Simplify game preparation

engine/actor.go

@@ -20,17 +20,18 @@ type Collider interface {
 
 // Actor handles basic movement.
 type Actor struct {
-	Position image.Point
-	Size     image.Point
+	CollisionDomain string
+	Pos             image.Point
+	Size            image.Point
 
-	game       *Game
-	xRem, yRem float64
+	collisionDomain interface{}
+	xRem, yRem      float64
 }
 
 func (a *Actor) CollidesAt(p image.Point) bool {
 	// TODO: more efficient test?
 	hit := false
-	Walk(a.game, func(c interface{}) bool {
+	Walk(a.collisionDomain, func(c interface{}) bool {
 		if coll, ok := c.(Collider); ok {
 			if coll.CollidesWith(image.Rectangle{Min: p, Max: p.Add(a.Size)}) {
 				hit = true
@@ -51,13 +52,13 @@ func (a *Actor) MoveX(dx float64, onCollide func()) {
 	a.xRem -= float64(move)
 	sign := sign(move)
 	for move != 0 {
-		if a.CollidesAt(a.Position.Add(image.Pt(sign, 0))) {
+		if a.CollidesAt(a.Pos.Add(image.Pt(sign, 0))) {
 			if onCollide != nil {
 				onCollide()
 			}
 			return
 		}
-		a.Position.X += sign
+		a.Pos.X += sign
 		move -= sign
 	}
 }
@@ -71,19 +72,19 @@ func (a *Actor) MoveY(dy float64, onCollide func()) {
 	a.yRem -= float64(move)
 	sign := sign(move)
 	for move != 0 {
-		if a.CollidesAt(a.Position.Add(image.Pt(0, sign))) {
+		if a.CollidesAt(a.Pos.Add(image.Pt(0, sign))) {
 			if onCollide != nil {
 				onCollide()
 			}
 			return
 		}
-		a.Position.Y += sign
+		a.Pos.Y += sign
 		move -= sign
 	}
 }
 
-func (a *Actor) Build(g *Game) {
-	a.game = g
+func (a *Actor) Prepare(g *Game) {
+	a.collisionDomain = g.Component(a.CollisionDomain)
 }
 
 func sign(m int) int {

engine/debug.go

@@ -43,8 +43,8 @@ type GobDumper struct {
 	game *Game
 }
 
-// Build simply stores the reference to the Game.
-func (d *GobDumper) Build(g *Game) { d.game = g }
+// Prepare simply stores the reference to the Game.
+func (d *GobDumper) Prepare(g *Game) { d.game = g }
 
 // Update waits for the key combo, then dumps the game state into a gzipped gob.
 func (d *GobDumper) Update() error {

engine/game.go

@@ -10,26 +10,6 @@ func init() {
 	gob.Register(Game{})
 }
 
-// Identifier components have a sense of self. This makes it easier for
-// components to find and interact with one another.
-type Identifier interface {
-	Ident() string
-}
-
-// Builder components can be built. It is called when the game
-// component database is being constructed. It should store the Game reference
-// (if needed later on).
-type Builder interface {
-	Build(game *Game)
-}
-
-// Scanner components can be scanned. It is called when the game tree is walked
-// (such as when the game component database is constructed).
-// Scan should return a slice containing all immediate subcomponents.
-type Scanner interface {
-	Scan() []interface{}
-}
-
 // Game implements the ebiten methods using a collection of components.
 type Game struct {
 	ScreenWidth  int
@@ -103,15 +83,19 @@ func Walk(c interface{}, v func(interface{}) bool) {
 	}
 }
 
-// Build builds the component database, and calls Build, on all components
-// reachable via Scan.
-func (g *Game) Build() {
+// PrepareToRun builds the component database (using Walk) and then calls
+// Prepare on every Preparer. You must call PrepareToRun before passing to
+// ebiten.RunGame.
+func (g *Game) PrepareToRun() {
 	g.componentsByID = make(map[string]interface{})
-	Walk(g.Scene, func(c interface{}) bool {
-		if b, ok := c.(Builder); ok {
-			b.Build(g)
-		}
+	Walk(g, func(c interface{}) bool {
 		g.RegisterComponent(c)
 		return true
 	})
+	Walk(g, func(c interface{}) bool {
+		if p, ok := c.(Prepper); ok {
+			p.Prepare(g)
+		}
+		return true
+	})
 }

