User:Gazyi/CS:GO Bot Behavior Trees

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← Counter-Strike: Global Offensive Level Creation

In Counter-Strike: Global Offensive, bots can be given a Behavior Tree to follow. A behavior tree dictates how the bot senses things (vision, hearing, damage sensing), moves, attacks, and does other actions.

They use Valve's proprietary KeyValues3 format (.kv3), which is a text-based format with somewhat strict syntax. They typically use the bt_ prefix, to signify that file is a Behavior Tree. They are stored in csgo/scripts/ai. One can create and use his own behavior trees, see below.

Officially, behavior trees are used for the game modes Co-op Strike, Guardian and Deathmatch.

Behavior trees were first added to the game on September 16, 2019. Since September 1, 2020, behavior trees can be packed into BSP files.

Using a Behavior Tree

The ConVar mp_bot_ai_bt can assign a behavior tree to all bots on the server. Its value is a string representing the path to a .kv3 file, starting from csgo/. For example, the following line is used for official Deathmatch and can be found in csgo/cfg/gamemode_deathmatch.cfg:

mp_bot_ai_bt "scripts/ai/deathmatch/bt_default.kv3"

For the Co-op game mode, info_enemy_terrorist_spawn entities have the KeyValue behavior_tree_file that can be used to specify a behavior tree only for bots spawning at this entity.

Related Console Commands

ConVar	Default Value	Description
`cv_bot_ai_bt_debug_target`	-1	Draw the behavior tree of the given bot.
`cv_bot_ai_bt_hiding_spot_show`	0	Draw hiding spots.
`cv_bot_ai_bt_moveto_show_next_hiding_spot`	0	Draw the hiding spot the bot will check next.
`mp_bot_ai_bt`	""	Use the specified behavior tree file to drive the bot behavior.
`mp_bot_ai_bt_clear_cache`	ConCommand	Clears the cache for behavior tree files.

Format

The first line of a .kv3 file is always a header specifying the KV3 version. For CS:GO, use this header:

<!-- kv3 encoding:text:version{e21c7f3c-8a33-41c5-9977-a76d3a32aa0d} format:generic:version{7412167c-06e9-4698-aff2-e63eb59037e7} -->

Now define general bot configuration. Use "config" key, which should contain full path to that file, including file extension:

<!-- kv3 encoding:text:version{e21c7f3c-8a33-41c5-9977-a76d3a32aa0d} format:generic:version{7412167c-06e9-4698-aff2-e63eb59037e7} -->
{
	config = "scripts/ai/<path to bt_config>/<bt_config_name>.kv3"
}

Behavior trees always start with root. Define it with "root" key. Every behavior node should be inside it.

<!-- kv3 encoding:text:version{e21c7f3c-8a33-41c5-9977-a76d3a32aa0d} format:generic:version{7412167c-06e9-4698-aff2-e63eb59037e7} -->
{
	config = "scripts/ai/<path to bt_config>/<bt_config_name>.kv3"
	root = 
	{
		<Behavior Node>
	}
}

Behavior Node format depends on its type and parameters:

<!-- kv3 encoding:text:version{e21c7f3c-8a33-41c5-9977-a76d3a32aa0d} format:generic:version{7412167c-06e9-4698-aff2-e63eb59037e7} -->
{
	config = "scripts/ai/<path to bt_config>/<bt_config_name>.kv3"
	root = 
	{
		type = <Node Type>
		<parameter> = <value>
		...
		child = 
		{
			<Behavior Node>
		}
	}
}

Some nodes allows to define new global variables. Their input name should contain both double and single quotes:

type = "action_set_global_counter"
input_name = "'Test'" // Note those quotation marks.
input_value = 1

Configuration

Todo:

Explain parameters in bt_config

These parameters define general bot reaction and combat behavior for every bot skill ( low, fair, normal, tough, hard, very_hard, expert, default ), like a botprofile.db.

