Eris low walls & windows.

Still needs work blocked by better entity parenting, but oh well.

Content.Client/EntryPoint.cs

@@ -109,6 +109,8 @@ namespace Content.Client
             factory.Register<ConstructorComponent>();
             factory.Register<ConstructionGhostComponent>();
             factory.Register<IconSmoothComponent>();
+            factory.Register<LowWallComponent>();
+            factory.RegisterReference<LowWallComponent, IconSmoothComponent>();
             factory.Register<DamageableComponent>();
             factory.Register<ClothingComponent>();
             factory.Register<ItemComponent>();
@@ -159,6 +161,8 @@ namespace Content.Client
             factory.Register<ExaminerComponent>();
             factory.Register<CharacterInfoComponent>();
 
+            factory.Register<WindowComponent>();
+
             IoCManager.Register<IGameHud, GameHud>();
             IoCManager.Register<IClientNotifyManager, ClientNotifyManager>();
             IoCManager.Register<ISharedNotifyManager, ClientNotifyManager>();

Content.Client/GameObjects/Components/IconSmoothing/IconSmoothComponent.cs

@@ -1,10 +1,14 @@
-using System.Diagnostics.CodeAnalysis;
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using Content.Client.GameObjects.EntitySystems;
 using JetBrains.Annotations;
 using Robust.Client.Interfaces.GameObjects.Components;
 using Robust.Shared.GameObjects;
 using Robust.Shared.GameObjects.Components.Transform;
+using Robust.Shared.Interfaces.GameObjects;
 using Robust.Shared.Map;
+using Robust.Shared.Maths;
 using Robust.Shared.Serialization;
 using static Robust.Client.GameObjects.SpriteComponent;
 
@@ -21,7 +25,7 @@ namespace Content.Client.GameObjects.Components.IconSmoothing
     ///     To use, set <c>base</c> equal to the prefix of the corner states in the sprite base RSI.
     ///     Any objects with the same <c>key</c> will connect.
     /// </remarks>
-    public sealed class IconSmoothComponent : Component
+    public class IconSmoothComponent : Component
     {
         private string _smoothKey;
         private string _stateBase;
@@ -76,9 +80,9 @@ namespace Content.Client.GameObjects.Components.IconSmoothing
 
             SnapGrid.OnPositionChanged += SnapGridOnPositionChanged;
             Owner.EntityManager.RaiseEvent(Owner, new IconSmoothDirtyEvent(null, SnapGrid.Offset, Mode));
-            var state0 = $"{StateBase}0";
             if (Mode == IconSmoothingMode.Corners)
             {
+                var state0 = $"{StateBase}0";
                 Sprite.LayerMapSet(CornerLayers.SE, Sprite.AddLayerState(state0));
                 Sprite.LayerSetDirOffset(CornerLayers.SE, DirectionOffset.None);
                 Sprite.LayerMapSet(CornerLayers.NE, Sprite.AddLayerState(state0));
@@ -90,6 +94,107 @@ namespace Content.Client.GameObjects.Components.IconSmoothing
             }
         }
 
