building falling from orbit sound

Assets/_Project/Scripts/Combat/TowerFallingSound.cs

@@ -0,0 +1,46 @@
+// Assets/_Project/Scripts/Combat/TowerFallingSound.cs
+using TD.Audio;
+using TD.Gameplay;
+using UnityEngine;
+
+namespace TD.Combat
+{
+    /// <summary>
+    /// Local-only audio for the tower falling from the sky. Attached to
+    /// <see cref="BuildSiteVisual"/> (not <see cref="TowerInstance"/>, which doesn't exist
+    /// yet) and polled every frame: plays a sound on every peer once construction has
+    /// <see cref="triggerSecondsBeforeCompletion"/> seconds or less remaining, so the whoosh
+    /// leads the tower's actual fall/land animation (see <see cref="TowerLandingVisual"/>,
+    /// which starts once <see cref="BuildSiteVisual"/> is replaced by the real
+    /// <see cref="TowerInstance"/> at construction-complete).
+    /// </summary>
+    [RequireComponent(typeof(BuildSiteVisual))]
+    public class TowerFallingSound : MonoBehaviour
+    {
+        [SerializeField] private SoundConfig fallingSound;
+
+        [Tooltip("Sound fires once remaining construction time drops to this many seconds " +
+                 "or less.")]
+        [SerializeField] private float triggerSecondsBeforeCompletion = 1f;
+
+        private BuildSiteVisual buildSiteVisual;
+        private bool played;
+
+        private void Awake()
+        {
+            buildSiteVisual = GetComponent<BuildSiteVisual>();
+        }
+
+        private void Update()
+        {
+            if (played || buildSiteVisual == null) return;
+            if (buildSiteVisual.CurrentStage != BuildStage.Constructing) return;
+
+            if (buildSiteVisual.ComputeRemainingSeconds() <= triggerSecondsBeforeCompletion)
+            {
+                played = true;
+                AudioManager.Instance?.Play(fallingSound.clip, AudioCategory.UI, fallingSound.RandomPitch(), fallingSound.volume);
+            }
+        }
+    }
+}