void setup(){
 size(800,500); 
}

void draw() {
  //do some drawing
  background(0);
  
 
 // Box widths and positions. 
  int x1, x2, y1, y2;
  x1 = int(random(width));
  x2 = int(random(width/2));
  y1 = int(random(height));
  y2 = int(random(height/2));

  
  stroke(255,255,0);
  strokeWeight(5);

  
  fill(255,0,0);
  rect(x1,y1,x2,y2); 
}




// line(x1,y1,x2,y2);

//first two coordinates are the top left corner (the origin)