0407ballbouncing

var x, y;

var d = 50;

var velocity, angle;

​

function setup() {

  createCanvas(windowWidth, windowHeight);

  resetthatstuff();

}

​

function draw() {

  background(0);

  fill(255, 128, 0);

  ellipse(x, y, d, d);

  x = x + velocity * cos(angle);

  y = y + velocity * sin(angle);

  // boundary checking:

  // OPTION #1 : TELEPORT

  // if(x>width) x = 0;

  // if(x<0) x = width;

  // if(y>height) y = 0;

  // if(y<0) y = height;

​

  // OPTION #2 : VELOCITY INVERSION

  // if(x>width) velocity = -velocity;

  // if(x<0) velocity = -velocity;

  // if(y>height) velocity = -velocity;

  // if(y<0) velocity = -velocity;

​

  // OPTION #3 : ANGULAR REFLECTION

  if(x>width) angle = PI - angle;

  if(x<0) angle = PI - angle;

  if(y>height) angle = TWO_PI - angle;

  if(y<0) angle = TWO_PI - angle;

}

​

function keyTyped()

{

  resetthatstuff();

}

​

function resetthatstuff()

{

  x = width/2;

  y = height/2;

  velocity = random(10, 40); // how fast is the circle moving

  angle = random(0, TWO_PI); // random angle  

}