[HDRP][Compositor] Fix errors when resizing the compositor's output

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

@@ -137,6 +137,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fix decal being applied twice with LOD Crossfade.
 - Fixed camera stacking for AOVs in the graphics compositor (case 1273223).
 - Disable quad overdraw on ps4.
+- Fixed error when resizing the graphics compositor's output and when re-adding a compositor in the scene
 
 ### Changed
 - Preparation pass for RTSSShadows to be supported by render graph.

com.unity.render-pipelines.high-definition/Editor/Compositor/CompositionUtils.cs

@@ -69,16 +69,15 @@ static public void RemoveAudioListeners(Camera camera)
 
         static public void SetDefaultCamera(CompositionManager compositor)
         {
-            var camera = CompositionManager.GetSceceCamera();
-            if (camera != null)
+            // Create a new camera for the compositor's output
+            var newCameraGameObject = new GameObject(k_DefaultCameraName);
+            var camera = newCameraGameObject.AddComponent<Camera>();
             {
-                var outputCamera = Object.Instantiate(camera);
-                RemoveAudioListeners(outputCamera);
-                outputCamera.name = k_DefaultCameraName;
-                outputCamera.tag = "Untagged";
-                outputCamera.cullingMask = 0; // we don't want to render any 3D objects on the compositor camera
-                compositor.outputCamera = outputCamera;
+                camera.tag = "Untagged";
+                camera.cullingMask = 0; // we don't want to render any 3D objects on the compositor camera
             }
+            newCameraGameObject.AddComponent<HDAdditionalCameraData>();
+            compositor.outputCamera = camera;
         }
 
         static public void SetDefaultLayers(CompositionManager compositor)

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

@@ -134,7 +134,7 @@ public float aspectRatio
         [SerializeField] Camera m_LayerCamera;
 
         // Returns true if this layer is using a camera that was cloned internally for drawing
-        bool isUsingACameraClone => !m_LayerCamera.Equals(m_Camera);
+        internal bool isUsingACameraClone => !m_LayerCamera.Equals(m_Camera);
 
         // The input alpha will be mapped between the min and max range when blending between the post-processed and plain image regions. This way the user can controls how steep is the transition.
         [SerializeField] float m_AlphaMin = 0.0f;   
@@ -266,7 +266,11 @@ public void Init(string layerID = "")
 
             if (m_OutputTarget != OutputTarget.CameraStack && m_RenderTarget == null)
             {
-                m_RenderTarget = new RenderTexture(pixelWidth, pixelHeight, 24, (GraphicsFormat)m_ColorBufferFormat);
+                // If we don't have a valid camera (zero width or height) avoid creating the RT
+                if (pixelWidth > 0 && pixelHeight > 0)
+                {
+                    m_RenderTarget = new RenderTexture(pixelWidth, pixelHeight, 24, (GraphicsFormat)m_ColorBufferFormat);
+                }
             }
 
             // check and fix RT handle

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

@@ -66,7 +66,7 @@ public bool enableOutput
                     // also change the layers
                     foreach(var layer in m_InputLayers)
                     {
-                        if (layer.camera)
+                        if (layer.camera && layer.isUsingACameraClone)
                         {
                             layer.camera.enabled = value;
                         }
@@ -351,10 +351,25 @@ public void OnEnable()
 
         public void DeleteLayerRTs()
         {
+            int numRTReferences = 0;
+
             // delete the layer from last to first, in order to release first the camera and then the associated RT
             for (int i = m_InputLayers.Count - 1; i >= 0; --i)
             {
-                m_InputLayers[i].DestroyRT();
+                // Since some layers are not useing cloned cameras, we have to count the number of references in a RT and only delete if it is zero   
+                if (numRTReferences == 0)
+                {
+                    m_InputLayers[i].DestroyRT();
+                }
+
+                if (m_InputLayers[i].outputTarget == CompositorLayer.OutputTarget.CompositorLayer)
+                {
+                    numRTReferences = 0;
+                }
+                else
+                {
+                    numRTReferences += (m_InputLayers[i].camera != null) ? 1 : 0;
+                }
             }
         }
 
@@ -522,11 +537,7 @@ void Update()
 
         void OnDestroy()
         {
-            // We need to destroy the layers from last to first, to avoid releasing a RT that is used by a camera
-            for (int i = m_InputLayers.Count - 1; i >= 0; --i)
-            {
-                m_InputLayers[i].Destroy();
-            }
+            DeleteLayerRTs();
 
             if (m_CompositorGameObject != null)
             {
@@ -804,6 +815,11 @@ void CustomRender(ScriptableRenderContext context, HDCamera camera)
         /// <returns>Returns true if this camera is used to render in more than one layer</returns>
         internal bool IsThisCameraShared(Camera camera)
         {
+            if (camera == null)
+            {
+                return false;
+            }
+
             int count = 0;
             foreach (var layer in m_InputLayers)
             {