/*
title:: Bouncing Ball
description: ball deflects off sketch window edges
created: August 9, 2005
by: Ira Greenburg
*/

//declare globalvariables
int xspeed, yspeed;
int xpos, ypos, wdth, ht;

//initialize sketch
void setup (){
  
  //set sketch window size and background color
  size(400, 400);
  background(0);
  
  //ball speed
  xspeed = 3;
  yspeed = 6;
  
  //ball size
  wdth = 10;
  ht = 10;
  
  // turn off shape stroke rendering
  noStroke();
  
  //initial ball placement
  xpos = width/2;
  ypos = height/2;
  
  frameRate(30);
  
}

// begin animation loop
void draw(){
  
  //update background
  background(0);
  
  //drawball
  ellipse(xpos, ypos, wdth, ht);
  
  //upgrade position values
  xpos+=xspeed;
  ypos+=yspeed;
  
  /*conditionals
  detects ball collission with sketch window edges
  also accounts for thickness of ball
  */
  if (xpos>=width-wdth/2 || xpos<=wdth/2){
    xspeed*=-1;
  }
  if (ypos>=height-ht/2 || ypos<=ht/2){
    yspeed*=-1;
  }
}