二つ重なった半ブロックを片方だけ壊したい

on break:
 if "%event-block%" starts with "double":
  set {_v} to vector from yaw yaw of player and pitch pitch of player
  set vector length of {_v} to 0.05
  set {_pos} to eye of player
  loop 800 times:
   set {_pos} to {_pos} ~ {_v}
   if block at {_pos} is type of event-block:
    set {_float} to y-pos of {_pos} - floor(y-pos of {_pos})
    
    if {_float} >= 0.5:
     send "upper"
    else:
     send "lower"
    
    stop loop
  cancel event

on break:
 if "%event-block%" starts with "double":
  set {_v} to vector from yaw yaw of player and pitch pitch of player
  set vector length of {_v} to 0.05
  set {_pos} to eye of player
  loop 800 times:
   set {_pos} to {_pos} ~ {_v}
   if block at {_pos} is type of event-block:
    set {_float} to y-pos of {_pos} - floor(y-pos of {_pos})
    
    if {_float} >= 0.5:
     send "upper"
    else:
     send "lower"
    
    stop loop
  cancel event