Stripe[] stripes = new Stripe[20];

float colVar_r;
float colVar_g;
float colVar_b;

void setup(){
  size(400, 300);
  //initialise stripes
  for(int i = 0; i< stripes.length; i++){
    stripes[i] = new Stripe();
  }
}

void draw(){
  background(150);
  //move and display stripes
  for(int i = 0; i< stripes.length; i++){
    //is mouse over stripe?
    stripes[i].rollover(mouseX,mouseY);
    stripes[i].move();
    stripes[i].display();
  }
}

class Stripe{
  float x;
  float speed;
  float w;
  boolean mouse;
  
  Stripe(){
    x = 0;
    speed = random(1);
    w = random(10,40);
    mouse = false;
  }
  
  //draw stripe
  void display(){
    if(mouse){
      colVar_r = random(255);
      colVar_g = random(255);
      colVar_b = random(255);
      fill(colVar_r,colVar_g,colVar_b);
      //fill(255);
    }else{
      fill(255,60);
    }
    noStroke();
    rect(x,0,w,height);
  }
  
  //move stripe
  void move(){
    x += speed;
    if(x > width+20)x = - 20;
  }
  
  //check if point is inside stripe
  void rollover(int mx, int my){
    //left edge = x, right edge = x+w
    if(mx > x && mx < x + w){
      mouse = true;
    }else{
      mouse = false;
    }
  }
}