feat: implement tick-based synchronized NetworkVar

com.unity.multiplayer.mlapi/Runtime/Core/NetworkedBehaviour.cs

@@ -366,6 +366,11 @@ public bool HasNetworkedObject
         internal bool networkedStartInvoked = false;
         internal bool internalNetworkedStartInvoked = false;
         /// <summary>
+        /// Stores the network tick at the NetworkedBehaviourUpdate time
+        /// This allows sending NetworkedVars not more often than once per network tick, regardless of the update rate
+        /// </summary>
+        public static ushort currentTick { get; private set; }
+        /// <summary>
         /// Gets called when message handlers are ready to be registered and the networking is setup
         /// </summary>
         public virtual void NetworkStart()
@@ -521,6 +526,14 @@ internal void InitializeVars()
 
         internal static void NetworkedBehaviourUpdate()
         {
+            // Don't NetworkedBehaviourUpdate more than once per network tick
+            ushort tick = NetworkingManager.Singleton.networkTickSystem.GetTick();
+            if (tick == currentTick)
+            {
+                return;
+            }
+            currentTick = tick;
+
 #if DEVELOPMENT_BUILD || UNITY_EDITOR
             s_NetworkedBehaviourUpdate.Begin();
 #endif
@@ -574,7 +587,6 @@ internal static void NetworkedBehaviourUpdate()
                         }
                     }
                 }
-
             }
             finally
             {
@@ -615,8 +627,8 @@ internal void VarUpdate(ulong clientId)
 
         private void NetworkedVarUpdate(ulong clientId)
         {
-           if (!CouldHaveDirtyNetworkedVars())
-               return;
+            if (!CouldHaveDirtyNetworkedVars())
+                return;
 
             for (int j = 0; j < channelMappedNetworkedVarIndexes.Count; j++)
             {
@@ -627,6 +639,10 @@ private void NetworkedVarUpdate(ulong clientId)
                         writer.WriteUInt64Packed(NetworkId);
                         writer.WriteUInt16Packed(NetworkedObject.GetOrderIndex(this));
 
+                        // Write the current tick frame
+                        // todo: this is currently done per channel, per tick. The snapshot system might improve on this
+                        writer.WriteUInt16Packed(currentTick);
+
                         bool writtenAny = false;
                         for (int k = 0; k < networkedVarFields.Count; k++)
                         {
@@ -716,6 +732,9 @@ internal static void HandleNetworkedVarDeltas(List<INetworkedVar> networkedVarLi
         {
             using (PooledBitReader reader = PooledBitReader.Get(stream))
             {
+                // read the remote network tick at which this variable was written.
+                ushort remoteTick = reader.ReadUInt16Packed();
+
                 for (int i = 0; i < networkedVarList.Count; i++)
                 {
                     ushort varSize = 0;
@@ -766,9 +785,13 @@ internal static void HandleNetworkedVarDeltas(List<INetworkedVar> networkedVarLi
                         }
                     }
 
+                    // read the local network tick at which this variable was written.
+                    // if this var was updated from our machine, this local tick will be locally valid
+                    ushort localTick = reader.ReadUInt16Packed();
+
                     long readStartPos = stream.Position;
 
-                    networkedVarList[i].ReadDelta(stream, IsServer);
+                    networkedVarList[i].ReadDelta(stream, IsServer, localTick, remoteTick);
                     ProfilerStatManager.networkVarsRcvd.Record();
 
                     if (NetworkingManager.Singleton.NetworkConfig.EnsureNetworkedVarLengthSafety)
@@ -835,7 +858,7 @@ internal static void HandleNetworkedVarUpdate(List<INetworkedVar> networkedVarLi
 
                     long readStartPos = stream.Position;
 
