Added path finder & visualization (F5).

cmd/krampus19/playlevel.go

@@ -3,6 +3,7 @@ package main
 import (
 	"fmt"
 	"log"
+	"strconv"
 
 	"opslag.de/schobers/allg5"
 	"opslag.de/schobers/geom"
@@ -26,6 +27,7 @@ type playLevel struct {
 	scale   float32
 
 	state       playLevelState
+	pathFinding bool
 }
 
 type keyPressedState map[allg5.Key]bool
@@ -166,6 +168,8 @@ func (l *playLevel) Handle(e allg5.Event) {
 			case allg5.KeyEscape:
 				l.showMenu = true
 				l.menu.Activate(0)
+			case allg5.KeyF5:
+				l.pathFinding = !l.pathFinding
 			}
 			l.state.TryPlayerMove(e.KeyCode)
 		}
@@ -227,6 +231,17 @@ func (l *playLevel) Render(ctx *alui.Context, bounds geom.RectangleF32) {
 	}
 
 	font := ctx.Fonts.Get("default")
+
+	if l.pathFinding {
+		dists := soko.NewPathFinder(l.state.state).FindDistances()
+		for i := range level.Tiles {
+			pos := geom.Pt(i%level.Width, i/level.Width)
+			scr := entityLoc{pos.ToF32(), 0}
+			posDist := l.posToScreenF32(scr.pos, -20)
+			ctx.Fonts.DrawAlignFont(font, posDist.X, posDist.Y, posDist.X, ctx.Palette.Text, allg5.AlignCenter, strconv.Itoa(dists[pos]))
+		}
+	}
+
 	steps := fmt.Sprintf("STEPS: %d", l.state.Steps())
 	ctx.Fonts.DrawAlignFont(font, bounds.Min.X, 24, bounds.Max.X, ctx.Palette.Text, allg5.AlignCenter, steps)
 

soko/pathfinder.go

@@ -0,0 +1,99 @@
+package soko
+
+import (
+	"sort"
+
+	"opslag.de/schobers/geom"
+)
+
+type PathFinder struct {
+	state State
+}
+
+func NewPathFinder(s State) PathFinder {
+	return PathFinder{s}
+}
+
+type betterNeighbourFn func(geom.Point, int)
+
+func (p PathFinder) findBetterNeighbours(distances map[geom.Point]int, curr geom.Point, better betterNeighbourFn) {
+	currDistance := distances[curr]
+	newDistance := currDistance + 1
+
+	neighbours := Neighbours(curr)
+	for _, next := range neighbours {
+		if !p.state.IsWalkable(next) || p.state.Bricks.Has(next) { // filter neighbours
+			continue
+		}
+		if distance, ok := distances[next]; ok && distance <= newDistance { // skip when shorter path exists
+			continue
+		}
+		distances[next] = newDistance
+		better(next, newDistance)
+	}
+}
+
+func (p PathFinder) Find(target geom.Point) []geom.Point {
+	source := p.state.Player.Pos
+	frontier := []geom.Point{source}
+	distances := map[geom.Point]int{source: 0}
+	moves := map[geom.Point]geom.Point{source: source}
+	heuristic := func(i int) int {
+		pos := frontier[i]
+		return distances[pos] + pos.DistInt(target)
+	}
+	for {
+		curr := frontier[0]
+		if curr == target {
+			break
+		}
+		frontier = frontier[1:]
+
+		p.findBetterNeighbours(distances, curr, func(next geom.Point, newDistance int) {
+			moves[next] = curr
+			frontier = append(frontier, next)
+		})
+
+		if len(frontier) == 0 {
+			return nil // no path
+		}
+
+		// apply heuristic to frontier (favor points closer to target)
+		sort.Slice(frontier, func(i, j int) bool { return heuristic(i) < heuristic(j) })
+	}
+
+	// build reverse path
+	curr := target
+	path := []geom.Point{curr}
+	for {
+		curr = moves[curr]
+		if curr == source {
+			break
+		}
+		path = append(path, curr)
+	}
+	// reverse path
+	n := len(path)
+	for i := 0; i < n/2; i++ {
+		path[i], path[n-i-1] = path[n-i-1], path[i]
+	}
+	return path
+}
+
+func (p PathFinder) FindDistances() map[geom.Point]int {
+	source := p.state.Player.Pos
+	frontier := []geom.Point{source}
+	distances := map[geom.Point]int{source: 0}
+	for {
+		curr := frontier[0]
+		frontier = frontier[1:]
+
+		p.findBetterNeighbours(distances, curr, func(next geom.Point, newDistance int) {
+			frontier = append(frontier, next)
+		})
+
+		if len(frontier) == 0 {
+			return distances
+		}
+	}
+}

soko/state.go

@@ -41,14 +41,6 @@ func (s State) Clone() State {
 	}
 }
 
-func (s *State) addEntity(pos geom.Point, typ EntityType, add func(Entity)) {
-	id := s.nextEntityID
-	e := Entity{id, pos, typ}
-	add(e)
-	s.Entities[id] = e
-	s.nextEntityID++
-}
-
 func (s *State) AddBrick(pos geom.Point) {
 	s.addEntity(pos, EntityTypeBrick, func(e Entity) {
 		s.Bricks.Add(pos, e.ID)
@@ -124,11 +116,6 @@ func (s State) Mutate(fn func(s *State)) State {
 	return clone
 }
 
-func (s *State) movePlayer(to geom.Point) {
-	s.Player.Pos = to
-	s.Entities[s.Player.ID] = Entity{s.Player.ID, to, EntityTypePlayer}
-}
-
 func (s *State) SetPlayer(pos geom.Point) {
 	s.addEntity(pos, EntityTypePlayer, func(e Entity) {
 		s.Player = e
@@ -141,4 +128,17 @@ func (s *State) SetTarget(pos geom.Point) {
 	})
 }
 
+func (s *State) addEntity(pos geom.Point, typ EntityType, add func(Entity)) {
+	id := s.nextEntityID
+	e := Entity{id, pos, typ}
+	add(e)
+	s.Entities[id] = e
+	s.nextEntityID++
+}
+
+func (s *State) movePlayer(to geom.Point) {
+	s.Player.Pos = to
+	s.Entities[s.Player.ID] = Entity{s.Player.ID, to, EntityTypePlayer}
+}
+
 func IsMagma(s State, p geom.Point) bool { return s.MagmaTiles[p] }