Link Start Flags to Change Characters

New feature: link a Start Flag to another doodad in your level
and you will play as that doodad instead of Boy. All Creatures
are designed to be playable. Playing as "other" doodads leads
to interesting effects, like not being able to activate buttons,
switches, or warp doors and not having an inventory to pick up
keys. The Anvil is fun: it can destroy other mobile doodads by
jumping on them.

If the actor does not specify that it has gravity, the gameplay
starts in antigravity mode. This will be the vast majority of
non-mobile doodads and the Bird.

Other changes:

* The Blue and Red Azulians now share a doodad script.
* The Azulians AI is still to walk back and forth, pickup keys and
  press buttons. The Blue Azulian walks slower than the red one.
* The Blue Azulian is no longer hidden from the doodads list.
* Actor UUID values in levels are now V1 UUIDs (time-ordered).
  This will help to reliably resolve conflicts in draw order
  of overlapping doodads (newest added to level wins).
* Link Tool: clicking on a pair of already-linked doodads will
  now unlink them, so you don't have to delete one to delete
  the link.
* Actor Tool: deleting an actor immediately calls PruneLinks()
  to clean up any links that the deleted doodad might have.

dev-assets/doodads/azulian/Makefile

@@ -4,11 +4,13 @@ ALL: build
 build:
 	doodad convert -t "Blue Azulian" blu-front.png blu-back.png \
 		blu-wr{1,2,3,4}.png blu-wl{1,2,3,4}.png azu-blu.doodad
+	doodad edit-doodad --tag "color=blue" azu-blu.doodad
 	doodad install-script azulian.js azu-blu.doodad
 
 	doodad convert -t "Red Azulian" red-front.png red-back.png \
 		red-wr{1,2,3,4}.png red-wl{1,2,3,4}.png azu-red.doodad
-	doodad install-script azulian-red.js azu-red.doodad
+	doodad edit-doodad --tag "color=red" azu-red.doodad
+	doodad install-script azulian.js azu-red.doodad
 
 	# Tag the category for these doodads
 	for i in *.doodad; do\

dev-assets/doodads/azulian/azulian-red.js

@@ -1,3 +1,6 @@
+// Azulian (Red)
+// DEPRECATED: they both share azulian.js now.
+
 function main() {
 	var playerSpeed = 4;
 	var gravity = 4;

dev-assets/doodads/azulian/azulian.js

@@ -1,38 +1,74 @@
-function main() {
-	var playerSpeed = 12;
-	var gravity = 4;
-	var Vx = Vy = 0;
+// Azulian (Red and Blue)
+var playerSpeed = 12,
+	animating = false,
+	direction = "right";
 
-	var animating = false;
-	var animStart = animEnd = 0;
-	var animFrame = animStart;
+function setupAnimations(color) {
+	var left = color === 'blue' ? 'blu-wl' : 'red-wl',
+		right = color === 'blue' ? 'blu-wr' : 'red-wr',
+		leftFrames = [left + '1', left + '2', left + '3', left + '4'],
+		rightFrames = [right + '1', right + '2', right + '3', right + '4'];
+
+	Self.AddAnimation("walk-left", 100, leftFrames);
+	Self.AddAnimation("walk-right", 100, rightFrames);
+}
+
+function main() {
+	var color = Self.GetTag("color");
+	playerSpeed = color === 'blue' ? 2 : 4;
 
 	Self.SetMobile(true);
 	Self.SetGravity(true);
 	Self.SetInventory(true);
-	Self.SetHitbox(7, 4, 17, 28);
-	Self.AddAnimation("walk-left", 100, ["blu-wl1", "blu-wl2", "blu-wl3", "blu-wl4"]);
-	Self.AddAnimation("walk-right", 100, ["blu-wr1", "blu-wr2", "blu-wr3", "blu-wr4"]);
+	Self.SetHitbox(0, 0, 24, 32);
+	setupAnimations(color);
 