-                    networkedVarList[i].ReadField(stream);
+                    networkedVarList[i].ReadField(stream, NetworkTickSystem.k_NoTick, NetworkTickSystem.k_NoTick);
                     ProfilerStatManager.networkVarsRcvd.Record();
 
                     if (NetworkingManager.Singleton.NetworkConfig.EnsureNetworkedVarLengthSafety)
@@ -932,7 +955,7 @@ internal static void SetNetworkedVarData(List<INetworkedVar> networkedVarList, S
 
                     long readStartPos = stream.Position;
 
-                    networkedVarList[j].ReadField(stream);
+                    networkedVarList[j].ReadField(stream, NetworkTickSystem.k_NoTick, NetworkTickSystem.k_NoTick);
 
                     if (NetworkingManager.Singleton.NetworkConfig.EnsureNetworkedVarLengthSafety)
                     {

com.unity.multiplayer.mlapi/Runtime/NetworkedVar/Collections/NetworkedDictionary.cs

@@ -91,7 +91,7 @@ public Channel GetChannel()
         }
 
         /// <inheritdoc />
-        public void ReadDelta(Stream stream, bool keepDirtyDelta)
+        public void ReadDelta(Stream stream, bool keepDirtyDelta, ushort localTick, ushort remoteTick)
         {
             using (PooledBitReader reader = PooledBitReader.Get(stream))
             {
@@ -239,7 +239,7 @@ public void ReadDelta(Stream stream, bool keepDirtyDelta)
         }
 
         /// <inheritdoc />
-        public void ReadField(Stream stream)
+        public void ReadField(Stream stream, ushort localTick, ushort remoteTick)
         {
             using (PooledBitReader reader = PooledBitReader.Get(stream))
             {

com.unity.multiplayer.mlapi/Runtime/NetworkedVar/Collections/NetworkedList.cs

@@ -203,7 +203,7 @@ public void WriteField(Stream stream)
         }
 
         /// <inheritdoc />
-        public void ReadField(Stream stream)
+        public void ReadField(Stream stream, ushort localTick, ushort remoteTick)
         {
             using (PooledBitReader reader = PooledBitReader.Get(stream))
             {
@@ -217,7 +217,7 @@ public void ReadField(Stream stream)
         }
 
         /// <inheritdoc />
-        public void ReadDelta(Stream stream, bool keepDirtyDelta)
+        public void ReadDelta(Stream stream, bool keepDirtyDelta, ushort localTick, ushort remoteTick)
         {
             using (PooledBitReader reader = PooledBitReader.Get(stream))
             {

com.unity.multiplayer.mlapi/Runtime/NetworkedVar/Collections/NetworkedSet.cs

@@ -188,7 +188,7 @@ public void WriteField(Stream stream)
         }
 
         /// <inheritdoc />
-        public void ReadField(Stream stream)
+        public void ReadField(Stream stream, ushort localTick, ushort remoteTick)
         {
             using (PooledBitReader reader = PooledBitReader.Get(stream))
             {
@@ -203,7 +203,7 @@ public void ReadField(Stream stream)
         }
 
         /// <inheritdoc />
-        public void ReadDelta(Stream stream, bool keepDirtyDelta)
+        public void ReadDelta(Stream stream, bool keepDirtyDelta, ushort localTick, ushort remoteTick)
         {
             using (PooledBitReader reader = PooledBitReader.Get(stream))
             {

com.unity.multiplayer.mlapi/Runtime/NetworkedVar/INetworkedVar.cs

@@ -48,13 +48,17 @@ public interface INetworkedVar
         /// Reads the complete state from the reader and applies it
         /// </summary>
         /// <param name="stream">The stream to read the state from</param>
-        void ReadField(Stream stream);
+        /// <param name="localTick">The local network tick at which this var was written, on the machine it was written </param>
+        /// <param name="remoteTick">The remote network tick at which this var was sent by the host </param>
+        void ReadField(Stream stream, ushort localTick, ushort remoteTick);
         /// <summary>
         /// Reads delta from the reader and applies them to the internal value
         /// </summary>
         /// <param name="stream">The stream to read the delta from</param>
         /// <param name="keepDirtyDelta">Whether or not the delta should be kept as dirty or consumed</param>
-        void ReadDelta(Stream stream, bool keepDirtyDelta);
+        /// <param name="localTick">The local network tick at which this var was written, on the machine it was written </param>
+        /// <param name="remoteTick">The remote network tick at which this var was sent by the host </param>
+        void ReadDelta(Stream stream, bool keepDirtyDelta, ushort localTick, ushort remoteTick);
         /// <summary>
         /// Sets NetworkedBehaviour the container belongs to.
         /// </summary>

