commit 5b6a41ef55396832d58259c39b69072dd5f7b623
Author: Nhân <hi@imnhan.com>
Date:   Sun Sep 17 12:37:32 2023 +0700

    initial move to proper state machine: idle anim

diff --git a/main.go b/main.go
index 51dcdf5..aefab9e 100644
--- a/main.go
+++ b/main.go
@@ -285,7 +285,7 @@ func main() {
 	ebiten.SetWindowIcon([]image.Image{AppIcon})
 
 	must.Zero(ebiten.RunGameWithOptions(
-		&game,
+		NewStateMachine(),
 		&ebiten.RunGameOptions{ScreenTransparent: true},
 	))
 }
diff --git a/states.go b/states.go
new file mode 100644
index 0000000..3c333db
--- /dev/null
+++ b/states.go
@@ -0,0 +1,72 @@
+package main
+
+import (
+	"github.com/hajimehoshi/ebiten/v2"
+)
+
+type StateMachine struct {
+	state          State
+	anim           *Anim
+	animFrameCount int // number of frames in current anim
+	frameIdx       int // frame index in current animation
+	ticks          int // ticks since last animation frame change
+}
+
+func NewStateMachine() *StateMachine {
+	sm := StateMachine{state: StateIdle{}}
+	sm.state.Enter(&sm)
+	return &sm
+}
+
+func (sm *StateMachine) setAnim(anim *Anim) {
+	sm.anim = anim
+	sm.animFrameCount = len(anim.Frames)
+}
+func (sm *StateMachine) Frame() *ebiten.Image {
+	return sm.anim.Frames[sm.frameIdx]
+}
+
+func (sm *StateMachine) HandleInput() {
+	sm.state.HandleInput(sm)
+}
+func (sm *StateMachine) Update() error {
+	sm.state.Update(sm)
+
+	// Advance or reset animation frame
+	sm.ticks += 1
+	if sm.ticks < 10 {
+		return nil
+	}
+	sm.ticks = 0
+	if sm.frameIdx >= sm.animFrameCount-1 {
+		sm.frameIdx = 0
+	} else {
+		sm.frameIdx += 1
+	}
+	return nil
+}
+
+func (sm *StateMachine) Draw(screen *ebiten.Image) {
+	screen.DrawImage(sm.Frame(), nil)
+}
+func (sm *StateMachine) Layout(ow, oh int) (sw, sh int) {
+	return SPRITE_X, SPRITE_Y
+}
+
+type State interface {
+	Enter(sm *StateMachine)
+	HandleInput(sm *StateMachine)
+	Update(sm *StateMachine)
+}
+
+type StateIdle struct{}
+type StateDrag struct{}
+type StateRClick struct{}
+type StateHungry struct{}
+type StateFeed struct{}
+type StateWalkL struct{}
+type StateWalkR struct{}
+
+func (s StateIdle) Enter(sm *StateMachine)       { sm.setAnim(Idle) }
+func (s StateIdle) HandleInput(sm *StateMachine) {}
+func (s StateIdle) Update(sm *StateMachine)      {}