BugFix: RTHandle doesn't try to destroy persistent object in editor (UUM-36359)

Fix for [UUM-36359](https://jira.unity3d.com/browse/UUM-36359). Originally `RTHandle` manages external texture but doesn't have the same check for `RenderTexture` that generated as external resources.

Author: giulia-u3d

Packages/com.unity.render-pipelines.core/Runtime/Textures/RTHandle.cs

@@ -2,6 +2,10 @@
 using System.Collections.Generic;
 using UnityEngine.Rendering;
 
+#if UNITY_EDITOR
+using UnityEditor;
+#endif
+
 namespace UnityEngine.Rendering
 {
     /// <summary>
@@ -64,6 +68,7 @@ public class RTHandle
         internal bool m_EnableMSAA = false;
         internal bool m_EnableRandomWrite = false;
         internal bool m_EnableHWDynamicScale = false;
+        internal bool m_RTHasOwnership = true;
         internal string m_Name;
 
         internal bool m_UseCustomHandleScales = false;
@@ -175,10 +180,11 @@ public static implicit operator RenderTexture(RTHandle handle)
             return handle.rt;
         }
 
-        internal void SetRenderTexture(RenderTexture rt)
+        internal void SetRenderTexture(RenderTexture rt, bool transferOwnership = true)
         {
             m_RT = rt;
             m_ExternalTexture = null;
+            m_RTHasOwnership = transferOwnership;
             m_NameID = new RenderTargetIdentifier(rt);
         }
 
@@ -216,10 +222,12 @@ public int GetInstanceID()
         public void Release()
         {
             m_Owner.Remove(this);
-            CoreUtils.Destroy(m_RT);
+            if (m_RTHasOwnership)
+                CoreUtils.Destroy(m_RT);
             m_NameID = BuiltinRenderTextureType.None;
             m_RT = null;
             m_ExternalTexture = null;
+            m_RTHasOwnership = true;
         }
 
         /// <summary>

Packages/com.unity.render-pipelines.core/Runtime/Textures/RTHandleSystem.cs

@@ -3,6 +3,10 @@
 using UnityEngine.Assertions;
 using UnityEngine.Experimental.Rendering;
 
+//#if UNITY_EDITOR
+using UnityEditor;
+//#endif
+
 namespace UnityEngine.Rendering
 {
     /// <summary>
@@ -1162,11 +1166,16 @@ RTHandle AllocAutoSizedRenderTexture(int width, int height, RTHandleAllocInfo in
         /// Allocate a RTHandle from a regular RenderTexture.
         /// </summary>
         /// <param name="texture">Input texture</param>
+        /// <param name="transferOwnership">Says if the RTHandleSystem has the ownership of the external RenderTarget, false by default</param>
         /// <returns>A new RTHandle referencing the input texture.</returns>
-        public RTHandle Alloc(RenderTexture texture)
+        public RTHandle Alloc(RenderTexture texture, bool transferOwnership = false)
         {
             var rth = new RTHandle(this);
-            rth.SetRenderTexture(texture);
+#if UNITY_EDITOR
+            Debug.Assert(!(EditorUtility.IsPersistent(texture) == true && transferOwnership == true),
+                    "RTHandle should not have ownership of RenderTarget asset, set transfer ownership as false");
+#endif
+            rth.SetRenderTexture(texture, transferOwnership);
             rth.m_EnableMSAA = false;
             rth.m_EnableRandomWrite = false;
             rth.useScaling = false;

Packages/com.unity.render-pipelines.core/Runtime/Textures/RTHandles.cs

@@ -533,10 +533,11 @@ public static RTHandle Alloc(Texture tex)
         /// Allocate a RTHandle from a regular RenderTexture for the default RTHandle system.
         /// </summary>
         /// <param name="tex">Input texture</param>
+        /// <param name="transferOwnership">To transfer ownership of the RenderTexture to the default RTHandles system, false by default</param>
         /// <returns>A new RTHandle referencing the input texture.</returns>
-        public static RTHandle Alloc(RenderTexture tex)
+        public static RTHandle Alloc(RenderTexture tex, bool transferOwnership = false)
         {
-            return s_DefaultInstance.Alloc(tex);
+            return s_DefaultInstance.Alloc(tex, transferOwnership);
         }
 
