/**
 * Welcome to Skanaar microBilliard<br><br>
 * 
 * Click, drag and release on a ball to give it a push.<br>
 * numerical keys 1-4 respawns different number of balls
 **/

Table game;
//--------------
void setup(){
  size(210,330);
  smooth();
  game = new Table(6,5,200,300);
  game.startGame();
}
//--------------
void draw(){
  background(32);
  game.update();
  game.visualize();
}
//--------------
void keyPressed(){
  println( game.kineticEnergy() );
}
//--------------
void mousePressed(){
  game.mousePressed(mouseX-game.x,mouseY-game.y);
}
//--------------
void mouseReleased(){
  game.mouseReleased(mouseX-game.x,mouseY-game.y);
}
//=============================
class Table{
  float drag = 0.985;
  float elasticity = 0.9;
  float wallElasticity = 0.8;
  float pushFactor = 0.05;
  float maxPush = 10;
  color[] ballColors = new color[]{color(192),color(192,64,32),color(64,192,0)};
  Ball[] balls;
  Ball selectedBall;
  int x,y,width,height;
  //--------------
  Table(int x, int y, int w, int h){
    this.x = x;
    this.y = y;
    width = w;
    height = h;
  }
  //--------------
  void startGame(){
    buildBalls(8);
  }
  //--------------
  void buildBalls(int count){
    balls = new Ball[2*count+1];
    for(int i=0;i<count;i++)
      balls[i] = new Ball( random(width), random(height),1, this);
    for(int i=0;i<count;i++)
      balls[count+i] = new Ball( random(width), random(height),2, this);
    balls[2*count] = new Ball( 0.5*(width), 0.5*(height),0, this);
  }
  //--------------
  void update(){
    //simulation
    for(int i=0;i<balls.length;i++)
      balls[i].update();

    //collision detection
    for(int i=0;i<balls.length;i++)
      for(int j=i+1;j<balls.length;j++)
        balls[i].collisionDetect(balls[j]);
  }
  //--------------
  void visualize(){
  
    translate(x,y);
    noStroke();
    fill(0,128,0);
    rect(0,0,width,height);

    //draw que
    stroke(255);
    if(mousePressed && selectedBall != null)
      line(selectedBall.x,selectedBall.y,mouseX-x,mouseY-y); 

    //drawing
    for(int i=0;i<balls.length;i++)
      balls[i].visualize();
  }
  //--------------
  float kineticEnergy(){
    float energy=0;
    for(int i=0;i<balls.length;i++)
      energy += mag( balls[i].vx, balls[i].vy );
    return energy;
  }
  //--------------
  void mousePressed(int mx, int my){
    for(int i=0;i<balls.length;i++)
      if( dist(balls[i].x,balls[i].y,mx,my) < balls[i].radius) {
        selectedBall = balls[i];
        break;
      }
  }
  //--------------
  void mouseReleased(int mx, int my){
    if(selectedBall != null){
      float px = (selectedBall.x-mx) * pushFactor;
      float py = (selectedBall.y-my) * pushFactor;
      float push = mag(px,py);
      if( push > maxPush ){
        px = maxPush*px/push;
        py = maxPush*py/push;
      }
      selectedBall.push(px,py);
    }
    selectedBall = null;
  }
}