/* 
 title: bouncing ball 
 description: ball deflects off sketch window edges 
 based on: sketch created August 9, 2005 by Ira Greenberg 
 modified: With 3 balls, and initial random ball
           placement, Sept. 13, 2006 by Fred Green
 further modified: Done with Vector2D objects,
           10/22/2007
 */ 
 
// declare global variables 
int wdth, ht;
Vector2D velocity1, velocity2, velocity3; 
Vector2D position1, position2, position3;
 
//initialize sketch 
void setup(){ 
  
  //set sketch window size and background color 
  size(500, 400); 
  background(0); 
   
  //first ball velocity 
  velocity1 = new Vector2D(3, 4);
 
  //2nd ball velocity
  velocity2 = new Vector2D(5, 6); 
  
  // ... and 3rd
  velocity3 = new Vector2D(7, 8);
   
  //ball size 
  wdth = 20; 
  ht = 20; 
   
  // turn off shape stroke rendering 
  noStroke(); 
  
  //initial ball placement 
  position1 = new Vector2D(random(10, width-10), random(10, height-10));
  position2 = new Vector2D(random(10, width-10), random(10, height-10));
  position3 = new Vector2D(random(10, width-10), random(10, height-10));
  
 //set the animation loop speed 
  frameRate(30); 
  smooth();
} 
 
// begin animation loop 
void draw(){ 
 
  //update background 
  background(0); 
 
  //draw balls
  fill(200, 200, 0);
  ellipse(position1.getX(), position1.getY(), wdth, ht); 
  ellipse(position2.getX(), position2.getY(), wdth, ht);
  ellipse(position3.getX(), position3.getY(), wdth, ht);
 
  //upgrade position values 
  position1 = position1.plus(velocity1);
  position2 = position2.plus(velocity2);
  position3 = position3.plus(velocity3);
 
  //detect collisions with sides of screen
  velocity1.detectCollision(position1, wdth, ht, width, height);
  velocity2.detectCollision(position2, wdth, ht, width, height);
  velocity3.detectCollision(position3, wdth, ht, width, height);
  
}