Default format is:

<!-- kv3 encoding:text:version{e21c7f3c-8a33-41c5-9977-a76d3a32aa0d} format:generic:version{7412167c-06e9-4698-aff2-e63eb59037e7} -->
{
	<skill level>
	{
		<Variables from table below>
		attack = <Attack table>
	}
}

List of parameters

Variable	Description
`aim_target_acquisition_lerp_time`
`aim_target_acquisition_lerp_time_deviation`
`aim_target_acquisition_angle_penalty`
`aim_target_acquisition_angle_penalty_deviation`
`aim_target_acquisition_angle_penalty_reduction_ratio`
`aim_target_acquisition_angle_tolerance`
`aim_target_acquisition_angle_lerp_bias`
`aim_target_tracking_lerp_time`
`aim_target_tracking_lerp_time_deviation`
`aim_target_tracking_focus_interval`
`aim_target_tracking_focus_interval_deviation`
`aim_target_tracking_angle_lerp_bias`
`aim_new_target_angle_tolerance`
`aim_max_duration`
`aim_max_duration_deviation`
`aim_punch_angle_reaction_chance`
`look_around_awareness_yaw_range`	Max angle to horizontal rotate viewcamera from this viewpoint.
`look_around_awareness_pitch_range`	Max angle to vertical rotate viewcamera from this viewpoint.
`look_around_focus_interval`	Delay between next viewcamera rotation.
`look_around_focus_interval_deviation`
`look_around_lerp_time`	Time to rotate viewcamera to next position.
`look_around_lerp_time_deviation`
`look_around_lerp_bias`	Smooths viewcamera movement.
`reaction_time`	Delay before reaction on event.
`combat_crouch_chance`
`combat_dodge_command_duration`
`combat_dodge_command_duration_deviation`

Attack Table

Attack table defines handling of different weapon types.

Example:

attack =
[
	// duration, duration deviation, cadence, cooldown, cooldown deviation

	// KNIFE						PISTOL							SUBMACHINEGUN
	[ -1.0, -1.0, -1.0, -1.0, -1.0 ],[ 0.95, 0.25, 0.5, 0.15, 0.05 ],[ 0.42, 0.07, 0.0, 0.15, 0.05 ],
	// RIFLE						SHOTGUN							SNIPER_RIFLE
	[ 0.22, 0.07, 0.0, 0.45, 0.15 ],[ 0.3, 0.0, 0.0, 0.95, 0.25 ],[ 0.22, 0.07, 0.0, 2.0, 0.0 ],
	// MACHINEGUN					C4								TASER
	[ 0.75, 0.15, 0.0, 0.3, 0.1 ],[ -1.0, -1.0, -1.0, -1.0, -1.0 ],	[ -1.0, -1.0, -1.0, -1.0, -1.0 ],
	// GRENADE						EQUIPMENT						STACKABLEITEM
	[ -1.0, -1.0, -1.0, -1.0, -1.0 ],[ -1.0, -1.0, -1.0, -1.0, -1.0 ],[ -1.0, -1.0, -1.0, -1.0, -1.0 ],
	// FISTS						BREACHCHARGE					BUMPMINE
	[ -1.0, -1.0, -1.0, -1.0, -1.0 ],[ -1.0, -1.0, -1.0, -1.0, -1.0 ],[ -1.0, -1.0, -1.0, -1.0, -1.0 ],
	// TABLET						MELEE							SHIELD
	[ -1.0, -1.0, -1.0, -1.0, -1.0 ],[ -1.0, -1.0, -1.0, -1.0, -1.0 ],[ -1.0, -1.0, -1.0, -1.0, -1.0 ],
	// WEAPONTYPE_ZONE_REPULSOR		UNKNOWN
	[ -1.0, -1.0, -1.0, -1.0, -1.0 ],[ -1.0, -1.0, -1.0, -1.0, -1.0 ]
]

Nodes

This is a list of all nodes on November 9, 2021.

Todo:

Complete node parameters and descriptions, check for inaccuracies.
Define variable types for parameters.
Explain all parameters.

Combinators

Type	Parameters	Description
`parallel`		Executes all child functions in one script tick.
`selector`		Executes child functions as sequence until meeting child with true condition.
`sequencer`		Executes child functions as sequence until meeting child with false condition.
`subtree`	`string file, string name`	Executes behavior tree from file.

