Screen View Camera Unexpectedly Re-Created

[jelling]

At various times we need to assign SceneCamera to objects so they can receive worldspace clicks. But the SceneCamera appears to be created multiple times on scene / layout load.

As a result, this happens:

• SceneCamera is created for first time
• OurClass.Canvas.worldCamera is assigned the SceneCamera.Camera
• First SceneCamera is destroyed for some reason
• Second SceneCamera is created
• OurClass.Canvas.worldCamera is now set to an invalid camera

We patched this by checking the worldCamera for validity during the Update() loop, but that feels hacky.

Is there an event we can watch to know when the scene is done updating cameras? I tried AfterLayout but it doesn't help here

Also, is there a diagram somewhere showing the event sequences for when a scene loads or a layout changes? That would be helpful in understanding where we can hook into things.

SceneCamera created twice on initial editor load

I detected these events by pausing when gameObject.name == "SceneCamera"

Battlehub.RTCommon.RTECamera.Awake (c:\dev\studio\Assets\Battlehub\RTEditor\Runtime\RTCommon\Graphics\RTECamera.cs:134)
UnityEngine.GameObject.SetActive (Unknown Source:0)
Battlehub.RTCommon.RTEGraphics.CreateRTECamera (c:\dev\studio\Assets\Battlehub\RTEditor\Runtime\RTCommon\Graphics\RTEGraphics.cs:223)
Battlehub.RTCommon.RTEGraphics.CreateSharedMeshesCache (c:\dev\studio\Assets\Battlehub\RTEditor\Runtime\RTCommon\Graphics\RTEGraphics.cs:151)
Battlehub.RTCommon.SpriteGizmoManager.Start (c:\dev\studio\Assets\Battlehub\RTEditor\Runtime\RTCommon\Graphics\SpriteGizmoManager.cs:57)

Battlehub.RTCommon.RTECamera.Awake (c:\dev\studio\Assets\Battlehub\RTEditor\Runtime\RTCommon\Graphics\RTECamera.cs:134)
UnityEngine.GameObject.Internal_AddComponentWithType (Unknown Source:0)
UnityEngine.GameObject.AddComponent (Unknown Source:0)
UnityEngine.GameObject.AddComponent<Battlehub.RTCommon.RTECamera> (Unknown Source:0)
Battlehub.RTHandles.SceneGrid.Init (c:\dev\studio\Assets\Battlehub\RTEditor\Runtime\RTHandles\SceneGrid.cs:103)
Battlehub.RTHandles.SceneGrid.Start (c:\dev\studio\Assets\Battlehub\RTEditor\Runtime\RTHandles\SceneGrid.cs:67)

Scene Camera created twice on layout change

Battlehub.RTCommon.RTECamera.Awake (c:\dev\studio\Assets\Battlehub\RTEditor\Runtime\RTCommon\Graphics\RTECamera.cs:134)
UnityEngine.GameObject.SetActive (Unknown Source:0)
Battlehub.RTEditor.Workspace.OnTabActivated (c:\dev\studio\Assets\Battlehub\RTEditor\Runtime\RTEditor\Workspace.cs:1269)
Battlehub.UIControls.DockPanels.DockPanel.OnTabActivated (c:\dev\studio\Assets\Battlehub\RTEditor\Runtime\UIControls\DockPanels\DockPanel.cs:262)
Battlehub.UIControls.DockPanels.Region.OnTabToggle (c:\dev\studio\Assets\Battlehub\RTEditor\Runtime\UIControls\DockPanels\Region.cs:1607)
Battlehub.UIControls.DockPanels.Tab.OnToggleValueChanged (c:\dev\studio\Assets\Battlehub\RTEditor\Runtime\UIControls\DockPanels\Tab.cs:331)
UnityEngine.Events.InvokableCall<bool>.Invoke (Unknown Source:0)
UnityEngine.Events.UnityEvent<bool>.Invoke (Unknown Source:0)
UnityEngine.UI.Toggle.Set (c:\dev\studio\Library\PackageCache\[email protected]\Runtime\UI\Core\Toggle.cs:280)
UnityEngine.UI.Toggle.set_isOn (c:\dev\studio\Library\PackageCache\[email protected]\Runtime\UI\Core\Toggle.cs:243)
Battlehub.UIControls.DockPanels.Tab.set_IsOn (c:\dev\studio\Assets\Battlehub\RTEditor\Runtime\UIControls\DockPanels\Tab.cs:149)
Battlehub.UIControls.DockPanels.Region.Insert (c:\dev\studio\Assets\Battlehub\RTEditor\Runtime\UIControls\DockPanels\Region.cs:1345)
Battlehub.UIControls.DockPanels.Region.Insert (c:\dev\studio\Assets\Battlehub\RTEditor\Runtime\UIControls\DockPanels\Region.cs:1314)
Battlehub.UIControls.DockPanels.Region.Add (c:\dev\studio\Assets\Battlehub\RTEditor\Runtime\UIControls\DockPanels\Region.cs:1141)
Battlehub.UIControls.DockPanels.Region.Build (c:\dev\studio\Assets\Battlehub\RTEditor\Runtime\UIControls\DockPanels\Region.cs:777)
Battlehub.UIControls.DockPanels.Region.Build (c:\dev\studio\Assets\Battlehub\RTEditor\Runtime\UIControls\DockPanels\Region.cs:698)
Battlehub.RTEditor.Workspace.CoSetLayout (c:\dev\studio\Assets\Battlehub\RTEditor\Runtime\RTEditor\Workspace.cs:345)
UnityEngine.SetupCoroutine.InvokeMoveNext (Unknown Source:0)
UnityEngine.MonoBehaviour.StartCoroutineManaged2 (Unknown Source:0)
UnityEngine.MonoBehaviour.StartCoroutine (Unknown Source:0)

Battlehub.RTCommon.RTECamera.Awake (c:\dev\studio\Assets\Battlehub\RTEditor\Runtime\RTCommon\Graphics\RTECamera.cs:134)
UnityEngine.GameObject.Internal_AddComponentWithType (Unknown Source:0)
UnityEngine.GameObject.AddComponent (Unknown Source:0)
UnityEngine.GameObject.AddComponent<Battlehub.RTCommon.RTECamera> (Unknown Source:0)
Battlehub.RTHandles.SceneGrid.Init (c:\dev\studio\Assets\Battlehub\RTEditor\Runtime\RTHandles\SceneGrid.cs:103)
Battlehub.RTHandles.SceneGrid.Start (c:\dev\studio\Assets\Battlehub\RTEditor\Runtime\RTHandles\SceneGrid.cs:67)