class Ball{
  float x,y,vx,vy,radius,diameter;
  Environment env;
  color ballColor;
  //--------------
  Ball(float x, float y){
    this.x = x;
    this.y = y;
    diameter = 10;
    radius = diameter/2;
    env = new Environment();
  }
  //--------------
  void update(){
    vx *= env.drag;
    vy *= env.drag;
    
    wallBounce();
    
    x += vx;
    y += vy;
  }
  //--------------
  void wallBounce(){
    if(x<radius){
      vx = -vx;
      x = radius;
    }
    if(x>width-radius){
      vx = -vx;
      x = width-radius;
    }
    if(y<radius){
      vy = -vy;
      y = radius;
    }
    if(y>height-radius){
      vy = -vy;
      y = height-radius;
    }
  }
  //--------------
  void visualize(){
    stroke(255);
    strokeWeight(2);
    fill(255,128,128);
    ellipse(x,y,diameter,diameter);
  }
  //--------------
  void push(float dx, float dy){
    vx += dx * env.pushFactor;
    vy += dy * env.pushFactor;
  }
  //--------------
  void collisionDetect(float cx, float cy, float cradius){
    float distance = dist(x,y,cx,cy);
    if( distance < radius+cradius ){
      x = cx + (radius+cradius)*(x-cx)/distance;
      y = cy + (radius+cradius)*(y-cy)/distance;
      vx = (x-cx)/distance;
      vy = (y-cy)/distance;
    }
  }
}
//=================================
class Environment{
  float drag = 0.98;
  float elasticity = 0.01;
  float pushFactor = 0.05;
}