a = place_free(x + 1, y) || place_free(x - 1, y)
|| place_free(x, y - 1) || place_free(x, y + 1);
if instance_exists(objPlayer)
{
     if distance_to_object(objPlayer) > 50
     && collision_line(x, y, objPlayer.x, objPlayer.y, objBlockPar, 1, 1)
     {
         if !a
         {
             alpha = 0;
             draw_sprite_ext(sprite_index, -1, x, y, 1, 1, 0, make_color_rgb(alpha, alpha, alpha), 1);
         }
     }
}