WIP: topsort adjustments

engine/drawlist.go

@@ -1,7 +1,7 @@
 package engine
 
 import (
-	"errors"
+	"log"
 
 	"github.com/hajimehoshi/ebiten/v2"
 )
@@ -81,52 +81,65 @@ func (d drawList) Swap(i, j int) {
 }
 
 // Bad, slow, topological sort
-func (d *drawList) topsort() error {
+func (d *drawList) topsort() {
-	// Count indegrees - O(|V|^2)
+	// Produce edge lists - O(|V|^2)
-	indegree := make(map[Drawer]int)
+	// Count indegrees - also O(|V|^2)
-	for _, u := range d.list {
+	edges := make([][]int, len(d.list))
-		indegree[u] += 0
+	indegree := make([]int, len(d.list))
-		for _, v := range d.list {
+	for i, u := range d.list {
-			if u == v {
+		if u == (tombstone{}) {
+			continue
+		}
+		for j, v := range d.list {
+			if i == j {
+				continue
+			}
+			if v == (tombstone{}) {
 				continue
 			}
 			if u.DrawBefore(v) || v.DrawAfter(u) {
-				indegree[v]++
+				edges[i] = append(edges[i], j)
+				indegree[j]++
 			}
 		}
 	}
-	//log.Printf("indegree: %v", indegree)
+
-	// Sort into new list
+	// Start queue with all zero-indegree vertices
+	var queue []int
+	for i, n := range indegree {
+		if d.list[i] == (tombstone{}) {
+			continue
+		}
+		if n == 0 {
+			queue = append(queue, i)
+		}
+	}
+
+	// Process into new list
 	list := make([]Drawer, 0, len(d.list))
-	for len(indegree) > 0 {
+	for len(queue) > 0 {
-		var bag []Drawer
+		i := queue[0]
-		for v, n := range indegree {
+		queue = queue[1:]
-			if n == 0 {
+		if false {
-				bag = append(bag, v)
+			d.rev[d.list[i]] = len(list)
-			}
 		}
-		//log.Printf("zero indegree vertices: %v", bag)
+		list = append(list, d.list[i])
-		if len(bag) == 0 {
+		for _, j := range edges[i] {
-			//log.Printf("remaining vertices: %v", indegree)
+			indegree[j]--
-			return errors.New("no vertices with zero indegree")
+			if indegree[j] <= 0 {
-		}
+				if indegree[j] < 0 {
-		list = append(list, bag...)
+					log.Printf("indegree[%d] = %d (component %v)", j, indegree[j], d.list[j])
-		for _, u := range bag {
-			delete(indegree, u)
-		}
-		for _, u := range bag {
-			for v := range indegree {
-				if u.DrawBefore(v) || v.DrawAfter(u) {
-					indegree[v]--
 				}
+				queue = append(queue, j)
 			}
 		}
 	}
+
 	// Replace list
 	d.list = list
 	// Update rev
+	d.rev = make(map[Drawer]int, len(list))
 	for i, v := range list {
 		d.rev[v] = i
 	}
-	return nil
 }

engine/game.go

@@ -8,6 +8,7 @@ import (
 	"io/fs"
 	"log"
 	"reflect"
+	"sort"
 	"sync"
 	"time"
 
@@ -16,6 +17,8 @@ import (
 	"github.com/hajimehoshi/ebiten/v2/ebitenutil"
 )
 
+const topologicalDrawSort = true
+
 var _ interface {
 	Disabler
 	Hider
@@ -182,16 +185,18 @@ func (g *Game) Update() error {
 	}
 
 	// Sort the draw list (on every frame - this isn't as bad as it sounds)
-	//sort.Stable(g.drawList)
+	if topologicalDrawSort {
-	if err := g.drawList.topsort(); err != nil {
+		g.drawList.topsort()
-		return fmt.Errorf("drawList.topsort: %v", err)
+	} else {
-	}
+		sort.Stable(g.drawList)
-	// Truncate tombstones from the end.
+
-	for i := g.drawList.Len() - 1; i >= 0; i-- {
+		// Truncate tombstones from the end.
-		if g.drawList.list[i] != (tombstone{}) {
+		for i := g.drawList.Len() - 1; i >= 0; i-- {
-			break
+			if g.drawList.list[i] != (tombstone{}) {
+				break
+			}
+			g.drawList.list = g.drawList.list[:i]
 		}
-		g.drawList.list = g.drawList.list[:i]
 	}
 	return nil
 }

game/aw.go

@@ -114,7 +114,7 @@ func (aw *Awakeman) realUpdate() error {
 		aw.bubbleTimer--
 		if aw.bubbleTimer <= 0 {
 			aw.bubbleTimer = bubblePeriod
-			bubble := NewBubble(aw.Sprite.Actor.Pos.Add(geom.Pt3(1, -15, -1)))
+			bubble := NewBubble(aw.Sprite.Actor.Pos.Add(geom.Pt3(-3, -20, -1)))
 			if err := engine.PreorderWalk(bubble, func(c, _ interface{}) error {
 				if p, ok := c.(engine.Loader); ok {
 					return p.Load(Assets)

game/bubble.go

@@ -67,10 +67,15 @@ func (b *Bubble) Update() error {
 	if b.Life <= 0 {
 		b.game.Unregister(b)
 	}
-	// not using MoveX/MoveY/... because collisions are unnecessary -
+	if false { // not using MoveX/MoveY/... because collisions are unnecessary -
-	// this is an effect particle, if it overlaps a solid, who cares
+		// this is an effect particle, if it overlaps a solid, who cares
-	b.Sprite.Actor.Pos = b.Sprite.Actor.Pos.Add(geom.Pt3(
+		b.Sprite.Actor.Pos = b.Sprite.Actor.Pos.Add(geom.Pt3(
-		rand.Intn(3)-1, -1, rand.Intn(2)-1,
+			// --lint:ignore SA4000 one random minus another is not always zero...
-	))
+			rand.Intn(3)-1, rand.Intn(2)-1, 0, // rand.Intn(2)-rand.Intn(2),
+		))
+	} else {
+		b.Sprite.Actor.MoveX(float64(rand.Intn(3)-1), nil)
+		b.Sprite.Actor.MoveY(float64(rand.Intn(2)-1), nil)
+	}
 	return nil
 }