feat: network physics (#1175)

* feat: NetworkRigidbody and sample scene

* feat: NetworkRigidbody2D component to support 2d physics

* test: add network rigidbody tests

Author: LukeStampfli

com.unity.netcode.gameobjects/Components/NetworkRigidbody.cs

@@ -0,0 +1,72 @@
+using UnityEngine;
+
+namespace Unity.Netcode.Components
+{
+    /// <summary>
+    /// NetworkRigidbody allows for the use of <see cref="Rigidbody"/> on network objects. By controlling the kinematic
+    /// mode of the rigidbody and disabling it on all peers but the authoritative one.
+    /// </summary>
+    [RequireComponent(typeof(Rigidbody))]
+    [RequireComponent(typeof(NetworkTransform))]
+    public class NetworkRigidbody : NetworkBehaviour
+    {
+        private Rigidbody m_Rigidbody;
+
+        private bool m_OriginalKinematic;
+
+        // Used to cache the authority state of this rigidbody during the last frame
+        private bool m_IsAuthority;
+
+        /// <summary>
+        /// Gets a bool value indicating whether this <see cref="NetworkRigidbody"/> on this peer currently holds authority.
+        /// </summary>
+        internal bool HasAuthority => NetworkManager.IsServer; // TODO update this once we support owner authoritative NetworkTransform.
+
+        private void Awake()
+        {
+            m_Rigidbody = GetComponent<Rigidbody>();
+        }
+
+        // Currently commented out because it is not needed as authority currently can't change at runtime.
+        // private void FixedUpdate()
+        // {
+        //     if (NetworkManager.IsListening)
+        //     {
+        //         if (HasAuthority != m_IsAuthority)
+        //         {
+        //             m_IsAuthority = HasAuthority;
+        //             UpdateRigidbodyKinematicMode();
+        //         }
+        //     }
+        // }
+
+        // Puts the rigidbody in a kinematic non-interpolated mode on everyone but the server.
+        private void UpdateRigidbodyKinematicMode()
+        {
+            if (m_IsAuthority == false)
+            {
+                m_OriginalKinematic = m_Rigidbody.isKinematic;
+                m_Rigidbody.isKinematic = true;
+            }
+            else
+            {
+                // Resets the rigidbody back to it's non replication only state. Happens on shutdown and when authority is lost
+                m_Rigidbody.isKinematic = m_OriginalKinematic;
+            }
+        }
+
+        /// <inheritdoc />
+        public override void OnNetworkSpawn()
+        {
+            m_IsAuthority = HasAuthority;
+            m_OriginalKinematic = m_Rigidbody.isKinematic;
+            UpdateRigidbodyKinematicMode();
+        }
+
+        /// <inheritdoc />
+        public override void OnNetworkDespawn()
+        {
+            UpdateRigidbodyKinematicMode();
+        }
+    }
+}

com.unity.netcode.gameobjects/Components/NetworkRigidbody.cs.meta

@@ -0,0 +1,73 @@
+using UnityEngine;
+
+namespace Unity.Netcode.Components
+{
+    /// <summary>
+    /// NetworkRigidbody allows for the use of <see cref="Rigidbody2D"/> on network objects. By controlling the kinematic
+    /// mode of the rigidbody and disabling it on all peers but the authoritative one.
+    /// </summary>
+    [RequireComponent(typeof(Rigidbody2D))]
+    [RequireComponent(typeof(NetworkTransform))]
+    public class NetworkRigidbody2D : NetworkBehaviour
+    {
+        private Rigidbody2D m_Rigidbody;
+
+        private bool m_OriginalKinematic;
+
+        // Used to cache the authority state of this rigidbody during the last frame
+        private bool m_IsAuthority;
+
+        /// <summary>
+        /// Gets a bool value indicating whether this <see cref="NetworkRigidbody2D"/> on this peer currently holds authority.
+        /// </summary>
+        internal bool HasAuthority => NetworkManager.IsServer; // TODO update this once we support owner authoritative NetworkTransform.
+
+        private void Awake()
+        {
+            m_Rigidbody = GetComponent<Rigidbody2D>();
+        }
+
+        // Currently commented out because it is not needed as authority currently can't change at runtime.
+        // private void FixedUpdate()
+        // {
+        //     if (NetworkManager.IsListening)
+        //     {
+        //         if (HasAuthority != m_IsAuthority)
+        //         {
+        //             m_IsAuthority = HasAuthority;
+        //             UpdateRigidbodyKinematicMode();
+        //         }
+        //     }
+        // }
+
+        // Puts the rigidbody in a kinematic non-interpolated mode on everyone but the server.
+        private void UpdateRigidbodyKinematicMode()
+        {
+            if (m_IsAuthority == false)
+            {
+                m_OriginalKinematic = m_Rigidbody.isKinematic;
+                m_Rigidbody.isKinematic = true;
+            }
+            else
+            {
+                // Resets the rigidbody back to it's non replication only state. Happens on shutdown and when authority is lost
+                m_Rigidbody.isKinematic = m_OriginalKinematic;
+            }
+        }
+
+        /// <inheritdoc />
+        public override void OnNetworkSpawn()
+        {
+            m_IsAuthority = HasAuthority;
+            m_OriginalKinematic = m_Rigidbody.isKinematic;
+            UpdateRigidbodyKinematicMode();
+        }
+
+        /// <inheritdoc />
+        public override void OnNetworkDespawn()
+        {
+            m_IsAuthority = false;
+            UpdateRigidbodyKinematicMode();
+        }
+    }
+}

