width;
  if (positionY < 0)      positionY = 0;
  if (positionY > height) positionY = height;
  
  // Draw ellipse
  ellipse(positionX, positionY, 
      50*( sin(0.1*positionX)+2), 
      50*( cos(0.1*positionY)+2) );
}

void keyPressed() {
    // Change direction based on key code
    switch (keyCode) {
    case 37:
      deltaX = -2;
      deltaY = 0;
      break;
    case 39:
      deltaX = 2;
      deltaY = 0;
      break;
    case 38:
      deltaY = -2;
      deltaX = 0;
      break;
    case 40:
      deltaY = 2;
      deltaX = 0;
      break;
    case 32:
      deltaX = 0;
      deltaY = 0;
      break;
  }
}