Since we've already such a nice passage it would be even nicer to see a door connecting the two rooms. I widened the whole connection, put a brush into the middle which will be the door and added something like a threshold.

(Image start)

Select the door, press the right mouse button, go to func and then click on func_door. The former brush has now been converted into a door (blue lines) and counts as an entity.

(Image func)

Leave the door selected and open the entity window:

(Image doorsettings)

health: Normally a door opens when the player is close to it, but setting the health key avoids this and the door can only be opened by shooting it.

wait: When the key and value box is set like in the picture, the door will shut itself after 2 seconds. "-1" provokes the door to return immediately after it hit the end of its move. If you are not using that key the door will open and close itself when the player comes near.

speed: Defines the moving speed of the door when it's opening and closing (default: 100).

dmg: When the player stands between a door and the connected wall, the door bumps into the player, moves again in its direction and the player will loose as much health as it is defined in the value box (default: 4).

spawnflags: Contrary to the health key a "crusher" decreases the player's health points until he dies. The door won't move until the player has been removed. When you've ticked "start_open" the door will spawn in an opened state when the map has loaded.

The "lip" key determines the units remaining at the end of a move. For this, two screenshots of our tutorial map:

(Image lip8) (Image lip16)

Now compile your map and play around with the values and keys so you get a better understanding of the functions.
When you look at the texture you can see that it was made for a two-part door. So let's create such one. Take the existing door, halve and copy it and put the copied brush next to the original.

(Image halved)

Adjust the textures (select the wrong textured brush, hover over the original with the cursor in the 3D view and press the mouse wheel) and convert the clone into a func_door again. Now take over the keys and values from the first door, except the angle key. In our case use 180° for the left part of the door and 360° for the right one. Before our door works correctly we need to add one more key. Select both sides, open the entity window and type in following:

(Image team)

Our door parts with the team name "door1" will now slide aside together. Of course you can also create a door with three, four, five... parts. As long as you use the same team name for all parts it will be fine.
Just one more thing: Don't forget to texture the inner faces of the brushes. Select the first door and hide it, texture the other part and then vice versa.

Here you can get the maps for this tutorial (place them into baseq3/maps):
Written by Bliccer