wip

Assets/Mirror/Components/ForecastRigidbody/ForecastRigidbody.cs

@@ -10,6 +10,13 @@
 
 namespace Mirror
 {
+    enum ForecastState
+    {
+        PREDICT, // 100% client side physics prediction
+        BLEND,   // blending client prediction with server state
+        FOLLOW,  // 100% server sided physics, client only follows .transform
+    }
+
     [RequireComponent(typeof(Rigidbody))]
     public class ForecastRigidbody : NetworkBehaviour
     {
@@ -25,6 +32,7 @@ public class ForecastRigidbody : NetworkBehaviour
 
         [Header("Blending")]
         [Range(0.01f, 1)] public float blendPerSync = 0.1f;
+        ForecastState state = ForecastState.FOLLOW; // follow until the player interacts
 
         // motion smoothing happen on-demand, because it requires moving physics components to another GameObject.
         // this only starts at a given velocity and ends when stopped moving.
@@ -81,6 +89,10 @@ protected virtual void Awake()
             if (predictedRigidbody == null) throw new InvalidOperationException($"Prediction: {name} is missing a Rigidbody component.");
             predictedRigidbodyTransform = predictedRigidbody.transform;
 
+            // set Rigidbody as kinematic by default.
+            // it's only dynamic while predicting.
+            predictedRigidbody.isKinematic = true;
+
             // in fast mode, we need to force enable Rigidbody.interpolation.
             // otherwise there's not going to be any smoothing whatsoever.
             predictedRigidbody.interpolation = RigidbodyInterpolation.Interpolate;
@@ -91,6 +103,17 @@ protected virtual void Awake()
             positionCorrectionThresholdSqr = positionCorrectionThreshold * positionCorrectionThreshold;
         }
 
+        // client prediction API
+        public void AddPredictedForce(Vector3 force, ForceMode mode)
+        {
+            // explicitly start predicting physics
+            predictedRigidbody.isKinematic = false;
+            predictedRigidbody.AddForce(force, mode);
+            state = ForecastState.PREDICT;
+            OnBeginPrediction();
+            Debug.Log($"{name} PREDICTING");
+        }
+
         void UpdateServer()
         {
             // bandwidth optimization while idle.
@@ -127,37 +150,26 @@ protected virtual bool IsMoving() =>
         // when using Fast mode, we don't create any ghosts.
         // but we still want to check IsMoving() in order to support the same
         // user callbacks.
-        bool lastMoving = false;
+        void UpdateClient()
-        void UpdateState()
         {
-            // perf: enough to check ghosts every few frames.
+            if (state == ForecastState.PREDICT)
-            // PredictionBenchmark: only checking every 4th frame: 770 => 800 FPS
-            if (Time.frameCount % checkGhostsEveryNthFrame != 0) return;
-
-            bool moving = IsMoving();
-
-            // started moving?
-            if (moving && !lastMoving)
             {
-                OnBeginPrediction();
+
-                lastMoving = true;
             }
-            // stopped moving?
+            else if (state == ForecastState.BLEND)
-            else if (!moving && lastMoving)
             {
-                // ensure a minimum time since starting to move, to avoid on/off/on effects.
+
-                if (NetworkTime.time >= motionSmoothingLastMovedTime + motionSmoothingTimeTolerance)
+            }
-                {
+            else if (state == ForecastState.FOLLOW)
-                    OnEndPrediction();
+            {
-                    lastMoving = false;
+
-                }
             }
         }
 
         void Update()
         {
             if (isServer) UpdateServer();
-            if (isClientOnly) UpdateState();
+            if (isClientOnly) UpdateClient();
         }
 
         void FixedUpdate()
@@ -468,8 +480,8 @@ void OnReceivedState(double timestamp, RigidbodyState state)//, bool sleeping)
                 // blend the final correction towards current server state over time.
                 // this is the idea of ForecastRigidbody.
                 // TODO once we are at server state, let snapshot interpolation take over.
-                RigidbodyState blended = RigidbodyState.Interpolate(recomputed, state, blendPerSync);
+                // RigidbodyState blended = RigidbodyState.Interpolate(recomputed, state, blendPerSync);
-                Debug.DrawLine(recomputed.position, blended.position, Color.green, 10.0f);
+                // Debug.DrawLine(recomputed.position, blended.position, Color.green, 10.0f);
 
