Add subfloor appearance data, pipes correctly render subfloor. (#4393)

Content.Client/Atmos/Visualizers/PipeConnectorVisualizer.cs

@@ -1,6 +1,7 @@
 using System;
 using Content.Shared.Atmos;
 using Content.Shared.Atmos.Piping;
+using Content.Shared.SubFloor;
 using JetBrains.Annotations;
 using Robust.Client.GameObjects;
 using Robust.Client.Graphics;
@@ -69,13 +70,16 @@ namespace Content.Client.Atmos.Visualizers
             if (!component.TryGetData(PipeVisuals.VisualState, out PipeVisualState state))
                 return;
 
+            if(!component.TryGetData(SubFloorVisuals.SubFloor, out bool subfloor))
+                subfloor = true;
+
             foreach (Layer layerKey in Enum.GetValues(typeof(Layer)))
             {
                 var dir = (PipeDirection) layerKey;
                 var layerVisible = state.ConnectedDirections.HasDirection(dir);
 
                 var layer = sprite.LayerMapGet(layerKey);
-                sprite.LayerSetVisible(layer, layerVisible);
+                sprite.LayerSetVisible(layer, layerVisible && subfloor);
                 sprite.LayerSetColor(layer, color);
             }
         }

Content.Client/SubFloor/SubFloorShowLayerVisualizer.cs

@@ -0,0 +1,40 @@
+using Content.Shared.SubFloor;
+using JetBrains.Annotations;
+using Robust.Client.GameObjects;
+
+namespace Content.Client.SubFloor
+{
+    [UsedImplicitly]
+    public class SubFloorShowLayerVisualizer : AppearanceVisualizer
+    {
+        public override void OnChangeData(AppearanceComponent component)
+        {
+            base.OnChangeData(component);
+
+            if (!component.Owner.TryGetComponent(out SpriteComponent? sprite))
+                return;
+
+            if (component.TryGetData(SubFloorVisuals.SubFloor, out bool subfloor))
+            {
+                sprite.Visible = true;
+
+                // Due to the way this visualizer works, you might want to specify it before any other
+                // visualizer that hides/shows layers depending on certain conditions, such as PipeConnectorVisualizer.
+                foreach (var layer in sprite.AllLayers)
+                {
+                    layer.Visible = subfloor;
+                }
+
+                if (sprite.LayerMapTryGet(Layers.FirstLayer, out var firstLayer))
+                {
+                    sprite.LayerSetVisible(firstLayer, true);
+                }
+            }
+        }
+
+        public enum Layers : byte
+        {
+            FirstLayer,
+        }
+    }
+}