Remove the 'Moved" event

We currently emit a 'Move' event when the position is set,
and a separate 'Moved' event when the position is set by the 'Motion' event.
(I believe this is baggage left over from how Multiway/etc used to work?)

This has a fairly high cost, since on a typical motion tick we emit 4 events,
two for each axis.

This PR simplifies things by
- Removing the 'Moved' event completely
- Adding a method that handles both x and y change in one pass.

The result is that linearMotionTick will only emit one move-related event per frame.
In limited performance testing, this had a fairly large impact.
In a test involving several hundred falling entities, linearMotion + event callbacks went from
consuming 13% of the total CPU time to 5.5%.

src/spatial/2d.js

@@ -678,8 +678,7 @@ Crafty.c("2D", {
      * for an opposite direction.
      */
     shift: function (x, y, w, h) {
-        if (x) this.x += x;
-        if (y) this.y += y;
+        if (x || y) this._setPosition(this._x + x, this._y + y);
         if (w) this.w += w;
         if (h) this.h += h;
 
@@ -877,6 +876,28 @@ Crafty.c("2D", {
         this._setter2d('_y', y2 );
     },
 
+    // A separate setter for the common case of moving an entity along both axes
+    _setPosition: function(x, y) {
+        if (x === this._x && y === this._y) return;
+        var old = Crafty.rectManager._pool.copy(this);
+        var mbr = this._mbr;
+        if (mbr) {
+            mbr._x -= this._x - x;
+            mbr._y -= this._y - y;
+            // cbr is a non-minimal bounding rectangle that contains both hitbox and mbr
+            // It will exist only when the collision hitbox sits outside the entity
+            if (this._cbr){
+                this._cbr._x -= this._x - x;
+                this._cbr._y -= this._y - y;
+            }
+        }
+        this._x = x;
+        this._y = y;
+        this.trigger("Move", old);
+        this.trigger("Invalidate");
+        Crafty.rectManager._pool.recycle(old);
+    },
+
     // This is a setter method for all 2D properties including
     // x, y, w, h, and rotation.
     _setter2d: function (name, value) {
@@ -897,7 +918,7 @@ Crafty.c("2D", {
             mbr = this._mbr;
             if (mbr) {
                 mbr[name] -= this[name] - value;
-                // cbr is a non-minmal bounding rectangle that contains both hitbox and mbr
+                // cbr is a non-minimal bounding rectangle that contains both hitbox and mbr
                 // It will exist only when the collision hitbox sits outside the entity
                 if (this._cbr){
                     this._cbr[name] -= this[name] - value;

src/spatial/motion.js

@@ -195,7 +195,6 @@ Crafty.c("AngularMotion", {
  * @category 2D
  * @kind Component
  * 
- * @trigger Moved - When entity has moved due to velocity/acceleration on either x or y axis a Moved event is triggered. If the entity has moved on both axes for diagonal movement the event is triggered twice. - { axis: 'x' | 'y', oldValue: Number } - Old position
  * @trigger NewDirection - When entity has changed direction due to velocity on either x or y axis a NewDirection event is triggered. The event is triggered once, if direction is different from last frame. - { x: -1 | 0 | 1, y: -1 | 0 | 1 } - New direction
  * @trigger MotionChange - When a motion property has changed a MotionChange event is triggered. - { key: String, oldValue: Number } - Motion property name and old value
  *
@@ -474,12 +473,12 @@ Crafty.c("Motion", {
      */
     _linearMotionTick: function(frameData) {
         var dt = frameData.dt / 1000; // time in s
-        var oldX = this._x, vx = this._vx, ax = this._ax,
-            oldY = this._y, vy = this._vy, ay = this._ay;
+        var vx = this._vx, ax = this._ax,
+            vy = this._vy, ay = this._ay;
 
