Adding major combat changes and features

Assets/_Project/Scripts/Combat/TowerRangeIndicator.cs

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+// Assets/_Project/Scripts/Combat/TowerRangeIndicator.cs
+using UnityEngine;
+using UnityEngine.Rendering.Universal;
+using TD.Gameplay;
+
+namespace TD.Combat
+{
+    /// <summary>
+    /// Displays a translucent decal circle representing this tower's attack range
+    /// when the local player selects the tower.
+    /// </summary>
+    /// <remarks>
+    /// <b>Visual only.</b> No networking — selection is a local UI concept.
+    /// All clients independently show the range indicator for whatever tower
+    /// they have selected.
+    ///
+    /// <b>Prefab setup:</b>
+    /// <list type="number">
+    ///   <item>Add this component to the tower prefab root (alongside TowerInstance).</item>
+    ///   <item>Add a child GameObject named "RangeIndicator".</item>
+    ///   <item>Add a <c>DecalProjector</c> to that child and assign it to
+    ///         <see cref="rangeProjector"/> (or leave it unassigned — auto-found
+    ///         via <c>GetComponentInChildren</c> in Start).</item>
+    ///   <item>Assign a translucent range-circle material to the DecalProjector.</item>
+    /// </list>
+    ///
+    /// <b>Sizing:</b> The projector diameter is set once in <c>Start</c> from
+    /// <c>TowerDefinition.Range</c>. Towers are static, so no per-frame resize is needed.
+    ///
+    /// <b>Subscription timing:</b> Follows the same deferred-subscribe pattern as
+    /// <see cref="SelectionVisualizer"/> — retries until <see cref="SelectionState"/>
+    /// is available, then stops polling.
+    /// </remarks>
+    public class TowerRangeIndicator : MonoBehaviour
+    {
+        [Tooltip("DecalProjector used to render the range circle on the ground. " +
+                 "Auto-found via GetComponentInChildren if left empty.")]
+        [SerializeField] private DecalProjector rangeProjector;
+
+        [Tooltip("Vertical extent of the decal projection volume in world units. " +
+                 "Must be tall enough to project onto terrain at any height in your map.")]
+        [SerializeField] private float projectionDepth = 50f;
+
+        private TowerInstance towerInstance;
+        private bool          subscribed;
+
+        // ----- Lifecycle ---------------------------------------------------
+
+        private void Start()
+        {
+            towerInstance = GetComponent<TowerInstance>();
+            if (towerInstance == null)
+            {
+                Debug.LogError("[TowerRangeIndicator] No TowerInstance found on this " +
+                               "GameObject. TowerRangeIndicator must sit on the same " +
+                               "prefab root as TowerInstance.");
+                enabled = false;
+                return;
+            }
+
+            if (rangeProjector == null)
+                rangeProjector = GetComponentInChildren<DecalProjector>();
+            if (rangeProjector == null)
+            {
+                Debug.LogError("[TowerRangeIndicator] No DecalProjector found. " +
+                               "Add one as a child of this GameObject and assign it " +
+                               "to the rangeProjector field.");
+                enabled = false;
+                return;
+            }
+
+            // TowerInstance resolves its Definition in OnNetworkSpawn, which runs
+            // before Start, so Definition is guaranteed available here.
+            float range    = towerInstance.Definition != null ? towerInstance.Definition.Range : 0f;
+            float diameter = range * 2f;
+
+            rangeProjector.size  = new Vector3(diameter, diameter, projectionDepth);
+            rangeProjector.pivot = Vector3.zero;
+
+            // DecalProjector projects along its local +Z axis; rotate 90° around X
+            // to project downward onto the ground plane.
+            rangeProjector.transform.localRotation = Quaternion.Euler(90f, 0f, 0f);
+            rangeProjector.transform.localPosition = Vector3.zero;
+
+            rangeProjector.enabled = false;
+
+            TrySubscribe();
+        }
+
+        private void OnDestroy()
+        {
+            Unsubscribe();
+        }
+
+        private void Update()
+        {
+            // Retry subscription each frame until SelectionState is ready.
+            // Once subscribed the branch short-circuits immediately.
+            if (!subscribed) TrySubscribe();
+        }
+
+        // ----- Subscription -----------------------------------------------
+
+        private void TrySubscribe()
+        {
+            if (subscribed) return;
+            var sel = SelectionState.Instance;
+            if (sel == null) return;
+
+            sel.OnSelectionChanged += HandleSelectionChanged;
+            subscribed = true;
+
+            // Catch whatever is already selected before we subscribed.
+            HandleSelectionChanged(sel.SelectedObject);
+        }
+
+        private void Unsubscribe()
+        {
+            if (!subscribed) return;
+            var sel = SelectionState.Instance;
+            if (sel != null) sel.OnSelectionChanged -= HandleSelectionChanged;
+            subscribed = false;
+        }
+
+        // ----- Selection handler ------------------------------------------
+
+        private void HandleSelectionChanged(ISelectable newSelection)
+        {
+            if (rangeProjector == null) return;
+
+            // Show only when THIS tower's TowerInstance is the selected object.
+            rangeProjector.enabled = (object)newSelection == (object)towerInstance;
+        }
+    }
+}