What is an entity-component (ec-)table?
A table where the rows correspond to entities and columns correspond to component types.
Each entry is a particular entity's particular component (or null if the entity does not have that type of component).
Rows (entities) are created/destroyed at run-time however columns (types of components) must be specified at compile-time.
It corresponds to a scene from a non-technical perspective.
Example:
| name | audio_listener | audio_source | button | camera | collider | light | mesh | transform |
|---|---|---|---|---|---|---|---|---|
| "terrain" | null | null | null | null | {...} | null | {...} | {...} |
| "wind" | null | {...} | null | null | null | null | null | {...} |
| "sun" | null | null | null | null | null | {...} | null | {...} |
| "player" | {...} | null | null | {...} | {...} | null | {...} | {...} |
| "ui" | null | null | {...} | null | {...} | null | null | {...} |
What is an entity?
Simply a handle referring to a row in an ec-table.
What is a component?
A data type representing a particular aspect of an entity.
It is not required to derive from a base class.
Examples: audio_source, audio_listener, button, camera, collider, light, mesh, name, transform, ...
What is a system?
A system regularly traverses an ec-table, and processes the components relevant to it.
It is not required to derive from a base class.
Examples: audio_system, physics_world, renderer, ui_system, ...
Limitations
An entity can only have one of each component type since multiple identical types are not allowed in the ec-table.