feat: add ghost piece

README.md

@@ -65,7 +65,8 @@ go build tetris.go
 ## Roadmap
 
 - [x] Line clear animations
-- [ ] Hard drop and ghost piece
+- [x] ghost piece
+- [ ] Hard drop
 - [ ] Level/speed progression and pause
 - [ ] High score persistence
 - [ ] Custom key bindings

game/block.go

@@ -16,12 +16,22 @@ const (
 	BLOCK_ORANGE
 	BLOCK_MAGENTA
 	BLOCK_TEAL
+	BLOCK_GHOST
 )
 
 func (c Block) Tile() graphics.Tile {
-	if c >= 8 {
+	if c >= 9 {
 		c = BLOCK_EMPTY
 	}
+
+	if c == BLOCK_GHOST {
+		return graphics.Tile{
+			Size: assets.BLOCK_TILE_SIZE,
+			X:    byte(7),
+			Y:    byte(1),
+		}
+	}
+
 	return graphics.Tile{
 		Size: assets.BLOCK_TILE_SIZE,
 		X:    byte(c),

game/config/config.go

@@ -9,11 +9,13 @@ import (
 type Config struct {
 	fd          *os.File
 	SoundVolume byte `json:"sound_volume"`
+	GhostPiece  bool `json:"ghost_piece"`
 }
 
 func DefaultConfig(fd *os.File) *Config {
 	cfg := Config{
 		SoundVolume: 255,
+		GhostPiece:  false,
 	}
 	cfg.fd = fd
 	return &cfg

game/draw/shape.go

@@ -14,8 +14,10 @@ type Shape interface {
 }
 
 func DrawShape(offset rl.Vector2, pos core.Vec2i8, shape Shape) {
-	tile := shape.Tile()
+	DrawShapeTile(offset, pos, shape, shape.Tile())
+}
 
+func DrawShapeTile(offset rl.Vector2, pos core.Vec2i8, shape Shape, tile graphics.Tile) {
 	for _, coord := range shape.Coordinates() {
 		block := pos.Add(coord)
 		grid.DrawBlock(offset, byte(block.X), byte(block.Y), tile)

game/ghost_shape.go

@@ -0,0 +1,39 @@
+package game
+
+import (
+	"tetris/engine/core"
+	"tetris/game/draw"
+
+	rl "github.com/gen2brain/raylib-go/raylib"
+)
+
+type GhostShape struct {
+	posY int8 // only need Y coordinate
+}
+
+func (gs *GhostShape) UpdatePos(shape *Shape, pos core.Vec2i8, grid *Grid) {
+	for gs.posY = pos.Y; pos.Y <= int8(grid.Height()); pos.Y++ {
+		if CheckShapeCollision(pos, shape, grid) {
+			gs.posY = pos.Y - 1
+			break
+		}
+	}
+}
+
+func (gs *GhostShape) Draw(offset rl.Vector2, shape *Shape, pos core.Vec2i8) {
+	draw.DrawShapeTile(offset, core.NewVec2(pos.X, gs.posY), shape, BLOCK_GHOST.Tile())
+}
+
+func UpdateGhostShapeY(shape *Shape, pos core.Vec2i8, grid *Grid) int8 {
+	for ; pos.Y <= int8(grid.Height()); pos.Y++ {
+		if CheckShapeCollision(pos, shape, grid) {
+			pos.Y = pos.Y - 1
+			break
+		}
+	}
+	return pos.Y
+}
+
+func DrawGhost(offset rl.Vector2, shape *Shape, pos core.Vec2i8, ghost_y int8) {
+	draw.DrawShapeTile(offset, core.NewVec2(pos.X, ghost_y), shape, BLOCK_GHOST.Tile())
+}

game/line_clear_animation.go

@@ -32,15 +32,15 @@ func (lca *LineClearAnimation) SetLines(rows []byte) {
 	}
 }
 
-func (lca *LineClearAnimation) Update(grid *Grid) {
+func (lca *LineClearAnimation) Update(grid *Grid) bool {
 	if lca.Completed() {
-		return
+		return false
 	}
 
 	if lca.leftIndex < 0 || lca.rightIndex > GRID_WIDTH {
 		grid.MoveLinesDown(lca.lines...)
 		lca.Reset()
-		return
+		return true
 	}
 
 	for _, lineIndex := range lca.lines {
@@ -50,6 +50,8 @@ func (lca *LineClearAnimation) Update(grid *Grid) {
 
 	lca.leftIndex--
 	lca.rightIndex++
+
+	return false
 }
 
 func (lca LineClearAnimation) Completed() bool {

game/shape.go

@@ -58,6 +58,10 @@ func (s Shape) Coordinates() [4]core.Vec2i8 {
 }
 
 func (s Shape) RotateCW() Shape {
+	if s.typ == SHAPE_O {
+		return s
+	}
+
 	rotated := [3]core.Vec2i8{}
 
 	for i, block := range s.coordinates {
@@ -71,6 +75,10 @@ func (s Shape) RotateCW() Shape {
 }
 
 func (s Shape) RotateCCW() Shape {
+	if s.typ == SHAPE_O {
+		return s
+	}
+
 	rotated := [3]core.Vec2i8{}
 
 	for i, block := range s.coordinates {

game/state/handlers/gameplay.go

@@ -18,6 +18,8 @@ import (
 type GamePlay struct {
 	shape              game.Shape
 	shape_pos          core.Vec2i8
+	ghost              game.GhostShape
+	ghost_needs_update bool
 	score              game.Score
 	dropTimer          core.IntervalTimer
 	moveTimer          core.IntervalTimer
@@ -66,6 +68,7 @@ func (gp *GamePlay) SpawnShape() {
 	gp.shape = gp.nextShape
 	gp.nextShape = gp.shapeQueue.Next()
 	gp.shape_pos = core.Vec2i8{X: 4, Y: 0}
+	gp.ghost_needs_update = true
 }
 
