[Port] [2022.3] Fix perf when disabling decals

This is a backport of https://github.cds.internal.unity3d.com/unity/unity/pull/44365 andhttps://github.cds.internal.unity3d.com/unity/unity/pull/24079

Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Decal/DecalProjector.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 #if UNITY_EDITOR
 using UnityEditor;
 using UnityEditor.Rendering.HighDefinition;
@@ -341,6 +342,10 @@ void InitMaterial()
 
         void Reset() => InitMaterial();
 
+#if UNITY_EDITOR
+        static List<DecalProjector> m_DecalProjectorInstances;  // List of decal projectors that have had OnEnable() called on them
+        [NonSerialized] int m_EditorInstanceIndex = -1;
+#endif
         void OnEnable()
         {
             InitMaterial();
@@ -357,14 +362,32 @@ void OnEnable()
 #if UNITY_EDITOR
             cachedEditorLayer = gameObject.layer;
             // Handle scene visibility
-            SceneVisibilityManager.visibilityChanged += UpdateDecalVisibility;
-            PrefabStage.prefabStageOpened += RegisterDecalVisibilityUpdatePrefabStage;
-            if (PrefabStageUtility.GetCurrentPrefabStage() != null) // In case the prefab stage is already opened when enabling the decal
-                RegisterDecalVisibilityUpdatePrefabStage();
+
+            // Create a list to keep track of all active decal projectors and register our event handlers that dispatch events to each one.
+            // We do this instead of registering event handlers individually for each instance as that generates far more garbage on the heap
+            if (m_DecalProjectorInstances == null)
+            {
+                m_DecalProjectorInstances = new List<DecalProjector>();
+                SceneVisibilityManager.visibilityChanged += UpdateDecalVisibilityDispatcher;
+                PrefabStage.prefabStageOpened += RegisterDecalVisibilityUpdatePrefabStage;
+
+                if (PrefabStageUtility.GetCurrentPrefabStage() != null) // In case the prefab stage is already opened when enabling the decal
+                    RegisterDecalVisibilityUpdatePrefabStage();
+            }
+            m_EditorInstanceIndex = m_DecalProjectorInstances.Count;
+            m_DecalProjectorInstances.Add(this);
 #endif
         }
 
 #if UNITY_EDITOR
+        // Handler for the SceneVisibilityManager.visibilityChanged event, calls UpdateDecalVisibility() on each active decal projector
+        static void UpdateDecalVisibilityDispatcher()
+        {
+            foreach (DecalProjector decalProjector in m_DecalProjectorInstances)
+                decalProjector.UpdateDecalVisibility();
+        }
+
+        // Handle the SceneVisibilityManager.visibilityChanged event for this decal projector
         void UpdateDecalVisibility()
         {
             // This callback is called before HDRP is initialized after a domain reload
@@ -388,15 +411,27 @@ void UpdateDecalVisibility()
             }
         }
 
-        void RegisterDecalVisibilityUpdatePrefabStage(PrefabStage stage = null)
+        // Handler for the PrefabStage.prefabStageOpened event
+        static void RegisterDecalVisibilityUpdatePrefabStage(PrefabStage stage = null)
         {
-            SceneView.duringSceneGui -= UpdateDecalVisibilityPrefabStage;
-            SceneView.duringSceneGui += UpdateDecalVisibilityPrefabStage;
+            SceneView.duringSceneGui -= UpdateDecalVisibilityPrefabStageDispatcher;
+            SceneView.duringSceneGui += UpdateDecalVisibilityPrefabStageDispatcher;
         }
 
         void UnregisterDecalVisibilityUpdatePrefabStage()
-            => SceneView.duringSceneGui -= UpdateDecalVisibilityPrefabStage;
+        {
+            SceneView.duringSceneGui -= UpdateDecalVisibilityPrefabStageDispatcher;
+        }
+
+        // Handler for the SceneView.duringSceneGui event, calls UpdateDecalVisibilityPrefabStage() on each active decal projector
+        static void UpdateDecalVisibilityPrefabStageDispatcher(SceneView sv)
+        {
+            foreach (DecalProjector decalProjector in m_DecalProjectorInstances)
+                decalProjector.UpdateDecalVisibilityPrefabStage(sv);
+
+        }
 
