refact

lib/game.go

@@ -0,0 +1,174 @@
+package lib
+
+import (
+	"fmt"
+	"sort"
+
+	"github.com/hajimehoshi/ebiten/v2"
+)
+
+type State int
+
+const (
+	StateTitle State = iota
+	StatePlay
+	StateOver
+)
+
+type Game struct {
+	assets *Assets
+
+	state      State
+	playerLane int
+	score      int
+	miss       int
+	rabbits    []*Rabbit
+	spawnTimer int
+	frame      int
+	flash      int
+
+	lcd *ebiten.Image
+}
+
+func NewGame(a *Assets) *Game {
+	return &Game{
+		assets:     a,
+		state:      StateTitle,
+		playerLane: 2,
+		lcd:        ebiten.NewImage(LcdW, LcdH),
+	}
+}
+
+func (g *Game) reset() {
+	g.playerLane = 2
+	g.score = 0
+	g.miss = 0
+	g.rabbits = g.rabbits[:0]
+	g.spawnTimer = 0
+	g.flash = 0
+}
+
+// --- ebiten.Game ---
+
+func (g *Game) Update() error {
+	g.frame++
+	switch g.state {
+	case StateTitle, StateOver:
+		if startPressed() {
+			g.reset()
+			g.state = StatePlay
+		}
+	case StatePlay:
+		g.updatePlay()
+	}
+	return nil
+}
+
+func (g *Game) Draw(screen *ebiten.Image) {
+	screen.DrawImage(g.assets.Bg, nil)
+
+	switch g.state {
+	case StateTitle:
+		g.drawTitle(g.lcd)
+	case StatePlay:
+		g.drawPlay(g.lcd)
+	case StateOver:
+		g.drawOver(g.lcd)
+	}
+
+	opts := &ebiten.DrawImageOptions{}
+	opts.GeoM.Scale(LcdScale, LcdScale)
+	opts.GeoM.Translate(LcdDrawX, LcdDrawY)
+	screen.DrawImage(g.lcd, opts)
+}
+
+func (g *Game) Layout(_, _ int) (int, int) {
+	return ScreenW, ScreenH
+}
+
+// --- play loop ---
+
+func (g *Game) updatePlay() {
+	if pressedRepeat(ebiten.KeyLeft, 12, 6) && g.playerLane > 0 {
+		g.playerLane--
+	}
+	if pressedRepeat(ebiten.KeyRight, 12, 6) && g.playerLane < LaneCount-1 {
+		g.playerLane++
+	}
+
+	g.spawnTimer++
+	interval := 70 - g.score/2
+	if interval < 22 {
+		interval = 22
+	}
+	if g.spawnTimer >= interval {
+		g.spawnTimer = 0
+		g.rabbits = append(g.rabbits, newRabbit(g.score))
+	}
+
+	for i := len(g.rabbits) - 1; i >= 0; i-- {
+		r := g.rabbits[i]
+		r.T += r.Speed
+		if r.T < 1 {
+			continue
+		}
+		if r.Lane == g.playerLane {
+			g.miss++
+			g.flash = 12
+			if g.miss >= MaxMiss {
+				g.state = StateOver
+			}
+		} else {
+			g.score++
+		}
+		g.rabbits = append(g.rabbits[:i], g.rabbits[i+1:]...)
+	}
+
+	if g.flash > 0 {
+		g.flash--
+	}
+}
+
+// --- scene composition ---
+
+func (g *Game) drawPlay(dst *ebiten.Image) {
+	dst.Fill(ColorBg)
+	drawRoad(dst)
+	drawHud(dst, g.assets.HudFont, g.score, g.miss)
+	// far rabbits first so closer ones overlap on top
+	sort.Slice(g.rabbits, func(i, j int) bool { return g.rabbits[i].T < g.rabbits[j].T })
+	for _, r := range g.rabbits {
+		r.Draw(dst, g.assets.Rabbit)
+	}
+	drawScooter(dst, g.assets.Scooter, LaneX[g.playerLane], PlayerY, g.flash > 0, g.frame)
+}
+
+func (g *Game) drawTitle(dst *ebiten.Image) {
+	dst.Fill(ColorBg)
+	drawRoad(dst)
+	for i := 0; i < LaneCount; i++ {
+		drawScooter(dst, g.assets.Scooter, LaneX[i], PlayerY, false, g.frame)
+	}
+	for i := 1; i <= 3; i++ {
+		demo := &Rabbit{
+			Lane: (g.frame/30 + i) % LaneCount,
+			T:    float64((g.frame+i*25)%90) / 90.0,
+		}
+		demo.Draw(dst, g.assets.Rabbit)
+	}
+	if (g.frame/30)%2 == 0 {
+		drawTextCentered(dst, "PRESS SPACE TO START", 120, 56, g.assets.HudFont, ColorFg)
+	}
+	drawTextCentered(dst, "ARROWS MOVE   SPACE START", 120, 72, g.assets.HudFont, ColorFg)
+}
+
+func (g *Game) drawOver(dst *ebiten.Image) {
+	g.drawPlay(dst)
+	rectFill(dst, 60, 50, 120, 36, ColorBg)
+	rectStroke(dst, 60, 50, 120, 36, ColorFg)
+	drawTextCentered(dst, "GAME OVER", 120, 54, g.assets.HudFont, ColorFg)
+	drawTextCentered(dst, fmt.Sprintf("SCORE  %03d", g.score), 120, 66, g.assets.HudFont, ColorFg)
+	if (g.frame/30)%2 == 0 {
+		drawTextCentered(dst, "SPACE = RETRY", 120, 76, g.assets.HudFont, ColorFg)
+	}
+}