using UnityEngine;
using UnityEditor;

[ExecuteInEditMode]
public class VoxelizationTool : MonoBehaviour
{
    public Vector3 gridSize = new Vector3(10, 10, 10); // 体素化区域的尺寸
    public float voxelSize = 1.0f;                     // 每个体素的大小
    public Color gridColor = Color.cyan;              // 网格颜色
    public bool showGrid = true;                      // 是否显示网格
    public bool onlyShowMeshVoxels = true;            // 是否仅显示包含 Mesh 的体素

    private Bounds gridBounds;                        // 网格的总体包围盒

    private void OnDrawGizmos()
    {
        if (!showGrid) return;

        Gizmos.color = gridColor;

        // 定义整个体素网格的包围盒
        gridBounds = new Bounds(transform.position + gridSize * voxelSize / 2, gridSize * voxelSize);

        // 获取场景中的所有 MeshFilter
        MeshFilter[] meshFilters = FindObjectsOfType<MeshFilter>();

        foreach (MeshFilter meshFilter in meshFilters)
        {
            Bounds meshBounds = meshFilter.sharedMesh.bounds;
            meshBounds = TransformBounds(meshBounds, meshFilter.transform);

            // 遍历体素，检查是否与当前 Mesh 的 Bounds 相交
            for (int x = 0; x < gridSize.x; x++)
            {
                for (int y = 0; y < gridSize.y; y++)
                {
                    for (int z = 0; z < gridSize.z; z++)
                    {
                        Vector3 voxelCenter = transform.position + new Vector3(x, y, z) * voxelSize + Vector3.one * voxelSize / 2;

                        // 跳过不在包围盒内的体素
                        if (!gridBounds.Contains(voxelCenter)) continue;

                        // 检查体素是否与 Mesh 的 Bounds 相交
                        Bounds voxelBounds = new Bounds(voxelCenter, Vector3.one * voxelSize);
                        if (meshBounds.Intersects(voxelBounds))
                        {
                            Gizmos.DrawWireCube(voxelCenter, Vector3.one * voxelSize);
                        }
                    }
                }
            }
        }
    }

    /// <summary>
    /// 将本地 Bounds 转换为世界空间的 Bounds
    /// </summary>
    private Bounds TransformBounds(Bounds localBounds, Transform transform)
    {
        Vector3 worldCenter = transform.TransformPoint(localBounds.center);
        Vector3 worldExtents = Vector3.Scale(localBounds.extents, transform.lossyScale);
        return new Bounds(worldCenter, worldExtents * 2);
    }
}