Added a function to reset the reference size of RTHandle systems.

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

@@ -242,6 +242,17 @@ public void UnRegisterDebug()
             //m_DebugParameters.UnRegisterDebug();
         }
 
+        /// <summary>
+        /// Resets the reference size of the internal RTHandle System.
+        /// This allows users to reduce the memory footprint of render textures after doing a super sampled rendering pass for example.
+        /// </summary>
+        /// <param name="width">New width of the internal RTHandle System.</param>
+        /// <param name="height">New height of the internal RTHandle System.</param>
+        public void ResetRTHandleReferenceSize(int width, int height)
+        {
+            m_Resources.ResetRTHandleReferenceSize(width, height);
+        }
+
         /// <summary>
         /// Import an external texture to the Render Graph.
         /// </summary>

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

@@ -771,6 +771,11 @@ internal void Clear()
 #endif
         }
 
+        internal void ResetRTHandleReferenceSize(int width, int height)
+        {
+            m_RTHandleSystem.ResetReferenceSize(width, height);
+        }
+
         internal void Cleanup()
         {
             foreach (var value in m_TexturePool)

com.unity.render-pipelines.core/Runtime/Textures/BufferedRTHandleSystem.cs

@@ -134,6 +134,17 @@ public void SwapAndSetReferenceSize(int width, int height, MSAASamples msaaSampl
             m_RTHandleSystem.SetReferenceSize(width, height, msaaSamples);
         }
 
+        /// <summary>
+        /// Reset the reference size of the system and reallocate all textures.
+        /// </summary>
+        /// <param name="width">New width.</param>
+        /// <param name="height">New height.</param>
+        public void ResetReferenceSize(int width, int height)
+        {
+            m_RTHandleSystem.ResetReferenceSize(width, height);
+        }
+
+
         void Swap()
         {
             foreach (var item in m_RTHandles)

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

@@ -125,13 +125,25 @@ internal void Remove(RTHandle rth)
             m_AutoSizedRTs.Remove(rth);
         }
 
+        /// <summary>
+        /// Reset the reference size of the system and reallocate all textures.
+        /// </summary>
+        /// <param name="width">New width.</param>
+        /// <param name="height">New height.</param>
+        public void ResetReferenceSize(int width, int height)
+        {
+            m_MaxWidths = width;
+            m_MaxHeights = height;
+            SetReferenceSize(width, height, m_ScaledRTCurrentMSAASamples, reset: true);
+        }
+
         /// <summary>
         /// Sets the reference rendering size for subsequent rendering for the RTHandle System
         /// </summary>
         /// <param name="width">Reference rendering width for subsequent rendering.</param>
         /// <param name="height">Reference rendering height for subsequent rendering.</param>
         /// <param name="msaaSamples">Number of MSAA samples for multisampled textures for subsequent rendering.</param>
-        public void SetReferenceSize(int width, int height, MSAASamples msaaSamples)
+        public void SetReferenceSize(int width, int height, MSAASamples msaaSamples, bool reset = false)
         {
             m_RTHandleProperties.previousViewportSize = m_RTHandleProperties.currentViewportSize;
             m_RTHandleProperties.previousRenderTargetSize = m_RTHandleProperties.currentRenderTargetSize;
@@ -140,7 +152,7 @@ public void SetReferenceSize(int width, int height, MSAASamples msaaSamples)
             width = Mathf.Max(width, 1);
             height = Mathf.Max(height, 1);
 
-            bool sizeChanged = width > GetMaxWidth() || height > GetMaxHeight();
+            bool sizeChanged = width > GetMaxWidth() || height > GetMaxHeight() || reset;
             bool msaaSamplesChanged = (msaaSamples != m_ScaledRTCurrentMSAASamples);
 
             if (sizeChanged || msaaSamplesChanged)

