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examples/2048: Improve comments

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This commit is contained in:
Hajime Hoshi 2017-06-04 18:42:35 +09:00
parent 242565d629
commit 3390393014
1 changed files with 19 additions and 6 deletions
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21
examples/2048/2048/tile.go
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@ -37,7 +37,11 @@ type TileData struct {
// Tile represents a tile infomation including TileData and animation states. // Tile represents a tile infomation including TileData and animation states.
type Tile struct { type Tile struct {
current TileData current TileData
// next represents a next tile information after moving.
// next is empty when the tile is not about to move.
next TileData next TileData
movingCount int movingCount int
startPoppingCount int startPoppingCount int
poppingCount int poppingCount int
@ -104,7 +108,7 @@ func tileAt(tiles map[*Tile]struct{}, x, y int) *Tile {
return result return result
} }
func nextTileAt(tiles map[*Tile]struct{}, x, y int) *Tile { func currentOrNextTileAt(tiles map[*Tile]struct{}, x, y int) *Tile {
var result *Tile var result *Tile
for t := range tiles { for t := range tiles {
if 0 < t.movingCount { if 0 < t.movingCount {
@ -131,6 +135,8 @@ const (
// MoveTiles moves tiles in the given tiles map if possible. // MoveTiles moves tiles in the given tiles map if possible.
// MoveTiles returns true if there are tiles that are to move, otherwise false. // MoveTiles returns true if there are tiles that are to move, otherwise false.
//
// When MoveTiles is called, all tiles must not be about to move.
func MoveTiles(tiles map[*Tile]struct{}, size int, dir Dir) bool { func MoveTiles(tiles map[*Tile]struct{}, size int, dir Dir) bool {
vx, vy := dir.Vector() vx, vy := dir.Vector()
tx := []int{} tx := []int{}
@ -159,6 +165,9 @@ func MoveTiles(tiles map[*Tile]struct{}, size int, dir Dir) bool {
if t.IsMoving() { if t.IsMoving() {
panic("not reach") panic("not reach")
} }
// (ii, jj) is the next position for tile t.
// (ii, jj) is updated until a mergeable tile is found or
// the tile t can't be moved any more.
ii := i ii := i
jj := j jj := j
for { for {
@ -167,7 +176,7 @@ func MoveTiles(tiles map[*Tile]struct{}, size int, dir Dir) bool {
if ni < 0 || ni >= size || nj < 0 || nj >= size { if ni < 0 || ni >= size || nj < 0 || nj >= size {
break break
} }
tt := nextTileAt(tiles, ni, nj) tt := currentOrNextTileAt(tiles, ni, nj)
if tt == nil { if tt == nil {
ii = ni ii = ni
jj = nj jj = nj
@ -178,7 +187,8 @@ func MoveTiles(tiles map[*Tile]struct{}, size int, dir Dir) bool {
break break
} }
if 0 < tt.movingCount && tt.current.value != tt.next.value { if 0 < tt.movingCount && tt.current.value != tt.next.value {
// already merged // tt is already being merged with another tile.
// Break here without updating (ii, jj).
break break
} }
ii = ni ii = ni
@ -186,9 +196,12 @@ func MoveTiles(tiles map[*Tile]struct{}, size int, dir Dir) bool {
moved = true moved = true
break break
} }
// next is the next state of the tile t.
next := TileData{} next := TileData{}
next.value = t.current.value next.value = t.current.value
if tt := nextTileAt(tiles, ii, jj); tt != t && tt != nil { // If there is a tile at the next position (ii, jj), this should be
// mergeable. Let's merge.
if tt := currentOrNextTileAt(tiles, ii, jj); tt != t && tt != nil {
next.value = t.current.value + tt.current.value next.value = t.current.value + tt.current.value
tt.next.value = 0 tt.next.value = 0
tt.next.x = ii tt.next.x = ii