         /// <summary>

Packages/com.unity.render-pipelines.high-definition/Runtime/Compositor/CompositionLayer.cs

@@ -299,7 +299,7 @@ public void Init(string layerID = "", bool allowUndo = false)
             // check and fix RT handle
             if (m_OutputTarget != OutputTarget.CameraStack && m_RTHandle == null && m_RenderTarget != null)
             {
-                m_RTHandle = RTHandles.Alloc(m_RenderTarget);
+                m_RTHandle = RTHandles.Alloc(m_RenderTarget, transferOwnership: true);
             }
 
             if (m_OutputTarget != OutputTarget.CameraStack && m_AOVBitmask != MaterialSharedProperty.None)
@@ -320,7 +320,7 @@ public void Init(string layerID = "", bool allowUndo = false)
                         {
                             m_AOVMap[aovNames[i]] = outputIndex;
                             m_AOVRenderTargets.Add(new RenderTexture(pixelWidth, pixelHeight, 24, (GraphicsFormat)m_ColorBufferFormat));
-                            m_AOVHandles.Add(RTHandles.Alloc(m_AOVRenderTargets[outputIndex]));
+                            m_AOVHandles.Add(RTHandles.Alloc(m_AOVRenderTargets[outputIndex], transferOwnership: true));
                             outputIndex++;
                         }
                     }

Packages/com.unity.render-pipelines.high-definition/Runtime/Lighting/Reflection/HDProbe.cs

@@ -410,7 +410,7 @@ public RenderTexture realtimeTexture
             {
                 if (m_RealtimeTexture != null)
                     m_RealtimeTexture.Release();
-                m_RealtimeTexture = RTHandles.Alloc(value);
+                m_RealtimeTexture = RTHandles.Alloc(value, transferOwnership: true);
                 m_RealtimeTexture.rt.name = $"ProbeRealTimeTexture_{name}";
             }
         }
@@ -428,7 +428,7 @@ public RenderTexture realtimeDepthTexture
             {
                 if (m_RealtimeDepthBuffer != null)
                     m_RealtimeDepthBuffer.Release();
-                m_RealtimeDepthBuffer = RTHandles.Alloc(value);
+                m_RealtimeDepthBuffer = RTHandles.Alloc(value, transferOwnership: true);
                 m_RealtimeDepthBuffer.rt.name = $"ProbeRealTimeDepthTexture_{name}";
             }
         }

Packages/com.unity.render-pipelines.universal/Runtime/ReflectionProbeManager.cs

@@ -83,7 +83,7 @@ void Init()
             m_AtlasTexture0.filterMode = FilterMode.Bilinear;
             m_AtlasTexture0.hideFlags = HideFlags.HideAndDontSave;
             m_AtlasTexture0.Create();
-            m_AtlasTexture0Handle = RTHandles.Alloc(m_AtlasTexture0);
+            m_AtlasTexture0Handle = RTHandles.Alloc(m_AtlasTexture0, transferOwnership: true);
 
             m_AtlasTexture1 = new RenderTexture(m_AtlasTexture0.descriptor);
             m_AtlasTexture1.name = k_ReflectionProbeAtlasName;

Packages/com.unity.render-pipelines.universal/Runtime/UniversalRendererDebug.cs

@@ -78,7 +78,7 @@ private void SetupRenderGraphFinalPassDebug(RenderGraph renderGraph, ContextCont
                             width = targetWidth;
                         }
 
-                        m_RenderGraphDebugTextureHandle = RTHandles.Alloc(m_ForwardLights.reflectionProbeManager.atlasRT);
+                        m_RenderGraphDebugTextureHandle = RTHandles.Alloc(m_ForwardLights.reflectionProbeManager.atlasRT, transferOwnership: true);
                     }
                     else // visualize RG internal resources
                     {