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What Is an Attribute Definition?

An Attribute Definition is the blueprint of a single stat inside UMAS.
It defines:
  • Attribute Handle / Name
  • Base Value
  • Min/Max
  • Optional regen settings
  • Optional progression settings
  • Modifier behavior
These definitions live inside an AttributeProfile. UMAS treats every attribute as a number, but categories and Gameplay Tags can be used to group and organize them.

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Fields Defined in UAttributeDefinition

(Summarized from the plugin source)
  • AttributeHandle
    The unique FName/handle used internally to identify the attribute.
  • BaseValue
    The initial value for this attribute when the profile loads.
  • MinValue / MaxValue
    Hard clamps to ensure the attribute stays within valid bounds.
  • bCanRegenerate
    Whether the attribute supports passive regeneration.
  • RegenRate / RegenDelay
    Optional regeneration configuration.
  • ProgressionConfig
    A reference to a struct used for leveling, XP, and scaling.
  • Tags
    Optional tags used for filtering, tooltips, UI, or effect logic.

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Runtime Data Structure

At runtime, definitions are converted into FAttributeInstance records stored inside the Attribute Manager Component. These instances contain:
  • Current Value
  • Base Value
  • Delta Modifiers
  • Active Effects
  • Cached Scaled Values
  • Flags for replication

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Designer Notes

  • Keep attribute names simple and consistent
    (e.g., Health, MaxHealth, Strength, Defense).
  • Use tags to group attributes for UI or effects.
  • For survival games, use regen settings for stamina/energy, not for health.
  • For RPGs, use progression config + link definitions for stat scaling.

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Developer Notes

  • Attribute handles are used internally as efficient lookup keys.
  • Definitions are immutable at runtime.
  • Editing the profile updates future spawns, not existing characters.
  • Use modifiers and effects to change stats at runtime.