Add wall-based ambient occlusion (#38276)

* Add wall ambient occlusion

* wawawewa

* Work

* cvars

* Comment to make slart happy

Content.Client/Light/EntitySystems/PlanetLightSystem.cs

@@ -1,17 +1,51 @@
+using Content.Shared.CCVar;
 using Robust.Client.Graphics;
+using Robust.Shared.Configuration;
 
 namespace Content.Client.Light.EntitySystems;
 
 public sealed class PlanetLightSystem : EntitySystem
 {
+    [Dependency] private readonly IConfigurationManager _cfgManager = default!;
     [Dependency] private readonly IOverlayManager _overlayMan = default!;
 
+    /// <summary>
+    /// Enables / disables the ambient occlusion overlay.
+    /// </summary>
+    public bool AmbientOcclusion
+    {
+        get => _ambientOcclusion;
+        set
+        {
+            if (_ambientOcclusion == value)
+                return;
+
+            _ambientOcclusion = value;
+
+            if (value)
+            {
+                _overlayMan.AddOverlay(new AmbientOcclusionOverlay());
+            }
+            else
+            {
+                _overlayMan.RemoveOverlay<AmbientOcclusionOverlay>();
+            }
+        }
+    }
+
+    private bool _ambientOcclusion;
+
     public override void Initialize()
     {
         base.Initialize();
 
         SubscribeLocalEvent<GetClearColorEvent>(OnClearColor);
 
+        _cfgManager.OnValueChanged(CCVars.AmbientOcclusion, val =>
+        {
+            AmbientOcclusion = val;
+        }, true);
+
         _overlayMan.AddOverlay(new BeforeLightTargetOverlay());
         _overlayMan.AddOverlay(new RoofOverlay(EntityManager));
         _overlayMan.AddOverlay(new TileEmissionOverlay(EntityManager));