lerp approach

src/client/game.ts

@@ -118,15 +118,19 @@ export class Game {
     });
 
     this.socket.on('playerupdate', (data) => {
-      const player = this.players.find((player) => player.user.id === data.id);
+      data.forEach((item) => {
+        const player = this.players.find(
+          (player) => player.user.id === item.id,
+        );
         if (
           player &&
           player instanceof PlayerEntity &&
           player.user.id !== this.me.id
         ) {
-        player.addUncommittedChanges(data);
+          player.addUncommittedChanges(item);
         }
       });
+    });
 
     this.socket.on('chat', (event) => {
       const player = this.players.find(

src/client/object/player-entity.ts

@@ -1,16 +1,29 @@
 import { IcyNetUser } from '../../common/types/user';
 import * as THREE from 'three';
 import { PonyEntity } from './pony';
-import { Packet } from '../../common/types/packet';
+import {
+  FullStatePacket,
+  PositionUpdatePacket,
+} from '../../common/types/packet';
 import { CanvasUtils } from './canvas-utils';
 import { ChatBubble } from './chat-bubble';
 
 const chatBuilder = new CanvasUtils();
 
 export class PlayerEntity extends PonyEntity {
-  private uncommittedPacket: Packet = {};
+  private _updateQueue: PositionUpdatePacket[] = [];
+  private _targetFrame: any = null;
+  private _lastFrame: any = null;
   private _chats: ChatBubble[] = [];
 
+  private _p1 = new THREE.Vector3();
+  private _p2 = new THREE.Vector3();
+  private _q1 = new THREE.Vector3();
+  private _q2 = new THREE.Vector3();
+
+  private _pf = new THREE.Vector3();
+  private _qf = new THREE.Vector3();
+
   constructor(public user: IcyNetUser) {
     super();
   }
@@ -84,18 +97,31 @@ export class PlayerEntity extends PonyEntity {
     );
   }
 
-  public addUncommittedChanges(packet: Packet) {
-    this.uncommittedPacket = { ...this.uncommittedPacket, ...packet };
+  public addUncommittedChanges(packet: PositionUpdatePacket) {
+    const appendix = { ...packet, time: 0.1 };
+    this._updateQueue.push(appendix);
+    if (!this._targetFrame) {
+      this.setFromPacket(packet);
+      this._targetFrame = appendix;
+    }
   }
 
   public update(dt: number) {
-    this.commitServerUpdate();
+    this.commitServerUpdate(dt);
     super.update(dt);
   }
 
-  private setFromPacket(packet: Packet) {
-    if (packet.velocity) {
-      this.setVelocity(new THREE.Vector3().fromArray(packet.velocity));
+  private setFromPacket(packet: FullStatePacket | PositionUpdatePacket) {
+    if ((packet as FullStatePacket).velocity) {
+      this.setVelocity(
+        new THREE.Vector3().fromArray((packet as FullStatePacket).velocity),
+      );
+    }
+
+    if ((packet as FullStatePacket).angular) {
+      this.setAngularVelocity(
+        new THREE.Vector3().fromArray((packet as FullStatePacket).angular),
+      );
     }
 
     if (packet.position) {
@@ -106,17 +132,47 @@ export class PlayerEntity extends PonyEntity {
       this.setRotation(new THREE.Euler().fromArray(packet.rotation));
     }
 
-    if (packet.angular) {
-      this.setAngularVelocity(new THREE.Vector3().fromArray(packet.angular));
-    }
-
     if (packet.animState) {
       this.setWalkAnimationState(packet.animState);
     }
   }
 
-  private commitServerUpdate() {
-    this.setFromPacket(this.uncommittedPacket);
-    this.uncommittedPacket = {};
+  private commitServerUpdate(dt: number) {
+    if (this._updateQueue.length == 0) {
+      return;
+    }
+
+    for (let i = 0; i < this._updateQueue.length; ++i) {
+      this._updateQueue[i].time -= dt;
+    }
+
+    while (this._updateQueue.length > 0 && this._updateQueue[0].time <= 0.0) {
+      this._lastFrame = {
+        animState: this._targetFrame.animState,
+        position: this.container.position.toArray(),
+        rotation: this.container.rotation.toArray(),
+      };
+      this._targetFrame = this._updateQueue.shift();
+      this._targetFrame.time = 0.0;
+    }
+
+    // Lerp the position and rotation
+    if (this._targetFrame && this._lastFrame) {
+      this._targetFrame.time += dt;
+      this._p1.fromArray(this._lastFrame.position);
+      this._p2.fromArray(this._targetFrame.position);
+      this._q1.fromArray(this._lastFrame.rotation);
+      this._q2.fromArray(this._targetFrame.rotation);
+      this._pf.copy(this._p1);
+      this._qf.copy(this._q1);
+
+      const t = Math.max(Math.min(this._targetFrame.time / 0.1, 1.0), 0.0);
+      this._pf.lerp(this._p2, t);
+      this._qf.lerp(this._q2, t);
+
+      this.setPosition(this._pf);
+      this.setRotation(this._qf);
+      this.setWalkAnimationState(this._lastFrame.animState);
+    }
   }
 }

src/client/object/player.ts

@@ -92,20 +92,24 @@ export class Player extends PonyEntity {
     } else if (this._wasTurning && !wasExternalForce) {
       this._wasTurning = false;
       this.angularVelocity.set(0, 0, 0);
-      this.changes.rotation = this.container.rotation.toArray();
       this.changes.angular = this.angularVelocity.toArray();
     }
 