+	if (Self.IsPlayer()) {
+		return playerControls();
+	}
+
+	// A.I. pattern: walks back and forth, turning around
+	// when it meets resistance.
+
+	// Sample our X position every few frames and detect if we've hit a solid wall.
+	var sampleTick = 0;
+	var sampleRate = 5;
+	var lastSampledX = 0;
+
+	setInterval(function () {
+		if (sampleTick % sampleRate === 0) {
+			var curX = Self.Position().X;
+			var delta = Math.abs(curX - lastSampledX);
+			if (delta < 5) {
+				direction = direction === "right" ? "left" : "right";
+			}
+			lastSampledX = curX;
+		}
+		sampleTick++;
+
+		var Vx = parseFloat(playerSpeed * (direction === "left" ? -1 : 1));
+		Self.SetVelocity(Vector(Vx, 0.0));
+
+		if (!Self.IsAnimating()) {
+			Self.PlayAnimation("walk-" + direction, null);
+		}
+	}, 100);
+}
+
+function playerControls() {
+	// Note: player speed is controlled by the engine.
 	Events.OnKeypress(function (ev) {
-		Vx = 0;
-		Vy = 0;
-
 		if (ev.Right) {
 			if (!Self.IsAnimating()) {
 				Self.PlayAnimation("walk-right", null);
 			}
-			Vx = playerSpeed;
 		} else if (ev.Left) {
 			if (!Self.IsAnimating()) {
 				Self.PlayAnimation("walk-left", null);
 			}
-			Vx = -playerSpeed;
 		} else {
 			Self.StopAnimation();
 			animating = false;
 		}
-
-		// Self.SetVelocity(Point(Vx, Vy));
 	})
 }

dev-assets/doodads/build.sh

@@ -91,5 +91,5 @@ objects
 onoff
 warpdoor
 doodad edit-doodad -quiet -lock -author "Noah" ../../assets/doodads/*.doodad
-doodad edit-doodad -hide ../../assets/doodads/azu-blu.doodad
+doodad edit-doodad ../../assets/doodads/azu-blu.doodad
 doodad edit-doodad -hide ../../assets/doodads/boy.doodad

dev-assets/doodads/objects/Makefile

@@ -4,6 +4,7 @@ ALL: build
 build:
 	# Start Flag
 	doodad convert -t "Start Flag" start-flag.png start-flag.doodad
+	doodad install-script start-flag.js start-flag.doodad
 
 	# Exit Flag
 	doodad convert -t "Exit Flag" exit-flag.png exit-flag.doodad

dev-assets/doodads/objects/start-flag.js

@@ -0,0 +1,11 @@
+// Start Flag.
+function main() {
+    Self.SetHitbox(22 + 16, 16, 75 - 16, 86);
+
+    // Linking a doodad to the Start Flag sets the
+    // player character. Destroy the original doodads.
+    var links = Self.GetLinks();
+    for (var i = 0; i < links.length; i++) {
+        links[i].Destroy();
+    }
+}

pkg/balance/numbers.go

@@ -13,7 +13,7 @@ var (
 
 	// Window scrolling behavior in Play Mode.
 	ScrollboxOffset = render.Point{ // from center of screen
-		X: 40,
+		X: 60,
 		Y: 100,
 	}
 

pkg/doodads/drawing.go

@@ -22,7 +22,7 @@ type Drawing struct {
 // an empty ID string, it will make a random UUIDv4 ID.
 func NewDrawing(id string, doodad *Doodad) *Drawing {
 	if id == "" {
-		id = uuid.Must(uuid.NewRandom()).String()
+		id = uuid.Must(uuid.NewUUID()).String()
 	}
 	return &Drawing{
 		id:     id,

pkg/editor_ui.go

@@ -378,6 +378,7 @@ func (u *EditorUI) SetupCanvas(d *Doodle) *uix.Canvas {
 			for _, actor := range actors {
 				u.Scene.Level.Actors.Remove(actor)
 			}
+			u.Scene.Level.PruneLinks()
 			drawing.InstallActors(u.Scene.Level.Actors)
 		}
 	}
@@ -395,8 +396,15 @@ func (u *EditorUI) SetupCanvas(d *Doodle) *uix.Canvas {
 		// The actors are a uix.Actor which houses a level.Actor which we
 		// want to update to map each other's IDs.
 		idA, idB := a.Actor.ID(), b.Actor.ID()
+
+		// Are they already linked?
+		if a.Actor.IsLinked(idB) || b.Actor.IsLinked(idA) {
+			a.Actor.Unlink(idB)
+			b.Actor.Unlink(idA)
+		} else {
 			a.Actor.AddLink(idB)
 			b.Actor.AddLink(idA)
+		}
 
