Return False: Solid Collision Between Actors

* Implement the handler code for `return false` when actors are
  colliding with each other and wish to act like solid walls.
* The locked doors will `return false` when they're closed and the
  colliding actor does not have the matching key.
* Add arbitrary key/value storage to Actors. The colored keys will set
  an actor value "key:%TITLE%" on the one who touched the key before
  destroying itself. The colored doors check that key when touched to
  decide whether to open.
* The trapdoor now only opens if you're touching it from the top (your
  overlap box Y value is 0), but if you touch it from below and the door
  is closed, it acts like a solid object.

dev-assets/doodads/azulian/azulian.js

@@ -10,6 +10,7 @@ function main() {
 	var animFrame = animStart;
 
 	Self.SetGravity(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"]);
 

dev-assets/doodads/doors/keys.js

@@ -1,5 +1,7 @@
 function main() {
 	Events.OnCollide(function(e) {
+		console.log("%s picked up by %s", Self.Doodad.Title, e.Actor.Title);
+		e.Actor.SetData("key:" + Self.Doodad.Title, "true");
 		Self.Destroy();
 	})
 }

dev-assets/doodads/doors/locked-door.js

@@ -2,25 +2,33 @@ function main() {
 	Self.AddAnimation("open", 0, [1]);
 	var unlocked = false;
 
+	// Map our door names to key names.
+	var KeyMap = {
+		"Blue Door": "Blue Key",
+		"Red Door": "Red Key",
+		"Green Door": "Green Key",
+		"Yellow Door": "Yellow Key"
+	}
+
+	log.Warn("%s loaded!", Self.Doodad.Title);
+	console.log("%s Setting hitbox", Self.Doodad.Title);
+	Self.SetHitbox(16, 0, 32, 64);
+
 	Events.OnCollide(function(e) {
-		console.log("%s was touched by %s!", Self.Doodad.Title, e.Actor.ID());
-		console.log("my box: %+v and theirs: %+v", Self.GetBoundingRect(), e.Actor.GetBoundingRect());
-		console.warn("But the overlap is: %+v", e.Overlap);
-		console.log(Object.keys(e));
-
-		if (e.Overlap.X + e.Overlap.W >= 16 && e.Overlap.X < 48) {
-			Self.Canvas.SetBackground(RGBA(255, 0, 0, 153));
-		} else {
-			Self.Canvas.SetBackground(RGBA(0, 255, 0, 153));
-			return;
-		}
-
 		if (unlocked) {
 			return;
 		}
 
-		unlocked = true;
+		if (e.InHitbox) {
-		Self.PlayAnimation("open", null);
+			var data = e.Actor.GetData("key:" + KeyMap[Self.Doodad.Title]);
+			if (data === "") {
+				// Door is locked.
+				return false;
+			}
+
+			unlocked = true;
+			Self.PlayAnimation("open", null);
+		}
 	});
 	Events.OnLeave(function(e) {
 		console.log("%s has stopped touching %s", e, Self.Doodad.Title)

dev-assets/doodads/trapdoors/down.js

@@ -3,6 +3,8 @@ function main() {
 
 	var timer = 0;
 
+	Self.SetHitbox(0, 0, 72, 9);
+
 	var animationSpeed = 100;
 	var opened = false;
 	Self.AddAnimation("open", animationSpeed, ["down1", "down2", "down3", "down4"]);
@@ -13,18 +15,24 @@ function main() {
 			return;
 		}
 
-		// Not touching the top of the door means door doesn't open.
+		// Is the actor colliding our solid part?
-		if (e.Overlap.Y > 9) {
+		if (e.InHitbox) {
-			return;
+			// Touching the top or the bottom?
+			if (e.Overlap.Y > 0) {
+				return false; // solid wall when touched from below
+			} else {
+				opened = true;
+				Self.PlayAnimation("open", function() {
+				});
+			}
 		}
-
-		opened = true;
-		Self.PlayAnimation("open", function() {
-		});
 	});
+
 	Events.OnLeave(function() {
-		Self.PlayAnimation("close", function() {
+		if (opened) {
-			opened = false;
+			Self.PlayAnimation("close", function() {
-		});
+				opened = false;
+			});
+		}
 	})
 }