Decorators

Type	Parameters	Description
`decorator_bot_service`	`array memory_to_expire(variable? domain (GroupID or AllBots), flag key (ShortTermAttackMemory, ShortTermDamageMemory, ShortTermAreaDamageMemory, ShortTermInvestigateMemory, LongTermMemory, DamageThroughSmokeMemory, Threats), int time, int distance), array tagged_entities_to_expire, int_flag? basic_chatter_enable, vector? input_chatter_enemies, int chatter_outnumbered_threshold`	Kinda main bot behavior function? Usually contains all subtree routines.
`decorator_buy_service`	`array output`	Returns array of items that bot will buy, then executes function.
`decorator_dec_global_counter`	`variable input_name`	Decreases input variable by 1, then executes function?
`decorator_find_utility_strat`	`vector input_location, int distance_threshold, vector output_location, vector output_angles, string output_weapon`	Unused.
`decorator_game_event`		Warning:Release Notes for 21/10/2021 say about it but it doesn't exist in code?
`decorator_hiding_spot_service`	`variable? domain (GroupID or AllBots), vector output_hiding_spot, int distance_threshold, int expiration_time`	Returns hiding spot, then executes function? Usually located right after script root.
`decorator_invert`		Unused. Valve scripts usually use `negated = 1` flag in node parameters.
`decorator_maybe`	`float chance`	Executes child functions with specified chance (1 - 100%, 0.7 - 70% etc).
`decorator_memory`	`vector? input, memory? output, string output_domain`	Saves input in specified memory buffer?
`decorator_need_healing`	`int health_threshold`	Executes child functions if bot health is lower that input threshold.
`decorator_picker_blocked_by_smoke`	`vector? input, int distance_threshold`	Executes child functions if input position is behind smoke volume?
`decorator_picker_dedup`	`vector? input, memory? against, int distance_threshold`	??? Only used in noise picker in Valve scripts.
`decorator_picker_grenade_type`	`array input, array types (EXPLOSIVE, FLASH, FIRE, DECOY, SMOKE, SENSOR, SNOWBALL)`	Executes child functions on specified grenade types.
`decorator_picker_max_score`	`array input`	???
`decorator_picker_nearby`	`array input, int cutoff_distance`	Executes child functions if input entities are within distance.
`decorator_picker_random_by_distance`	`array input, int distance_min, int distance_max`	Executes child functions if random entity from input is within distance limits?
`decorator_picker_reaction_time`	`variable? input_domain (GroupID or AllBots), memory? input, vector? output`	Executes child functions after delay, that depends of bot skill reaction time?
`decorator_picker_visible`	`array input, int_flag? check_fov`	Executes function if input entity in LOS?
`decorator_picker_weight_as_distance`	`array input`	??? Only used in noise picker in Valve scripts.
`decorator_random_approach_point`	`vector output`	Returns a random point in navmesh.
`decorator_random_int`	`int min, int max, int output`	Returns a random int the range of min to max.
`decorator_ranker_dist`	`array input`	Sorts entities depending on distance?
`decorator_remove`	`variable? input_domain (GroupID or AllBots), memory? input, array? remove`	Removes selected entities from input memory.
`decorator_remove_key`	`variable? input`	Removes input variable from script scope.
`decorator_repeat`		Executes child functions in loop.
`decorator_route_service`	`array config (array routes, array strategies), vector? output_waypoint, string output_waypoint_name, string output_domain`	Unused.
`decorator_run_once`	`int max_attempts = 1`	Executes child functions limited amount of times?
`decorator_sensor`	`flag entity_type_filter (ALL, PLAYERS, HUMAN_PLAYERS, NOISE, DAMAGE, AREA_DAMAGE, CLASSNAME, GRENADE), function? shape(flag type (sensor_shape_fov, sensor_shape_sphere), int radius), flag team_filter (ANY, CT, TERRORIST, SAME, OPPOSITE, ENEMY), int_flag orphan_only, int_flag priority, string class_name, vector? output`	Returns entity detected by sensor and executes child functions.
`decorator_set_barrier`		Unused.
`decorator_set_reaction_time`	`array? input`	Executes child functions on input after delay, that depends of bot skill reaction time?
`decorator_succeed`		Executes child functions if previous decorator is succeed?
`decorator_tag_entity`	`vector? input, array? output, flag operation_type (BT_DECORATOR_TAG_ENTITY_CLEAR, BT_DECORATOR_TAG_ENTITY_SET), int expiration_time`	??? Used in picking target tree in Valve scripts.
`decorator_tag_threshold`	`vector? entity_input, vector? tagged_entities_input, int amount, flag check_type (BT_DECORATOR_TAG_THRESHOLD_AT_MOST, BT_DECORATOR_TAG_THRESHOLD_AT_LEAST)`	??? Used to determine if it's safe to do objective in Valve scripts?
`decorator_token_service`	`variable? domain, string output_token_name, string output_token_domain, function config(array tokens, array assignments)`	In Guardian Mode: defines bot GroupID, then executes child functions.
`decorator_try_lock`	`variable? domain`	Checks if other bot is already doing same function???
`decorator_wait_success`	`int timeout`	Executres child functions after delay?
`decorator_wait_success`	`int timeout`	Executres child functions after delay?