+    this.changes.rotation = this.container.rotation.toArray();
+
     if (vector.y !== 0) {
       this.velocity.copy(this._lookVector.clone().multiplyScalar(vector.y));
       this.changes.velocity = this.velocity.toArray();
       this._wasMoving = true;
+      this.setWalkAnimationState(1);
     } else if (this._wasMoving && !wasExternalForce) {
       this._wasMoving = false;
       this.velocity.set(0, 0, 0);
-      this.changes.position = this.container.position.toArray();
       this.changes.velocity = this.velocity.toArray();
+      this.setWalkAnimationState(0);
     }
+
+    this.changes.position = this.container.position.toArray();
   }
 
   update(dt: number): void {

src/client/object/pony.ts

@@ -1,7 +1,7 @@
 import * as SkeletonUtils from 'three/examples/jsm/utils/SkeletonUtils';
 import * as THREE from 'three';
 import modelLoaderInstance from './pony-loader';
-import { Packet } from '../../common/types/packet';
+import { FullStatePacket } from '../../common/types/packet';
 import { NameTag } from './nametag';
 import { CanvasUtils } from './canvas-utils';
 
@@ -17,7 +17,7 @@ export class PonyEntity {
   public idleAction: THREE.AnimationAction;
   public walkAction: THREE.AnimationAction;
   public nameTag?: NameTag;
-  public changes: Packet = {};
+  public changes: FullStatePacket = {};
 
   initialize() {
     this.model = (SkeletonUtils as any).clone(modelLoaderInstance.ponyModel);
@@ -39,12 +39,6 @@ export class PonyEntity {
       ).add(this.angularVelocity.clone().multiplyScalar(dt)),
     );
     this.mixer.update(dt);
-
-    if (this.velocity.length() > 0) {
-      this.setWalkAnimationState(1);
-    } else {
-      this.setWalkAnimationState(0);
-    }
   }
 
   public addNameTag(name: string) {

src/common/types/packet.ts

@@ -1,6 +1,14 @@
 import { IcyNetUser } from './user';
 
-export interface Packet {
+export interface PositionUpdatePacket {
+  id?: number;
+  position?: number[];
+  rotation?: (number | string)[];
+  animState?: number;
+  time?: number;
+}
+
+export interface FullStatePacket {
   velocity?: number[];
   angular?: number[];
   position?: number[];
@@ -8,4 +16,4 @@ export interface Packet {
   animState?: number;
 }
 
-export interface CompositePacket extends IcyNetUser, Packet {}
+export interface CompositePacket extends IcyNetUser, FullStatePacket {}

src/server/object/game.ts

@@ -1,7 +1,10 @@
 import { Server, Socket } from 'socket.io';
-import { config } from '../config';
 import { RequestHandler } from 'express';
 import { IcyNetUser } from '../../common/types/user';
+import {
+  CompositePacket,
+  PositionUpdatePacket,
+} from '../../common/types/packet';
 
 const PLACEHOLDER_USER = (socket: Socket): IcyNetUser => {
   const randomName = `player-${socket.id.substring(0, 8)}`;
@@ -16,6 +19,7 @@ const PLACEHOLDER_USER = (socket: Socket): IcyNetUser => {
 
 export class Game {
   private _connections: Socket[] = [];
+  private _changedPlayers: number[] = [];
 
   constructor(private io: Server, private session: RequestHandler) {}
 
@@ -50,9 +54,9 @@ export class Game {
         socket.data.user = user;
         socket.data.playerinfo = {
           velocity: [0, 0, 0],
-          angular: [0, 0, 0],
+          angular: [0, 0, 0, 'XYZ'],
           position: [0, 0, 0],
-          rotation: [0, 0, 0],
+          rotation: [0, 0, 0, 'XYZ'],
           animState: 0,
         };
 
@@ -71,10 +75,10 @@ export class Game {
             ...socket.data.playerinfo,
             ...packet,
           };
-          socket.broadcast.emit('playerupdate', {
-            id: user.id,
-            ...packet,
-          });
+
+          if (!this._changedPlayers.includes(socket.data.user.id)) {
+            this._changedPlayers.push(socket.data.user.id);
+          }
         });
 
         socket.on('chat-send', (raw) => {
@@ -91,5 +95,24 @@ export class Game {
         }
       });
     });
+
+    setInterval(() => {
+      const playerInfo: PositionUpdatePacket[] = [];
+      this._connections
+        .filter(
+          (conn) =>
+            conn.data.user && this._changedPlayers.includes(conn.data.user.id),
+        )
+        .forEach((conn) =>
+          playerInfo.push({
+            position: conn.data.playerinfo.position,
+            rotation: conn.data.playerinfo.rotation,
+            animState: conn.data.playerinfo.animState,
+            id: conn.data.user.id,
+          }),
+        );
+      this.io.emit('playerupdate', playerInfo);
+      this._changedPlayers.length = 0;
+    }, 100);
   }
 }