lib/debugging/debugging.go

@@ -102,3 +102,10 @@ func PrintCallers() {
 		fmt.Printf("%d: %s\n", i, caller)
 	}
 }
+
+// Pause until the user hits enter in the console.
+func Pause() {
+	var x string
+	fmt.Print("Press enter to continue . . .")
+	fmt.Scanf("%s", &x)
+}

lib/render/rect_test.go

@@ -54,6 +54,16 @@ func TestIntersection(t *testing.T) {
 			B:      newRect(0, -240, 874, 490),
 			Expect: false, // XXX: must be true
 		},
+		{
+			A:      newRect(0, 30, 9, 62),
+			B:      newRect(16, 0, 32, 64),
+			Expect: false,
+		},
+		{
+			A:      newRect(0, 30, 11, 62),
+			B:      newRect(7, 4, 17, 28),
+			Expect: false,
+		},
 	}
 
 	for _, test := range tests {

pkg/collision/collide_actors.go

@@ -1,6 +1,7 @@
 package collision
 
 import (
+	"errors"
 	"math"
 
 	"git.kirsle.net/apps/doodle/lib/render"
@@ -32,22 +33,11 @@ func BetweenBoxes(boxes []render.Rect) chan BoxCollision {
 		for i, box := range boxes {
 			for j := i + 1; j < len(boxes); j++ {
 				other := boxes[j]
-				if box.Intersects(other) {
+				collision, err := CompareBoxes(box, other)
-					var (
+				if err == nil {
-						overlap     = OverlapRelative(box, other)
+					collision.A = i
-						topLeft     = overlap.TopLeft()
+					collision.B = j
-						bottomRight = overlap.BottomRight()
+					generator <- collision
-					)
-					generator <- BoxCollision{
-						A: i,
-						B: j,
-						Overlap: render.Rect{
-							X: topLeft.X,
-							Y: topLeft.Y,
-							W: bottomRight.X,
-							H: bottomRight.Y,
-						},
-					}
 				}
 			}
 		}
@@ -58,6 +48,28 @@ func BetweenBoxes(boxes []render.Rect) chan BoxCollision {
 	return generator
 }
 
+// CompareBoxes checks if two boxes overlaps and returns information about
+// the overlap. The boxes are bounding rectangles like those given to
+// BetweenBoxes().
+func CompareBoxes(box, other render.Rect) (BoxCollision, error) {
+	if box.Intersects(other) {
+		var (
+			overlap     = OverlapRelative(box, other)
+			topLeft     = overlap.TopLeft()
+			bottomRight = overlap.BottomRight()
+		)
+		return BoxCollision{
+			Overlap: render.Rect{
+				X: topLeft.X,
+				Y: topLeft.Y,
+				W: bottomRight.X,
+				H: bottomRight.Y,
+			},
+		}, nil
+	}
+	return BoxCollision{}, errors.New("boxes do not intersect")
+}
+
 /*
 OverlapRelative returns the Overlap box using coordinates relative
 to the source rect instead of absolute coordinates.

pkg/doodads/actor.go

@@ -16,6 +16,10 @@ type Actor interface {
 	Grounded() bool
 	SetGrounded(bool)
 
+	// Actor's elected hitbox set by their script.
+	SetHitbox(x, y, w, h int)
+	Hitbox() render.Rect
+
 	// Movement commands.
 	MoveBy(render.Point) // Add {X,Y} to current Position.
 	MoveTo(render.Point) // Set current Position to {X,Y}.

pkg/doodads/doodad.go

@@ -9,10 +9,11 @@ import (
 // Doodad is a reusable component for Levels that have scripts and graphics.
 type Doodad struct {
 	level.Base
-	Filename string         `json:"-"` // used internally, not saved in json
+	Filename string            `json:"-"` // used internally, not saved in json
-	Palette  *level.Palette `json:"palette"`
+	Palette  *level.Palette    `json:"palette"`
-	Script   string         `json:"script"`
+	Script   string            `json:"script"`
-	Layers   []Layer        `json:"layers"`
+	Layers   []Layer           `json:"layers"`
+	Tags     map[string]string `json:"data"` // arbitrary key/value data storage
 }
 
