statemanager

README

StateManager

StateManager is simple state management for ebiten games

Documentation

Read GoDoc

Usage

    stateManager := New()
    stateManager.Add(menuState)
    stateManager.SetActive(menuState.ID())

    // Main game loop function
    func GameLoop(screen *ebiten.Image) error {
       if err := stateManager.Update(); err != nil {
		    return err
	    }

        if ebiten.IsRunningSlowly() {
            return nil
        }

        if err := stateManager.Draw(screen); err != nil {
		    return err
	    }
    }

License

MIT License

Documentation

Overview

Package statemanager provides a way to manage states simply.

Create a new statemanager

stateManager := New()

You will need to create your own states that have a Update, Draw, ID, OnExit, and OnEnter function following the State interface. The ID is used to keep track the states and allow you to switch to them. It must be unique.

type menuState struct {}

// Draw takes a screen and hanles any drawing
func (s *menuState) Draw(screen *ebiten.Image) error {
    return nil
}

// Update Handle any updating this state needs to do.
func (s *menuState) Update() error {
    return nil
}

// ID is the unique ID of this state
func (s *menuState) ID() string {
    return "Main_Menu"
}

// OnEnter does any setup for the state. It could be used to reset a state.
func (s *menuState) OnEnter() error {
    return nil
}

// OnExit handles teardown of this state if required.
func (s *menuState) OnExit() error {
    return nil
}

Add your states. Add will not allow you to add states with the same ID.

err := stateManager.Add(menuState)
err = stateManager.Add(gameState)

Make sure to set the first active state. An error will be returned if the id is not in stateManager. When setting the active state the State.OnExit and State.OnEnter methods are run to handle any setup or teardown.

err := stateManager.SetActive(menuState.ID())

The states manage themselves so you just need to run the Update and Draw functions correctly in your main game loop.

    func GameLoop(screen *ebiten.Image) error {
       if err := stateManager.Update(); err != nil {
		    return err
	    }

        if ebiten.IsRunningSlowly() {
            return nil
        }

        if err := stateManager.Draw(screen); err != nil {
		    return err
	    }
    }

Index

• type State
• type StateManager
  • func New() StateManager

Types

type State

type State interface {
	OnEnter() error
	OnExit() error
	Draw(screen *ebiten.Image) error
	Update() error
	ID() string
}

State is a game state

type StateManager

type StateManager interface {
	// Add a new state to the manager
	Add(state State) error

	// SetActive sets the state to update/draw
	SetActive(id string) error

	// Update and Draw need to be run from the game
	Update() error
	Draw(screen *ebiten.Image) error

	// States is a list of ids that are currently in statemanager
	States() []string
}

StateManager manages States by IDs and knows which State is active. It runs update/draw for that State.

func New

func New() StateManager

New returns a new StateManager