 		// Reset the Link tool.
 		d.Flash("Linked '%s' and '%s' together", a.Doodad().Title, b.Doodad().Title)

pkg/level/actors.go

@@ -19,7 +19,7 @@ func (m ActorMap) Inflate() {
 // given a random UUIDv4 ID.
 func (m ActorMap) Add(a *Actor) {
 	if a.id == "" {
-		a.id = uuid.Must(uuid.NewRandom()).String()
+		a.id = uuid.Must(uuid.NewUUID()).String()
 	}
 	m[a.id] = a
 }
@@ -57,3 +57,25 @@ func (a *Actor) AddLink(id string) {
 	}
 	a.Links = append(a.Links, id)
 }
+
+// Unlink removes the linked actor's ID.
+func (a *Actor) Unlink(id string) {
+	var newLinks []string
+	for _, exist := range a.Links {
+		if exist == id {
+			continue
+		}
+		newLinks = append(newLinks, exist)
+	}
+	a.Links = newLinks
+}
+
+// IsLinked checks if the actor is linked to the other actor's ID.
+func (a *Actor) IsLinked(id string) bool {
+	for _, exist := range a.Links {
+		if exist == id {
+			return true
+		}
+	}
+	return false
+}

pkg/level/chunk.go

@@ -134,7 +134,7 @@ func (c *Chunk) generateTexture(mask render.Color) (render.Texturer, error) {
 	// Generate a unique name for this chunk cache.
 	var name string
 	if c.uuid == uuid.Nil {
-		c.uuid = uuid.Must(uuid.NewRandom())
+		c.uuid = uuid.Must(uuid.NewUUID())
 	}
 	name = c.uuid.String()
 

pkg/play_scene.go

@@ -251,39 +251,50 @@ func (s *PlayScene) setupAsync(d *Doodle) error {
 
 // setupPlayer creates and configures the Player Character in the level.
 func (s *PlayScene) setupPlayer() {
-	// Load in the player character.
-	player, err := doodads.LoadFile(balance.PlayerCharacterDoodad)
-	if err != nil {
-		log.Error("PlayScene.Setup: failed to load player doodad: %s", err)
-		player = doodads.NewDummy(32)
-	}
-
 	// Find the spawn point of the player. Search the level for the
 	// "start-flag.doodad"
 	var (
+		playerCharacterFilename = balance.PlayerCharacterDoodad
+
 		spawn     render.Point
+		flag      *level.Actor
+		flagSize  = render.NewRect(86, 86) // TODO: start-flag.doodad is 86x86 px
 		flagCount int
 	)
 	for actorID, actor := range s.Level.Actors {
 		if actor.Filename == "start-flag.doodad" {
-			if flagCount > 1 {
+			// Support alternative player characters: if the Start Flag is linked
+			// to another actor, that actor becomes the player character.
+			for _, linkID := range actor.Links {
+				if linkedActor, ok := s.Level.Actors[linkID]; ok {
+					playerCharacterFilename = linkedActor.Filename
+					log.Info("Playing as: %s", playerCharacterFilename)
+				}
 				break
 			}
 
 			// TODO: start-flag.doodad is 86x86 pixels but we can't tell that
 			// from right here.
-			size := render.NewRect(86, 86)
 			log.Info("Found start-flag.doodad at %s (ID %s)", actor.Point, actorID)
+			flag = actor
+			break
+		}
+	}
+
+	// Load in the player character.
+	player, err := doodads.LoadFile(playerCharacterFilename)
+	if err != nil {
+		log.Error("PlayScene.Setup: failed to load player doodad: %s", err)
+		player = doodads.NewDummy(32)
+	}
+
 	spawn = render.NewPoint(
 		// X: centered inside the flag.
-				actor.Point.X+(size.W/2)-(player.Layers[0].Chunker.Size/2),
+		flag.Point.X+(flagSize.W/2)-(player.Layers[0].Chunker.Size/2),
 
 		// Y: the bottom of the flag, 4 pixels from the floor.
-				actor.Point.Y+size.H-4-(player.Layers[0].Chunker.Size),
+		flag.Point.Y+flagSize.H-4-(player.Layers[0].Chunker.Size),
 	)
-			flagCount++
-		}
-	}
 
 	// Surface warnings around the spawn flag.
 	if flagCount == 0 {

pkg/uix/actor.go

@@ -63,7 +63,7 @@ type Actor struct {
 // If the id is blank, a new UUIDv4 is generated.
 func NewActor(id string, levelActor *level.Actor, doodad *doodads.Doodad) *Actor {
 	if id == "" {
-		id = uuid.Must(uuid.NewRandom()).String()
+		id = uuid.Must(uuid.NewUUID()).String()
 	}
 
 	size := doodad.Layers[0].Chunker.Size