float getx(int y, struct entry *theline){ //epistrefei to x kapoias eytheias se kapoio sigkekrimeno y
  float x1, x2, y1, y2;
  float yy;
  yy = (float)y;
  
  x1 = (float)theline->myline.end1->x;
  x2 = (float)theline->myline.end2->x;
  y1 = (float)theline->myline.end1->y;
  y2 = (float)theline->myline.end2->y;
  
  return (float) ((x2 -  x1)/(y2 - y1)) * (y - y1) + x1;
}