com.unity.netcode.gameobjects/Components/NetworkRigidbody2D.cs

@@ -0,0 +1,77 @@
+using System.Collections;
+using NUnit.Framework;
+using Unity.Netcode.Components;
+using UnityEngine;
+using UnityEngine.TestTools;
+
+namespace Unity.Netcode.RuntimeTests.Physics
+{
+    public class NetworkRigidbody2DDynamicTest : NetworkRigidbodyTestBase
+    {
+        public override bool Kinematic => false;
+    }
+
+    public class NetworkRigidbody2DKinematicTest : NetworkRigidbodyTestBase
+    {
+        public override bool Kinematic => true;
+    }
+
+    public abstract class NetworkRigidbody2DTestBase : BaseMultiInstanceTest
+    {
+        protected override int NbClients => 1;
+
+        public abstract bool Kinematic { get; }
+
+        [UnitySetUp]
+        public override IEnumerator Setup()
+        {
+            yield return StartSomeClientsAndServerWithPlayers(true, NbClients, playerPrefab =>
+            {
+                playerPrefab.AddComponent<NetworkTransform>();
+                playerPrefab.AddComponent<Rigidbody2D>();
+                playerPrefab.AddComponent<NetworkRigidbody>();
+                playerPrefab.GetComponent<Rigidbody2D>().isKinematic = Kinematic;
+            });
+        }
+
+        /// <summary>
+        /// Tests that a server can destroy a NetworkObject and that it gets despawned correctly.
+        /// </summary>
+        /// <returns></returns>
+        [UnityTest]
+        public IEnumerator TestRigidbodyKinematicEnableDisable()
+        {
+            // This is the *SERVER VERSION* of the *CLIENT PLAYER*
+            var serverClientPlayerResult = new MultiInstanceHelpers.CoroutineResultWrapper<NetworkObject>();
+            yield return MultiInstanceHelpers.Run(MultiInstanceHelpers.GetNetworkObjectByRepresentation((x => x.IsPlayerObject && x.OwnerClientId == m_ClientNetworkManagers[0].LocalClientId), m_ServerNetworkManager, serverClientPlayerResult));
+            var serverPlayer = serverClientPlayerResult.Result.gameObject;
+
+            // This is the *CLIENT VERSION* of the *CLIENT PLAYER*
+            var clientClientPlayerResult = new MultiInstanceHelpers.CoroutineResultWrapper<NetworkObject>();
+            yield return MultiInstanceHelpers.Run(MultiInstanceHelpers.GetNetworkObjectByRepresentation((x => x.IsPlayerObject && x.OwnerClientId == m_ClientNetworkManagers[0].LocalClientId), m_ClientNetworkManagers[0], clientClientPlayerResult));
+            var clientPlayer = clientClientPlayerResult.Result.gameObject;
+
+            Assert.IsNotNull(serverPlayer);
+            Assert.IsNotNull(clientPlayer);
+
+            int waitFor = Time.frameCount + 2;
+            yield return new WaitUntil(() => Time.frameCount >= waitFor);
+
+            // server rigidbody has authority and should have a kinematic mode of false
+            Assert.True(serverPlayer.GetComponent<Rigidbody2D>().isKinematic == Kinematic);
+
+            // client rigidbody has no authority and should have a kinematic mode of true
+            Assert.True(clientPlayer.GetComponent<Rigidbody2D>().isKinematic);
+
+            // despawn the server player
+            serverPlayer.GetComponent<NetworkObject>().Despawn(false);
+
+            yield return null;
+
+            Assert.IsTrue(serverPlayer.GetComponent<Rigidbody2D>().isKinematic == Kinematic);
+
+            yield return null;
+            Assert.IsTrue(clientPlayer == null); // safety check that object is actually despawned.
+        }
+    }
+}

