using UnityEngine;
using UnityEditor;
using System;
using System.IO;
using System.Text;
internal enum SaveFormat { Triangles, Quads }
internal enum SaveResolution { Full = 0, Half, Quarter, Eighth, Sixteenth }
internal class Terrain2Obj : EditorWindow
{
private SaveFormat _saveFormat = SaveFormat.Triangles;
private SaveResolution _saveResolution = SaveResolution.Half;
private static TerrainData _terrain;
private static Vector3 _terrainPos;
private int _tCount;
private int _counter;
private int _totalCount;
private const int ProgressUpdateInterval = 10000;
[MenuItem("Terrain/Export To Obj...")]
private static void Init()
{
_terrain = null;
var terrainObject = Selection.activeObject as Terrain;
if (!terrainObject)
{
terrainObject = Terrain.activeTerrain;
}
if (terrainObject)
{
_terrain = terrainObject.terrainData;
_terrainPos = terrainObject.transform.position;
}
EditorWindow.GetWindow<Terrain2Obj>().Show();
}
private void OnGUI()
{
if (!_terrain)
{
GUILayout.Label("No terrain found");
if (GUILayout.Button("Cancel"))
{
EditorWindow.GetWindow<Terrain2Obj>().Close();
}
return;
}
_saveFormat = (SaveFormat)EditorGUILayout.EnumPopup("Export Format", _saveFormat);
_saveResolution = (SaveResolution)EditorGUILayout.EnumPopup("Resolution", _saveResolution);
if (GUILayout.Button("Export"))
{
Export();
}
}
private void Export()
{
var fileName = EditorUtility.SaveFilePanel("Export .obj file", "", "Terrain", "obj");
var w = _terrain.heightmapResolution;
var h = _terrain.heightmapResolution;
var meshScale = _terrain.size;
var tRes = (int)Mathf.Pow(2, (int)_saveResolution);
meshScale = new Vector3(meshScale.x / (w - 1) * tRes, meshScale.y, meshScale.z / (h - 1) * tRes);
var uvScale = new Vector2(1.0f / (w - 1), 1.0f / (h - 1));
var tData = _terrain.GetHeights(0, 0, w, h);
w = (w - 1) / tRes + 1;
h = (h - 1) / tRes + 1;
var tVertices = new Vector3[w * h];
var tUV = new Vector2[w * h];
int[] tPolys;
tPolys = _saveFormat == SaveFormat.Triangles ? new int[(w - 1) * (h - 1) * 6] : new int[(w - 1) * (h - 1) * 4];
// Build vertices and UVs
for (var y = 0; y < h; y++)
{
for (var x = 0; x < w; x++)
{
tVertices[y * w + x] = Vector3.Scale(meshScale, new Vector3(-y, tData[x * tRes, y * tRes], x)) + _terrainPos;
tUV[y * w + x] = Vector2.Scale(new Vector2(x * tRes, y * tRes), uvScale);
}
}
var index = 0;
if (_saveFormat == SaveFormat.Triangles)
{
// Build triangle indices: 3 indices into vertex array for each triangle
for (var y = 0; y < h - 1; y++)
{
for (var x = 0; x < w - 1; x++)
{
// For each grid cell output two triangles
tPolys[index++] = (y * w) + x;
tPolys[index++] = ((y + 1) * w) + x;
tPolys[index++] = (y * w) + x + 1;
tPolys[index++] = ((y + 1) * w) + x;
tPolys[index++] = ((y + 1) * w) + x + 1;
tPolys[index++] = (y * w) + x + 1;
}
}
}
else
{
// Build quad indices: 4 indices into vertex array for each quad
for (var y = 0; y < h - 1; y++)
{
for (var x = 0; x < w - 1; x++)
{
// For each grid cell output one quad
tPolys[index++] = (y * w) + x;
tPolys[index++] = ((y + 1) * w) + x;
tPolys[index++] = ((y + 1) * w) + x + 1;
tPolys[index++] = (y * w) + x + 1;
}
}
}
// Export to .obj
var sw = new StreamWriter(fileName);
try
{
sw.WriteLine("# Unity terrain OBJ File");
// Write vertices
System.Threading.Thread.CurrentThread.CurrentCulture = new System.Globalization.CultureInfo("en-US");
_counter = _tCount = 0;
_totalCount = (tVertices.Length * 2 + (_saveFormat == SaveFormat.Triangles ? tPolys.Length / 3 : tPolys.Length / 4)) / ProgressUpdateInterval;
for (var i = 0; i < tVertices.Length; i++)
{
UpdateProgress();
var sb = new StringBuilder("v ", 20);
// StringBuilder stuff is done this way because it's faster than using the "{0} {1} {2}"etc. format
// Which is important when you're exporting huge terrains.
sb.Append(tVertices[i].x.ToString()).Append(" ").
Append(tVertices[i].y.ToString()).Append(" ").
Append(tVertices[i].z.ToString());
sw.WriteLine(sb);
}
// Write UVs
for (int i = 0; i < tUV.Length; i++)
{
UpdateProgress();
var sb = new StringBuilder("vt ", 22);
sb.Append(tUV[i].x.ToString()).Append(" ").
Append(tUV[i].y.ToString());
sw.WriteLine(sb);
}
if (_saveFormat == SaveFormat.Triangles)
{
// Write triangles
for (int i = 0; i < tPolys.Length; i += 3)
{
UpdateProgress();
var sb = new StringBuilder("f ", 43);
sb.Append(tPolys[i] + 1).Append("/").Append(tPolys[i] + 1).Append(" ").
Append(tPolys[i + 1] + 1).Append("/").Append(tPolys[i + 1] + 1).Append(" ").
Append(tPolys[i + 2] + 1).Append("/").Append(tPolys[i + 2] + 1);
sw.WriteLine(sb);
}
}
else
{
// Write quads
for (var i = 0; i < tPolys.Length; i += 4)
{
UpdateProgress();
var sb = new StringBuilder("f ", 57);
sb.Append(tPolys[i] + 1).Append("/").Append(tPolys[i] + 1).Append(" ").
Append(tPolys[i + 1] + 1).Append("/").Append(tPolys[i + 1] + 1).Append(" ").
Append(tPolys[i + 2] + 1).Append("/").Append(tPolys[i + 2] + 1).Append(" ").
Append(tPolys[i + 3] + 1).Append("/").Append(tPolys[i + 3] + 1);
sw.WriteLine(sb);
}
}
}
catch (Exception err)
{
Debug.Log("Error saving file: " + err.Message);
}
sw.Close();
_terrain = null;
EditorUtility.DisplayProgressBar("Saving file to disc.", "This might take a while...", 1f);
EditorWindow.GetWindow<Terrain2Obj>().Close();
EditorUtility.ClearProgressBar();
}
private void UpdateProgress()
{
if (_counter++ != ProgressUpdateInterval) return;
_counter = 0;
EditorUtility.DisplayProgressBar("Saving...", "", Mathf.InverseLerp(0, _totalCount, ++_tCount));
}
}