+        internal virtual void CalculateNewSprite()
+        {
+            switch (Mode)
+            {
+                case IconSmoothingMode.Corners:
+                    CalculateNewSpriteCorers();
+                    break;
+
+                case IconSmoothingMode.CardinalFlags:
+                    CalculateNewSpriteCardinal();
+                    break;
+
+                default:
+                    throw new ArgumentOutOfRangeException();
+            }
+        }
+
+        private void CalculateNewSpriteCardinal()
+        {
+            var dirs = CardinalConnectDirs.None;
+
+            if (MatchingEntity(SnapGrid.GetInDir(Direction.North)))
+                dirs |= CardinalConnectDirs.North;
+            if (MatchingEntity(SnapGrid.GetInDir(Direction.South)))
+                dirs |= CardinalConnectDirs.South;
+            if (MatchingEntity(SnapGrid.GetInDir(Direction.East)))
+                dirs |= CardinalConnectDirs.East;
+            if (MatchingEntity(SnapGrid.GetInDir(Direction.West)))
+                dirs |= CardinalConnectDirs.West;
+
+            Sprite.LayerSetState(0, $"{StateBase}{(int) dirs}");
+        }
+
+        private void CalculateNewSpriteCorers()
+        {
+            var n = MatchingEntity(SnapGrid.GetInDir(Direction.North));
+            var ne = MatchingEntity(SnapGrid.GetInDir(Direction.NorthEast));
+            var e = MatchingEntity(SnapGrid.GetInDir(Direction.East));
+            var se = MatchingEntity(SnapGrid.GetInDir(Direction.SouthEast));
+            var s = MatchingEntity(SnapGrid.GetInDir(Direction.South));
+            var sw = MatchingEntity(SnapGrid.GetInDir(Direction.SouthWest));
+            var w = MatchingEntity(SnapGrid.GetInDir(Direction.West));
+            var nw = MatchingEntity(SnapGrid.GetInDir(Direction.NorthWest));
+
+            // ReSharper disable InconsistentNaming
+            var cornerNE = CornerFill.None;
+            var cornerSE = CornerFill.None;
+            var cornerSW = CornerFill.None;
+            var cornerNW = CornerFill.None;
+            // ReSharper restore InconsistentNaming
+
+            if (n)
+            {
+                cornerNE |= CornerFill.CounterClockwise;
+                cornerNW |= CornerFill.Clockwise;
+            }
+
+            if (ne)
+            {
+                cornerNE |= CornerFill.Diagonal;
+            }
+
+            if (e)
+            {
+                cornerNE |= CornerFill.Clockwise;
+                cornerSE |= CornerFill.CounterClockwise;
+            }
+
+            if (se)
+            {
+                cornerSE |= CornerFill.Diagonal;
+            }
+
+            if (s)
+            {
+                cornerSE |= CornerFill.Clockwise;
+                cornerSW |= CornerFill.CounterClockwise;
+            }
+
+            if (sw)
+            {
+                cornerSW |= CornerFill.Diagonal;
+            }
+
+            if (w)
+            {
+                cornerSW |= CornerFill.Clockwise;
+                cornerNW |= CornerFill.CounterClockwise;
+            }
+
+            if (nw)
+            {
+                cornerNW |= CornerFill.Diagonal;
+            }
+
+            Sprite.LayerSetState(CornerLayers.NE, $"{StateBase}{(int) cornerNE}");
+            Sprite.LayerSetState(CornerLayers.SE, $"{StateBase}{(int) cornerSE}");
+            Sprite.LayerSetState(CornerLayers.SW, $"{StateBase}{(int) cornerSW}");
+            Sprite.LayerSetState(CornerLayers.NW, $"{StateBase}{(int) cornerNW}");
+        }
+
         public override void Shutdown()
         {
             SnapGrid.OnPositionChanged -= SnapGridOnPositionChanged;
@@ -104,6 +209,52 @@ namespace Content.Client.GameObjects.Components.IconSmoothing
             _lastPosition = (Owner.Transform.GridID, SnapGrid.Position);
         }
 
+        [System.Diagnostics.Contracts.Pure]
+        protected bool MatchingEntity(IEnumerable<IEntity> candidates)
+        {
+            foreach (var entity in candidates)
+            {
+                if (!entity.TryGetComponent(out IconSmoothComponent other))
+                {
+                    continue;
+                }
+
+                if (other.SmoothKey == SmoothKey)
+                {
+                    return true;
+                }
+            }
+
+            return false;
+        }
+
+        [Flags]
+        private enum CardinalConnectDirs : byte
+        {
+            None = 0,
+            North = 1,
+            South = 2,
+            East = 4,
+            West = 8
+        }
+
+        [Flags]
+        public enum CornerFill : byte
+        {
+            // These values are pulled from Baystation12.
+            // I'm too lazy to convert the state names.
+            None = 0,
+
+            // The cardinal tile counter-clockwise of this corner is filled.
+            CounterClockwise = 1,
+
+            // The diagonal tile in the direction of this corner.
+            Diagonal = 2,
+
+            // The cardinal tile clockwise of this corner is filled.
+            Clockwise = 4,
+        }
+
         [SuppressMessage("ReSharper", "InconsistentNaming")]
         public enum CornerLayers
         {