Conditions

Type	Parameters	Description
`condition_barrier`		Unused.
`condition_distance_less`	`vector input, int distance_threshold_min, int distance_threshold_max`	Returns true, if distance to input position is less than distance_threshold?
`condition_has_parachute`		Returns true, if bot has parachute in inventory.
`condition_inactive`	`array input(memory? key), int round_start_threshold_seconds, int sensor_inactivity_threshold_seconds`	Returns true, if bot doesn't have any memory and sensor input within timing.
`condition_is_airborne`		Returns true, if bot is mid-air.
`condition_is_at_bomb_site`		Returns true, if bot is at bombsite zone.
`condition_is_empty`	`int_flag? global, any input`	Returns true, if input variable is empty or doesn't exist.
`condition_is_equal`	`any source, any destination`	Returns true, if source variable is equal to "destination" input.
`condition_is_greater`	`any source, any destination`	Unused. Returns true, if source variable is greater than "destination" input.
`condition_is_greater_equal`	`any source, any destination`	Unused. Returns true, if source variable is equal or greater than "destination" input.
`condition_is_inv_slot_empty`	`flag slot (KNIFE, PISTOL, RIFLE, GRENADES)`	Returns true, if input equipment slot is empty.
`condition_is_less`	`any source, any destination`	Unused. Returns true, if source variable is less than "destination" input.
`condition_is_less_equal`	`any source, any destination`	Unused. Returns true, if source variable is equal or less than "destination" input.
`condition_is_reloading`		Unused. Returns true, if active weapon is in reloading state.
`condition_is_weapon_equipped`	`string weapon`	Returns true, if bot has active weapon with input classname.
`condition_is_weapon_suitable`	`string weapon`	Unused.
`condition_out_of_ammo`		Returns true, if active weapon is out of ammo.
`condition_owns_item`	`string weapon`	Returns true, if bot has item with input classname.

