From 828595010094e313cc4f9232d6306ebb41e9fb19 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Sun, 4 Jun 2017 18:00:47 +0900
Subject: [PATCH] examples/2048: Add comments

---
 examples/2048/2048/board.go | 6 ++++++
 examples/2048/2048/game.go  | 4 ++++
 examples/2048/2048/input.go | 8 ++++++++
 examples/2048/2048/tile.go  | 3 ++-
 4 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/examples/2048/2048/board.go b/examples/2048/2048/board.go
index 46ae56f74..4254550f0 100644
--- a/examples/2048/2048/board.go
+++ b/examples/2048/2048/board.go
@@ -26,12 +26,14 @@ var taskTerminated = errors.New("twenty48: task terminated")
 
 type task func() error
 
+// Board represents the game board.
 type Board struct {
 	size  int
 	tiles map[*Tile]struct{}
 	tasks []task
 }
 
+// NewBoard generates a new Board with giving a size.
 func NewBoard(size int) (*Board, error) {
 	b := &Board{
 		size:  size,
@@ -49,6 +51,7 @@ func (b *Board) tileAt(x, y int) *Tile {
 	return tileAt(b.tiles, x, y)
 }
 
+// Update updates the board state.
 func (b *Board) Update(input *Input) error {
 	for t := range b.tiles {
 		if err := t.Update(); err != nil {
@@ -72,6 +75,7 @@ func (b *Board) Update(input *Input) error {
 	return nil
 }
 
+// Move enqueues tile moving tasks.
 func (b *Board) Move(dir Dir) error {
 	for t := range b.tiles {
 		t.stopAnimation()
@@ -110,12 +114,14 @@ func (b *Board) Move(dir Dir) error {
 	return nil
 }
 
+// Size returns the board size.
 func (b *Board) Size() (int, int) {
 	x := b.size*tileSize + (b.size+1)*tileMargin
 	y := x
 	return x, y
 }
 
+// Draw draws the board to the given boardImage.
 func (b *Board) Draw(boardImage *ebiten.Image) {
 	boardImage.Fill(frameColor)
 	for j := 0; j < b.size; j++ {
diff --git a/examples/2048/2048/game.go b/examples/2048/2048/game.go
index e42569566..28825e9c6 100644
--- a/examples/2048/2048/game.go
+++ b/examples/2048/2048/game.go
@@ -33,12 +33,14 @@ const (
 	boardSize    = 4
 )
 
+// Game represents a game state.
 type Game struct {
 	input      *Input
 	board      *Board
 	boardImage *ebiten.Image
 }
 
+// NewGame generates a new Game object.
 func NewGame() (*Game, error) {
 	g := &Game{
 		input: NewInput(),
@@ -51,6 +53,7 @@ func NewGame() (*Game, error) {
 	return g, nil
 }
 
+// Update updates the current game state.
 func (g *Game) Update() error {
 	g.input.Update()
 	if err := g.board.Update(g.input); err != nil {
@@ -59,6 +62,7 @@ func (g *Game) Update() error {
 	return nil
 }
 
+// Draw draws the current game to the given screen.
 func (g *Game) Draw(screen *ebiten.Image) {
 	if g.boardImage == nil {
 		w, h := g.board.Size()
diff --git a/examples/2048/2048/input.go b/examples/2048/2048/input.go
index 552d714b1..6473e7381 100644
--- a/examples/2048/2048/input.go
+++ b/examples/2048/2048/input.go
@@ -20,6 +20,7 @@ import (
 	"github.com/hajimehoshi/ebiten"
 )
 
+// Dir represents a direction.
 type Dir int
 
 const (
@@ -29,6 +30,7 @@ const (
 	DirLeft
 )
 
+// String returns a string representing the direction.
 func (d Dir) String() string {
 	switch d {
 	case DirUp:
@@ -43,6 +45,7 @@ func (d Dir) String() string {
 	panic("not reach")
 }
 
+// Vector returns a [-1, 1] value for each axis.
 func (d Dir) Vector() (x, y int) {
 	switch d {
 	case DirUp:
@@ -57,10 +60,12 @@ func (d Dir) Vector() (x, y int) {
 	panic("not reach")
 }
 
+// Input represents the current key states.
 type Input struct {
 	keyState map[ebiten.Key]int
 }
 
+// NewInput generates a new Input object.
 func NewInput() *Input {
 	return &Input{
 		keyState: map[ebiten.Key]int{},
@@ -76,6 +81,7 @@ var (
 	}
 )
 
+// Update updates the current input states.
 func (i *Input) Update() {
 	for k := range dirKeys {
 		if ebiten.IsKeyPressed(k) {
@@ -86,6 +92,8 @@ func (i *Input) Update() {
 	}
 }
 
+// Dir returns a currenly pressed direction.
+// Dir returns false if no direction key is pressed.
 func (i *Input) Dir() (Dir, bool) {
 	for k, d := range dirKeys {
 		if i.keyState[k] == 1 {
diff --git a/examples/2048/2048/tile.go b/examples/2048/2048/tile.go
index 893b8ed34..35cd3bdd4 100644
--- a/examples/2048/2048/tile.go
+++ b/examples/2048/2048/tile.go
@@ -131,7 +131,7 @@ const (
 )
 
 // MoveTiles moves tiles in the given tiles map if possible.
-// MoveTiles returns true if there are movable tiles, otherwise false.
+// MoveTiles returns true if there are tiles that are to move, otherwise false.
 func MoveTiles(tiles map[*Tile]struct{}, size int, dir Dir) bool {
 	vx, vy := dir.Vector()
 	tx := []int{}
@@ -244,6 +244,7 @@ func addRandomTile(tiles map[*Tile]struct{}, size int) error {
 	return nil
 }
 
+// Update updates the tile's animation states.
 func (t *Tile) Update() error {
 	switch {
 	case 0 < t.movingCount: