Fixed some render texture leaks.

com.unity.render-pipelines.core/Runtime/RenderGraph/RenderGraphResourceComputeBuffer.cs

@@ -203,7 +203,7 @@ override public void PurgeUnusedResources(int currentFrameIndex)
                 var list = kvp.Value;
                 list.RemoveAll(obj =>
                 {
-                    if (obj.frameIndex < s_CurrentFrameIndex)
+                    if (ShouldReleaseResource(obj.frameIndex, s_CurrentFrameIndex))
                     {
                         obj.resource.Release();
                         return true;

com.unity.render-pipelines.core/Runtime/RenderGraph/RenderGraphResourcePool.cs

@@ -21,6 +21,7 @@ abstract class RenderGraphResourcePool<Type> : IRenderGraphResourcePool where Ty
         List<(int, Type)> m_FrameAllocatedResources = new List<(int, Type)>();
 
         protected static int s_CurrentFrameIndex;
+        const int kStaleResourceLifetime = 10;
 
         // Release the GPU resource itself
         protected abstract void ReleaseInternalResource(Type res);
@@ -123,5 +124,13 @@ public override void LogResources(RenderGraphLogger logger)
             foreach (var element in allocationList)
                 logger.LogLine("[{0}]\t[{1:#.##} MB]\t{2}", index++, element.size / 1024.0f, element.name);
         }
+
+        static protected bool ShouldReleaseResource(int lastUsedFrameIndex, int currentFrameIndex)
+        {
+            // We need to have a delay of a few frames before releasing resources for good.
+            // Indeed, when having multiple off-screen cameras, they are rendered in a separate SRP render call and thus with a different frame index than main camera
+            // This causes texture to be deallocated/reallocated every frame if the two cameras don't need the same buffers.
+            return (lastUsedFrameIndex + kStaleResourceLifetime) < currentFrameIndex;
+        }
     }
 }

com.unity.render-pipelines.core/Runtime/RenderGraph/RenderGraphResourceTexture.cs

@@ -406,7 +406,7 @@ override public void PurgeUnusedResources(int currentFrameIndex)
                 var list = kvp.Value;
                 list.RemoveAll(obj =>
                 {
-                    if (obj.frameIndex < s_CurrentFrameIndex)
+                    if (ShouldReleaseResource(obj.frameIndex, s_CurrentFrameIndex))
                     {
                         obj.resource.Release();
                         return true;

com.unity.render-pipelines.high-definition/CHANGELOG.md

@@ -21,6 +21,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed undo-redo on layered lit editor.
 - Fixed tesselation culling, big triangles using lit tesselation shader would dissapear when camera is too close to them (case 1299116)
 - Fixed issue with compositor related custom passes still active after disabling the compositor (case 1305330)
+- Fixed some render texture leaks.
 
 ### Changed
 - Change the source value for the ray tracing frame index iterator from m_FrameCount to the camera frame count (case 1301356).

com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Camera/HDCamera.cs

@@ -1365,6 +1365,8 @@ Matrix4x4 ComputePixelCoordToWorldSpaceViewDirectionMatrix(ViewConstants viewCon
 
         void Dispose()
         {
+            HDRenderPipeline.DestroyVolumetricHistoryBuffers(this);
+
             VolumeManager.instance.DestroyStack(volumeStack);
 
             if (m_HistoryRTSystem != null)

com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Utility/Texture3DAtlas.cs

@@ -525,7 +525,8 @@ void GenerateMip(CommandBuffer cmd, Texture source, Vector3Int sourceOffset, int
         public void Release()
         {
             ClearTextures();
-            m_Atlas.Release();
+            CoreUtils.Destroy(m_Atlas);
+            CoreUtils.Destroy(m_MipMapGenerationTemp);
         }
 
         public static long GetApproxCacheSizeInByte(int elementSize, int elementCount, GraphicsFormat format, bool hasMipMaps)