 // Layer holds a layer of drawing data for a Doodad.
@@ -38,6 +39,7 @@ func New(size int) *Doodad {
 				Chunker: level.NewChunker(size),
 			},
 		},
+		Tags: map[string]string{},
 	}
 }
 

pkg/doodads/drawing.go

@@ -14,6 +14,7 @@ type Drawing struct {
 	velocity render.Point
 	accel    int
 	size     render.Rect
+	hitbox   render.Rect
 	grounded bool
 }
 
@@ -75,6 +76,21 @@ func (d *Drawing) SetGrounded(v bool) {
 	d.grounded = v
 }
 
+// SetHitbox sets the actor's elected hitbox.
+func (d *Drawing) SetHitbox(x, y, w, h int) {
+	d.hitbox = render.Rect{
+		X: int32(x),
+		Y: int32(y),
+		W: int32(w),
+		H: int32(h),
+	}
+}
+
+// Hitbox returns the actor's elected hitbox.
+func (d *Drawing) Hitbox() render.Rect {
+	return d.hitbox
+}
+
 // MoveBy a relative value.
 func (d *Drawing) MoveBy(by render.Point) {
 	d.point.Add(by)

pkg/uix/actor.go

@@ -29,6 +29,8 @@ type Actor struct {
 
 	// Actor runtime variables.
 	hasGravity bool
+	hitbox     render.Rect
+	data       map[string]string
 
 	// Animation variables.
 	animations        map[string]*Animation
@@ -78,6 +80,41 @@ func (a *Actor) GetBoundingRect() render.Rect {
 	return doodads.GetBoundingRect(a)
 }
 
+// SetHitbox sets the actor's elected hitbox.
+func (a *Actor) SetHitbox(x, y, w, h int) {
+	a.hitbox = render.Rect{
+		X: int32(x),
+		Y: int32(y),
+		W: int32(w),
+		H: int32(h),
+	}
+}
+
+// Hitbox returns the actor's elected hitbox.
+func (a *Actor) Hitbox() render.Rect {
+	return a.hitbox
+}
+
+// SetData sets an arbitrary field in the actor's K/V storage.
+func (a *Actor) SetData(key, value string) {
+	if a.data == nil {
+		a.data = map[string]string{}
+	}
+	a.data[key] = value
+}
+
+// GetData gets an arbitrary field from the actor's K/V storage.
+// Missing keys just return a blank string (friendly to the JavaScript
+// environment).
+func (a *Actor) GetData(key string) string {
+	if a.data == nil {
+		return ""
+	}
+
+	v, _ := a.data[key]
+	return v
+}
+
 // LayerCount returns the number of layers in this actor's drawing.
 func (a *Actor) LayerCount() int {
 	return len(a.Doodad.Layers)

