Entity: AreaVolume

An area volume is an invisible entity which sends messages when other entities enter or exit its associated collision volume. Area volumes are similar to triggers, with the main differences being that area volumes always use a collision volume rather than having different means of triggering, and that the entry message is sent repeatedly while an entity is inside it, rather than only on the first frame it enters. The exit message is sent once on the frame an entity leaves the volume.

Because of these characteristics, area volumes are usually used for persistent areas of effect, such as part of a room that damages the player, a low-gravity zone, or an area where the player can't switch forms. They are less often used to trigger room events in single-player mode. Another unique feature of area volumes is the priority and overlap system, which is used in Head Shot to create a volume of normal gravity inside the structure, encompassed in a larger volume of low gravity which only takes effect if the player is not also inside the inner volume.

The trigger flags field determines what can trigger this entity; in practice, area volumes are never set to be triggered by beams. Normally, the entry message is sent to the parent entity, and the exit message is set the child entity. However, the following message types are always sent instead to the player who triggered the volume (or player who owns the beam which did so): damage, death, gravity, prevent form switch, and Drip Moat platform lock.

Entity type: 8

See also: Visualization Guide (Part 1, Part 2)

File struct

Size: 0x94 (148)

Offset	Size	Type	Name	Description
0x00	40	EntityDataHeader	Header
0x28	64	CollisionVolume	Volume	Effective area
0x68	2	---	Unused68
0x6A	1	byte	Active	Boolean
0x6B	1	byte	AlwaysActive	Boolean
0x6C	1	byte	AllowOverlap	Boolean; whether to trigger if player is in more than one
0x6D	1	byte	MessageDelay	Number of frames to queue outgoing message (0 or 1)
0x6E	2	---	Unused6E	Boolean?
0x70	4	uint	EntryMessageType	Message type ID to send when player is inside
0x74	4	uint	EntryMessageParam1	Message-specific data
0x78	4	uint	EntryMessageParam2	Message-specific data
0x7C	2	short	ParentId	Entity ID or -1
0x7E	2	---	---	Padding
0x80	4	uint	ExitMessageType	Message type ID to send when player is outside
0x84	4	uint	ExitMessageParam1	Message-specific data
0x88	4	uint	ExitMessageParam2	Message-specific data
0x8C	2	short	ChildId	Entity ID or -1
0x8E	2	ushort	Cooldown
0x90	4	byte	Priority	Boolean
0x94	4	uint	Flags

Runtime class

Size: 0xBC (188)

Offset	Size	Type	Name	Description
0x00	24	CEntity	Entity	Runtime entity base class
0x18	12	vec3	Position
0x24	12	vec3	Facing	Unit facing avector
0x30	12	vec3	Up	Unit up vector
0x3C	1	byte	Active	Boolean
0x3D	1	byte	AllowOverlap	Boolean; whether to trigger if player is in more than one
0x3E	1	byte	MessageDelay	Number of frames to queue outgoing message (0 or 1)
0x3F	4	byte[4]	TriggeredSlots	Which players have triggered this, indexed by player slot
0x43	4	byte[4]	PrioritySlots	Indexed by player slot
0x47	1	---	---	Padding
0x48	4	uint	EntryMessageType	Message type ID to send when player is inside
0x4C	4	uint	EntryMessageParam1	Message-specific data
0x50	4	uint	EntryMessageParam2	Message-specific data
0x54	4	uint	ExitMessageType	Message type ID to send when player is outside
0x58	4	uint	ExitMessageParam1	Message-specific data
0x5C	4	uint	ExitMessageParam2	Message-specific data
0x60	4	uint	Flags	Same as file struct
0x64	2	ushort	Priority
0x66	2	ushort	Cooldown
0x68	8	ushort[4]	CooldownSlots	Indexed by player slot
0x70	4	uint	Parent	Pointer to parent entity (Initially set to `ParentId`)
0x74	4	uint	Child	Pointer to child entity (Initially set to `ChildId`)
0x78	4	uint	NodeRef	Pointer to node ref
0x7C	64	Collision volume	Volume	Effective area

Flags

Bit	Mask	Flag	Description
0-7		Beams	Triggered by the corresponding beam if `1 << beam_id` is set
8	0x100	Charged	If set, beams only trigger if charged
9	0x200	Biped	Triggered by player in biped form
10	0x400	Alt	Triggered by player in alt form
12	0x1000	Bots	If cleared, players only trigger if not bots

Only players and player beams are checked for collision with the volume. Weavel's Halfturret does not count as a player.

Note: The Omega Cannon (beam ID 8) will trigger volumes with the Charged flag set, platform beams (beam ID 9) will trigger volumes with the Biped flag set, and enemy beams (beam ID 10) will trigger volumes with the Alt flag set (subject also to the Charged flag). These behaviors are not observable in practice with either area volumes or triggers.