com.unity.multiplayer.mlapi/Runtime/NetworkedVar/NetworkedVar.cs

@@ -2,6 +2,7 @@
 using UnityEngine;
 using System.IO;
 using System;
+using MLAPI.Logging;
 using MLAPI.Serialization.Pooled;
 using MLAPI.Transports;
 
@@ -22,9 +23,13 @@ public class NetworkedVar<T> : INetworkedVar
         /// </summary>
         public readonly NetworkedVarSettings Settings = new NetworkedVarSettings();
         /// <summary>
-        /// Gets the last time the variable was synced
+        /// The last time the variable was written to locally
         /// </summary>
-        public float LastSyncedTime { get; internal set; }
+        public ushort LocalTick { get; internal set; }
+        /// <summary>
+        /// The last time the variable was written to remotely. Uses the remote timescale
+        /// </summary>
+        public ushort RemoteTick { get; internal set; }
         /// <summary>
         /// Delegate type for value changed event
         /// </summary>
@@ -89,6 +94,10 @@ public T Value
             {
                 if (!EqualityComparer<T>.Default.Equals(InternalValue, value))
                 {
+                    // Setter is assumed to be called locally, by game code.
+                    // When used by the host, it is its responsibility to set the RemoteTick
+                    RemoteTick = NetworkTickSystem.k_NoTick;
+
                     isDirty = true;
                     T previousValue = InternalValue;
                     InternalValue = value;
@@ -102,17 +111,12 @@ public T Value
         public void ResetDirty()
         {
             isDirty = false;
-            LastSyncedTime = NetworkingManager.Singleton.NetworkTime;
         }
 
         /// <inheritdoc />
         public bool IsDirty()
         {
-            if (!isDirty) return false;
-            if (Settings.SendTickrate == 0) return true;
-            if (Settings.SendTickrate < 0) return false;
-            if (NetworkingManager.Singleton.NetworkTime - LastSyncedTime >= (1f / Settings.SendTickrate)) return true;
-            return false;
+            return isDirty;
         }
 
         /// <inheritdoc />
@@ -139,7 +143,18 @@ public bool CanClientRead(ulong clientId)
         /// Writes the variable to the writer
         /// </summary>
         /// <param name="stream">The stream to write the value to</param>
-        public void WriteDelta(Stream stream) => WriteField(stream); //The NetworkedVar is built for simple data types and has no delta.
+        public void WriteDelta(Stream stream)
+        {
+            using (PooledBitWriter writer = PooledBitWriter.Get(stream))
+            {
+                // write the network tick at which this NetworkedVar was modified remotely
+                // this will allow lag-compensation
+                // todo: this is currently only done on delta updates. Consider whether it should be done in WriteField
+                writer.WriteUInt16Packed(RemoteTick);
+            }
+
+            WriteField(stream);
+        }
 
         /// <inheritdoc />
         public bool CanClientWrite(ulong clientId)
@@ -167,8 +182,13 @@ public bool CanClientWrite(ulong clientId)
         /// </summary>
         /// <param name="stream">The stream to read the value from</param>
         /// <param name="keepDirtyDelta">Whether or not the container should keep the dirty delta, or mark the delta as consumed</param>
-        public void ReadDelta(Stream stream, bool keepDirtyDelta)
+        public void ReadDelta(Stream stream, bool keepDirtyDelta, ushort localTick, ushort remoteTick)
         {
+            // todo: This allows the host-returned value to be set back to an old value
+            // this will need to be adjusted to check if we're have a most recent value
+            LocalTick = localTick;
+            RemoteTick = remoteTick;
+
             using (PooledBitReader reader = PooledBitReader.Get(stream))
             {
                 T previousValue = InternalValue;
@@ -188,14 +208,16 @@ public void SetNetworkedBehaviour(NetworkedBehaviour behaviour)
         }
 