Content.Client/GameObjects/Components/LowWallComponent.cs

@@ -0,0 +1,206 @@
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using Content.Client.GameObjects.Components.IconSmoothing;
+using Robust.Shared.Interfaces.GameObjects;
+using Robust.Shared.Maths;
+using static Robust.Client.GameObjects.SpriteComponent;
+
+namespace Content.Client.GameObjects.Components
+{
+    // TODO: Over layers should be placed ABOVE the window itself too.
+    // This is gonna require a client entity & parenting,
+    // so IsMapTransform being naive is gonna be a problem.
+
+    /// <summary>
+    ///     Override of icon smoothing to handle the specific complexities of low walls.
+    /// </summary>
+    public class LowWallComponent : IconSmoothComponent
+    {
+        public override string Name => "LowWall";
+
+        public CornerFill LastCornerNE { get; private set; }
+        public CornerFill LastCornerSE { get; private set; }
+        public CornerFill LastCornerSW { get; private set; }
+        public CornerFill LastCornerNW { get; private set; }
+
+        public override void Startup()
+        {
+            base.Startup();
+
+            var overState0 = $"{StateBase}over_0";
+            Sprite.LayerMapSet(OverCornerLayers.SE, Sprite.AddLayerState(overState0));
+            Sprite.LayerSetDirOffset(OverCornerLayers.SE, DirectionOffset.None);
+            Sprite.LayerMapSet(OverCornerLayers.NE, Sprite.AddLayerState(overState0));
+            Sprite.LayerSetDirOffset(OverCornerLayers.NE, DirectionOffset.CounterClockwise);
+            Sprite.LayerMapSet(OverCornerLayers.NW, Sprite.AddLayerState(overState0));
+            Sprite.LayerSetDirOffset(OverCornerLayers.NW, DirectionOffset.Flip);
+            Sprite.LayerMapSet(OverCornerLayers.SW, Sprite.AddLayerState(overState0));
+            Sprite.LayerSetDirOffset(OverCornerLayers.SW, DirectionOffset.Clockwise);
+        }
+
+        internal override void CalculateNewSprite()
+        {
+            base.CalculateNewSprite();
+
+            var (n, nl) = MatchingWall(SnapGrid.GetInDir(Direction.North));
+            var (ne, nel) = MatchingWall(SnapGrid.GetInDir(Direction.NorthEast));
+            var (e, el) = MatchingWall(SnapGrid.GetInDir(Direction.East));
+            var (se, sel) = MatchingWall(SnapGrid.GetInDir(Direction.SouthEast));
+            var (s, sl) = MatchingWall(SnapGrid.GetInDir(Direction.South));
+            var (sw, swl) = MatchingWall(SnapGrid.GetInDir(Direction.SouthWest));
+            var (w, wl) = MatchingWall(SnapGrid.GetInDir(Direction.West));
+            var (nw, nwl) = MatchingWall(SnapGrid.GetInDir(Direction.NorthWest));
+
+            // ReSharper disable InconsistentNaming
+            var cornerNE = CornerFill.None;
+            var cornerSE = CornerFill.None;
+            var cornerSW = CornerFill.None;
+            var cornerNW = CornerFill.None;
+
+            var lowCornerNE = CornerFill.None;
+            var lowCornerSE = CornerFill.None;
+            var lowCornerSW = CornerFill.None;
+            var lowCornerNW = CornerFill.None;
+            // ReSharper restore InconsistentNaming
+
+            if (n)
+            {
+                cornerNE |= CornerFill.CounterClockwise;
+                cornerNW |= CornerFill.Clockwise;
+
+                if (!nl)
+                {
+                    lowCornerNE |= CornerFill.CounterClockwise;
+                    lowCornerNW |= CornerFill.Clockwise;
+                }
+            }
+
+            if (ne)
+            {
+                cornerNE |= CornerFill.Diagonal;
+
+                if (!nel && (nl || el || n && e))
+                {
+                    lowCornerNE |= CornerFill.Diagonal;
+                }
