Make Tilemap a collider

engine/actor.go

@@ -39,7 +39,7 @@ type Actor struct {
 func (a *Actor) collidesAt(p image.Point) bool {
 	// TODO: more efficient test?
 	hit := false
-	a.game.Walk(func(c interface{}) bool {
+	Walk(a.game, func(c interface{}) bool {
 		if coll, ok := c.(Collider); ok {
 			if coll.CollidesWith(image.Rectangle{Min: p, Max: p.Add(a.Size)}) {
 				hit = true

engine/game.go

@@ -84,13 +84,12 @@ func (g *Game) UnregisterComponent(c interface{}) {
 // Component returns the component with a given ID, or nil if there is none.
 func (g *Game) Component(id string) interface{} { return g.componentsByID[id] }
 
-// Walk calls v with every component reachable via Scan, for as long as visit
-// returns true.
-func (g *Game) Walk(v func(interface{}) bool) {
-	g.walk(g.Scene, v)
-}
+// Scan implements Scanner.
+func (g *Game) Scan() []interface{} { return []interface{}{g.Scene} }
 
-func (g *Game) walk(c interface{}, v func(interface{}) bool) {
+// Walk calls v with every component reachable from c via Scan, recursively,
+// for as long as visit returns true.
+func Walk(c interface{}, v func(interface{}) bool) {
 	if !v(c) {
 		return
 	}
@@ -99,7 +98,7 @@ func (g *Game) walk(c interface{}, v func(interface{}) bool) {
 			if !v(c) {
 				return
 			}
-			g.walk(c, v)
+			Walk(c, v)
 		}
 	}
 }
@@ -108,7 +107,7 @@ func (g *Game) walk(c interface{}, v func(interface{}) bool) {
 // reachable via Scan.
 func (g *Game) Build() {
 	g.componentsByID = make(map[string]interface{})
-	g.Walk(func(c interface{}) bool {
+	Walk(g.Scene, func(c interface{}) bool {
 		if b, ok := c.(Builder); ok {
 			b.Build(g)
 		}

engine/tiles.go

@@ -19,12 +19,31 @@ type Tilemap struct {
 	Hidden   bool
 	ID
 	Map       [][]Tile
+	Ersatz     bool // "fake wall"
 	Src       ImageRef
 	TileSize  int
 	Transform GeoMDef
 	ZPos
 }
 
+// CollidesWith implements Collider.
+func (t *Tilemap) CollidesWith(r image.Rectangle) bool {
+	if t.Ersatz {
+		return false
+	}
+	for j, row := range t.Map {
+		for i, tile := range row {
+			if tile == nil {
+				continue
+			}
+			if r.Overlaps(image.Rect(i*t.TileSize, j*t.TileSize, (i+1)*t.TileSize, (j+1)*t.TileSize)) {
+				return true
+			}
+		}
+	}
+	return false
+}
+
 // Draw draws the tilemap.
 func (t *Tilemap) Draw(screen *ebiten.Image, geom ebiten.GeoM) {
 	if t.Hidden {

main.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"embed"
-	"fmt"
 	"image"
 	_ "image/png"
 	"log"
@@ -92,18 +91,6 @@ func main() {
 		},
 	}
 
-	// TODO: something better...
-	for j, row := range tiles {
-		for i, tile := range row {
-			if tile != nil {
-				level1.Components = append(level1.Components, &engine.SolidRect{
-					ID:   engine.ID(fmt.Sprintf("tile_%d_%d", j, i)),
-					Rect: image.Rect(i*16, j*16, (i+1)*16, (j+1)*16),
-				})
-			}
-		}
-	}
-
 	game := &engine.Game{
 		ScreenHeight: screenHeight,
 		ScreenWidth:  screenWidth,