Fixed issue with compositor custom pass hooks added/removed repeatedly (

#3613)

Co-authored-by: sebastienlagarde <sebastien@unity3d.com>

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

@@ -50,6 +50,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed error when increasing the maximum planar reflection limit (case 1306530).
 - Fixed alpha output in debug view and AOVs when using shadow matte (case 1311830).
 - Fixed an issue with transparent meshes writing their depths and recursive rendering (case 1314409).
+- Fixed issue with compositor custom pass hooks added/removed repeatedly (case 1315971).
 
 ### Changed
 - Changed Window/Render Pipeline/HD Render Pipeline Wizard to Window/Rendering/HDRP Wizard

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

@@ -61,6 +61,10 @@ public bool enableOutput
             {
                 if (m_OutputCamera)
                 {
+                    // If the state did not change, don't do anything
+                    if (m_OutputCamera.enabled == value)
+                        return;
+
                     m_OutputCamera.enabled = value;
 
                     // Aside from the output compositor camera, we also have to change the cameras of the layers
@@ -496,7 +500,7 @@ public void UpdateLayerSetup()
         void Update()
         {
             // TODO: move all validation calls to onValidate. Before doing it, this needs some extra testing to ensure nothing breaks
-            if (ValidatePipeline() == false || ValidateAndFixRuntime() == false || RuntimeCheck() == false)
+            if (enableOutput == false || ValidatePipeline() == false || ValidateAndFixRuntime() == false || RuntimeCheck() == false)
             {
                 return;
             }