+            }
+
+            if (e)
+            {
+                cornerNE |= CornerFill.Clockwise;
+                cornerSE |= CornerFill.CounterClockwise;
+
+                if (!el)
+                {
+                    lowCornerNE |= CornerFill.Clockwise;
+                    lowCornerSE |= CornerFill.CounterClockwise;
+                }
+            }
+
+            if (se)
+            {
+                cornerSE |= CornerFill.Diagonal;
+
+                if (!sel && (sl || el || s && e))
+                {
+                    lowCornerSE |= CornerFill.Diagonal;
+                }
+            }
+
+            if (s)
+            {
+                cornerSE |= CornerFill.Clockwise;
+                cornerSW |= CornerFill.CounterClockwise;
+
+                if (!sl)
+                {
+                    lowCornerSE |= CornerFill.Clockwise;
+                    lowCornerSW |= CornerFill.CounterClockwise;
+                }
+            }
+
+            if (sw)
+            {
+                cornerSW |= CornerFill.Diagonal;
+
+                if (!swl && (sl || wl || s && w))
+                {
+                    lowCornerSW |= CornerFill.Diagonal;
+                }
+            }
+
+            if (w)
+            {
+                cornerSW |= CornerFill.Clockwise;
+                cornerNW |= CornerFill.CounterClockwise;
+
+                if (!wl)
+                {
+                    lowCornerSW |= CornerFill.Clockwise;
+                    lowCornerNW |= CornerFill.CounterClockwise;
+                }
+            }
+
+            if (nw)
+            {
+                cornerNW |= CornerFill.Diagonal;
+
+                if (!nwl && (nl || wl || n && w))
+                {
+                    lowCornerNW |= CornerFill.Diagonal;
+                }
+            }
+
+            Sprite.LayerSetState(CornerLayers.NE, $"{StateBase}{(int) cornerNE}");
+            Sprite.LayerSetState(CornerLayers.SE, $"{StateBase}{(int) cornerSE}");
+            Sprite.LayerSetState(CornerLayers.SW, $"{StateBase}{(int) cornerSW}");
+            Sprite.LayerSetState(CornerLayers.NW, $"{StateBase}{(int) cornerNW}");
+
+            Sprite.LayerSetState(OverCornerLayers.NE, $"{StateBase}over_{(int) lowCornerNE}");
+            Sprite.LayerSetState(OverCornerLayers.SE, $"{StateBase}over_{(int) lowCornerSE}");
+            Sprite.LayerSetState(OverCornerLayers.SW, $"{StateBase}over_{(int) lowCornerSW}");
+            Sprite.LayerSetState(OverCornerLayers.NW, $"{StateBase}over_{(int) lowCornerNW}");
+
+            LastCornerNE = cornerNE;
+            LastCornerSE = cornerSE;
+            LastCornerSW = cornerSW;
+            LastCornerNW = cornerNW;
+
+            foreach (var entity in SnapGrid.GetLocal())
+            {
+                if (entity.TryGetComponent(out WindowComponent window))
+                {
+                    window.UpdateSprite();
+                }
+            }
+        }
+
+        [System.Diagnostics.Contracts.Pure]
+        private (bool connected, bool lowWall) MatchingWall(IEnumerable<IEntity> candidates)
+        {
+            foreach (var entity in candidates)
+            {
+                if (!entity.TryGetComponent(out IconSmoothComponent other))
+                {
+                    continue;
+                }
+
+                if (other.SmoothKey == SmoothKey)
+                {
+                    return (true, other is LowWallComponent);
+                }
+            }
+
+            return (false, false);
+        }
+
+        [SuppressMessage("ReSharper", "InconsistentNaming")]
+        private enum OverCornerLayers
+        {
+            SE,
+            NE,
+            NW,
+            SW,
+        }
+    }
+}

