MonsterAIAutomata.xml

Defines the state transition rules that drive monster behavior. Each Automata is a state machine: "when in state X and condition Y, go to state Z". Each automata number holds up to 30 rules per state, evaluated in Priority order.

File Location#

Data/Monster/MonsterAIAutomata.xml

Loaded once at GameServer startup. Changes require a restart.

AI Hierarchy#

The monster AI system layers four files:

MonsterAIGroup.xml   -> which monsters spawn where, with what AI
         |
         v
MonsterAIUnit.xml    -> AI personality (Automata + Element mappings)
         |
         +-> MonsterAIAutomata.xml   <-- this file (transition rules)
         +-> MonsterAIElement.xml    (the actual actions)

AI States#

State	Name	Meaning
`0`	NORMAL	Idle / general
`1`	MOVE	Chasing target or patrolling
`2`	ATTACK	Attacking target
`3`	HEAL	Self or group healing
`4`	AVOID	Fleeing danger
`5`	HELP	Supporting allies (heal, buff)
`6`	SPECIAL	Summon, invisibility, immunity, teleport, skill attack, AI change
`7`	EVENT	Reserved for event-class actions

Each state uses the Element slot with the matching index in MonsterAIUnit.xml (ElementNormal, ElementMove, ElementAttack, ElementHeal, ElementAvoid, ElementHelp, ElementSpecial, ElementEvent).

Transition Types#

Type	Name	Triggered when
`0`	NO_ENEMY	No enemy currently targeted (or target left viewport)
`1`	IN_ENEMY	Target is within the monster's AttackRange
`2`	OUT_ENEMY	Target is at or beyond AttackRange (out of attack range)
`3`	DIE_ENEMY	Current target died. TODO: verify (declared in enum, not handled in evaluator switch)
`4`	DEC_HP	Monster's current HP is less than or equal to `TransitionValue` (absolute HP)
`5`	DEC_HP_PER	Monster's current HP is at or below `TransitionValue` percent of max HP
`6`	IMMEDIATELY	Rolls `TransitionRate` unconditionally
`7`	AGRO_UP	Aggro on current target is at or above `TransitionValue`
`8`	AGRO_DOWN	Aggro on current target is at or below `TransitionValue`
`10`	GROUP_SUMMON	A dead group member is available to re-summon
`11`	GROUP_HEAL	A group member within 6 tiles has HP below `TransitionValue` percent
`12`	SUPPORT_HEAL	An allied monster within 6 tiles has HP below `TransitionValue` percent

Attributes#

<Automata Number="..." Description="..." Priority="..."
         CurrentState="..." NextState="..."
         TransitionType="..." TransitionRate="..."
         TransitionValueType="..." TransitionValue="..."
         DelayTime="..." />

Attribute	Type	Effect
`Number`	0-299	Automata group ID. Referenced by `MonsterAIUnit.Automata`.
`Description`	string	Human-readable label. Stored but not used for logic.
`Priority`	0-29	Check order within the CurrentState bucket. Lower fires first.
`CurrentState`	0-7	State this rule applies FROM.
`NextState`	0-7	State to transition TO on success.
`TransitionType`	enum	Condition type (see table above).
`TransitionRate`	0-100	Probability the transition fires when the condition matches (random 0-99 is compared against the rate).
`TransitionValueType`	int or `*`	`*` is stored as -1. Currently unused by the evaluator.
`TransitionValue`	int or `*`	Condition parameter (HP amount, HP percent, aggro threshold). `*` is stored as -1.
`DelayTime`	ms	Applied as `LastAutomataDelay` when the rule fires; controls the wait before the next transition check.

How a Tick Works#

Monster spawns in State 0 (NORMAL) with the Unit referenced by StartAI.
Each AI tick iterates rules whose CurrentState equals the monster's current state, ordered by insertion (effectively by Priority 0, 1, 2 ...).
For each rule, the evaluator checks the TransitionType condition. If the condition holds, it rolls a random 0-99 against TransitionRate.
The first rule that passes returns immediately. The monster moves to NextState, its LastAutomataDelay is set to DelayTime, and the matching Element from the AI Unit executes.
If no rule passes, the monster stays in the current state.

Cross-File Dependencies#

Attribute	Related in
`Number`	Referenced by `MonsterAIUnit.Automata` in MonsterAIUnit.xml
`NextState` mapping	Action defined by the matching Element in MonsterAIElement.xml via the AI Unit
AttackRange used by Types 1 and 2	See Monster.xml and MonsterAIRule.xml

Common Issues#

Monster never attacks - no transition from state 0 (NORMAL) to state 2 (ATTACK) with a matching TransitionType.
Monster goes passive after a hit - transition from 2 (ATTACK) to 0 (NORMAL) firing too easily; raise Priority of the stay-in-combat rule or lower the NORMAL rule's TransitionRate.
Boss phases never advance - no transition to state 6 or 7 with DEC_HP_PER and a NextState Element of Type 68 (AI Change).
Monster heals forever - transition into state 3 (HEAL) fires but no transition out; add a rule from state 3 with Type 6 (IMMEDIATELY) back to NORMAL/MOVE/ATTACK.
Group summon never fires - group members still alive, or monster is not assigned a valid GroupNumber.