Replace square with cone for Basic Arrow Tower.

Assets/_Project/Scripts/Visuals.meta

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Assets/_Project/Scripts/Visuals/ConeMesh.cs

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+// Assets/_Project/Scripts/Visuals/ConeMesh.cs
+using UnityEngine;
+
+namespace TD.Visuals
+{
+    /// <summary>
+    /// Procedurally generates a cone mesh and assigns it to the GameObject's
+    /// <see cref="MeshFilter"/>. Unity ships no built-in cone primitive, so this
+    /// fills that gap for tower visuals (e.g. the Basic Arrow Tower).
+    /// </summary>
+    /// <remarks>
+    /// <b>Visual only.</b> No networking, no collision — the mesh is purely cosmetic.
+    /// The existing MeshRenderer + material (and any owner/paint tinting via
+    /// <c>TowerInstance.tintedRenderers</c>) keep working unchanged.
+    ///
+    /// <b>Pivot.</b> The cone is centred on the local origin: its base ring sits at
+    /// <c>y = -height/2</c> and its apex at <c>y = +height/2</c>, matching the vertical
+    /// extents of a unit cube so it sits on a build tile the same way the old cube did.
+    ///
+    /// <b>Edit-time.</b> <c>[ExecuteAlways]</c> rebuilds the mesh in the editor so the
+    /// cone is visible without entering play mode. The generated mesh is flagged
+    /// <c>HideFlags.DontSave</c> so it is never written out as a project asset.
+    /// </remarks>
+    [ExecuteAlways]
+    [RequireComponent(typeof(MeshFilter))]
+    public class ConeMesh : MonoBehaviour
+    {
+        [Tooltip("Number of radial segments around the base. Higher = smoother circle.")]
+        [Range(3, 64)]
+        [SerializeField] private int sides = 16;
+
+        [Tooltip("Radius of the cone's base in local units.")]
+        [Min(0.001f)]
+        [SerializeField] private float radius = 0.5f;
+
+        [Tooltip("Height of the cone from base to apex in local units.")]
+        [Min(0.001f)]
+        [SerializeField] private float height = 1f;
+
+        private Mesh mesh;
+
+        private void OnEnable() => Rebuild();
+
+        private void OnValidate()
+        {
+            // OnValidate can fire before OnEnable in the editor; guard the component.
+            if (isActiveAndEnabled) Rebuild();
+        }
+
+        private void OnDisable()
+        {
+            // Clean up the generated mesh so it doesn't linger when the object is destroyed.
+            if (mesh != null)
+            {
+                if (Application.isPlaying) Destroy(mesh);
+                else DestroyImmediate(mesh);
+                mesh = null;
+            }
+        }
+
+        private void Rebuild()
+        {
+            var filter = GetComponent<MeshFilter>();
+            if (filter == null) return;
+
+            if (mesh == null)
+            {
+                mesh = new Mesh { name = "ProceduralCone", hideFlags = HideFlags.DontSave };
+            }
+
+            BuildCone(mesh);
+            filter.sharedMesh = mesh;
+        }
+
+        private void BuildCone(Mesh target)
+        {
+            target.Clear();
+
+            float halfHeight = height * 0.5f;
+
+            // Vertex layout:
+            //   [0 .. sides-1]      base ring
+            //   [sides]             apex
+            //   [sides + 1]         base centre (for the bottom cap)
+            int baseRingStart = 0;
+            int apexIndex = sides;
+            int baseCentreIndex = sides + 1;
+
+            var vertices = new Vector3[sides + 2];
+            for (int i = 0; i < sides; i++)
+            {
+                float angle = (i / (float)sides) * Mathf.PI * 2f;
+                vertices[baseRingStart + i] = new Vector3(
+                    Mathf.Cos(angle) * radius,
+                    -halfHeight,
+                    Mathf.Sin(angle) * radius);
+            }
+            vertices[apexIndex] = new Vector3(0f, halfHeight, 0f);
+            vertices[baseCentreIndex] = new Vector3(0f, -halfHeight, 0f);
+
+            // Side faces (base ring -> apex) + base cap (fan from centre).
+            // Wind both so they face outward / downward respectively.
+            var triangles = new int[sides * 3 * 2];
+            int t = 0;
+            for (int i = 0; i < sides; i++)
+            {
+                int next = (i + 1) % sides;
+
+                // Side triangle, outward-facing.
+                triangles[t++] = baseRingStart + i;
+                triangles[t++] = apexIndex;
+                triangles[t++] = baseRingStart + next;
+
+                // Base cap triangle, downward-facing.
+                triangles[t++] = baseCentreIndex;
+                triangles[t++] = baseRingStart + next;
+                triangles[t++] = baseRingStart + i;
+            }
+
+            target.vertices = vertices;
+            target.triangles = triangles;
+            target.RecalculateNormals();
+            target.RecalculateBounds();
+        }
+    }
+}

Assets/_Project/Scripts/Visuals/ConeMesh.cs.meta

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