Content.Client/GameObjects/Components/WindowComponent.cs

@@ -0,0 +1,91 @@
+using Content.Client.GameObjects.EntitySystems;
+using Robust.Client.GameObjects;
+using Robust.Client.Interfaces.GameObjects.Components;
+using Robust.Shared.GameObjects;
+using Robust.Shared.GameObjects.Components.Transform;
+using Robust.Shared.Serialization;
+using static Content.Client.GameObjects.Components.IconSmoothing.IconSmoothComponent;
+
+namespace Content.Client.GameObjects.Components
+{
+    public sealed class WindowComponent : Component
+    {
+        public override string Name => "Window";
+
+        private string _stateBase;
+        private ISpriteComponent _sprite;
+        private SnapGridComponent _snapGrid;
+
+        public override void Initialize()
+        {
+            base.Initialize();
+
+            _sprite = Owner.GetComponent<ISpriteComponent>();
+            _snapGrid = Owner.GetComponent<SnapGridComponent>();
+        }
+
+        public override void Startup()
+        {
+            base.Startup();
+
+            _snapGrid.OnPositionChanged += SnapGridOnPositionChanged;
+            Owner.EntityManager.RaiseEvent(Owner, new WindowSmoothDirtyEvent());
+
+            var state0 = $"{_stateBase}0";
+            _sprite.LayerMapSet(CornerLayers.SE, _sprite.AddLayerState(state0));
+            _sprite.LayerSetDirOffset(CornerLayers.SE, SpriteComponent.DirectionOffset.None);
+            _sprite.LayerMapSet(CornerLayers.NE, _sprite.AddLayerState(state0));
+            _sprite.LayerSetDirOffset(CornerLayers.NE, SpriteComponent.DirectionOffset.CounterClockwise);
+            _sprite.LayerMapSet(CornerLayers.NW, _sprite.AddLayerState(state0));
+            _sprite.LayerSetDirOffset(CornerLayers.NW, SpriteComponent.DirectionOffset.Flip);
+            _sprite.LayerMapSet(CornerLayers.SW, _sprite.AddLayerState(state0));
+            _sprite.LayerSetDirOffset(CornerLayers.SW, SpriteComponent.DirectionOffset.Clockwise);
+        }
+
+        public override void Shutdown()
+        {
+            _snapGrid.OnPositionChanged -= SnapGridOnPositionChanged;
+
+            base.Shutdown();
+        }
+
+        private void SnapGridOnPositionChanged()
+        {
+            Owner.EntityManager.RaiseEvent(Owner, new WindowSmoothDirtyEvent());
+        }
+
+        public void UpdateSprite()
+        {
+            var lowWall = FindLowWall();
+            if (lowWall == null)
+            {
+                return;
+            }
+
+            _sprite.LayerSetState(CornerLayers.NE, $"{_stateBase}{(int) lowWall.LastCornerNE}");
+            _sprite.LayerSetState(CornerLayers.SE, $"{_stateBase}{(int) lowWall.LastCornerSE}");
+            _sprite.LayerSetState(CornerLayers.SW, $"{_stateBase}{(int) lowWall.LastCornerSW}");
+            _sprite.LayerSetState(CornerLayers.NW, $"{_stateBase}{(int) lowWall.LastCornerNW}");
+        }
+
+        private LowWallComponent FindLowWall()
+        {
+            foreach (var entity in _snapGrid.GetLocal())
+            {
+                if (entity.TryGetComponent(out LowWallComponent lowWall))
+                {
+                    return lowWall;
+                }
+            }
+
+            return null;
+        }
+
+        public override void ExposeData(ObjectSerializer serializer)
+        {
+            base.ExposeData(serializer);
+
+            serializer.DataField(ref _stateBase, "base", null);
+        }
+    }
+}

