how to load from a file

engine/actor.go

@@ -12,7 +12,7 @@ var _ Prepper = &Actor{}
 var errCollision = errors.New("collision detected")
 
 func init() {
-	gob.Register(Actor{})
+	gob.Register(&Actor{})
 }
 
 // Thorson-style movement:

engine/anim.go

@@ -1,8 +1,14 @@
 package engine
 
+import "encoding/gob"
+
 // Ensure Anim satisfies Animer.
 var _ Animer = &Anim{}
 
+func init() {
+	gob.Register(&Anim{})
+}
+
 // AnimFrame describes a frame in an animation.
 type AnimFrame struct {
 	Frame    int // show this frame

engine/animref.go

@@ -13,7 +13,7 @@ var (
 )
 
 func init() {
-	gob.Register(AnimRef{})
+	gob.Register(&AnimRef{})
 }
 
 // AnimRef manages an Anim using a premade AnimDef from the cache.

engine/asset.go

@@ -5,6 +5,7 @@ import (
 	"encoding/gob"
 	"image"
 	"io/fs"
+	"os"
 
 	"github.com/hajimehoshi/ebiten/v2"
 )
@@ -38,6 +39,28 @@ func loadGobz(dst interface{}, assets fs.FS, path string) error {
 	return gob.NewDecoder(gz).Decode(dst)
 }
 
+// SaveGobz takes an object, gob-encodes it, gzips it, and writes to disk.
+func SaveGobz(src interface{}, name string) error {
+	f, err := os.CreateTemp(".", name)
+	if err != nil {
+		return err
+	}
+	defer os.Remove(f.Name())
+	defer f.Close()
+
+	gz := gzip.NewWriter(f)
+	if err := gob.NewEncoder(gz).Encode(src); err != nil {
+		return err
+	}
+	if err := gz.Close(); err != nil {
+		return err
+	}
+	if err := f.Close(); err != nil {
+		return err
+	}
+	return os.Rename(f.Name(), name)
+}
+
 // ImageRef loads images from the AssetFS into *ebiten.Image form.
 // It is your responsibility to import _ "image/..." for whatever
 // format the files are in, and to load it (either return it as a

engine/camera.go

@@ -17,7 +17,7 @@ var (
 )
 
 func init() {
-	gob.Register(Camera{})
+	gob.Register(&Camera{})
 }
 
 // Camera models a camera that is viewing a scene.

engine/debug.go

@@ -24,8 +24,8 @@ var (
 )
 
 func init() {
-	gob.Register(GobDumper{})
+	gob.Register(&GobDumper{})
-	gob.Register(PerfDisplay{})
+	gob.Register(&PerfDisplay{})
 }
 
 // DebugToast debugprints a string for a while, then disappears.

engine/fill.go

@@ -1,6 +1,7 @@
 package engine
 
 import (
+	"encoding/gob"
 	"image/color"
 
 	"github.com/hajimehoshi/ebiten/v2"
@@ -9,6 +10,12 @@ import (
 // Ensure Fill satisfies Drawer.
 var _ Drawer = &Fill{}
 
+func init() {
+	gob.Register(Fill{})
+	gob.Register(color.Gray{})
+	gob.Register(color.RGBA{})
+}
+
 // Fill fills the screen with a colour.
 type Fill struct {
 	ID

engine/game.go

@@ -8,7 +8,7 @@ import (
 )
 
 func init() {
-	gob.Register(Game{})
+	gob.Register(&Game{})
 }
 
 // Game implements the ebiten methods using a collection of components.

engine/image.go

@@ -17,7 +17,7 @@ var (
 )
 
 func init() {
-	gob.Register(Image{})
+	gob.Register(&Image{})
 }
 
 // Image draws an image at a position.

engine/scene.go

@@ -12,7 +12,7 @@ import (
 var _ Scener = &Scene{}
 
 func init() {
-	gob.Register(Scene{})
+	gob.Register(&Scene{})
 }
 
 // Scene manages drawing and updating a bunch of components.

engine/sceneref.go

@@ -24,7 +24,7 @@ func init() {
 //
 //    var sc = &Scene{
 //	    Components: []interface{}{
-//			SceneRef{Path: "assets/foo.gob.gz"}  // inflated at Load time
+//			&SceneRef{Path: "assets/foo.gob.gz"}  // inflated at Load time
 //		},
 //    }
 type SceneRef struct {

engine/solid.go

@@ -8,7 +8,7 @@ import (
 var _ Collider = SolidRect{}
 
 func init() {
-	gob.Register(SolidRect{})
+	gob.Register(&SolidRect{})
 }
 
 type SolidRect struct {

engine/sprite.go

@@ -17,7 +17,7 @@ var (
 )
 
 func init() {
-	gob.Register(Sprite{})
+	gob.Register(&Sprite{})
 }
 
 // Sprite combines an Actor with the ability to Draw from a single spritesheet.

engine/tiles.go

@@ -19,9 +19,9 @@ var (
 )
 
 func init() {
-	gob.Register(AnimatedTile{})
+	gob.Register(&AnimatedTile{})
 	gob.Register(StaticTile(0))
-	gob.Register(Tilemap{})
+	gob.Register(&Tilemap{})
 }
 
 // Tilemap renders a grid of tiles.

game/aw.go

@@ -11,7 +11,7 @@ import (
 )
 
 func init() {
-	gob.Register(Awakeman{})
+	gob.Register(&Awakeman{})
 }
 
 type Awakeman struct {

main.go

@@ -16,6 +16,7 @@ func main() {
 	ebiten.SetWindowSize(640, 480)
 	ebiten.SetWindowTitle("TODO")
 
+	if false {
 		redTileAnim := &engine.Anim{Frames: []engine.AnimFrame{
 			{Frame: 3, Duration: 12},
 			{Frame: 4, Duration: 12},
@@ -107,6 +108,11 @@ func main() {
 			},
 		}
 
+		if err := engine.SaveGobz(level1, "level1.gobz"); err != nil {
+			log.Fatalf("Couldn't save level1.gobz: %v", err)
+		}
+	}
+
 	g := &engine.Game{
 		ScreenHeight: 240,
 		ScreenWidth:  320,
@@ -118,7 +124,7 @@ func main() {
 				},
 				&engine.Camera{
 					ID:    "game_camera",
-					Scene: level1,
+					Scene: &engine.SceneRef{Path: "assets/level1.gobz"},
 				},
 				&engine.DebugToast{
 					ID: "toast",