NPC Door Navigation

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NPCs are able to open unlocked prop_door_rotating entities, if their programming permits it. The process is automated and requires only that a valid nodegraph link travel through the doorframe.


Valve's AI does not yet contain any door-specific combat code. NPCs will stand in doorways when others from their squad attempt to pass through, and do not understand the principle of clearing a room from a door entry. For these reasons, combat in or around doorways should be either avoided, or semi-scripted with assaults.

It is quite possible to have NPCs enter a combat area through a door, but without custom AI code the door itself should not be a point of interaction.

Optimal node pattern

Optimal node pattern for a doorway
Main movement targets
Guarantee a nodegraph link by presenting a straight line through the doorframe.
Placed slightly ahead to decrease the likelihood of NPCs stopping too close to the door and causing congestion.
Flank nodes
Create alternate exit points, and are a solid choice for FIND_COVER routines.
Entrance / Exit Pinch
info_node_hint of type Entrance / Exit Pinch.
Ensures that NPCs travelling through the doorway do so one at a time.
Limitation: NPCs that are not using the node (i.e. are not travelling through the door) may still choose to stand on it! This is a bug that should be fixed.

See Also