refactor(srp): align urp renderer slot semantics

managed/XCEngine.RenderPipelines.Universal/Rendering/Universal/ScriptableRendererData.cs

@@ -6,6 +6,7 @@ namespace XCEngine.Rendering.Universal
 {
     public abstract class ScriptableRendererData : Object
     {
+        public ScriptableRendererFeature[] rendererFeatures;
         private ScriptableRendererFeature[] m_rendererFeatures;
         private ScriptableRenderer m_rendererInstance;
         private bool m_rendererInvalidated;
@@ -13,6 +14,8 @@ namespace XCEngine.Rendering.Universal
 
         protected ScriptableRendererData()
         {
+            rendererFeatures =
+                Array.Empty<ScriptableRendererFeature>();
         }
 
         internal ScriptableRenderer CreateRendererInstance()
@@ -196,13 +199,20 @@ namespace XCEngine.Rendering.Universal
 
         protected virtual ScriptableRendererFeature[] CreateRendererFeatures()
         {
-            return Array.Empty<ScriptableRendererFeature>();
+            return rendererFeatures ??
+                   Array.Empty<ScriptableRendererFeature>();
         }
 
         protected virtual void ReleaseRuntimeResources()
         {
         }
 
+        protected virtual ScriptableRendererFeature[]
+        CreateDefaultRendererFeatures()
+        {
+            return Array.Empty<ScriptableRendererFeature>();
+        }
+
         protected bool isInvalidated
         {
             get
@@ -279,6 +289,13 @@ namespace XCEngine.Rendering.Universal
             }
         }
 
+        protected void ResetRendererFeaturesToDefault()
+        {
+            rendererFeatures =
+                CreateDefaultRendererFeatures() ??
+                Array.Empty<ScriptableRendererFeature>();
+        }
+
         private ScriptableRendererFeature[] GetRendererFeatures()
         {
             if (m_rendererFeatures == null)