Add initial "event loop" and scene

Start with the main menu with only one option, and build the
abstractions between the event loop and what the scene itself handles.

.gitignore

@@ -0,0 +1 @@
+/gotris

go.mod

@@ -1,3 +1,14 @@
-module gotris/main
+module git.shanti.wtf/shanti/gotris
 
 go 1.24.1
+
+require github.com/hajimehoshi/ebiten/v2 v2.8.6
+
+require (
+	github.com/ebitengine/gomobile v0.0.0-20240911145611-4856209ac325 // indirect
+	github.com/ebitengine/hideconsole v1.0.0 // indirect
+	github.com/ebitengine/purego v0.8.0 // indirect
+	github.com/jezek/xgb v1.1.1 // indirect
+	golang.org/x/sync v0.8.0 // indirect
+	golang.org/x/sys v0.25.0 // indirect
+)

go.sum

@@ -0,0 +1,16 @@
+github.com/ebitengine/gomobile v0.0.0-20240911145611-4856209ac325 h1:Gk1XUEttOk0/hb6Tq3WkmutWa0ZLhNn/6fc6XZpM7tM=
+github.com/ebitengine/gomobile v0.0.0-20240911145611-4856209ac325/go.mod h1:ulhSQcbPioQrallSuIzF8l1NKQoD7xmMZc5NxzibUMY=
+github.com/ebitengine/hideconsole v1.0.0 h1:5J4U0kXF+pv/DhiXt5/lTz0eO5ogJ1iXb8Yj1yReDqE=
+github.com/ebitengine/hideconsole v1.0.0/go.mod h1:hTTBTvVYWKBuxPr7peweneWdkUwEuHuB3C1R/ielR1A=
+github.com/ebitengine/purego v0.8.0 h1:JbqvnEzRvPpxhCJzJJ2y0RbiZ8nyjccVUrSM3q+GvvE=
+github.com/ebitengine/purego v0.8.0/go.mod h1:iIjxzd6CiRiOG0UyXP+V1+jWqUXVjPKLAI0mRfJZTmQ=
+github.com/hajimehoshi/ebiten/v2 v2.8.6 h1:Dkd/sYI0TYyZRCE7GVxV59XC+WCi2BbGAbIBjXeVC1U=
+github.com/hajimehoshi/ebiten/v2 v2.8.6/go.mod h1:cCQ3np7rdmaJa1ZnvslraVlpxNb3wCjEnAP1LHNyXNA=
+github.com/jezek/xgb v1.1.1 h1:bE/r8ZZtSv7l9gk6nU0mYx51aXrvnyb44892TwSaqS4=
+github.com/jezek/xgb v1.1.1/go.mod h1:nrhwO0FX/enq75I7Y7G8iN1ubpSGZEiA3v9e9GyRFlk=
+golang.org/x/image v0.20.0 h1:7cVCUjQwfL18gyBJOmYvptfSHS8Fb3YUDtfLIZ7Nbpw=
+golang.org/x/image v0.20.0/go.mod h1:0a88To4CYVBAHp5FXJm8o7QbUl37Vd85ply1vyD8auM=
+golang.org/x/sync v0.8.0 h1:3NFvSEYkUoMifnESzZl15y791HH1qU2xm6eCJU5ZPXQ=
+golang.org/x/sync v0.8.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
+golang.org/x/sys v0.25.0 h1:r+8e+loiHxRqhXVl6ML1nO3l1+oFoWbnlu2Ehimmi34=
+golang.org/x/sys v0.25.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=

lib/lib.go

@@ -0,0 +1,98 @@
+package lib
+
+import (
+	"github.com/hajimehoshi/ebiten/v2"
+	"github.com/hajimehoshi/ebiten/v2/ebitenutil"
+	"github.com/hajimehoshi/ebiten/v2/inpututil"
+)
+
+// Scenes: Main Menu
+// Game Mode
+
+//Scene - is the highest-level element of state the game can be in.
+
+type GameEvent struct {
+	Type int
+}
+
+type HandleResult int
+
+const (
+	EventNoOp int = iota
+	EventKeyRelease
+)
+
+const (
+	DoNothing HandleResult = iota
+	EndProgram
+)
+
+type Scene interface {
+	HandleEvent(*GameEvent) HandleResult
+	Draw(screen *ebiten.Image)
+}
+
+// Implements ebiten.Game
+type TetrisGame struct {
+	activeScene Scene
+}
+
+type MainMenuScene struct {
+	selections            [1]string
+	currentSelectionIndex int
+}
+
+func (menu *MainMenuScene) HandleEvent(e *GameEvent) HandleResult {
+	if e.Type == 1 {
+		if menu.selections[menu.currentSelectionIndex] == "Quit" {
+			return EndProgram
+		}
+	}
+	return DoNothing
+}
+
+func (menu *MainMenuScene) Draw(screen *ebiten.Image) {
+	ebitenutil.DebugPrint(screen, menu.selections[menu.currentSelectionIndex])
+}
+
+func NewGame() (*TetrisGame, error) {
+	return &TetrisGame{
+		activeScene: &MainMenuScene{
+			selections:            [1]string{"Quit"},
+			currentSelectionIndex: 0,
+		},
+	}, nil
+}
+
+func (g *TetrisGame) Layout(outsideWidth, outsideHeight int) (int, int) {
+	//TODO: Make this do whatever it is supposed to do : resizing etc
+	return 640, 480
+}
+
+func (g *TetrisGame) Update() error {
+	//while there are events
+
+	var keys []ebiten.Key
+	keys = inpututil.AppendJustReleasedKeys(keys)
+
+	var event GameEvent
+	if len(keys) > 0 {
+		event = GameEvent{Type: EventKeyRelease}
+	} else {
+		event = GameEvent{Type: EventNoOp}
+	}
+
+	switch g.activeScene.HandleEvent(&event) {
+	case EndProgram:
+		return ebiten.Termination
+	case DoNothing:
+		return nil
+	default:
+		return nil
+	}
+	return nil
+}
+
+func (g *TetrisGame) Draw(screen *ebiten.Image) {
+	g.activeScene.Draw(screen)
+}

main.go

@@ -1,7 +1,22 @@
 package main
 
-import "fmt"
+import (
+	"log"
 
+	"git.shanti.wtf/shanti/gotris/lib"
+
+	"github.com/hajimehoshi/ebiten/v2"
+)
+
+// Entry point; initialize global state and begin ebiten game loop
 func main() {
-	fmt.Println("Hello, World!")
+	game, err := lib.NewGame()
+	if err != nil {
+		log.Fatal(err)
+	}
+	ebiten.SetWindowSize(640, 480)
+	ebiten.SetWindowTitle("Gotris")
+	if err := ebiten.RunGame(game); err != nil {
+		log.Fatal(err)
+	}
 }