How to make the door open from both sides?

[Noob234]

How  to  always  make  the  doom guy  open the  door  from  both: outside and  inside? Doom Builder.  Sometimes  it  works  fine  , sometimes it  doesn't 

[Jack9955]

Use Shift+D when making doors, it is much simple. Make sure both lines have action tag 1

[RataUnderground]

 

See that little stick sticking out of the center of the line? It indicates which is the front part of the linedef. Actions can only be triggered by the player from the front.
For a door to work from both sides, both sides must show the front of the linedef to the player.
To change the direction of the linedef, select it and press F. 
Like this: 

[Noob234]

Thank  you  guys  ,  and  now  the  texture  doesn't  work  properly. The  Doom guy  can open  and  close  the  doors from  both  sides ,  but  it  shows  as if  the  texture  is  missing in the  game though in  the  doom builder  everything is cool from  both sides and  in  the  ceiling .  The  textures  are  temporarily standard, I  didn't  pick  up  the  view  for  that  part of  the  map  yet

[Stabbey]

I suggest skimming through the basic tutorials on level building. There's a lot of helpful knowledge, with explanations for beginning mappers.