all in on interfaces

engine/asset.go

@@ -126,12 +126,12 @@ func (r *SceneRef) Load(assets fs.FS) error {
 	return nil
 }
 
-// Scene returns the loaded scene, or nil if not yet loaded.
-func (r SceneRef) Scene() *Scene { return r.scene }
-
 // The rest of the methods forward to r.scene, as such they will
 // panic if the scene isn't loaded.
 
+// BoundingRect returns the Bounds from the scene.
+func (r SceneRef) BoundingRect() image.Rectangle { return r.scene.BoundingRect() }
+
 // Draw draws the scene.
 func (r SceneRef) Draw(screen *ebiten.Image, opts ebiten.DrawImageOptions) {
 	r.scene.Draw(screen, opts)
@@ -140,6 +140,15 @@ func (r SceneRef) Draw(screen *ebiten.Image, opts ebiten.DrawImageOptions) {
 // DrawOrder returns the value of DrawOrder from the scene.
 func (r SceneRef) DrawOrder() float64 { return r.scene.DrawOrder() }
 
+// IsHidden returns the value of IsHidden from the scene.
+func (r SceneRef) IsHidden() bool { return r.scene.IsHidden() }
+
+// Hide calls Hide on the scene.
+func (r SceneRef) Hide() { r.scene.Hide() }
+
+// Show calls Show on the scene.
+func (r SceneRef) Show() { r.scene.Show() }
+
 // Ident returns the value of Ident from the scene.
 func (r SceneRef) Ident() string { return r.scene.Ident() }
 

engine/camera.go

@@ -37,14 +37,16 @@ type Camera struct {
 
 // Draw applies transformations to opts, then calls c.Scene.Draw with it.
 func (c *Camera) Draw(screen *ebiten.Image, opts ebiten.DrawImageOptions) {
-	if c.Scene.Scene().Hidden {
+	if c.Scene.IsHidden() {
 		return
 	}
 
+	br := c.Scene.BoundingRect()
+
 	// The lower bound on zoom is the larger of
 	// { (ScreenWidth / BoundsWidth), (ScreenHeight / BoundsHeight) }
 	zoom := c.Zoom
-	sz := c.Scene.Scene().Bounds.Size()
+	sz := br.Size()
 	if z := float64(c.game.ScreenWidth) / float64(sz.X); zoom < z {
 		zoom = z
 	}
@@ -57,17 +59,17 @@ func (c *Camera) Draw(screen *ebiten.Image, opts ebiten.DrawImageOptions) {
 	// Camera frame currently Rectangle{ centre ± (screen/(2*zoom)) }.
 	sw2, sh2 := float64(c.game.ScreenWidth/2), float64(c.game.ScreenHeight/2)
 	swz, shz := int(sw2/zoom), int(sh2/zoom)
-	if centre.X-swz < c.Scene.Scene().Bounds.Min.X {
+	if centre.X-swz < br.Min.X {
-		centre.X = c.Scene.Scene().Bounds.Min.X + swz
+		centre.X = br.Min.X + swz
 	}
-	if centre.Y-shz < c.Scene.Scene().Bounds.Min.Y {
+	if centre.Y-shz < br.Min.Y {
-		centre.Y = c.Scene.Scene().Bounds.Min.Y + shz
+		centre.Y = br.Min.Y + shz
 	}
-	if centre.X+swz > c.Scene.Scene().Bounds.Max.X {
+	if centre.X+swz > br.Max.X {
-		centre.X = c.Scene.Scene().Bounds.Max.X - swz
+		centre.X = br.Max.X - swz
 	}
-	if centre.Y+shz > c.Scene.Scene().Bounds.Max.Y {
+	if centre.Y+shz > br.Max.Y {
-		centre.Y = c.Scene.Scene().Bounds.Max.Y - shz
+		centre.Y = br.Max.Y - shz
 	}
 
 	// Apply other options
@@ -101,7 +103,7 @@ func (c *Camera) Draw(screen *ebiten.Image, opts ebiten.DrawImageOptions) {
 }
 
 // Update passes the call to c.Scene.
-func (c *Camera) Update() error { return c.Scene.Scene().Update() }
+func (c *Camera) Update() error { return c.Scene.Update() }
 
 // Scan returns the only child (c.Scene).
 func (c *Camera) Scan() []interface{} { return []interface{}{c.Scene} }

engine/interface.go

@@ -7,6 +7,11 @@ import (
 	"github.com/hajimehoshi/ebiten/v2"
 )
 