Content.Client/GameObjects/EntitySystems/IconSmoothSystem.cs

@@ -1,9 +1,7 @@
-using System;
 using System.Collections.Generic;
 using System.Linq;
 using Content.Client.GameObjects.Components.IconSmoothing;
 using JetBrains.Annotations;
-using Robust.Client.Interfaces.GameObjects.Components;
 using Robust.Shared.GameObjects;
 using Robust.Shared.GameObjects.Components.Transform;
 using Robust.Shared.GameObjects.Systems;
@@ -132,157 +130,10 @@ namespace Content.Client.GameObjects.EntitySystems
                 return;
             }
 
-            var sprite = smoothing.Sprite;
+            smoothing.CalculateNewSprite();
-            var snapGrid = smoothing.SnapGrid;
-
-            switch (smoothing.Mode)
-            {
-                case IconSmoothingMode.Corners:
-                    _calculateNewSpriteCorers(smoothing, snapGrid, sprite);
-                    break;
-
-                case IconSmoothingMode.CardinalFlags:
-                    _calculateNewSpriteCardinal(smoothing, snapGrid, sprite);
-                    break;
-
-                default:
-                    throw new ArgumentOutOfRangeException();
-            }
 
             smoothing.UpdateGeneration = _generation;
         }
-
-        private static void _calculateNewSpriteCardinal(IconSmoothComponent smoothing, SnapGridComponent snapGrid,
-            ISpriteComponent sprite)
-        {
-            var dirs = CardinalConnectDirs.None;
-
-            if (MatchingEntity(smoothing, snapGrid.GetInDir(Direction.North)))
-                dirs |= CardinalConnectDirs.North;
-            if (MatchingEntity(smoothing, snapGrid.GetInDir(Direction.South)))
-                dirs |= CardinalConnectDirs.South;
-            if (MatchingEntity(smoothing, snapGrid.GetInDir(Direction.East)))
-                dirs |= CardinalConnectDirs.East;
-            if (MatchingEntity(smoothing, snapGrid.GetInDir(Direction.West)))
-                dirs |= CardinalConnectDirs.West;
-
-            sprite.LayerSetState(0, $"{smoothing.StateBase}{(int) dirs}");
-        }
-
-        private static void _calculateNewSpriteCorers(IconSmoothComponent smoothing, SnapGridComponent snapGrid,
-            ISpriteComponent sprite)
-        {
-            var n = MatchingEntity(smoothing, snapGrid.GetInDir(Direction.North));
-            var ne = MatchingEntity(smoothing, snapGrid.GetInDir(Direction.NorthEast));
-            var e = MatchingEntity(smoothing, snapGrid.GetInDir(Direction.East));
-            var se = MatchingEntity(smoothing, snapGrid.GetInDir(Direction.SouthEast));
-            var s = MatchingEntity(smoothing, snapGrid.GetInDir(Direction.South));
-            var sw = MatchingEntity(smoothing, snapGrid.GetInDir(Direction.SouthWest));
-            var w = MatchingEntity(smoothing, snapGrid.GetInDir(Direction.West));
-            var nw = MatchingEntity(smoothing, snapGrid.GetInDir(Direction.NorthWest));
-
-            // ReSharper disable InconsistentNaming
-            var cornerNE = CornerFill.None;
-            var cornerSE = CornerFill.None;
-            var cornerSW = CornerFill.None;
-            var cornerNW = CornerFill.None;
-            // ReSharper restore InconsistentNaming
-
-            if (n)
-            {
-                cornerNE |= CornerFill.CounterClockwise;
-                cornerNW |= CornerFill.Clockwise;
-            }
-
-            if (ne)
-            {
-                cornerNE |= CornerFill.Diagonal;
-            }
-
-            if (e)
-            {
-                cornerNE |= CornerFill.Clockwise;
-                cornerSE |= CornerFill.CounterClockwise;
-            }
-
-            if (se)
-            {
-                cornerSE |= CornerFill.Diagonal;
-            }
-
-            if (s)
-            {
-                cornerSE |= CornerFill.Clockwise;
-                cornerSW |= CornerFill.CounterClockwise;
-            }
-
-            if (sw)
-            {
-                cornerSW |= CornerFill.Diagonal;
-            }
-
-            if (w)
-            {
-                cornerSW |= CornerFill.Clockwise;
-                cornerNW |= CornerFill.CounterClockwise;
-            }
-
-            if (nw)
-            {
-                cornerNW |= CornerFill.Diagonal;
-            }
-
-            sprite.LayerSetState(IconSmoothComponent.CornerLayers.NE, $"{smoothing.StateBase}{(int) cornerNE}");
-            sprite.LayerSetState(IconSmoothComponent.CornerLayers.SE, $"{smoothing.StateBase}{(int) cornerSE}");
-            sprite.LayerSetState(IconSmoothComponent.CornerLayers.SW, $"{smoothing.StateBase}{(int) cornerSW}");
-            sprite.LayerSetState(IconSmoothComponent.CornerLayers.NW, $"{smoothing.StateBase}{(int) cornerNW}");
-        }
-
-        [System.Diagnostics.Contracts.Pure]
-        private static bool MatchingEntity(IconSmoothComponent source, IEnumerable<IEntity> candidates)
-        {
-            foreach (var entity in candidates)
-            {
-                if (!entity.TryGetComponent(out IconSmoothComponent other))
-                {
-                    return false;
-                }
-
-                if (other.SmoothKey == source.SmoothKey)
-                {
-                    return true;
-                }
-            }
-
-            return false;
-        }
-
-        [Flags]
-        private enum CardinalConnectDirs : byte
-        {
-            None = 0,
-            North = 1,
-            South = 2,
-            East = 4,
-            West = 8
-        }
-
-        [Flags]
-        private enum CornerFill : byte
-        {
-            // These values are pulled from Baystation12.
-            // I'm too lazy to convert the state names.
-            None = 0,
-
-            // The cardinal tile counter-clockwise of this corner is filled.
-            CounterClockwise = 1,
-
-            // The diagonal tile in the direction of this corner.
-            Diagonal = 2,
-
-            // The cardinal tile clockwise of this corner is filled.
-            Clockwise = 4,
-        }
     }
 