pkg/uix/actor_collision.go

@@ -0,0 +1,157 @@
+package uix
+
+import (
+	"sync"
+	"time"
+
+	"git.kirsle.net/apps/doodle/lib/render"
+	"git.kirsle.net/apps/doodle/pkg/balance"
+	"git.kirsle.net/apps/doodle/pkg/collision"
+	"git.kirsle.net/apps/doodle/pkg/doodads"
+	"git.kirsle.net/apps/doodle/pkg/scripting"
+	"github.com/kirsle/blog/src/log"
+	"github.com/robertkrimen/otto"
+)
+
+// loopActorCollision is the Loop function that checks if pairs of
+// actors are colliding with each other, and handles their scripting
+// responses to such collisions.
+//
+// boxes: array of Actor bounding box rects.
+func (w *Canvas) loopActorCollision() error {
+	var (
+		// Current time of this tick so we can advance animations.
+		now = time.Now()
+
+		// As we iterate over all actors below to process their movement, track
+		// their bounding rectangles so we can later see if any pair of actors
+		// intersect each other. Also, in case of actor scripts protesting a
+		// collision later, store each actor's original position before the move.
+		boxes             = make([]render.Rect, len(w.actors))
+		originalPositions = map[string]render.Point{}
+	)
+
+	// Loop over all the actors in parallel, processing their movement and
+	// checking collision data against the level geometry.
+	var wg sync.WaitGroup
+	for i, a := range w.actors {
+		wg.Add(1)
+		go func(i int, a *Actor) {
+			defer wg.Done()
+			originalPositions[a.ID()] = a.Position()
+
+			// Advance any animations for this actor.
+			if a.activeAnimation != nil && a.activeAnimation.nextFrameAt.Before(now) {
+				if done := a.TickAnimation(a.activeAnimation); done {
+					// Animation has finished, run the callback script.
+					if a.animationCallback.IsFunction() {
+						a.animationCallback.Call(otto.NullValue())
+					}
+
+					// Clean up the animation state.
+					a.StopAnimation()
+				}
+			}
+
+			// Get the actor's velocity to see if it's moving this tick.
+			v := a.Velocity()
+			if a.hasGravity {
+				v.Y += int32(balance.Gravity)
+			}
+
+			// If not moving, grab the bounding box right now.
+			if v == render.Origin {
+				boxes[i] = doodads.GetBoundingRect(a)
+				return
+			}
+
+			// Create a delta point from their current location to where they
+			// want to move to this tick.
+			delta := a.Position()
+			delta.Add(v)
+
+			// Check collision with level geometry.
+			info, ok := collision.CollidesWithGrid(a, w.chunks, delta)
+			if ok {
+				// Collision happened with world.
+			}
+			delta = info.MoveTo // Move us back where the collision check put us
+
+			// Move the actor's World Position to the new location.
+			a.MoveTo(delta)
+
+			// Keep the actor from leaving the world borders of bounded maps.
+			w.loopContainActorsInsideLevel(a)
+
+			// Store this actor's bounding box after they've moved.
+			boxes[i] = doodads.GetBoundingRect(a)
+		}(i, a)
+		wg.Wait()
+	}
+
+	var collidingActors = map[string]string{}
+	for tuple := range collision.BetweenBoxes(boxes) {
+		a, b := w.actors[tuple.A], w.actors[tuple.B]
+		collidingActors[a.ID()] = b.ID()
+
+		// Call the OnCollide handler.
+		if w.scripting != nil {
+			// Tell actor A about the collision with B.
+			if err := w.scripting.To(a.ID()).Events.RunCollide(&CollideEvent{
+				Actor:    b,
+				Overlap:  tuple.Overlap,
+				InHitbox: tuple.Overlap.Intersects(a.Hitbox()),
+			}); err != nil {
+				if err == scripting.ErrReturnFalse {
+					if origPoint, ok := originalPositions[b.ID()]; ok {
+						// Trace a vector back from the actor's current position
+						// to where they originated from and find the earliest
+						// point where they are not violating the hitbox.
+						var (
+							rect   = doodads.GetBoundingRect(b)
+							hitbox = a.Hitbox()
+						)
+						for point := range render.IterLine2(
+							b.Position(),
+							origPoint,
+						) {
+							test := render.Rect{
+								X: point.X,
+								Y: point.Y,
+								W: rect.W,
+								H: rect.H,
+							}
+							info, err := collision.CompareBoxes(
+								boxes[tuple.A],
+								test,
+							)
+							if err != nil || !info.Overlap.Intersects(hitbox) {
+								b.MoveTo(point)
+								break
+							}
+						}
+					} else {
+						log.Error(
+							"ERROR: Actors %s and %s overlap and the script returned false,"+
+								"but I didn't store %s original position earlier??",
+							a.Doodad.Title, b.Doodad.Title, b.Doodad.Title,
+						)
+					}
+				} else {
+					log.Error(err.Error())
+				}
+			}
+		}
+	}
+
+	// Check for lacks of collisions since last frame.
+	for sourceID, targetID := range w.collidingActors {
+		if _, ok := collidingActors[sourceID]; !ok {
+			w.scripting.To(sourceID).Events.RunLeave(targetID)
+		}
+	}
+
+	// Store this frame's colliding actors for next frame.
+	w.collidingActors = collidingActors
+	return nil
+}

pkg/uix/actor_events.go

@@ -4,6 +4,7 @@ import "git.kirsle.net/apps/doodle/lib/render"
 
 // CollideEvent holds data sent to an actor's Collide handler.
 type CollideEvent struct {
-	Actor   *Actor
+	Actor    *Actor
-	Overlap render.Rect
+	Overlap  render.Rect
+	InHitbox bool // If the two elected hitboxes are overlapping
 }

pkg/uix/canvas.go

@@ -4,20 +4,16 @@ import (
 	"fmt"
 	"os"
 	"strings"
-	"sync"
-	"time"
 