         // s += v * Δt + (0.5 * a) * Δt * Δt
-        var newX = oldX + vx * dt + 0.5 * ax * dt * dt;
-        var newY = oldY + vy * dt + 0.5 * ay * dt * dt;
+        var dx = vx * dt + 0.5 * ax * dt * dt;
+        var dy = vy * dt + 0.5 * ay * dt * dt;
         // v += a * Δt
         this.vx = vx + ax * dt;
         this.vy = vy + ay * dt;
@@ -494,22 +493,10 @@ Crafty.c("Motion", {
             this.trigger('NewDirection', oldDirection);
         }
 
-        // Check if velocity has changed
-        var movedEvent = this.__movedEvent;
-        // Δs = s[t] - s[t-1]
-        this._dx = newX - oldX;
-        this._dy = newY - oldY;
-        if (this._dx !== 0) {
-            this.x = newX;
-            movedEvent.axis = 'x';
-            movedEvent.oldValue = oldX;
-            this.trigger('Moved', movedEvent);
-        }
-        if (this._dy !== 0) {
-            this.y = newY;
-            movedEvent.axis = 'y';
-            movedEvent.oldValue = oldY;
-            this.trigger('Moved', movedEvent);
-        }
+        this._dx = dx;
+        this._dy = dy;
+
+        // Set the position using the optimized _setPosition method
+        this._setPosition(this._x + dx, this._y + dy);
     }
 });

tests/unit/spatial/motion.js

@@ -189,7 +189,6 @@
 
     var newDirectionEvents = 0,
         newRotationDirectionEvents = 0,
-        movedEvents = 0,
         rotatedEvents = 0,
         motionEvents = 0;
     e.bind("NewDirection", function(evt) {
@@ -198,9 +197,6 @@
     e.bind("NewRotationDirection", function(evt) {
       newRotationDirectionEvents++;
     });
-    e.bind("Moved", function(evt) {
-      movedEvents++;
-    });
     e.bind("Rotated", function(evt) {
       rotatedEvents++;
     });
@@ -213,10 +209,6 @@
       _.strictEqual(evt.x, 0, "[1] - no motion along x axis");
       _.strictEqual(evt.y, 1, "[1] - moving along +y axis");
     });
-    e.one("Moved", function(evt) { 
-      _.strictEqual(evt.axis, "y", "[1] - moved along y axis"); 
-      _.strictEqual(evt.oldValue, 0, "[1] - old y was 0"); 
-    });
     e.one("MotionChange", function(evt) { 
       _.strictEqual(evt.key, "vy", "[1] - vy was set"); 
       _.strictEqual(evt.oldValue, 0, "[1] - old vy was 0");
@@ -225,19 +217,10 @@
     Crafty.timer.simulateFrames(1);
 
     // group 2: set both vy and vx to be negative
-    var old_y = e.y;
     e.one("NewDirection", function(evt) {
       _.strictEqual(evt.x, -1, "[2] - Now moving along -x axis" );
       _.strictEqual(evt.y, -1, "[2] - Now moving along -y axis");
     });
-    e.one("Moved", function(evt) { 
-      _.strictEqual(evt.axis, "x", "[2] - Moved along x axis"); 
-      _.strictEqual(evt.oldValue, 0, "[2] - old x was 0"); 
-      e.one("Moved", function(evt) { 
-        _.strictEqual(evt.axis, "y", "[2] - Moved along y axis"); 
-        _.strictEqual(evt.oldValue, old_y, "[2] - old y value matches cached"); 
-      });
-    });
     e.one("MotionChange", function(evt) { 
       _.strictEqual(evt.key, "vx", "[2] - vx was changed"); 
       _.strictEqual(evt.oldValue, 0, "[2] - old vx was 0");
@@ -321,7 +304,6 @@
     _.strictEqual(newDirectionEvents, 3, "NewDirection fired 3 times.");
     _.strictEqual(newRotationDirectionEvents, 4, "NewRotationDirection fired 4 times.");
     _.strictEqual(motionEvents, 13, "MotionChange fired 13 times.");
-    _.strictEqual(movedEvents, 3, "Moved fired 3 times.");
     _.strictEqual(rotatedEvents, 3, "Rotated fired 3 times.");
     e.destroy();
   });