Update README with project details and setup instructions; add data directories to .gitignore

src/TheLivingWorld.Core/Systems/ComputeBoundsSystem.cs

@@ -0,0 +1,31 @@
+using Arch.Core;
+using TheLivingWorld.Core.Ecs;
+using TheLivingWorld.Core.Geo;
+using TheLivingWorld.Core.Worlds;
+
+namespace TheLivingWorld.Core.Systems;
+
+/// <summary>Fills every feature's cached world-space extent from the geometry it points at.</summary>
+public sealed class ComputeBoundsSystem : IWorldSystem
+{
+    private static readonly QueryDescription AreaFeatures = new QueryDescription().WithAll<Outline, Bounds>();
+    private static readonly QueryDescription LineFeatures = new QueryDescription().WithAll<Polyline, Bounds>();
+
+    public string Name => nameof(ComputeBoundsSystem);
+
+    public void Execute(GameWorld world)
+    {
+        var shapes = world.Shapes;
+
+        // Holes are contained by their outline, so the outline alone determines the extent.
+        world.Ecs.Query(in AreaFeatures, (ref Outline outline, ref Bounds bounds) =>
+        {
+            bounds.Value = RectBounds.FromPoints(shapes.Get(outline.ShapeId));
+        });
+
+        world.Ecs.Query(in LineFeatures, (ref Polyline line, ref Bounds bounds) =>
+        {
+            bounds.Value = RectBounds.FromPoints(shapes.Get(line.ShapeId));
+        });
+    }
+}