     /// <summary>

Content.Client/GameObjects/EntitySystems/WindowSystem.cs

@@ -0,0 +1,51 @@
+using System.Collections.Generic;
+using Content.Client.GameObjects.Components;
+using Content.Client.GameObjects.Components.IconSmoothing;
+using JetBrains.Annotations;
+using Robust.Shared.GameObjects;
+using Robust.Shared.GameObjects.Components.Transform;
+using Robust.Shared.GameObjects.Systems;
+using Robust.Shared.Interfaces.GameObjects;
+using Robust.Shared.Map;
+
+namespace Content.Client.GameObjects.EntitySystems
+{
+    [UsedImplicitly]
+    public sealed class WindowSystem : EntitySystem
+    {
+        private readonly Queue<IEntity> _dirtyEntities = new Queue<IEntity>();
+
+        public override void Initialize()
+        {
+            base.Initialize();
+
+            SubscribeEvent<WindowSmoothDirtyEvent>(HandleDirtyEvent);
+        }
+
+        private void HandleDirtyEvent(object sender, WindowSmoothDirtyEvent ev)
+        {
+            if (sender is IEntity senderEnt && senderEnt.HasComponent<WindowComponent>())
+            {
+                _dirtyEntities.Enqueue(senderEnt);
+            }
+        }
+
+        public override void FrameUpdate(float frameTime)
+        {
+            base.FrameUpdate(frameTime);
+
+            // Performance: This could be spread over multiple updates, or made parallel.
+            while (_dirtyEntities.Count > 0)
+            {
+                _dirtyEntities.Dequeue().GetComponent<WindowComponent>().UpdateSprite();
+            }
+        }
+    }
+
+    /// <summary>
+    ///     Event raised by a <see cref="WindowComponent"/> when it needs to be recalculated.
+    /// </summary>
+    public sealed class WindowSmoothDirtyEvent : EntitySystemMessage
+    {
+    }
+}

Resources/Prototypes/Entities/walls.yml

@@ -5,7 +5,7 @@
   - type: Clickable
   - type: Sprite
     netsync: false
-    color: "#636769"
+    color: "#71797a"
     drawdepth: Walls
     sprite: Buildings/wall.rsi
 