         /// <inheritdoc />
-        public void ReadField(Stream stream)
+        public void ReadField(Stream stream, ushort localTick, ushort remoteTick)
         {
-            ReadDelta(stream, false);
+            ReadDelta(stream, false, localTick, remoteTick);
         }
 
         /// <inheritdoc />
         public void WriteField(Stream stream)
         {
+            // Store the local tick at which this NetworkedVar was modified
+            LocalTick = NetworkedBehaviour.currentTick;
             using (PooledBitWriter writer = PooledBitWriter.Get(stream))
             {
                 writer.WriteObjectPacked(InternalValue); //BOX

testproject/Assets/Prefabs/Cube.prefab

@@ -20,6 +20,7 @@ GameObject:
   - component: {fileID: -745482209883575862}
   - component: {fileID: -7468455824255952951}
   - component: {fileID: -4978466230159947418}
+  - component: {fileID: 2690316626396496521}
   m_Layer: 0
   m_Name: Cube
   m_TagString: Target
@@ -170,7 +171,7 @@ MonoBehaviour:
   m_Script: {fileID: 11500000, guid: 3e34656ebae784afca7d1f7f6dc18580, type: 3}
   m_Name: 
   m_EditorClassIdentifier: 
-  range: 10
+  m_Range: 10
 --- !u!120 &-745482209883575862
 LineRenderer:
   m_ObjectHideFlags: 0
@@ -328,3 +329,15 @@ MonoBehaviour:
   m_Script: {fileID: 11500000, guid: 9548116c10df1486ea12b7329b77c5cf, type: 3}
   m_Name: 
   m_EditorClassIdentifier: 
+--- !u!114 &2690316626396496521
+MonoBehaviour:
+  m_ObjectHideFlags: 0
+  m_CorrespondingSourceObject: {fileID: 0}
+  m_PrefabInstance: {fileID: 0}
+  m_PrefabAsset: {fileID: 0}
+  m_GameObject: {fileID: 8685790303553767886}
+  m_Enabled: 1
+  m_EditorHideFlags: 0
+  m_Script: {fileID: 11500000, guid: 962d0654df408407d8055453c9020f2b, type: 3}
+  m_Name: 
+  m_EditorClassIdentifier: 

testproject/Assets/Scripts/SyncTransform.cs

@@ -1,4 +1,3 @@
-using MLAPI.Logging;
 using MLAPI.NetworkedVar;
 using UnityEngine;
 
@@ -50,7 +49,6 @@ void SyncPosChanged(Vector3 before, Vector3 after)
                 {
                     gameObject.transform.position = after;
                 }
-                //Debug.Log("[1] received position from " + before + " to " + after);
             }
         }
 
@@ -68,7 +66,6 @@ void SyncRotChanged(Quaternion before, Quaternion after)
                 {
                     gameObject.transform.rotation = after;
                 }
-                //Debug.Log("[2] received rotation from " + before + " to " + after);
             }
         }
 
@@ -118,10 +115,6 @@ void FixedUpdate()
                     {
                         gameObject.transform.position = m_PosStore[1];
                     }
-
-                    var after = gameObject.transform.position;
-
-                    //Debug.Log("[3] Updated position from " + before + " to " + after);
                 }
 
                 if (m_RotTimes[0] >= 0.0 && m_RotTimes[1] >= 0.0)
@@ -142,10 +135,6 @@ void FixedUpdate()
                     {
                         gameObject.transform.rotation = m_RotStore[1];
                     }
-
-                    var after = gameObject.transform.rotation;
-
-                    //Debug.Log("[4] Updated rotation from " + before + " to " + after);
                 }
             }
         }