Tweaks

engine/debug.go

@@ -8,14 +8,14 @@ import (
 	"github.com/hajimehoshi/ebiten/v2/ebitenutil"
 )
 
-// TPSDisplay debugprints CurrentTPS in the top left.
+// PerfDisplay debugprints CurrentTPS and CurrentFPS in the top left.
-type TPSDisplay struct{}
+type PerfDisplay struct{}
 
-func (TPSDisplay) Draw(screen *ebiten.Image) {
+func (PerfDisplay) Draw(screen *ebiten.Image) {
-	ebitenutil.DebugPrint(screen, fmt.Sprintf("TPS: %0.2f", ebiten.CurrentTPS()))
+	ebitenutil.DebugPrint(screen, fmt.Sprintf("TPS: %0.2f  FPS: %0.2f", ebiten.CurrentTPS(), ebiten.CurrentFPS()))
 }
 
-func (TPSDisplay) Z() float64 {
+func (PerfDisplay) Z() float64 {
 	// Always draw on top
 	return math.MaxFloat64
 }

engine/game.go

@@ -23,6 +23,8 @@ type Game struct {
 	ScreenWidth  int
 	ScreenHeight int
 	Components   []interface{}
+
+	needsSort bool
 }
 
 // Update calls Update on all Updater components.
@@ -34,6 +36,10 @@ func (g *Game) Update() error {
 			}
 		}
 	}
+	if g.needsSort {
+		g.needsSort = false
+		g.sortDrawers()
+	}
 	return nil
 }
 
@@ -51,9 +57,15 @@ func (g *Game) Layout(outsideWidth, outsideHeight int) (w, h int) {
 	return g.ScreenWidth, g.ScreenHeight
 }
 
-// Sort sorts the components by Z position.
+// SetNeedsSort tells the game that the Drawers need sorting.
+// This will be done in the current update.
+func (g *Game) SetNeedsSort() {
+	g.needsSort = true
+}
+
+// sortDrawers sorts the components by Z position.
 // Non-Drawers are sorted before all Drawers.
-func (g *Game) Sort() {
+func (g *Game) sortDrawers() {
 	// Stable sort to avoid z-fighting (among Non-Drawers and equal Drawers)
 	sort.SliceStable(g.Components, func(i, j int) bool {
 		a, aok := g.Components[i].(Drawer)

main.go

@@ -19,14 +19,19 @@ func main() {
 	ebiten.SetWindowSize(screenWidth*2, screenHeight*2)
 	ebiten.SetWindowTitle("TODO")
 
-	boxesFile, err := assets.Open("assets/boxes.png")
+	var boxesPNG image.Image
-	if err != nil {
+	func() {
-		log.Fatalf("Couldn't open asset: %v", err)
+		boxesFile, err := assets.Open("assets/boxes.png")
-	}
+		if err != nil {
-	boxesPNG, _, err := image.Decode(boxesFile)
+			log.Fatalf("Couldn't open asset: %v", err)
-	if err != nil {
+		}
-		log.Fatalf("Couldn't decode asset: %v", err)
+		defer boxesFile.Close()
-	}
+		boxesPNG, _, err = image.Decode(boxesFile)
+		if err != nil {
+			log.Fatalf("Couldn't decode asset: %v", err)
+		}
+	}()
+
 	tiles := &engine.Tilemap{
 		Map: [][]int{
 			{0, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 1},
@@ -49,14 +54,17 @@ func main() {
 		TileSize: 16,
 	}
 
-	if err := ebiten.RunGame(&engine.Game{
+	game := &engine.Game{
 		ScreenHeight: screenHeight,
 		ScreenWidth:  screenWidth,
 		Components: []interface{}{
 			tiles,
-			engine.TPSDisplay{},
+			engine.PerfDisplay{},
 		},
-	}); err != nil {
+	}
+	game.SetNeedsSort()
+
+	if err := ebiten.RunGame(game); err != nil {
 		log.Fatalf("Game error: %v", err)
 	}
 }