+// Bounder components have a bounding rectangle.
+type Bounder interface {
+	BoundingRect() image.Rectangle
+}
+
 // Collider components have tangible form.
 type Collider interface {
 	CollidesWith(image.Rectangle) bool
@@ -31,6 +36,13 @@ type DrawUpdater interface {
 	Updater
 }
 
+// Hider components can be hidden.
+type Hider interface {
+	IsHidden() bool
+	Hide()
+	Show()
+}
+
 // Identifier components have a sense of self. This makes it easier for
 // components to find and interact with one another.
 type Identifier interface {
@@ -75,14 +87,14 @@ type Scener interface {
 	// }
 	// It seems cleaner to let the engine assert only for the interface it needs at that moment.
 
+	Bounder
 	Drawer
 	DrawOrderer
+	Hider
 	Identifier
 	Prepper
 	Scanner
 	Updater
-
-	Scene() *Scene
 }
 
 // Updater components can update themselves. Update is called repeatedly.

engine/misc.go

@@ -1,11 +1,31 @@
 package engine
 
+import "image"
+
 // ID implements Identifier directly (as a string value).
 type ID string
 
 // Ident returns id as a string.
 func (id ID) Ident() string { return string(id) }
 
+// Bounds implements Bounder directly (as an image.Rectangle value).
+type Bounds image.Rectangle
+
+// BoundingRect returns b as an image.Rectangle.
+func (b Bounds) BoundingRect() image.Rectangle { return image.Rectangle(b) }
+
+// Hidden implements Hider directly (as a bool).
+type Hidden bool
+
+// IsHidden returns h as a bool.
+func (h Hidden) IsHidden() bool { return bool(h) }
+
+// Hide sets h to true.
+func (h *Hidden) Hide() { *h = true }
+
+// Show sets h to false.
+func (h *Hidden) Show() { *h = false }
+
 // Parallax implements ParallaxScaler directly (as a float64 value).
 type Parallax float64
 

engine/scene.go

@@ -2,7 +2,6 @@ package engine
 
 import (
 	"encoding/gob"
-	"image"
 	"math"
 	"sort"
 
@@ -18,11 +17,11 @@ func init() {
 
 // Scene manages drawing and updating a bunch of components.
 type Scene struct {
-	Bounds     image.Rectangle // world coordinates
+	ID
+	Bounds     // world coordinates
 	Components []interface{}
 	Disabled   bool
-	Hidden     bool
+	Hidden
-	ID
 	ZOrder
 }
 

engine/solid.go

@@ -13,7 +13,7 @@ func init() {
 
 type SolidRect struct {
 	ID
-	Rect image.Rectangle
+	Bounds
 }
 
-func (s SolidRect) CollidesWith(r image.Rectangle) bool { return s.Rect.Overlaps(r) }
+func (s SolidRect) CollidesWith(r image.Rectangle) bool { return s.BoundingRect().Overlaps(r) }

main.go

@@ -51,7 +51,7 @@ func main() {
 
 	level1 := &engine.Scene{
 		ID:     "level_1",
-		Bounds: image.Rect(-32, -32, 320+32, 240+32),
+		Bounds: engine.Bounds(image.Rect(-32, -32, 320+32, 240+32)),
 		Components: []interface{}{
 			&engine.Fill{
 				Color:  color.Gray{100},
@@ -72,16 +72,16 @@ func main() {
 				TileSize: 16,
 			},
 			&engine.SolidRect{
-				ID:   "ceiling",
+				ID:     "ceiling",
-				Rect: image.Rect(0, -1, 320, 0),
+				Bounds: engine.Bounds(image.Rect(0, -1, 320, 0)),
 			},
 			&engine.SolidRect{
-				ID:   "left_wall",
+				ID:     "left_wall",
-				Rect: image.Rect(-1, 0, 0, 240),
+				Bounds: engine.Bounds(image.Rect(-1, 0, 0, 240)),
 			},
 			&engine.SolidRect{
-				ID:   "right_wall",
+				ID:     "right_wall",
-				Rect: image.Rect(320, 0, 321, 240),
+				Bounds: engine.Bounds(image.Rect(320, 0, 321, 240)),
 			},
 			&game.Awakeman{
 				CameraID: "game_camera",