using UnityEngine;
using UnityEditor;
using System.IO;

public class ExportSplatMaps : EditorWindow
{
    private Terrain terrain;

    [MenuItem("Tools/ShirakaTool/Export Terrain SplatMaps")]
    public static void ShowWindow()
    {
        GetWindow<ExportSplatMaps>("Export SplatMaps");
    }

    private void OnGUI()
    {
        GUILayout.Label("导出 Terrain SplatMaps", EditorStyles.boldLabel);
        terrain = EditorGUILayout.ObjectField("选择 Terrain", terrain, typeof(Terrain), true) as Terrain;

        if (terrain == null)
        {
            EditorGUILayout.HelpBox("请在场景中选择一个 Terrain 对象。", MessageType.Warning);
            return;
        }

        if (GUILayout.Button("导出 SplatMaps"))
        {
            ExportSplatMapsToPNG(terrain);
        }
    }

    private void ExportSplatMapsToPNG(Terrain terrain)
    {
        TerrainData terrainData = terrain.terrainData;
        Texture2D[] splatMaps = terrainData.alphamapTextures;

        string folderPath = EditorUtility.SaveFolderPanel("选择导出文件夹", "", "");
        if (string.IsNullOrEmpty(folderPath))
            return;

        for (int i = 0; i < splatMaps.Length; i++)
        {
            Texture2D splatMap = splatMaps[i];
            RenderTexture rt = RenderTexture.GetTemporary(splatMap.width, splatMap.height, 0, RenderTextureFormat.ARGB32);
            Graphics.Blit(splatMap, rt);

            RenderTexture.active = rt;
            Texture2D readableTex = new Texture2D(splatMap.width, splatMap.height, TextureFormat.ARGB32, false);
            readableTex.ReadPixels(new Rect(0, 0, rt.width, rt.height), 0, 0);
            readableTex.Apply();

            byte[] bytes = readableTex.EncodeToPNG();
            File.WriteAllBytes(Path.Combine(folderPath, $"SplatMap_{i}.png"), bytes);

            RenderTexture.active = null;
            RenderTexture.ReleaseTemporary(rt);
            DestroyImmediate(readableTex);
        }

        AssetDatabase.Refresh();
        EditorUtility.DisplayDialog("导出完成", "SplatMaps 已成功导出为 PNG 文件。", "确定");
    }
}