@@ -23,10 +23,10 @@
     sizeX: 32
     sizeY: 32
   - type: SnapGrid
-    offset: Edge
+    offset: Center
 
   - type: IconSmooth
-    key: walls. Seriously, just a wall. Nothing extraordinary here.
+    key: walls
     base: solid
 
   placement:

Resources/Prototypes/Entities/walls/structures/low_wall.yml

@@ -0,0 +1,32 @@
+- type: entity
+  id: low_wall
+  name: Low Wall
+  description: Goes up to about your waist.
+  components:
+  - type: Clickable
+  - type: Sprite
+    netsync: false
+    color: "#71797a"
+    drawdepth: Walls
+    sprite: Buildings/low_wall.rsi
+
+  - type: Icon
+    sprite: Buildings/low_wall.rsi
+    state: metal
+
+  - type: BoundingBox
+  - type: Collidable
+  - type: Damageable
+  - type: Destructible
+    thresholdvalue: 100
+
+  - type: SnapGrid
+    offset: Center
+
+  - type: LowWall
+    key: walls
+    base: metal_
+
+  placement:
+    snap:
+    - Wall

Resources/Prototypes/Entities/walls/structures/windows.yml

@@ -0,0 +1,30 @@
+- type: entity
+  id: window
+  name: Window
+  description: Don't smudge up the glass down there.
+  components:
+  - type: Clickable
+  - type: Sprite
+    netsync: false
+    drawdepth: WallTops
+    sprite: Buildings/window.rsi
+
+  - type: Icon
+    sprite: Buildings/window.rsi
+    state: window0
+
+  - type: BoundingBox
+  - type: Collidable
+  - type: Damageable
+  - type: Destructible
+    thresholdvalue: 100
+
+  - type: SnapGrid
+    offset: Center
+
+  - type: Window
+    base: window
+
+  placement:
+    snap:
+    - Wall

Resources/Textures/Buildings/low_wall.rsi/meta.json

@@ -0,0 +1 @@
+{"version": 1, "size": {"x": 32, "y": 32}, "license": "CC-BY-SA-3.0", "copyright": "Taken from https://github.com/discordia-space/CEV-Eris/blob/b503939d31b23c025ddb936b75e0a265d85154c5/icons/obj/structures/low_wall.dmi", "states": [{"name": "metal", "directions": 1, "delays": [[1.0]]}, {"name": "metal_0", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "metal_1", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "metal_2", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "metal_3", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "metal_4", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "metal_5", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "metal_6", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "metal_7", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "metal_over_0", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "metal_over_1", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "metal_over_2", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "metal_over_3", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "metal_over_4", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "metal_over_5", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "metal_over_6", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "metal_over_7", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}]}

Resources/Textures/Buildings/rwindow.rsi/meta.json

@@ -0,0 +1 @@
+{"version": 1, "size": {"x": 32, "y": 32}, "license": "CC-BY-SA-3.0", "copyright": "Taken from https://github.com/discordia-space/CEV-Eris/blob/c0293684320e7b70cbcac932b8dddeee35f3a51f/icons/obj/structures/windows.dmi", "states": [{"name": "rwindow0", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "rwindow1", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "rwindow2", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "rwindow3", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "rwindow4", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "rwindow5", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "rwindow6", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "rwindow7", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}]}

Resources/Textures/Buildings/window.rsi/meta.json

@@ -0,0 +1 @@
+{"version": 1, "size": {"x": 32, "y": 32}, "license": "CC-BY-SA-3.0", "copyright": "Taken from https://github.com/discordia-space/CEV-Eris/blob/c0293684320e7b70cbcac932b8dddeee35f3a51f/icons/obj/structures/windows.dmi", "states": [{"name": "window0", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "window1", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "window2", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "window3", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "window4", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "window5", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "window6", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}, {"name": "window7", "directions": 4, "delays": [[1.0], [1.0], [1.0], [1.0]]}]}