grid

type AOENotifier[T Locatable] struct {
	Center geometry.Vec3
	Apply  func(item T, distance float32)
}

type Config[T Locatable] struct {
	// CellSize is the edge length, in world units, of one cell.
	CellSize float32
	// Loader supplies on-demand cell contents. Required.
	Loader Loader[T]
	// Unload controls cell eviction. Zero IdleDuration disables idle
	// unload (cells stay loaded once activated).
	Unload UnloadPolicy
	// Spatial is the backing spatial index used by Visit*. Required.
	Spatial spatial.Index[T]
	// Clock supplies the current time; defaults to time.Now.
	Clock func() time.Time
}

type Grid[T Locatable] struct {
	// contains filtered or unexported fields
}

type GridKey struct {
	X, Z int32
}

type Loader[T any] interface {
	Load(ctx context.Context, key GridKey) ([]T, error)
	Save(ctx context.Context, key GridKey, items []T) error
}

type LoaderFunc[T any] struct {
	LoadFn func(ctx context.Context, key GridKey) ([]T, error)
	SaveFn func(ctx context.Context, key GridKey, items []T) error
}

type Locatable interface {
	spatial.Locatable
	Phaseable
}

type MessageNotifier[T Locatable, M any] struct {
	Msg  M
	Send func(item T, msg M)
}

type Notifier[T any] interface {
	OnVisit(cell GridKey, item T)
	OnDone()
}

type NotifierFunc[T any] func(cell GridKey, item T)

type ObserverID uint64

type Phase uint32

type Phaseable interface {
	// Phase returns the bitmask this object belongs to. PhaseAny (0)
	// means visible to every query.
	Phase() Phase
}

type UnloadPolicy struct {
	// IdleDuration: how long a cell must be unobserved before unload.
	// Zero disables idle unload.
	IdleDuration time.Duration
	// ObserverRange: distance within which an observer keeps surrounding
	// cells "observed" (loaded). Must be > 0.
	ObserverRange float32
}

type VisibilityNotifier[T Locatable] struct {
	Observer ObserverID
	Send     func(observer ObserverID, item T)
}