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Assets/Scripts/Test/Light/Dynamic3DTo2DCollider.cs

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+using UnityEngine;
+using System.Collections.Generic;
+
+public class Dynamic3DTo2DCollider : MonoBehaviour
+{
+    public Camera mainCamera;
+    public GameObject model3D;
+    [Range(4, 32)] public int edgeSegments = 16;
+
+    void Start()
+    {
+        if (mainCamera == null)
+            mainCamera = Camera.main;
+
+        Convert3DTo2DCollider();
+    }
+
+    void Convert3DTo2DCollider()
+    {
+        MeshFilter meshFilter = model3D.GetComponent<MeshFilter>();
+        if (meshFilter == null) return;
+
+        // 获取网格的所有顶点
+        Vector3[] vertices = meshFilter.mesh.vertices;
+        int[] triangles = meshFilter.mesh.triangles;
+
+        // 收集所有在轮廓边缘的顶点
+        List<Vector2> silhouettePoints = GetSilhouettePoints(vertices, triangles);
+
+        if (silhouettePoints.Count > 2)
+        {
+            // 创建2D碰撞器
+            GameObject obj = new GameObject(gameObject.name + "2D");
+            PolygonCollider2D collider2D = obj.AddComponent<PolygonCollider2D>();
+            collider2D.points = silhouettePoints.ToArray();
+
+            // 禁用3D碰撞器
+            Collider collider3D = model3D.GetComponent<Collider>();
+            if (collider3D != null) collider3D.enabled = false;
+        }
+    }
+
+    List<Vector2> GetSilhouettePoints(Vector3[] vertices, int[] triangles)
+    {
+        List<Vector2> screenPoints = new List<Vector2>();
+        HashSet<Vector2> uniquePoints = new HashSet<Vector2>();
+
+        // 转换所有顶点到屏幕空间
+        for (int i = 0; i < vertices.Length; i++)
+        {
+            Vector3 worldPos = model3D.transform.TransformPoint(vertices[i]);
+            Vector2 screenPos = mainCamera.WorldToScreenPoint(worldPos);
+
+            // 只添加在相机前方的点
+            if (IsInFrontOfCamera(worldPos))
+            {
+                uniquePoints.Add(screenPos);
+            }
+        }
+
+        screenPoints.AddRange(uniquePoints);
+
+        // 计算凸包来获得轮廓
+        return CalculateConvexHull(screenPoints);
+    }
+
+    bool IsInFrontOfCamera(Vector3 worldPos)
+    {
+        Vector3 viewportPos = mainCamera.WorldToViewportPoint(worldPos);
+        return viewportPos.z > 0;
+    }
+
+    // 计算凸包的Graham Scan算法
+    List<Vector2> CalculateConvexHull(List<Vector2> points)
+    {
+        if (points.Count < 3) return points;
+
+        // 找到最左下角的点
+        Vector2 pivot = points[0];
+        for (int i = 1; i < points.Count; i++)
+        {
+            if (points[i].y < pivot.y || (points[i].y == pivot.y && points[i].x < pivot.x))
+                pivot = points[i];
+        }
+
+        // 按极角排序
+        points.Sort((a, b) =>
+        {
+            float angleA = Mathf.Atan2(a.y - pivot.y, a.x - pivot.x);
+            float angleB = Mathf.Atan2(b.y - pivot.y, b.x - pivot.x);
+
+            if (angleA < angleB) return -1;
+            if (angleA > angleB) return 1;
+
+            // 如果角度相同，按距离排序
+            float distA = (a - pivot).sqrMagnitude;
+            float distB = (b - pivot).sqrMagnitude;
+            return distA.CompareTo(distB);
+        });
+
+        // Graham Scan算法
+        List<Vector2> hull = new List<Vector2>();
+        hull.Add(points[0]);
+        hull.Add(points[1]);
+
+        for (int i = 2; i < points.Count; i++)
+        {
+            while (hull.Count >= 2)
+            {
+                Vector2 a = hull[hull.Count - 2];
+                Vector2 b = hull[hull.Count - 1];
+                Vector2 c = points[i];
+
+                if (Cross(b - a, c - b) <= 0)
+                    hull.RemoveAt(hull.Count - 1);
+                else
+                    break;
+            }
+            hull.Add(points[i]);
+        }
+
+        return hull;
+    }
+
+    float Cross(Vector2 a, Vector2 b)
+    {
+        return a.x * b.y - a.y * b.x;
+    }
+}