Minimap!

Assets/_Project/Scripts/UI/Minimap/MinimapEntityRegistry.cs

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+// Assets/_Project/Scripts/UI/Minimap/MinimapEntityRegistry.cs
+using System;
+using System.Collections.Generic;
+using UnityEngine;
+
+namespace TD.UI.Minimap
+{
+    /// <summary>
+    /// Visual category for a minimap entity. Determines the shape and size of the icon drawn
+    /// by <see cref="MinimapView"/>. Color is supplied separately by the entity itself so the
+    /// view does not need to know about ownership / faction mapping.
+    /// </summary>
+    public enum MinimapIconKind : byte
+    {
+        Enemy,
+        Tower,
+        Builder,
+    }
+
+    /// <summary>
+    /// Anything that wants to appear on the minimap as a dynamic icon implements this. The view
+    /// reads every getter on each refresh tick, so values may change between reads (movement is
+    /// fine — no caching needed).
+    /// </summary>
+    public interface IMinimapEntity
+    {
+        Vector3 WorldPosition { get; }
+        Color MinimapColor { get; }
+        MinimapIconKind IconKind { get; }
+
+        /// <summary>
+        /// The entity's diameter (or footprint extent) in world units. The view converts this
+        /// to pixels using the current minimap zoom, so a 2×2 tower will appear as a 2-tile
+        /// square on the minimap and adjacent towers will visually touch — matching their
+        /// world-space relationship. For point-like entities (builders, enemies) the view
+        /// also enforces a minimum pixel size so they stay visible when fully zoomed out.
+        /// </summary>
+        float MinimapWorldSize { get; }
+    }
+
+    /// <summary>
+    /// Static registry of every entity currently visible on the minimap. Entities register
+    /// themselves on spawn and deregister on despawn; the <see cref="MinimapView"/> iterates the
+    /// set on each refresh.
+    /// </summary>
+    /// <remarks>
+    /// Backing store is a <see cref="HashSet{T}"/> so duplicate Register calls are no-ops and
+    /// Deregister is O(1). Iteration uses the struct enumerator via <see cref="ForEach"/> to
+    /// avoid the boxing that would happen if we exposed an <see cref="IEnumerable{T}"/>.
+    ///
+    /// Static lifetime is intentional: the registry survives scene transitions only if entities
+    /// remember to deregister. NGO's <c>OnNetworkDespawn</c> covers that for towers / builders /
+    /// enemies. Manual <see cref="Clear"/> is provided for tests and for explicit reset on match
+    /// teardown if needed.
+    /// </remarks>
+    public static class MinimapEntityRegistry
+    {
+        private static readonly HashSet<IMinimapEntity> s_entities = new HashSet<IMinimapEntity>();
+
+        /// <summary>Number of currently-registered entities. Cheap, no allocation.</summary>
+        public static int Count => s_entities.Count;
+
+        /// <summary>
+        /// Registers <paramref name="entity"/> for minimap rendering. No-op if already registered.
+        /// Safe to call from any thread that Unity allows (i.e., the main thread).
+        /// </summary>
+        public static void Register(IMinimapEntity entity)
+        {
+            if (entity == null) return;
+            s_entities.Add(entity);
+        }
+
+        /// <summary>Removes <paramref name="entity"/> from the registry. No-op if not present.</summary>
+        public static void Deregister(IMinimapEntity entity)
+        {
+            if (entity == null) return;
+            s_entities.Remove(entity);
+        }
+
+        /// <summary>
+        /// Invokes <paramref name="action"/> once per registered entity. Uses HashSet's struct
+        /// enumerator so iteration is allocation-free (the only allocation is the closure that
+        /// <paramref name="action"/> may carry, which is the caller's choice).
+        /// </summary>
+        public static void ForEach(Action<IMinimapEntity> action)
+        {
+            if (action == null) return;
+            foreach (var e in s_entities) action(e);
+        }
+
+        /// <summary>Drops every registered entity. Tests and explicit match-teardown use only.</summary>
+        public static void Clear() => s_entities.Clear();
+    }
+}