 	"git.kirsle.net/apps/doodle/lib/events"
 	"git.kirsle.net/apps/doodle/lib/render"
 	"git.kirsle.net/apps/doodle/lib/ui"
 	"git.kirsle.net/apps/doodle/pkg/balance"
-	"git.kirsle.net/apps/doodle/pkg/collision"
 	"git.kirsle.net/apps/doodle/pkg/doodads"
 	"git.kirsle.net/apps/doodle/pkg/level"
 	"git.kirsle.net/apps/doodle/pkg/log"
 	"git.kirsle.net/apps/doodle/pkg/scripting"
 	"git.kirsle.net/apps/doodle/pkg/wallpaper"
-	"github.com/robertkrimen/otto"
 )
 
 // Canvas is a custom ui.Widget that manages a single drawing.
@@ -178,7 +174,7 @@ func (w *Canvas) Loop(ev *events.State) error {
 	_ = w.loopConstrainScroll()
 
 	// Current time of this loop so we can advance animations.
-	now := time.Now()
+	// now := time.Now()
 
 	// Remove any actors that were destroyed the previous tick.
 	var newActors []*Actor
@@ -192,93 +188,11 @@ func (w *Canvas) Loop(ev *events.State) error {
 		w.actors = newActors
 	}
 
-	// Move any actors. As we iterate over all actors, track their bounding
-	// rectangles so we can later see if any pair of actors intersect each other.
-	boxes := make([]render.Rect, len(w.actors))
-	var wg sync.WaitGroup
-	for i, a := range w.actors {
-		wg.Add(1)
-		go func(i int, a *Actor) {
-			defer wg.Done()
-
-			// Advance any animations for this actor.
-			if a.activeAnimation != nil && a.activeAnimation.nextFrameAt.Before(now) {
-				if done := a.TickAnimation(a.activeAnimation); done {
-					// Animation has finished, run the callback script.
-					if a.animationCallback.IsFunction() {
-						a.animationCallback.Call(otto.NullValue())
-					}
-
-					// Clean up the animation state.
-					a.StopAnimation()
-				}
-			}
-
-			// Get the actor's velocity to see if it's moving this tick.
-			v := a.Velocity()
-			if a.hasGravity {
-				v.Y += int32(balance.Gravity)
-			}
-
-			// If not moving, grab the bounding box right now.
-			if v == render.Origin {
-				boxes[i] = doodads.GetBoundingRect(a)
-				return
-			}
-
-			// Create a delta point from their current location to where they
-			// want to move to this tick.
-			delta := a.Position()
-			delta.Add(v)
-
-			// Check collision with level geometry.
-			info, ok := collision.CollidesWithGrid(a, w.chunks, delta)
-			if ok {
-				// Collision happened with world.
-			}
-			delta = info.MoveTo // Move us back where the collision check put us
-
-			// Move the actor's World Position to the new location.
-			a.MoveTo(delta)
-
-			// Keep the actor from leaving the world borders of bounded maps.
-			w.loopContainActorsInsideLevel(a)
-
-			// Store this actor's bounding box after they've moved.
-			boxes[i] = doodads.GetBoundingRect(a)
-		}(i, a)
-		wg.Wait()
-	}
-
 	// Check collisions between actors.
-	var collidingActors = map[string]string{}
+	if err := w.loopActorCollision(); err != nil {
-	for tuple := range collision.BetweenBoxes(boxes) {
+		log.Error("loopActorCollision: %s", err)
-		a, b := w.actors[tuple.A], w.actors[tuple.B]
-
-		collidingActors[a.ID()] = b.ID()
-
-		// Call the OnCollide handler.
-		if w.scripting != nil {
-			// Tell actor A about the collision with B.
-			if err := w.scripting.To(a.ID()).Events.RunCollide(&CollideEvent{
-				Actor:   b,
-				Overlap: tuple.Overlap,
-			}); err != nil {
-				log.Error(err.Error())
-			}
-		}
 	}
 
-	// Check for lacks of collisions since last frame.
-	for sourceID, targetID := range w.collidingActors {
-		if _, ok := collidingActors[sourceID]; !ok {
-			w.scripting.To(sourceID).Events.RunLeave(targetID)
-		}
-	}
-
-	// Store this frame's colliding actors for next frame.
-	w.collidingActors = collidingActors
-
 	// If the canvas is editable, only care if it's over our space.
 	if w.Editable {
 		cursor := render.NewPoint(ev.CursorX.Now, ev.CursorY.Now)