engine/interface.go

@@ -0,0 +1,40 @@
+package engine
+
+import "github.com/hajimehoshi/ebiten/v2"
+
+// Drawer components can draw themselves. Draw is called often.
+// Each component is responsible for calling Draw on its child components.
+type Drawer interface {
+	Draw(screen *ebiten.Image, geom ebiten.GeoM)
+}
+
+// Identifier components have a sense of self. This makes it easier for
+// components to find and interact with one another.
+type Identifier interface {
+	Ident() string
+}
+
+// Prepper components can be prepared. It is called after the component
+// database has been populated but before the game is run. The component can
+// store the reference to game, if needed, and also query the component database.
+type Prepper interface {
+	Prepare(game *Game)
+}
+
+// Scanner components can be scanned. It is called when the game tree is walked
+// (such as when the game component database is constructed).
+// Scan should return a slice containing all immediate subcomponents.
+type Scanner interface {
+	Scan() []interface{}
+}
+
+// Updater components can update themselves. Update is called repeatedly.
+// Each component is responsible for calling Update on its child components.
+type Updater interface {
+	Update() error
+}
+
+// ZPositioner is used to reorder layers.
+type ZPositioner interface {
+	Z() float64
+}

engine/scene.go

@@ -12,21 +12,6 @@ func init() {
 	gob.Register(Scene{})
 }
 
-// Drawer components can draw themselves. Draw is called often.
-type Drawer interface {
-	Draw(screen *ebiten.Image, geom ebiten.GeoM)
-}
-
-// Updater components can update themselves. Update is called repeatedly.
-type Updater interface {
-	Update() error
-}
-
-// ZPositioner is used to reorder layers.
-type ZPositioner interface {
-	Z() float64
-}
-
 // Scene manages drawing and updating a bunch of components.
 type Scene struct {
 	Components []interface{}

engine/sprite.go

@@ -4,25 +4,17 @@ import (
 	"image"
 
 	"github.com/hajimehoshi/ebiten/v2"
-	"github.com/hajimehoshi/ebiten/v2/inpututil"
 )
 
-const dampen = 0.5
-const gravity = 0.2
-
-// Sprite combines an Actor with the ability to Draw...
+// Sprite combines an Actor with the ability to Draw from a single spritesheet.
 type Sprite struct {
 	Actor
-	*Anim  // TODO: better
 	Hidden bool
 	ID
 	Src ImageRef
 	ZPos
 
-	vx, vy     float64 // TODO: refactor
-	facingLeft bool
-
-	animIdleLeft, animIdleRight, animRunLeft, animRunRight *Anim
+	anim *Anim
 }
 
 func (s *Sprite) Draw(screen *ebiten.Image, geom ebiten.GeoM) {
@@ -30,59 +22,19 @@ func (s *Sprite) Draw(screen *ebiten.Image, geom ebiten.GeoM) {
 		return
 	}
 	var op ebiten.DrawImageOptions
-	op.GeoM.Translate(float64(s.Actor.Position.X), float64(s.Actor.Position.Y))
+	op.GeoM.Translate(float64(s.Pos.X), float64(s.Pos.Y))
 	op.GeoM.Concat(geom)
 
-	frame := s.Anim.CurrentFrame()
+	frame := s.anim.CurrentFrame()
 	src := s.Src.Image()
 	w, _ := src.Size()
-	sx, sy := (frame*s.Actor.Size.X)%w, ((frame*s.Actor.Size.X)/w)*s.Actor.Size.Y
+	sp := image.Pt((frame*s.Size.X)%w, ((frame*s.Size.X)/w)*s.Size.Y)
 
-	screen.DrawImage(src.SubImage(image.Rect(sx, sy, sx+s.Actor.Size.X, sy+s.Actor.Size.Y)).(*ebiten.Image), &op)
+	screen.DrawImage(src.SubImage(image.Rectangle{sp, sp.Add(s.Size)}).(*ebiten.Image), &op)
 }
 
-func (s *Sprite) Scan() []interface{} {
-	return []interface{}{&s.Actor}
-}
+func (s *Sprite) Scan() []interface{} { return []interface{}{&s.Actor} }
 
-func (s *Sprite) Update() error {
-	// TODO: delegate updating to something else
-	if s.Actor.CollidesAt(s.Actor.Position.Add(image.Pt(0, 1))) {
-		// Not falling
-		s.vy = 0
-		if inpututil.IsKeyJustPressed(ebiten.KeySpace) {
-			// Jump?
-			s.vy = -5
-		}
-	} else {
-		// Falling
-		s.vy += gravity
-	}
-	switch {
-	case ebiten.IsKeyPressed(ebiten.KeyLeft):
-		s.vx = -2
-		s.Anim = s.animRunLeft
-		s.facingLeft = true
-	case ebiten.IsKeyPressed(ebiten.KeyRight):
-		s.vx = 2
-		s.Anim = s.animRunRight
-		s.facingLeft = false
-	default:
-		s.vx = 0
-		s.Anim = s.animIdleRight
-		if s.facingLeft {
-			s.Anim = s.animIdleLeft
-		}
-	}
-	s.Actor.MoveX(s.vx, func() { s.vx = -s.vx * dampen })
-	s.Actor.MoveY(s.vy, func() { s.vy = -s.vy * dampen })
-	return s.Anim.Update()
-}
+func (s *Sprite) SetAnim(a *Anim) { s.anim = a }
 
