doctorlectro/game/game.go

package game

import (
	"fmt"
	"os"
	"strings"

	"github.com/hajimehoshi/ebiten/v2/inpututil"

	"code.rocketnine.space/tslocum/doctorlectro/asset"

	"code.rocketnine.space/tslocum/doctorlectro/entity"
	"code.rocketnine.space/tslocum/doctorlectro/level"
	"code.rocketnine.space/tslocum/doctorlectro/system"
	"code.rocketnine.space/tslocum/doctorlectro/world"
	"code.rocketnine.space/tslocum/gohan"
	"github.com/hajimehoshi/ebiten/v2"
	"github.com/jakecoffman/cp"
)

const introMessage = `
DOCTOR LECTRO, THE MAD SCIENTIST, HAS TAKEN
CHARGE OF EARTH'S MAGNETIC POLES!

ANIMALS, ELECTRONICS, AND HAIRSTYLES ACROSS
THE GLOBE ARE IN GRAVE DANGER!

STOP DOCTOR LECTRO BEFORE IT IS TOO LATE!
`

type Game struct {
	shownIntro bool
}

func NewGame() (*Game, error) {
	g := &Game{}
	g.reset()
	g.addSystems()

	return g, nil
}

// addSystems adds all systems to the game. Systems run in the order they are
// added in. Systems do not run in parallel.
func (g *Game) addSystems() {
	gohan.AddSystem(system.NewPhysicsSystem())
	gohan.AddSystem(system.NewPlayerMoveSystem())
	gohan.AddSystem(system.NewMovementSystem())
	for layer := world.LayerPlatform; layer <= world.LayerDefault; layer++ {
		gohan.AddSystem(system.NewRenderSystem(layer))
	}
	gohan.AddSystem(system.NewRenderMessageSystem())
	gohan.AddSystem(system.NewWinSystem())
	gohan.AddSystem(system.NewRenderDebugTextSystem())
}

func (g *Game) reset() {
	for _, e := range gohan.AllEntities() {
		e.Remove()
	}

	world.GameOver = false
	world.Tick = 0

	world.CanJump = false
	world.CanMagnetize = false
	world.CanFire = false
	world.CanDoubleJump = false

	world.LastFire = 0

	world.MetalRects = nil
	world.HazardRects = nil

	world.Clinging = false

	world.LastWalkDirL = true
	world.LastWalkDirU = true

	world.Space = cp.NewSpace()
	world.Space.Iterations = 1
	world.Space.SetGravity(cp.Vector{0, world.Gravity})

	world.Player = entity.NewPlayer()

	level.LoadMap()

	if world.Give != "" {
		for _, ability := range strings.Split(world.Give, ",") {
			switch strings.ToLower(ability) {
			case "jump":
				world.CanJump = true
			case "magnetize":
				world.CanMagnetize = true
			case "fire":
				world.CanFire = true
			case "switch":
				world.CanDoubleJump = true
			default:
				panic(fmt.Sprintf("unknown ability to give player: %s", ability))
			}
		}
	}
}

func (g *Game) Layout(outsideWidth, outsideHeight int) (screenWidth, screenHeight int) {
	return world.ScreenWidth, world.ScreenHeight
}

func (g *Game) Update() error {
	if ebiten.IsWindowBeingClosed() {
		g.Exit()
		return nil
	}

	if world.ResetGame {
		g.reset()
		world.ResetGame = false
	}

	if inpututil.IsKeyJustPressed(ebiten.KeyM) {
		if asset.SoundMusic.IsPlaying() {
			asset.SoundMusic.Pause()
		} else {
			asset.SoundMusic.Play()
		}
	}

	if world.MessageText != "" {
		if ebiten.IsKeyPressed(ebiten.KeyEnter) {
			world.MessageText = ""
		}
		return nil
	}

	if !world.ShownIntro && world.Tick == 0 {
		world.SetMessage(strings.TrimSpace(introMessage))
		world.ShownIntro = true

		if !world.StartMuted {
			asset.SoundMusic.Play()
		}
	}
	return gohan.Update()
}

func (g *Game) Draw(screen *ebiten.Image) {
	err := gohan.Draw(screen)
	if err != nil {
		panic(err)
	}
}

func (g *Game) Exit() {
	os.Exit(0)
}