fix: sidechannel position update

packages/entity/src/traits/mobile.js

@@ -240,6 +240,7 @@ export default () => class Mobile extends decorate(Trait) {
 
   tick(elapsed) {
     if (this.entity.isMobile && !Vector.isZero(this.actionMovement)) {
+      this.entity.markSidechannelPositionUpdate();
       this.entity.requestMovement(this.actionMovement);
     }
     if (Vector.isZero(this.#appliedMovement)) {

packages/entity/src/traits/positioned.js

@@ -7,25 +7,23 @@ const decorate = compose(
   Vector.Mixin('trackedPosition', 'x', 'y', {
     track: true,
   }),
-  Vector.Mixin('serverPosition', 'serverX', 'serverY', {
-    track: true,
-  }),
+  Vector.Mixin('serverPosition', 'serverX', 'serverY'),
 );
 
 // < 16768 will pack into 1 short per axe and give +/- 0.25 precision.
 export default () => class Positioned extends decorate(Trait) {
 
+  #sidechannelUpdate = false;
+
   constructor() {
     super();
     this.on('trackedPositionChanged', this.onTrackedPositionChanged, this);
-    if ('client' === process.env.SIDE) {
-      this.on('serverPositionChanged', this.onServerPositionChanged, this);
-    }
   }
 
   acceptPacket(packet) {
     if ('TraitUpdatePositionedPosition' === packet.constructor.type) {
       [this.serverX, this.serverY] = packet.data;
+      this.serverPositionDirty = true;
     }
   }
 
@@ -76,14 +74,12 @@ export default () => class Positioned extends decorate(Trait) {
 
   cleanPackets() {
     super.cleanPackets();
+    this.#sidechannelUpdate = false;
   }
 
   destroy() {
     super.destroy();
     this.off('trackedPositionChanged', this.ontrackedPositionChanged);
-    if ('client' === process.env.SIDE) {
-      this.off('serverPositionChanged', this.onServerPositionChanged);
-    }
   }
 
   async load(json) {
@@ -108,13 +104,9 @@ export default () => class Positioned extends decorate(Trait) {
     this.entity.emit('positionChanged', oldPosition, newPosition);
   }
 
-  onServerPositionChanged() {
-    this.serverPositionDirty = true;
-  }
-
-  packetsFor() {
+  packetsFor(informed) {
     const {x, y} = this.stateDifferences();
-    if (x || y) {
+    if ((informed === this.entity && this.#sidechannelUpdate) || x || y) {
       return [[
         'TraitUpdatePositionedPosition',
         this.entity.position,
@@ -128,6 +120,11 @@ export default () => class Positioned extends decorate(Trait) {
 
       distanceFrom: (other) => Vector.distance(this.entity.position, other.position),
 
+      markSidechannelPositionUpdate: () => {
+        this.#sidechannelUpdate = true;
+        this.markAsDirty();
+      },
+
       pointAround: (radius, angle) => {
         if (!this.entity.is('Positioned')) {
           return [0, 0];