decal system & crayons (#5183)

Co-authored-by: Paul <ritter.paul1+git@googlemail.com>

Content.Shared/Decals/Decal.cs

@@ -0,0 +1,38 @@
+using System;
+using Robust.Shared.Maths;
+using Robust.Shared.Serialization;
+using Robust.Shared.Serialization.Manager.Attributes;
+
+namespace Content.Shared.Decals
+{
+    [Serializable, NetSerializable]
+    [DataDefinition]
+    public class Decal
+    {
+        [DataField("coordinates")] public readonly Vector2 Coordinates = Vector2.Zero;
+        [DataField("id")] public readonly string Id = string.Empty;
+        [DataField("color")] public readonly Color? Color;
+        [DataField("angle")] public readonly Angle Angle = Angle.Zero;
+        [DataField("zIndex")] public readonly int ZIndex;
+        [DataField("cleanable")] public bool Cleanable;
+
+        public Decal() {}
+
+        public Decal(Vector2 coordinates, string id, Color? color, Angle angle, int zIndex, bool cleanable)
+        {
+            Coordinates = coordinates;
+            Id = id;
+            Color = color;
+            Angle = angle;
+            ZIndex = zIndex;
+            Cleanable = cleanable;
+        }
+
+        public Decal WithCoordinates(Vector2 coordinates) => new(coordinates, Id, Color, Angle, ZIndex, Cleanable);
+        public Decal WithId(string id) => new(Coordinates, id, Color, Angle, ZIndex, Cleanable);
+        public Decal WithColor(Color? color) => new(Coordinates, Id, color, Angle, ZIndex, Cleanable);
+        public Decal WithRotation(Angle angle) => new(Coordinates, Id, Color, angle, ZIndex, Cleanable);
+        public Decal WithZIndex(int zIndex) => new(Coordinates, Id, Color, Angle, zIndex, Cleanable);
+        public Decal WithCleanable(bool cleanable) => new(Coordinates, Id, Color, Angle, ZIndex, cleanable);
+    }
+}