ZPositioner -> DrawOrderer

README.md

@@ -1,2 +1,3 @@
 # gurgle
 
+Game development in progress.

engine/fill.go

@@ -11,7 +11,7 @@ type Fill struct {
 	Color  color.Color
 	Hidden bool
 	ID
-	ZPos
+	DrawOrder
 }
 
 func (f *Fill) Draw(screen *ebiten.Image, opts ebiten.DrawImageOptions) {

engine/interface.go

@@ -45,7 +45,7 @@ type Updater interface {
 	Update() error
 }
 
-// ZPositioner is used to reorder layers.
-type ZPositioner interface {
-	Z() float64
+// DrawOrderer is used to reorder layers.
+type DrawOrderer interface {
+	DrawOrder() float64
 }

engine/misc.go

@@ -6,8 +6,8 @@ type ID string
 // Ident returns id as a string.
 func (id ID) Ident() string { return string(id) }
 
-// ZPos implements ZPositioner directly (as a float64 value).
-type ZPos float64
+// DrawOrder implements DrawOrderer directly (as a float64 value).
+type DrawOrder float64
 
-// Z returns z as a float64.
-func (z ZPos) Z() float64 { return float64(z) }
+// DrawOrder returns z as a float64.
+func (z DrawOrder) DrawOrder() float64 { return float64(z) }

engine/scene.go

@@ -18,7 +18,7 @@ type Scene struct {
 	Disabled   bool
 	Hidden     bool
 	ID
-	ZPos
+	DrawOrder
 }
 
 // Draw draws all components in order.
@@ -34,17 +34,17 @@ func (s *Scene) Draw(screen *ebiten.Image, opts ebiten.DrawImageOptions) {
 }
 
 // Prepare does an initial Z-order sort.
-func (s *Scene) Prepare(*Game) { s.sortByZ() }
+func (s *Scene) Prepare(*Game) { s.sortByDrawOrder() }
 
-// sortByZ sorts the components by Z position.
+// sortByDrawOrder sorts the components by Z position.
 // Everything without a Z sorts first. Stable sort is used to avoid Z-fighting
 // (among layers without a Z, or those with equal Z).
-func (s *Scene) sortByZ() {
+func (s *Scene) sortByDrawOrder() {
 	sort.SliceStable(s.Components, func(i, j int) bool {
-		a, aok := s.Components[i].(ZPositioner)
-		b, bok := s.Components[j].(ZPositioner)
+		a, aok := s.Components[i].(DrawOrderer)
+		b, bok := s.Components[j].(DrawOrderer)
 		if aok && bok {
-			return a.Z() < b.Z()
+			return a.DrawOrder() < b.DrawOrder()
 		}
 		return !aok && bok
 	})
@@ -68,18 +68,18 @@ func (s *Scene) Update() error {
 		}
 	}
 	// Check if the updates put the components out of order; if so, sort
-	curZ := -math.MaxFloat64 // fun fact: this is min float64
+	cz := -math.MaxFloat64 // fun fact: this is min float64
 	for _, c := range s.Components {
-		z, ok := c.(ZPositioner)
+		z, ok := c.(DrawOrderer)
 		if !ok {
 			continue
 		}
-		t := z.Z()
-		if t < curZ {
-			s.sortByZ()
-			return nil
+		if t := z.DrawOrder(); t > cz {
+			cz = t
+			continue
 		}
-		curZ = t
+		s.sortByDrawOrder()
+		return nil
 	}
 	return nil
 }

engine/sprite.go

@@ -19,7 +19,7 @@ type Sprite struct {
 	Hidden      bool
 	ID
 	Src ImageRef
-	ZPos
+	DrawOrder
 
 	anim *Anim
 }

engine/tiles.go

@@ -23,7 +23,7 @@ type Tilemap struct {
 	Offset   image.Point // world coordinates
 	Src      ImageRef
 	TileSize int
-	ZPos
+	DrawOrder
 }
 
 // CollidesWith implements Collider.

main.go

@@ -52,14 +52,14 @@ func main() {
 		Components: []interface{}{
 			&engine.Fill{
 				Color: color.Gray{100},
-				ZPos:  0,
+				DrawOrder:  0,
 			},
 			&engine.Tilemap{
 				ID:       "terrain",
 				Map:      tiles,
 				Src:      engine.ImageRef{Path: "assets/boxes.png"},
 				TileSize: 16,
-				ZPos:     1,
+				DrawOrder:     1,
 			},
 			&engine.SolidRect{
 				ID:   "ceiling",
@@ -85,7 +85,7 @@ func main() {
 					FrameOffset: image.Pt(-1, 0),
 					FrameSize:   image.Pt(10, 16),
 					Src:         engine.ImageRef{Path: "assets/aw.png"},
-					ZPos:        2,
+					DrawOrder:        2,
 				},
 			},
 		},