If you are unfamiliar with Entity Component System (ECS), we recommend reading Introduction to ECS before proceeding.

Components are data attributes attached to an entity. They define the properties of an entity, but it does not implement logic or behavior.

In Cardinal, components are defined as Go structs.

Example:

  • A Position component may contain the x, y, and z coordinates of an entity.
  • A Health component may contain the current and max health of an entity.

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Defining Components

By convention, components are defined in the component directory in its own separate files.

You can easily create a new component and register it to the world by following these steps:

1

Define the component struct

A component is defined as a Go struct. It must implement the Name() method which returns a unique name of the component. This is used to identify the component in the world.

/component/component_health.go
package component

type Health struct {
    Current int,
    Max int
}

func (Health) Name() string {
    return "Health"
}
2

Register the component in main.go

Components must be registered in the world before they can be used. This is done by calling the RegisterComponent function.

main.go
package main

func main() {
    w, err := cardinal.NewWorld()
    if err != nil {
        log.Fatal().Err(err).Msg("failed to create world")
    }

    // Register components
    err := cardinal.RegisterComponent[component.Health](w)
    if err != nil {
        log.Fatal().Err(err).Msg("failed to register component")
    }

    // ...
}