using UnityEngine;

[RequireComponent(typeof(MeshFilter), typeof(MeshRenderer))]
public class TiledMeshGenerator : MonoBehaviour
{
    public Mesh originalMesh; // 原始 Mesh
    public int tileX = 2;     // X 轴上的平铺次数
    public int tileY = 2;     // Y 轴上的平铺次数

    void Start()
    {
        if (originalMesh == null)
        {
            Debug.LogError("请分配一个原始 Mesh!");
            return;
        }

        Mesh tiledMesh = CreateTiledMesh();
        GetComponent<MeshFilter>().mesh = tiledMesh;
    }

    Mesh CreateTiledMesh()
    {
        Mesh mesh = new Mesh();

        Vector3[] originalVertices = originalMesh.vertices;
        int[] originalTriangles = originalMesh.triangles;
        Vector2[] originalUVs = originalMesh.uv;

        int numOriginalVertices = originalVertices.Length;
        int numOriginalTriangles = originalTriangles.Length;

        int numNewVertices = numOriginalVertices * tileX * tileY;
        int numNewTriangles = numOriginalTriangles * tileX * tileY;

        Vector3[] newVertices = new Vector3[numNewVertices];
        int[] newTriangles = new int[numNewTriangles];
        Vector2[] newUVs = new Vector2[numNewVertices];

        int vertexIndex = 0;
        int triangleIndex = 0;

        for (int y = 0; y < tileY; y++)
        {
            for (int x = 0; x < tileX; x++)
            {
                // 复制顶点
                for (int i = 0; i < numOriginalVertices; i++)
                {
                    newVertices[vertexIndex] = originalVertices[i] + new Vector3(x, y, 0);
                    newUVs[vertexIndex] = originalUVs[i];
                    vertexIndex++;
                }

                // 复制三角形
                for (int i = 0; i < numOriginalTriangles; i += 3)
                {
                    newTriangles[triangleIndex] = originalTriangles[i] + (x + y * tileX) * numOriginalVertices;
                    newTriangles[triangleIndex + 1] = originalTriangles[i + 1] + (x + y * tileX) * numOriginalVertices;
                    newTriangles[triangleIndex + 2] = originalTriangles[i + 2] + (x + y * tileX) * numOriginalVertices;
                    triangleIndex += 3;
                }
            }
        }

        mesh.vertices = newVertices;
        mesh.triangles = newTriangles;
        mesh.uv = newUVs;
        mesh.RecalculateNormals();

        return mesh;
    }
}