                 // log, draw & apply the final position.
                 // always do this here, not when iterating above, in case we aren't iterating.
@@ -477,7 +489,11 @@ void OnReceivedState(double timestamp, RigidbodyState state)//, bool sleeping)
                 // int correctedAmount = stateHistory.Count - afterIndex;
                 // Debug.Log($"Correcting {name}: {correctedAmount} / {stateHistory.Count} states to final position from: {rb.position} to: {last.position}");
                 //Debug.DrawLine(physicsCopyRigidbody.position, recomputed.position, Color.green, lineTime);
-                ApplyState(blended.timestamp, blended.position, blended.rotation, blended.velocity, blended.angularVelocity);
+                ApplyState(recomputed.timestamp, recomputed.position, recomputed.rotation, recomputed.velocity, recomputed.angularVelocity);
+
+                // insert the blended state into the history.
+                // this makes it permanent, instead of blending every time but rarely recording.
+                RecordState();
 
                 // user callback
                 OnCorrected();

Assets/Mirror/Examples/BilliardsPredicted/Ball/RedPredicted.prefab

@@ -165,6 +165,7 @@ MonoBehaviour:
   syncMode: 0
   syncInterval: 0
   predictedRigidbody: {fileID: -177125271246800426}
+  blendPerSync: 0.1
   motionSmoothingVelocityThreshold: 0.1
   motionSmoothingAngularVelocityThreshold: 5
   motionSmoothingTimeTolerance: 0.5
@@ -177,7 +178,5 @@ MonoBehaviour:
   oneFrameAhead: 1
   snapThreshold: 2
   checkGhostsEveryNthFrame: 4
-  positionInterpolationSpeed: 15
-  rotationInterpolationSpeed: 10
   teleportDistanceMultiplier: 10
   reduceSendsWhileIdle: 1

Assets/Mirror/Examples/BilliardsPredicted/Ball/WhitePredicted.prefab

@@ -302,6 +302,7 @@ MonoBehaviour:
   syncMode: 0
   syncInterval: 0
   predictedRigidbody: {fileID: 1848203816128897140}
+  blendPerSync: 0.1
   motionSmoothingVelocityThreshold: 0.1
   motionSmoothingAngularVelocityThreshold: 5
   motionSmoothingTimeTolerance: 0.5
@@ -314,7 +315,5 @@ MonoBehaviour:
   oneFrameAhead: 1
   snapThreshold: 2
   checkGhostsEveryNthFrame: 4
-  positionInterpolationSpeed: 15
-  rotationInterpolationSpeed: 10
   teleportDistanceMultiplier: 10
   reduceSendsWhileIdle: 1

Assets/Mirror/Examples/BilliardsPredicted/Player/PlayerPredicted.cs

@@ -36,7 +36,7 @@ void Awake()
 
         // apply force to white ball.
         // common function to ensure we apply it the same way on server & client!
-        void ApplyForceToWhite(Vector3 force)
+        void ClientApplyForceToWhite(Vector3 force)
         {
             // https://docs.unity3d.com/2021.3/Documentation/ScriptReference/Rigidbody.AddForce.html
             // this is buffered until the next FixedUpdate.
@@ -44,26 +44,25 @@ void ApplyForceToWhite(Vector3 force)
             // get the white ball's Rigidbody.
             // prediction sometimes moves this out of the object for a while,
             // so we need to grab it this way:
-            Rigidbody rb = whiteBall.GetComponent<ForecastRigidbody>().predictedRigidbody;
+            ForecastRigidbody forecast = whiteBall.GetComponent<ForecastRigidbody>();
 
             // AddForce has different force modes, see this excellent diagram:
             // https://www.reddit.com/r/Unity3D/comments/psukm1/know_the_difference_between_forcemodes_a_little/
             // for prediction it's extremely important(!) to apply the correct mode:
             //   'Force' makes server & client drift significantly here
             //   'Impulse' is correct usage with significantly less drift
-            rb.AddForce(force, ForceMode.Impulse);
+            forecast.AddPredictedForce(force, ForceMode.Impulse);
         }
 
         // called when the local player dragged the white ball.
         // we reuse the white ball's OnMouseDrag and forward the event to here.
         public void OnDraggedBall(Vector3 force)
         {
-            // apply force locally immediately
+            // apply force on client (not in host mode)
-            ApplyForceToWhite(force);
+            if (!isServer) ClientApplyForceToWhite(force);
 
             // apply on server as well.
-            // not necessary in host mode, otherwise we would apply it twice.
+            CmdApplyForce(force);
-            if (!isServer) CmdApplyForce(force);
         }
 
         // while prediction is applied on clients immediately,
@@ -85,7 +84,8 @@ void CmdApplyForce(Vector3 force)
             }
 
             // apply force
-            ApplyForceToWhite(force);
+            Rigidbody rb = whiteBall.GetComponent<Rigidbody>();
+            rb.AddForce(force, ForceMode.Impulse);
         }
     }
 }