fix: NetworkAnimator parameters writebuffer is limited [backport] (#3124)

* fix

Pre-calculate the required parameter write size needed as opposed to using the legacy constant value.

* update

adding changelog entry

* update

Adding PR number to changelog entry

Author: NoelStephensUnity

com.unity.netcode.gameobjects/CHANGELOG.md

@@ -17,6 +17,7 @@ Additional documentation and release notes are available at [Multiplayer Documen
 
 ### Fixed
 
+- Fixed issue where `NetworkAnimator` would statically allocate write buffer space for `Animator` parameters that could cause a write error if the number of parameters exceeded the space allocated. (#3124)
 - Fixed issue with the in-scene network prefab instance update menu tool where it was not properly updating scenes when invoked on the root prefab instance. (#3084)
 - Fixed issue where `NetworkAnimator` would send updates to non-observer clients. (#3058)
 - Fixed issue where an exception could occur when receiving a universal RPC for a `NetworkObject` that has been despawned. (#3055)

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

@@ -481,10 +481,6 @@ protected virtual bool OnIsServerAuthoritative()
             return true;
         }
 
-        // Animators only support up to 32 parameters
-        // TODO: Look into making this a range limited property
-        private const int k_MaxAnimationParams = 32;
-
         private int[] m_TransitionHash;
         private int[] m_AnimationHash;
         private float[] m_LayerWeights;
@@ -508,7 +504,7 @@ private unsafe struct AnimatorParamCache
         }
 
         // 128 bytes per Animator
-        private FastBufferWriter m_ParameterWriter = new FastBufferWriter(k_MaxAnimationParams * sizeof(float), Allocator.Persistent);
+        private FastBufferWriter m_ParameterWriter;
 
         private NativeArray<AnimatorParamCache> m_CachedAnimatorParameters;
 
@@ -560,6 +556,14 @@ public override void OnDestroy()
 
         private void Awake()
         {
+            if (!m_Animator)
+            {
+#if !UNITY_EDITOR
+                Debug.LogError($"{nameof(NetworkAnimator)} {name} does not have an {nameof(UnityEngine.Animator)} assigned to it. The {nameof(NetworkAnimator)} will not initialize properly.");
+#endif
+                return;
+            }
+
             int layers = m_Animator.layerCount;
             // Initializing the below arrays for everyone handles an issue
             // when running in owner authoritative mode and the owner changes.
@@ -589,6 +593,9 @@ private void Awake()
                 }
             }
 
+            // The total initialization size calculated for the m_ParameterWriter write buffer.
+            var totalParameterSize = sizeof(uint);
+
             // Build our reference parameter values to detect when they change
             var parameters = m_Animator.parameters;
             m_CachedAnimatorParameters = new NativeArray<AnimatorParamCache>(parameters.Length, Allocator.Persistent);
@@ -629,7 +636,37 @@ private void Awake()
                 }
 
                 m_CachedAnimatorParameters[i] = cacheParam;
+
+                // Calculate parameter sizes (index + type size)
+                switch (parameter.type)
+                {
+                    case AnimatorControllerParameterType.Int:
+                        {
+                            totalParameterSize += sizeof(int) * 2;
+                            break;
+                        }
+                    case AnimatorControllerParameterType.Bool:
+                    case AnimatorControllerParameterType.Trigger:
+                        {
+                            // Bool is serialized to 1 byte
+                            totalParameterSize += sizeof(int) + 1;
+                            break;
+                        }
+                    case AnimatorControllerParameterType.Float:
+                        {
+                            totalParameterSize += sizeof(int) + sizeof(float);
+                            break;
+                        }
+                }
             }
+
+            if (m_ParameterWriter.IsInitialized)
+            {
+                m_ParameterWriter.Dispose();
+            }
+
+            // Create our parameter write buffer for serialization
+            m_ParameterWriter = new FastBufferWriter(totalParameterSize, Allocator.Persistent);
         }
 
         /// <summary>