User:CS:GO Bot Behavior Trees
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In Template:Game name, 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} -->
Configuration
- Explain parameters in bt_config
Nodes
This is a list of all nodes on 09/11/2021.
- Complete node descriptions
- Define variable types for parameters.
- Explain all parameters
| Function | Signature | Description |
|---|---|---|
InputInputName
|
bool InputInputName()
|
Called when the entity receives an input from the I/O system. The name of the function needs to be Input followed by the name of the input in CamelCase, for example InputFireUser1 for the FireUser1 input. The function needs to return a boolean value. Setting it to true allows the entity to process the input, while false cancels it.
|
OnPostSpawn
|
void OnPostSpawn()
|
This is called after the entity has spawned. |
Precache
|
void Precache()
|
This is called during entity spawning and after restore to allow scripts to precache any resources they need. |
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"
}
]
}
]
}
}
]
}
}
}
}