Component Types

com.artemis.Component

The original component type.

Pros

• Easiest to work with
• The only component type which "safely" can be shared between multiple entity instances (such as marker-type components, that don't hold any actual data except for the type itself).

Cons

• Potentially more work for the garbage collector, consider the other types if the component is frequent and short-lived.

com.artemis.PooledComponent

Pooled components are recycled once they're removed from an entity. Use in situations when components are re-created at frequent intervals.

Prerequisites

• Zero-argument constructor
• Must use Entity#edit#createComponent(Class<Component>) or World#edit(int eid) or ComponentMapper<Component>#create(int eid)
• Must not employ final fields.

Cons

• Somewhat cumbersome to implement vs normal components.
  • @PooledWeaver can however be used to automate the conversion.

com.artemis.PackedComponent

Packed components only exist as a single instance per ComponentMapper plus one held by the ComponentManager. The template implementation uses a static primitive array to hold the data for all entities.

Prerequisites

• Zero-argument constructor
• Calling the constructor must not reset the backing array, if any, else ComponentMappers will reset the component upon initialization.
• Must use Entity#edit#createComponent(Class<Component>) or World#edit(int eid) or ComponentMapper<Component>#create(int eid)
• No direct field access allowed.

Pros (assuming nearly all entities use have the component)

• Better memory layout, potentially improving access times.
• Consumes less memory by reducing component instances.

Cons

• Cumbersome to implement (unless in situation where @PackedWeaver can be used).