com.unity.netcode.gameobjects/Components/NetworkRigidbody2D.cs.meta

@@ -0,0 +1,77 @@
+using System.Collections;
+using NUnit.Framework;
+using Unity.Netcode.Components;
+using UnityEngine;
+using UnityEngine.TestTools;
+
+namespace Unity.Netcode.RuntimeTests.Physics
+{
+    public class NetworkRigidbodyDynamicTest : NetworkRigidbodyTestBase
+    {
+        public override bool Kinematic => false;
+    }
+
+    public class NetworkRigidbodyKinematicTest : NetworkRigidbodyTestBase
+    {
+        public override bool Kinematic => true;
+    }
+
+    public abstract class NetworkRigidbodyTestBase : BaseMultiInstanceTest
+    {
+        protected override int NbClients => 1;
+
+        public abstract bool Kinematic { get; }
+
+        [UnitySetUp]
+        public override IEnumerator Setup()
+        {
+            yield return StartSomeClientsAndServerWithPlayers(true, NbClients, playerPrefab =>
+            {
+                playerPrefab.AddComponent<NetworkTransform>();
+                playerPrefab.AddComponent<Rigidbody>();
+                playerPrefab.AddComponent<NetworkRigidbody>();
+                playerPrefab.GetComponent<Rigidbody>().isKinematic = Kinematic;
+            });
+        }
+
+        /// <summary>
+        /// Tests that a server can destroy a NetworkObject and that it gets despawned correctly.
+        /// </summary>
+        /// <returns></returns>
+        [UnityTest]
+        public IEnumerator TestRigidbodyKinematicEnableDisable()
+        {
+            // This is the *SERVER VERSION* of the *CLIENT PLAYER*
+            var serverClientPlayerResult = new MultiInstanceHelpers.CoroutineResultWrapper<NetworkObject>();
+            yield return MultiInstanceHelpers.Run(MultiInstanceHelpers.GetNetworkObjectByRepresentation((x => x.IsPlayerObject && x.OwnerClientId == m_ClientNetworkManagers[0].LocalClientId), m_ServerNetworkManager, serverClientPlayerResult));
+            var serverPlayer = serverClientPlayerResult.Result.gameObject;
+
+            // This is the *CLIENT VERSION* of the *CLIENT PLAYER*
+            var clientClientPlayerResult = new MultiInstanceHelpers.CoroutineResultWrapper<NetworkObject>();
+            yield return MultiInstanceHelpers.Run(MultiInstanceHelpers.GetNetworkObjectByRepresentation((x => x.IsPlayerObject && x.OwnerClientId == m_ClientNetworkManagers[0].LocalClientId), m_ClientNetworkManagers[0], clientClientPlayerResult));
+            var clientPlayer = clientClientPlayerResult.Result.gameObject;
+
+            Assert.IsNotNull(serverPlayer);
+            Assert.IsNotNull(clientPlayer);
+
+            int waitFor = Time.frameCount + 2;
+            yield return new WaitUntil(() => Time.frameCount >= waitFor);
+
+            // server rigidbody has authority and should have a kinematic mode of false
+            Assert.True(serverPlayer.GetComponent<Rigidbody>().isKinematic == Kinematic);
+
+            // client rigidbody has no authority and should have a kinematic mode of true
+            Assert.True(clientPlayer.GetComponent<Rigidbody>().isKinematic);
+
+            // despawn the server player
+            serverPlayer.GetComponent<NetworkObject>().Despawn(false);
+
+            yield return null;
+
+            Assert.IsTrue(serverPlayer.GetComponent<Rigidbody>().isKinematic == Kinematic);
+
+            yield return null;
+            Assert.IsTrue(clientPlayer == null); // safety check that object is actually despawned.
+        }
+    }
+}