 func (gp *GamePlay) LockShape() {
@@ -90,7 +93,9 @@ func (gp *GamePlay) Update(fsm state.Transitioner, delta float32) {
 
 	if !gp.lineClearAnimation.Completed() {
 		if gp.lineClearTimer.UpdateReset(delta) {
-			gp.lineClearAnimation.Update(&gp.grid)
+			if gp.lineClearAnimation.Update(&gp.grid) {
+				gp.ghost_needs_update = true
+			}
 		}
 		return
 	}
@@ -99,6 +104,7 @@ func (gp *GamePlay) Update(fsm state.Transitioner, delta float32) {
 		rotated := gp.shape.RotateCW()
 		if !game.CheckShapeCollision(gp.shape_pos, &rotated, &gp.grid) {
 			gp.shape = rotated
+			gp.ghost_needs_update = true
 		}
 	}
 
@@ -111,6 +117,7 @@ func (gp *GamePlay) Update(fsm state.Transitioner, delta float32) {
 		}
 		if !game.CheckShapeCollision(new_pos, &gp.shape, &gp.grid) {
 			gp.shape_pos.X = new_pos.X
+			gp.ghost_needs_update = true
 		}
 	}
 
@@ -136,12 +143,24 @@ func (gp *GamePlay) Update(fsm state.Transitioner, delta float32) {
 			gp.shape_pos = new_pos
 		}
 	}
+
+	if gp.ghost_needs_update {
+		if game.Config.GhostPiece {
+			gp.ghost.UpdatePos(&gp.shape, gp.shape_pos, &gp.grid)
+		}
+		gp.ghost_needs_update = false
+	}
 }
 
 func (gp GamePlay) Render() {
+	offset := rl.NewVector2(25, 25)
+
 	render.Begin(gp.r.Theme.GridBackground)
-	gp.r.DrawGrid(rl.NewVector2(25, 25), gp.grid)
-	draw.DrawShape(rl.NewVector2(25, 25), gp.shape_pos, gp.shape)
+	gp.r.DrawGrid(offset, gp.grid)
+	draw.DrawShape(offset, gp.shape_pos, gp.shape)
+	if game.Config.GhostPiece && gp.lineClearAnimation.Completed() {
+		gp.ghost.Draw(offset, &gp.shape, gp.shape_pos)
+	}
 	gp.r.DrawFrame(rl.RectangleInt32{X: 400, Y: 25, Width: 250, Height: 100})
 	gp.r.DrawHeaderText(410, 30, "Score")
 	gp.r.DrawText(410, 65, fmt.Sprintf("%.7d", gp.score))

game/state/handlers/options.go

@@ -16,8 +16,9 @@ import (
 )
 
 type OptionsMenu struct {
-	sndVolume *widgets.Slider
-	list      *layouts.ListBox
+	sndVolume  *widgets.Slider
+	ghostBlock *widgets.Checkbox
+	list       *layouts.ListBox
 }
 
 func soundVolumeChanged(widget *widgets.Slider) {
@@ -33,10 +34,15 @@ func soundVolumeChanged(widget *widgets.Slider) {
 
 func NewOptionsMenu() *OptionsMenu {
 	sndVolume := widgets.NewSlider(0, 255, 10).WithOnChange(soundVolumeChanged)
+	ghostPiece := widgets.NewCheckbox(game.Config.GhostPiece, func(value bool) {
+		game.Config.GhostPiece = value
+		game.Config.Save()
+	})
 	return &OptionsMenu{
 		sndVolume: sndVolume,
 		list: layouts.NewListBox([]ui.InputWidget{
 			layouts.NewInputControl(widgets.NewLabel("Sound Volume", 16), sndVolume),
+			layouts.NewInputControl(widgets.NewLabel("Show ghost piece", 16), ghostPiece),
 		}).Spacing(10).OnSelect(uievents.MenuSelect),
 	}
 }

game/ui/widgets/checkbox.go

@@ -0,0 +1,62 @@
+package widgets
+
+import (
+	"tetris/engine/core"
+	"tetris/engine/input"
+	"tetris/engine/render"
+	"tetris/game/ui/base"
+
+	rl "github.com/gen2brain/raylib-go/raylib"
+)
+
+type CheckboxAction func(value bool)
+
+type Checkbox struct {
+	*base.WithFocus
+	action CheckboxAction
+	value  bool
+}
+
+func NewCheckbox(value bool, action CheckboxAction) *Checkbox {
+	return &Checkbox{
+		WithFocus: &base.WithFocus{},
+		value:     value,
+		action:    action,
+	}
+}
+
+func (cb Checkbox) Size() core.Vec2i {
+	return core.NewVec2(24, 24)
+}
+
+func (cb *Checkbox) HandleInput() {
+	if input.KeyPressedWithRepeat(rl.KeyEnter) {
+		cb.value = !cb.value
+		cb.action(cb.value)
+	}
+}
+
+func (cb Checkbox) Draw(x, y int32) {
+	size := cb.Size()
+	space := int32(2)
+	color := rl.White
+	if cb.HasFocus() {
+		color = rl.Red
+	}
+
+	render.DrawRectOutlineBorder(rl.RectangleInt32{
+		X:      x,
+		Y:      y,
+		Width:  int32(size.X),
+		Height: int32(size.Y),
+	}, 4, color)
+
+	if cb.value {
+		render.DrawRectBorder(rl.RectangleInt32{
+			X:      x + space,
+			Y:      y + space,
+			Width:  int32(size.X) - (space * 2),
+			Height: int32(size.Y) - (space * 2),
+		}, color, 0, rl.Blank)
+	}
+}