+        // Handle the SceneView.duringSceneGui event for this decal projector
         bool m_LastPrefabStageVisibility = true;
         void UpdateDecalVisibilityPrefabStage(SceneView sv)
         {
@@ -424,7 +459,7 @@ void UpdateDecalVisibilityPrefabStage(SceneView sv)
                 DecalSystem.instance.RemoveDecal(m_Handle);
             m_LastPrefabStageVisibility = showDecal;
         }
-#endif
+#endif  // UNITY_EDITOR
 
         void OnDisable()
         {
@@ -434,9 +469,21 @@ void OnDisable()
                 m_Handle = null;
             }
 #if UNITY_EDITOR
-            SceneVisibilityManager.visibilityChanged -= UpdateDecalVisibility;
-            UnregisterDecalVisibilityUpdatePrefabStage();
-            PrefabStage.prefabStageOpened -= RegisterDecalVisibilityUpdatePrefabStage;
+            // Remove this instance from the list tracking active decal projectors.
+            // We do this by swapping the last element of the array into the slot we are deleting rather than shuffling the entire contents above the slot down as it's faster and the actual ordering is not significant
+            var movedInstance = m_DecalProjectorInstances[m_EditorInstanceIndex] = m_DecalProjectorInstances[m_DecalProjectorInstances.Count - 1];
+            movedInstance.m_EditorInstanceIndex = m_EditorInstanceIndex;
+            m_EditorInstanceIndex = -1;
+            m_DecalProjectorInstances.RemoveAt(m_DecalProjectorInstances.Count - 1);
+
+            // If the list of active instances is now empty delete it and un-register our event handlers
+            if (m_DecalProjectorInstances.Count == 0)
+            {
+                SceneVisibilityManager.visibilityChanged -= UpdateDecalVisibilityDispatcher;
+                PrefabStage.prefabStageOpened -= RegisterDecalVisibilityUpdatePrefabStage;
+                UnregisterDecalVisibilityUpdatePrefabStage();
+                m_DecalProjectorInstances = null;
+            }
 #endif
         }
 

Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Decal/DecalSystem.Jobs.cs

@@ -51,9 +51,12 @@ public void ResolveUpdateJob()
                 m_BoundingSpheres.CopyTo(m_CachedBoundingSpheres);
             }
 
-            private void ResizeJobArrays(int newCapacity)
+            private void GrowJobArrays(int growByAmount)
             {
-                m_CachedTransforms.ResizeArray(newCapacity);
+                int newCapacity = m_DecalsCount + growByAmount;
+
+                m_CachedTransforms.capacity = newCapacity;
+
                 m_Positions.ResizeArray(newCapacity);
                 m_Rotations.ResizeArray(newCapacity);
                 m_Scales.ResizeArray(newCapacity);

Packages/com.unity.render-pipelines.high-definition/Runtime/Material/Decal/DecalSystem.cs

@@ -266,6 +266,8 @@ public Camera CurrentCamera
         }
 
         private const int kDecalBlockSize = 128;
+        private const int kDecalBlockGrowthPercentage = 20;
+        private const int kDecalMaxBlockSize = 2048;
 
         // to work on Vulkan Mobile?
         // Core\CoreRP\ShaderLibrary\UnityInstancing.hlsl
@@ -565,11 +567,12 @@ public DecalHandle AddDecal(int materialID, DecalProjector decalProjector)
                 // increase array size if no space left
                 if (m_DecalsCount == m_Handles.Length)
                 {
-                    int newCapacity = m_DecalsCount + kDecalBlockSize;
+                    int growByAmount = Math.Min(Math.Max(m_DecalsCount * kDecalBlockGrowthPercentage / 100, kDecalBlockSize), kDecalMaxBlockSize);
+                    int newCapacity = m_DecalsCount + growByAmount;
 
                     m_ResultIndices = new int[newCapacity];
 
-                    ResizeJobArrays(newCapacity);
+                    GrowJobArrays(growByAmount);
 
                     ArrayExtensions.ResizeArray(ref m_Handles, newCapacity);
                     ArrayExtensions.ResizeArray(ref m_CachedDrawDistances, newCapacity);
@@ -977,12 +980,12 @@ void SetupMipStreamingSettings(Material material, bool allMips)
         public DecalHandle AddDecal(DecalProjector decalProjector)
         {
             var material = decalProjector.material;
-            SetupMipStreamingSettings(material, true);
 
             DecalSet decalSet = null;
             int key = material != null ? material.GetInstanceID() : kNullMaterialIndex;
             if (!m_DecalSets.TryGetValue(key, out decalSet))
             {
+				SetupMipStreamingSettings(material, true);
                 decalSet = new DecalSet(material);
                 m_DecalSets.Add(key, decalSet);
             }
@@ -1162,10 +1165,10 @@ public void UpdateTextureAtlas(CommandBuffer cmd)
                     AddTexture(cmd, textureScaleBias);
                 }
 
+#if UNITY_EDITOR || DEVELOPMENT_BUILD
                 if (!m_AllocationSuccess && m_PrevAllocationSuccess) // still failed to allocate, decal atlas size needs to increase, debounce so that we don't spam the console with warnings
-                {
                     Debug.LogWarning(s_AtlasSizeWarningMessage);
-                }
+#endif
             }
             m_PrevAllocationSuccess = m_AllocationSuccess;
             // now that textures have been stored in the atlas we can update their location info in decal data