PredictedSyncData struct first step: same reads & writes

Assets/Mirror/Components/PredictedRigidbody/PredictedRigidbody.cs

@@ -755,11 +755,17 @@ public override void OnSerialize(NetworkWriter writer, bool initialState)
 
             // FAST VERSION: this shows in profiler a lot, so cache EVERYTHING!
             tf.GetPositionAndRotation(out Vector3 position, out Quaternion rotation);  // faster than tf.position + tf.rotation. server's rigidbody is on the same transform.
-            writer.WriteFloat(Time.deltaTime);
-            writer.WriteVector3(position);
-            writer.WriteQuaternion(rotation);
-            writer.WriteVector3(predictedRigidbody.velocity);
-            writer.WriteVector3(predictedRigidbody.angularVelocity);
+
+            // simple but slow write:
+            // writer.WriteFloat(Time.deltaTime);
+            // writer.WriteVector3(position);
+            // writer.WriteQuaternion(rotation);
+            // writer.WriteVector3(predictedRigidbody.velocity);
+            // writer.WriteVector3(predictedRigidbody.angularVelocity);
+
+            // performance optimization: write a whole struct at once via blittable:
+            PredictedSyncData data = new PredictedSyncData(Time.deltaTime, position, rotation, predictedRigidbody.velocity, predictedRigidbody.angularVelocity);
+            writer.WritePredictedSyncData(data);
         }
 
         // read the server's state, compare with client state & correct if necessary.
@@ -769,12 +775,20 @@ public override void OnDeserialize(NetworkReader reader, bool initialState)
             // we want to know the time on the server when this was sent, which is remoteTimestamp.
             double timestamp = NetworkClient.connection.remoteTimeStamp;
 
-            // parse state
-            double serverDeltaTime = reader.ReadFloat();
-            Vector3 position        = reader.ReadVector3();
-            Quaternion rotation     = reader.ReadQuaternion();
-            Vector3 velocity        = reader.ReadVector3();
-            Vector3 angularVelocity = reader.ReadVector3();
+            // simple but slow read:
+            // double serverDeltaTime = reader.ReadFloat();
+            // Vector3 position        = reader.ReadVector3();
+            // Quaternion rotation     = reader.ReadQuaternion();
+            // Vector3 velocity        = reader.ReadVector3();
+            // Vector3 angularVelocity = reader.ReadVector3();
+
+            // performance optimization: read a whole struct at once via blittable:
+            PredictedSyncData data = reader.ReadPredictedSyncData();
+            double serverDeltaTime = data.deltaTime;
+            Vector3 position = data.position;
+            Quaternion rotation = data.rotation;
+            Vector3 velocity = data.velocity;
+            Vector3 angularVelocity = data.angularVelocity;
 
             // server sends state at the end of the frame.
             // parse and apply the server's delta time to our timestamp.

Assets/Mirror/Components/PredictedRigidbody/PredictedSyncData.cs

@@ -0,0 +1,61 @@
+// this struct exists only for OnDe/Serialize performance.
+// instead of WriteVector3+Quaternion+Vector3+Vector3,
+// we read & write the whole struct as blittable once.
+//
+// struct packing can cause odd results with blittable on different platforms,
+// so this is usually not recommended!
+//
+// in this case however, we need to squeeze everything we can out of prediction
+// to support low even devices / VR.
+using System.Runtime.InteropServices;
+using UnityEngine;
+
+namespace Mirror
+{
+    // struct packing
+
+    [StructLayout(LayoutKind.Sequential)] // explicitly force sequential
+    public struct PredictedSyncData
+    {
+        public float deltaTime; // 4 bytes (word aligned)
+        public Vector3 position; // 12 bytes (word aligned)
+        public Quaternion rotation; // 16 bytes (word aligned)
+        public Vector3 velocity; // 12 bytes (word aligned)
+        public Vector3 angularVelocity; // 12 bytes (word aligned)
+
+        // constructor for convenience
+        public PredictedSyncData(float deltaTime, Vector3 position, Quaternion rotation, Vector3 velocity, Vector3 angularVelocity)
+        {
+            this.deltaTime = deltaTime;
+            this.position = position;
+            this.rotation = rotation;
+            this.velocity = velocity;
+            this.angularVelocity = angularVelocity;
+        }
+    }
+
+    // NetworkReader/Writer extensions to write this struct
+    public static class PredictedSyncDataReadWrite
+    {
+        public static void WritePredictedSyncData(this NetworkWriter writer, PredictedSyncData data)
+        {
+            writer.WriteFloat(data.deltaTime);
+            writer.WriteVector3(data.position);
+            writer.WriteQuaternion(data.rotation);
+            writer.WriteVector3(data.velocity);
+            writer.WriteVector3(data.angularVelocity);
+        }
+
+        public static PredictedSyncData ReadPredictedSyncData(this NetworkReader reader)
+        {
+            return new PredictedSyncData
+            {
+                deltaTime = reader.ReadFloat(),
+                position = reader.ReadVector3(),
+                rotation = reader.ReadQuaternion(),
+                velocity = reader.ReadVector3(),
+                angularVelocity = reader.ReadVector3()
+            };
+        }
+    }
+}

Assets/Mirror/Components/PredictedRigidbody/PredictedSyncData.cs.meta

@@ -0,0 +1,3 @@
+fileFormatVersion: 2
+guid: f595f112a39e4634b670d56991b23823
+timeCreated: 1710387026