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

@@ -304,5 +304,15 @@ MSAASamples msaaSamples
                 msaaSamples
                 );
         }
+
+        /// <summary>
+        /// Reset the reference size of the system and reallocate all textures.
+        /// </summary>
+        /// <param name="width">New width.</param>
+        /// <param name="height">New height.</param>
+        public static void ResetReferenceSize(int width, int height)
+        {
+            s_DefaultInstance.ResetReferenceSize(width, height);
+        }
     }
 }

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

@@ -119,6 +119,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Added Min distance to contact shadows.
 - Added support for Depth of Field in path tracing (by sampling the lens aperture).
 - Added an API in HDRP to override the camera within the rendering of a frame (mainly for custom pass).
+- Added a function (HDRenderPipeline.ResetRTHandleReferenceSize) to reset the reference size of RTHandle systems.
 
 ### Fixed
 - Fix when rescale probe all direction below zero (1219246)

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

@@ -579,6 +579,20 @@ internal static void CleanUnused()
             s_Cleanup.Clear();
         }
 
+        internal static void ResetAllHistoryRTHandleSystems(int width, int height)
+        {
+            foreach (var kvp in s_Cameras)
+            {
+                var hdCamera = kvp.Value;
+                var currentHistorySize = hdCamera.m_HistoryRTSystem.rtHandleProperties.currentRenderTargetSize;
+                // We only reset if the new size if smaller than current reference (otherwise we might increase the size of off screen camera with lower resolution than the new reference.
+                if (width < currentHistorySize.x || height < currentHistorySize.y)
+                {
+                    hdCamera.m_HistoryRTSystem.ResetReferenceSize(width, height);
+                }
+            }
+        }
+
         unsafe internal void UpdateShaderVariablesGlobalCB(ref ShaderVariablesGlobal cb, int frameCount)
         {
             bool taaEnabled = frameSettings.IsEnabled(FrameSettingsField.Postprocess)

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

@@ -578,6 +578,20 @@ void ValidateResources()
 
 #endif
 
+        /// <summary>
+        /// Resets the reference size of the internal RTHandle System.
+        /// This allows users to reduce the memory footprint of render textures after doing a super sampled rendering pass for example.
+        /// </summary>
+        /// <param name="width">New width of the internal RTHandle System.</param>
+        /// <param name="height">New height of the internal RTHandle System.</param>
+        public void ResetRTHandleReferenceSize(int width, int height)
+        {
+            RTHandles.ResetReferenceSize(width, height);
+            HDCamera.ResetAllHistoryRTHandleSystems(width, height);
+            if (m_RenderGraph != null)
+                m_RenderGraph.ResetRTHandleReferenceSize(width, height);
+        }
+
         void InitializeRenderTextures()
         {
             RenderPipelineSettings settings = m_Asset.currentPlatformRenderPipelineSettings;
@@ -1005,7 +1019,7 @@ void DisposeProbeCameraPool()
             // Dispose of Render Pipeline can be call either by OnValidate() or by OnDisable().
             // Inside an OnValidate() call we can't call a DestroyImmediate().
             // Here we are releasing our singleton to not leak while doing a domain reload.
-            // However this is doing a call to DestroyImmediate(). 
+            // However this is doing a call to DestroyImmediate().
             // To workaround this, and was we only leak with Singleton while doing domain reload (and not in OnValidate)
             // we are detecting if we are in an OnValidate call and releasing the Singleton only if it is not the case.
             if (!m_Asset.isInOnValidateCall)
@@ -3219,7 +3233,7 @@ void RenderDBuffer(HDCamera hdCamera, CommandBuffer cmd, ScriptableRenderContext
             {
                 // We still bind black textures to make sure that something is bound (can be a problem on some platforms)
                 m_DbufferManager.BindBlackTextures(cmd);
-                
+
                 // Bind buffer to make sure that something is bound .
                 cmd.SetGlobalBuffer(HDShaderIDs._DecalPropertyMaskBufferSRV, m_DbufferManager.propertyMaskBuffer);