rvq_Processing/sketch_160909_10_7b_painting_with_pixels_Particles/Particle.pde
class Particle {
  float x;
  float y;
  
  float vx;
  float vy;
  
  Particle(){
    x=width/2;
    y=height/2;
    float a=random(TWO_PI);
    float speed=random(1,2);
    vx=cos(a)*speed;
    vy=sin(a)*speed;
  }
  
  void display(){
    noStroke();
    fill(255);
    ellipse(x,y,12,12);
   }
   
  void move(){
    x=x+vx;
    y=y+vy;
    if (y<0){
      y=height;
    }
    if (y>height){
      y=0;
    } if (x<0){
      x=width;
    }
    if (x>width){
      x=0;
    }
  }
}