Components

Components are data containers attached to entities. They define what an entity "is" and "has".

Accessing Components

// From a Ref (entity reference)
Player player = (Player) commandBuffer.getComponent(ref, Player.getComponentType());

// From an ArchetypeChunk (in tick systems)
Player player = (Player) chunk.getComponent(index, Player.getComponentType());

Common Components

Entity Data

Component	Description	Key Methods
Player	Player-specific data	getInventory(), getGameMode(), sendMessage()
TransformComponent	Position & rotation	getPosition(), getRotation()
Velocity	Movement velocity	getVelocity()
HeadRotation	Head direction	getRotation()
Nameplate	Display name	getText()
ModelComponent	Entity model	getModel()

Stats & Effects

Component	Description	Key Methods
EntityStatMap	Health, stamina, etc.	get(statType), setStatValue()
EffectControllerComponent	Active effects	getActiveEffects(), clearEffects()
DamageDataComponent	Combat tracking	getLastCombatAction()

State Components

Component	Description	When Present
DeathComponent	Death info	Entity is dead
Invulnerable	Marker	Entity can't be damaged
Intangible	Marker	Entity can't be hit

Checking Component Existence

// Check if entity has a component
Archetype<EntityStore> archetype = chunk.getArchetype();
boolean isDead = archetype.contains(DeathComponent.getComponentType());
boolean isPlayer = archetype.contains(Player.getComponentType());

Adding/Removing Components

// Add a component
commandBuffer.putComponent(ref, SomeComponent.getComponentType(), new SomeComponent());

// Remove a component
commandBuffer.removeComponent(ref, SomeComponent.getComponentType());

// Try to remove (no error if missing)
commandBuffer.tryRemoveComponent(ref, SomeComponent.getComponentType());

Component Types in Queries

Use components to filter which entities your system processes:

@Override
public Query getQuery() {
    return Query.and(
        Player.getComponentType(),           // Must have Player
        TransformComponent.getComponentType(), // Must have Transform
        Query.not(DeathComponent.getComponentType())  // Must NOT be dead
    );
}

See Also

• ECS Architecture - How components fit in the ECS
• Player Component - Full Player reference
• TransformComponent - Position & rotation