Fix for area light emissive mesh not appearing in playmode when Reload Scene is disabled (#1504)

* Create emissive mesh if not created but is requested.

* Changelog

* Remove unnecessary create function call

Co-authored-by: sebastienlagarde <[email protected]>

Author: FrancescoC-unity

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

@@ -761,6 +761,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed CoatMask block appearing when creating lit master node (case 1264632)
 - Fixed issue with SceneEV100 debug mode indicator when rescaling the window.
 - Fixed issue with PCSS filter being wrong on first frame. 
+- Fixed issue with emissive mesh for area light not appearing in playmode if Reload Scene option is disabled in Enter Playmode Settings.
 
 ### Changed
 - Improve MIP selection for decals on Transparents

com.unity.render-pipelines.high-definition/Runtime/Lighting/Light/HDAdditionalLightData.cs

@@ -2312,6 +2312,14 @@ void LateUpdate()
 #endif
 
 #if UNITY_EDITOR
+
+            // If we requested an emissive mesh but for some reason (e.g. Reload scene unchecked in the Enter Playmode options) Awake has not been called,
+            // we need to create it manually.
+            if (m_DisplayAreaLightEmissiveMesh && (m_ChildEmissiveMeshViewer == null || m_ChildEmissiveMeshViewer.Equals(null)))
+            {
+                UpdateAreaLightEmissiveMesh();
+            }
+
             //if not parented anymore, refresh it
             if (m_ChildEmissiveMeshViewer != null && !m_ChildEmissiveMeshViewer.Equals(null))
             {