Combat Behavior State Machines

The SM_Humanoid_CombatBehavior is a UObject-derived Blueprint class within the Combat AI Behavior System for Unreal Engine 5, extending SM_CombatBehavior to provide a pre-configured state machine for humanoid enemy AI behaviors in Action RPGs. It enables developers to manage complex AI behaviors, such as patrolling, chasing, attacking, and retreating, with extensive customization options. The class addresses the need for a robust, ready-to-use AI behavior framework, integrating seamlessly with BP_BehaviorManagerComponent in the Advanced ARPG Combat framework to support dynamic combat scenarios.

Basic Usage

This section outlines how to use SM_Behavior to define AI behavior states within the Combat AI Behavior System. The following functions are essential for managing behavior states.

1. CanEnterState:

   • Purpose: Checks if the behavior state machine can be entered based on initialization conditions.
   • Usage: Override in a custom SM_Behavior to enforce entry requirements, returning a boolean.
   • Example: Ensure the AI is valid before entering.

2. EnterState:

   • Purpose: Executes logic when the behavior state machine is entered, initializing the AI behavior.
   • Usage: Override in a custom SM_Behavior to set the initial state.
   • Example: When theState.Patrol starts, run the corresponding start patrol state function.

3. EndState:

   • Purpose: Executes cleanup logic when the behavior state machine is exited.
   • Usage: Override in a custom SM_Behavior to reset behavior data.
   • Example: When theState.Patrol ends, run the corresponding end patrol state function.

4. UpdateBehavior:

   • Purpose: Updates AI behavior every Behavior Tree tick for continuous adjustments.
   • Usage: Override in a custom SM_Behavior to handle frequent behavior updates, such as movement or targeting.
   • Example: Transition state based on distance to player

5. RunStateMachine:

   • Purpose: Manages complex state transitions, triggered when an ability ends or explicitly called with the correct Behavior State Machine Tag.
   • Usage: Override in a custom SM_Behavior to define transition logic for significant state changes.
   • Example: Transition from State.Idle to State.Chase on target detection.

6. OnTrackTargetUpdated:

   • Purpose: Updates AI targeting frequently for precise behavior adjustments.
   • Usage: Override in a custom SM_Behavior to handle frequent target tracking.
   • Example: Adjust movement toward a target.

7. OnBehaviorLogicStopped:

   • Purpose: Performs cleanup when behavior logic is stopped, such as on AI death.
   • Usage: Override in a custom SM_Behavior to handle cleanup.
   • Example: Reset Blackboard values or clear behavior related timers

Key Properties

Property Name	Purpose
State Tag	Gameplay Tag identifying the behavior state machine (e.g., Behavior.Combat.Humanoid), used for referencing in BP_BehaviorManagerComponent.
bTrackStateActiveTime	If true, tracks the active duration of the state, accessible via Get State Time.
Attack Distance	Sets the range for initiating attacks (e.g., 500 units).
Enemy Aggression	Controls attack frequency, with higher values increasing attack rate.
Enemy Aggression Multiplier	Adjusts aggression dynamically for custom scaling (e.g., for boss encounters).
Strafing Behavior Ranges	Defines distances for strafing during combat (e.g., close, medium).
Following Behavior Ranges	Sets distances for following targets (e.g., player or patrol point).
Behavior Movement Speed	Specifies movement speed for behaviors like chasing or patrolling.
Turning Distances	Determines distances for AI turning adjustments during movement.
Return To Post Distances	Sets the range for returning to a patrol post after deviation.
Retaliation Data	Configures retaliation behavior, such as counterattacks after damage.
Healing Behavior Data	Defines conditions and effects for AI healing actions.
Enemy Defense Data	Sets defensive behaviors, like blocking or dodging, with associated conditions.

Key Concepts

Pre-Configured Humanoid Behaviors

The SM_Humanoid_CombatBehavior provides a pre-configured state machine tailored for humanoid AI, supporting states like State.Idle, State.Patrol, State.Chase, and State.Attack. This concept simplifies setup for common enemy types while still allowing customization.

• Purpose: Offers a ready-to-use framework for humanoid AI behaviors.
• Usage: Assign SM_Humanoid_CombatBehavior in BP_EnemyInfo and adjust properties like Attack Distance.
• Benefit: Accelerates development of standard enemy AI with minimal setup.

Continuous Behavior Updates

The UpdateBehavior function runs every Behavior Tree tick, enabling real-time adjustments to AI actions, such as aligning to a target or adjusting movement speed. This concept ensures smooth, responsive AI behavior.

• Purpose: Maintains dynamic AI behavior during gameplay.
• Usage: Override UpdateBehavior to tweak continuous actions using properties like Behavior Movement Speed.
• Benefit: Enhances AI fluidity in combat and navigation.

Complex State Transitions

The RunStateMachine function handles significant state transitions, triggered by ability completion or explicit calls from BP_BehaviorManagerComponent. This concept supports critical AI behavior shifts, like entering combat or retreating.

• Purpose: Manages pivotal state changes for complex AI logic.
• Usage: Override RunStateMachine to define transitions based on Gameplay Tags or Blackboard data.
• Benefit: Provides precise control over major AI state changes.

Extensive Customization

The SM_Humanoid_CombatBehavior offers numerous properties (e.g., Enemy Aggression, Retaliation Data) for tailoring AI behavior without coding. This concept allows developers to create varied enemy types, from aggressive melee fighters to defensive healers.

• Purpose: Enables fine-tuned AI behavior for diverse roles.
• Usage: Configure properties in BP_EnemyInfo or a custom child class of SM_Humanoid_CombatBehavior.
• Benefit: Supports rapid prototyping and iteration of enemy behaviors.

Best Practices

• Workflows:
  • Use BP_EnemyInfo to configure SM_Humanoid_CombatBehavior properties for consistent setup.
  • Start with demo SM_Humanoid_CombatBehavior to test default behaviors before creating child classes.
  • Use hierarchical Gameplay Tags (e.g., Behavior.Combat.Humanoid.Attack) for clear state transitions in RunStateMachine.
• Pitfalls to Avoid:
  • Don’t overload UpdateBehavior with complex logic; reserve intricate transitions for RunStateMachine.
  • Avoid conflicting State Tag values across SM_Humanoid_CombatBehavior instances.
  • Don’t skip setting Retaliation Data or Enemy Defense Data to ensure robust combat behavior.