-func (s *Sprite) Build(g *Game) {
-	// TODO: better than this
-	s.animRunLeft = &Anim{Def: AnimDefs["aw_run_left"]}
-	s.animRunRight = &Anim{Def: AnimDefs["aw_run_right"]}
-	s.animIdleLeft = &Anim{Def: AnimDefs["aw_idle_left"]}
-	s.animIdleRight = &Anim{Def: AnimDefs["aw_idle_right"]}
-}
+func (s *Sprite) Update() error { return s.anim.Update() }

game/aw.go

@@ -0,0 +1,68 @@
+package game
+
+import (
+	"image"
+
+	"drjosh.dev/gurgle/engine"
+	"github.com/hajimehoshi/ebiten/v2"
+	"github.com/hajimehoshi/ebiten/v2/inpututil"
+)
+
+type Awakeman struct {
+	engine.Sprite
+
+	vx, vy     float64
+	facingLeft bool
+
+	animIdleLeft, animIdleRight, animRunLeft, animRunRight *engine.Anim
+}
+
+func (aw *Awakeman) Update() error {
+	const (
+		bounceDampen = 0.5
+		gravity      = 0.2
+		jumpVelocity = -5
+		runVelocity  = 2
+	)
+
+	// Standing on something?
+	if aw.CollidesAt(aw.Pos.Add(image.Pt(0, 1))) {
+		// Not falling
+		aw.vy = 0
+		if inpututil.IsKeyJustPressed(ebiten.KeySpace) {
+			// Jump?
+			aw.vy = jumpVelocity
+		}
+	} else {
+		// Falling
+		aw.vy += gravity
+	}
+	switch {
+	case ebiten.IsKeyPressed(ebiten.KeyLeft):
+		aw.vx = -runVelocity
+		aw.SetAnim(aw.animRunLeft)
+		aw.facingLeft = true
+	case ebiten.IsKeyPressed(ebiten.KeyRight):
+		aw.vx = runVelocity
+		aw.SetAnim(aw.animRunRight)
+		aw.facingLeft = false
+	default:
+		aw.vx = 0
+		aw.SetAnim(aw.animIdleRight)
+		if aw.facingLeft {
+			aw.SetAnim(aw.animIdleLeft)
+		}
+	}
+	aw.MoveX(aw.vx, func() { aw.vx = -aw.vx * bounceDampen })
+	aw.MoveY(aw.vy, func() { aw.vy = -aw.vy * bounceDampen })
+	return aw.Sprite.Update()
+}
+
+func (aw *Awakeman) Prepare(*engine.Game) {
+	aw.animRunLeft = &engine.Anim{Def: engine.AnimDefs["aw_run_left"]}
+	aw.animRunRight = &engine.Anim{Def: engine.AnimDefs["aw_run_right"]}
+	aw.animIdleLeft = &engine.Anim{Def: engine.AnimDefs["aw_idle_left"]}
+	aw.animIdleRight = &engine.Anim{Def: engine.AnimDefs["aw_idle_right"]}
+}
+
+func (aw *Awakeman) Scan() []interface{} { return []interface{}{&aw.Sprite} }

main.go

@@ -8,6 +8,7 @@ import (
 	"log"
 
 	"drjosh.dev/gurgle/engine"
+	"drjosh.dev/gurgle/game"
 	"github.com/hajimehoshi/ebiten/v2"
 )
 
@@ -124,18 +125,17 @@ func main() {
 				ID:   "right_wall",
 				Rect: image.Rect(320, 0, 321, 240),
 			},
-			/*&engine.SolidRect{
-				ID:   "ground",
-				Rect: image.Rect(0, 192, 320, 240),
-			},*/
-			&engine.Sprite{
-				ID: "protagonist",
-				Actor: engine.Actor{
-					Position: image.Pt(100, 100),
-					Size:     image.Pt(10, 16),
+			&game.Awakeman{
+				Sprite: engine.Sprite{
+					ID: "awakeman",
+					Actor: engine.Actor{
+						CollisionDomain: "level_1",
+						Pos:             image.Pt(100, 100),
+						Size:            image.Pt(10, 16),
+					},
+					Src:  engine.ImageRef{Path: "assets/aw.png"},
+					ZPos: 1,
 				},
-				Src:  engine.ImageRef{Path: "assets/aw.png"},
-				ZPos: 1,
 			},
 		},
 	}
@@ -154,7 +154,7 @@ func main() {
 			},
 		},
 	}
-	game.Build()
+	game.PrepareToRun()
 
 	if err := ebiten.RunGame(game); err != nil {
 		log.Fatalf("Game error: %v", err)