Actions

Type	Parameters	Description
`action_acquire_items`	`array items, int_flag? remove_all_items`	Equips bot with items from array.
`action_aim`	`vector input, int_flag? acquire_only, flag? ready`	Rotates bot towards input point?
`action_aim_projectile`	`vector input, vector output`	Calculates angles for throwing at input position?
`action_assign_guardian_loadout`	`string input_token_name, array assignments(string token, array loadout(array items, array wave_numbers, int wave_numbers_min, int wave_numbers_max, int weight))`	In Guardian mode: Chooses bot spawn loadout.
`action_attack`	`vector input, flag? output (e.g. output = "Attacking"), flag? ready (e.g. ready = "AimReady")`	Bot attack input entity?
`action_buy`		Bot buys weapons.
`action_choose_bomb_site_area`	`int input, navzone? output`	Gets bombzone nav position from index. Supports convars.
`action_choose_guardian_bomb_plant_location`	`vector? output`	Chooses plant position in navmesh? Guardian mode only?
`action_choose_random_waypoint`	`navzone? input, vector output`	Chooses random waypoint inside input navzone.
`action_choose_random_waypoint_within_radius`	`vector origin, vector output, float radius`	Choose random waypoint within specified origin and radius.
`action_choose_team_spawn_area`	`navzone? output`	Gets all navzones with spawnpoints?
`action_combat_positioning`	`vector input, flag? is_attacking`	Bot tries to reach best combat position against input entity?
`action_commit_suicide`		Kills bot.
`action_compare_global_counter`	`variable? input_name (e.g. input_name = "'Test'"), int input_value`	Compares value from variable "input_name" to input value.
`action_coordinated_buy`	`flag team_filter (ANY, CT, TERRORIST, SAME, OPPOSITE, ENEMY), int save_threshold, flag? id_no_purchase (e.g. id_no_purchase = "DidNotPurchase"), array purchases(array items, string id)`	In Guardian mode: restricts buying items to specific groupIDs?
`action_crouch`		Forces bot to crouch.
`action_custom_buy`	`array item_aliases`	Unused.
`action_drop_active_weapon`		Unused. Forces bot to drop active weapon.
`action_equip_item`	`string item, array items_one_of`	Forces bot to select item with classname from input.
`action_equip_weapon`	`string weapon (classname or BEST)`	Force bot to select item with classname from input or "best" weapon in inventory.
`action_flee_area_damage`	`vector? input, vector output, int max_search_range, int threat_min_keep_distance`	Returns safe spot from that position within search radius.
`action_hide`		Unused.
`action_inspect_current_weapon`		Unused. Forces bot to play inspect animation.
`action_jump`		Forces bot to jump.
`action_look_at`	`vector input_angles, navzone? input_location`	Rotates bot at specified angle.
`action_move_to`	`vector destination, flag movement_type (BT_ACTION_MOVETO_RUN, BT_ACTION_MOVETO_WALK), flag route_type (BT_ACTION_MOVETO_FASTEST_ROUTE,BT_ACTION_MOVETO_SAFEST_ROUTE), vector? hiding_spot, vector? threat, int damaging_areas_penalty_cost, int nearest_area_distance_threshold, int hiding_spot_check_distance_threshold, int arrival_epsilon, float additional_arrival_epsilon_2d, int_flag? auto_look_adjust`	Forces bot to move at destination point.
`action_parachute_positioning`		???
`action_pull_trigger`	`int ratio`	Forces bot primary attack.
`action_reload`		Forces bot to reload weapon.
`action_say`	`string phrase, flag? high_priority`	Forces bot to say radio command phrase. List of phrases is located in `botchatter.db`
`action_secondary_attack`		Unused. Forces bot secondary attack.
`action_select_areas_within_radius`	`vector input, float radius, navzone? output`	Returns navzones within specified origin and radius?
`action_set_global_counter`	`variable? input_name, int input_value`	Sets input value to variable "input_name".
`action_set_global_flag`	`variable? name, int expiration_time_min, int expiration_time_max`	Sets global variable "name" to 1 for specified time?
`action_set_value_float`	`variable? key, float value`	Sets float value to variable "key".
`action_set_value_vector`	`variable? key, vector value`	Sets vector value to variable "key".
`action_standup`		Unused. Forces bot to uncrouch.
`action_teleport`	`vector destination`	Teleports bot to destination position.
`action_use`		Forces bot "+use"
`action_wait`	`int wait_time_min, int wait_time_max`	Freezes bot AI and script execution for defined amount of time.

Reserved Variables

Those variables are defined in game code. They can be used to get some information about game mode and bot and as conditions.

Variable	Description
`int NumberOfTerrorists`	Number of players in T team.
`int NumberOfAliveTerrorists`	Number of alive players in T team.
`int NumberOfCounterTerrorists`	Number of players in CT team.
`int NumberOfAliveCounterTerrorists`	Number of alive players in CT team.
`int GuardianWaveNumber`	Wave number in Guardian Mode.
`int AccountBalance`	Amount of player money.
`float? BlindnessPercentage`	Amount of blindness applied by flash grenade.
`??? BombIsBeingDefused`	Returns ??? when bomb is being defused.
`variable? LastCoopSpawnPointName`	Targetname of last spawn point spawned that bot in Co-op Strike.
`Vector LastCoopSpawnPointLocation`	Origin point of last spawn point spawned that bot in Co-op Strike.
`int AmmoCount/weapon_name`	Remained amount of ammo in weapon with classname "weapon_name" (clip + reserve).
`int AmmoCount/current`	Remained amount of ammo in active weapon (clip + reserve).

Examples

Default Deathmatch Behavior Tree

Found in csgo/scripts/ai/bt_default.kv3.

