From f3cb8f973f373c802790e150751bbd21be144f92 Mon Sep 17 00:00:00 2001
From: vis2k <info@noobtuts.com>
Date: Mon, 3 Oct 2022 10:37:34 +0200
Subject: [PATCH] wip

---
 Assets/Mirror/Core/NetworkClient.cs           |  8 +++
 .../Core/NetworkClient_TimeInterpolation.cs   | 68 +++++++++++++++++++
 Assets/Mirror/Core/NetworkServer.cs           |  1 +
 3 files changed, 77 insertions(+)

diff --git a/Assets/Mirror/Core/NetworkClient.cs b/Assets/Mirror/Core/NetworkClient.cs
index 1c7b398bb..17ffc9cd0 100644
--- a/Assets/Mirror/Core/NetworkClient.cs
+++ b/Assets/Mirror/Core/NetworkClient.cs
@@ -93,6 +93,9 @@ public struct NetworkClientConfig
         // call this from Unity's OnValidate
         public void OnValidate()
         {
+            // snapshot interpolation thresholds need to be <0 and >0
+            catchupNegativeThreshold = Math.Min(catchupNegativeThreshold, 0);
+            catchupPositiveThreshold = Math.Max(catchupPositiveThreshold, 0);
         }
     }
 
@@ -245,6 +248,7 @@ public static void Connect(string address)
             // Debug.Log($"Client Connect: {address}");
             Debug.Assert(Transport.active != null, "There was no active transport when calling NetworkClient.Connect, If you are calling Connect manually then make sure to set 'Transport.active' first");
 
+            InitTimeInterpolation();
             RegisterSystemHandlers(false);
             Transport.active.enabled = true;
             AddTransportHandlers();
@@ -261,6 +265,7 @@ public static void Connect(Uri uri)
             // Debug.Log($"Client Connect: {uri}");
             Debug.Assert(Transport.active != null, "There was no active transport when calling NetworkClient.Connect, If you are calling Connect manually then make sure to set 'Transport.active' first");
 
+            InitTimeInterpolation();
             RegisterSystemHandlers(false);
             Transport.active.enabled = true;
             AddTransportHandlers();
@@ -1485,6 +1490,9 @@ internal static void NetworkEarlyUpdate()
             // process all incoming messages first before updating the world
             if (Transport.active != null)
                 Transport.active.ClientEarlyUpdate();
+
+            // time snapshot interpolation
+            UpdateTimeInterpolation();
         }
 
         // NetworkLateUpdate called after any Update/FixedUpdate/LateUpdate
diff --git a/Assets/Mirror/Core/NetworkClient_TimeInterpolation.cs b/Assets/Mirror/Core/NetworkClient_TimeInterpolation.cs
index 29505cd0f..e70809a5f 100644
--- a/Assets/Mirror/Core/NetworkClient_TimeInterpolation.cs
+++ b/Assets/Mirror/Core/NetworkClient_TimeInterpolation.cs
@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using UnityEngine;
 
 namespace Mirror
 {
@@ -45,5 +46,72 @@ public static partial class NetworkClient
 
         // average delivery time (standard deviation gives average jitter)
         static ExponentialMovingAverage deliveryTimeEma;
+
+        // OnValidate: see NetworkClient.cs
+        // add snapshot & initialize client interpolation time if needed
+
+        // initialization called from Awake
+        static void InitTimeInterpolation()
+        {
+            // initialize EMA with 'emaDuration' seconds worth of history.
+            // 1 second holds 'sendRate' worth of values.
+            // multiplied by emaDuration gives n-seconds.
+            driftEma        = new ExponentialMovingAverage(NetworkServer.config.sendRate * config.driftEmaDuration);
+            deliveryTimeEma = new ExponentialMovingAverage(NetworkServer.config.sendRate * config.deliveryTimeEmaDuration);
+        }
+
+        // see comments at the top of this file
+        public static void OnTimeSnapshot(TimeSnapshot snap)
+        {
+            // set local timestamp (= when it was received on our end)
+            snap.localTime = Time.timeAsDouble;
+
+            // (optional) dynamic adjustment
+            if (config.dynamicAdjustment)
+            {
+                // set bufferTime on the fly.
+                // shows in inspector for easier debugging :)
+                config.bufferTimeMultiplier = SnapshotInterpolation.DynamicAdjustment(
+                    NetworkServer.config.sendInterval,
+                    deliveryTimeEma.StandardDeviation,
+                    config.dynamicAdjustmentTolerance
+                );
+            }
+
+            // insert into the buffer & initialize / adjust / catchup
+            SnapshotInterpolation.InsertAndAdjust(
+                snapshots,
+                snap,
+                ref localTimeline,
+                ref localTimescale,
+                NetworkServer.config.sendInterval,
+                config.bufferTime,
+                config.catchupSpeed,
+                config.slowdownSpeed,
+                ref driftEma,
+                config.catchupNegativeThreshold,
+                config.catchupPositiveThreshold,
+                ref deliveryTimeEma);
+
+            // Debug.Log($"inserted TimeSnapshot remote={snap.remoteTime:F2} local={snap.localTime:F2} total={snapshots.Count}");
+        }
+
+        // call this from early update, so the timeline is safe to use in update
+        static void UpdateTimeInterpolation()
+        {
+            // only while we have snapshots.
+            // timeline starts when the first snapshot arrives.
+            if (snapshots.Count > 0)
+            {
+                // progress local timeline.
+                SnapshotInterpolation.StepTime(Time.unscaledDeltaTime, ref localTimeline, localTimescale);
+
+                // progress local interpolation.
+                // TimeSnapshot doesn't interpolate anything.
+                // this is merely to keep removing older snapshots.
+                SnapshotInterpolation.StepInterpolation(snapshots, localTimeline, out _, out _, out double t);
+                // Debug.Log($"NetworkClient SnapshotInterpolation @ {localTimeline:F2} t={t:F2}");
+            }
+        }
     }
 }
diff --git a/Assets/Mirror/Core/NetworkServer.cs b/Assets/Mirror/Core/NetworkServer.cs
index 557b402aa..0a30df17b 100644
--- a/Assets/Mirror/Core/NetworkServer.cs
+++ b/Assets/Mirror/Core/NetworkServer.cs
@@ -24,6 +24,7 @@ public struct NetworkServerConfig
             tickRate < int.MaxValue ? 1f / tickRate : 0; // for 30 Hz, that's 33ms
 
         // Mirror currently sends every tick
+        public int sendRate       => tickRate;
         public float sendInterval => tickInterval;
 
         // default settings in one place. used by both NetworkServer & Manager.