<!-- kv3 encoding:text:version{e21c7f3c-8a33-41c5-9977-a76d3a32aa0d} format:generic:version{7412167c-06e9-4698-aff2-e63eb59037e7} -->
{
	config = "scripts/ai/deathmatch/bt_config.kv3"
	root =
	{
		type = "decorator_bot_service"
		memory_to_expire =
		[
			{
				key = "ShortTermAttackMemory"
				time = 0.7
				distance = 0
			},
			{
				key = "LongTermMemory"
				time = 10
				distance = 500
			},
			{
				key = "ShortTermInvestigateMemory"
				time = 3
				distance = 200
			}
		]
		child =
		{
			type = "decorator_buy_service"
			output = "ShouldBuy"
			child =
			{
				type = "parallel"
				children =
				[
					{
						type = "decorator_repeat"
						child =
						{
							type = "parallel"
							children =
							[
								// memorize enemies through vision
								{
									type = "subtree"
									file = "scripts/ai/modules/bt_memorize_enemies_vision.kv3"
									name = "MemorizeEnemiesVision"
								},
								// memorize noises happening right now
								{
									type = "subtree"
									file = "scripts/ai/modules/bt_memorize_noises.kv3"
									name = "MemorizeNoises"
								},
								// record the nearest memorized event to investigate
								{
									type = "subtree"
									file = "scripts/ai/modules/bt_memorize_nearest_investigation.kv3"
									name = "MemorizeNearestInvestigation"
								}
							]
						}
					},
					{
						type = "decorator_repeat"
						child =
						{
							type = "selector"
							children =
							[
								// Buy if we have to
								{
									type = "condition_is_empty"
									input = "ShouldBuy"
									negated = 1
									child =
									{
										// sequencer: evaluate first to last child, in order
										type = "sequencer"
										children =
										[
											{
												type = "action_wait"
												wait_time_min = 3
												wait_time_max = 3
											},
											{
												type = "action_buy"
											},
											{
												type = "decorator_remove_key"
												input = "ShouldBuy"
											}
										]
									}
								},
								// Else: face the damage source if we're taking damage
								{
									type = "decorator_sensor"
									entity_type_filter = "DAMAGE"
									output = "Damage"
									priority = 0
									child =
									{
										type = "condition_is_empty"
										input = "Damage"
										negated = 1
										child =
										{
											type = "action_aim"
											input = "Damage"
											acquire_only = 1
										}
									}
								},
								// Else: attack if we see an enemy
								{
									type = "subtree"
									file = "scripts/ai/modules/bt_attack.kv3"
									name = "Attack"
								},
								{
									type = "subtree"
									file = "scripts/ai/modules/bt_heal_if_needed.kv3"
									name = "HealIfNeeded"
								},
								// Else: investigate the closest memorized event
								{
									type = "subtree"
									file = "scripts/ai/modules/bt_investigate_closest_memorized_event.kv3"
									name = "InvestigateClosestMemorizedEvent"
								},
								// Else: hunt
								{
									// sequencer: evaluate first to last child, in order
									type = "sequencer"
									children =
									[
										{
											type = "action_equip_weapon"
											weapon = "BEST"
										},
										{
											type = "decorator_random_int"
											min = 0
											max = 1
											output = "BombSiteIndex"
											child =
											{
												type = "action_choose_bomb_site_area"
												input = "BombSiteIndex"
												output = "HuntAreas"
											}
										},
										{
											type = "action_choose_team_spawn_area"
											output = "HuntAreas"
										},
										{
											type = "action_choose_random_waypoint"
											input = "HuntAreas"
											output = "TargetHuntArea"
										},
										{
											type = "action_move_to"
											destination = "TargetHuntArea"
											movement_type = "BT_ACTION_MOVETO_RUN"
											route_type = "BT_ACTION_MOVETO_FASTEST_ROUTE"
										}
									]
								}
							]
						}
					}
				]
			}
		}
	}
}

User:Gazyi/CS:GO Bot Behavior Trees

Contents

Using a Behavior Tree

Related Console Commands

Format

Configuration

List of parameters

Attack Table

Nodes

Combinators

Decorators

Conditions

Actions

Reserved Variables

Examples

Default Deathmatch Behavior Tree

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