/*
Based on ObjExporter.cs, this "wrapper" lets you export to .OBJ directly from the editor menu.
 
This should be put in your "Editor"-folder. Use by selecting the objects you want to export, and select
the appropriate menu item from "Custom->Export". Exported models are put in a folder called
"ExportedObj" in the root of your Unity-project. Textures should also be copied and placed in the
same folder.
N.B. there may be a bug so if the custom option doesn't come up refer to this thread http://answers.unity3d.com/questions/317951/how-to-use-editorobjexporter-obj-saving-script-fro.html 
 
Updated for Unity 5.3
*/

using UnityEngine;
using UnityEditor;
using UnityEditor.SceneManagement;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System;

struct ObjMaterial
{
	public string name;
	public string textureName;
}

public class EditorObjExporter : ScriptableObject
{
	private static int vertexOffset = 0;
	private static int normalOffset = 0;
	private static int uvOffset = 0;


	//User should probably be able to change this. It is currently left as an excercise for
	//the reader.
	private static string targetFolder = "ExportedObj";


	private static string MeshToString(MeshFilter mf, Dictionary<string, ObjMaterial> materialList) {
		Mesh m = mf.sharedMesh;
		Material mats = mf.GetComponent<MeshRenderer>().material;

		StringBuilder sb = new StringBuilder();

		sb.Append("g ").Append(mf.name).Append("\n");
		foreach (Vector3 lv in m.vertices) {
			Vector3 wv = mf.transform.TransformPoint(lv);

			//This is sort of ugly - inverting x-component since we're in
			//a different coordinate system than "everyone" is "used to".
			sb.Append(string.Format("v {0} {1} {2}\n", -wv.x, wv.y, wv.z));
		}
		sb.Append("\n");

		foreach (Vector3 lv in m.normals) {
			Vector3 wv = mf.transform.TransformDirection(lv);

			sb.Append(string.Format("vn {0} {1} {2}\n", -wv.x, wv.y, wv.z));
		}
		sb.Append("\n");

		foreach (Vector3 v in m.uv) {
			sb.Append(string.Format("vt {0} {1}\n", v.x, v.y));
		}

			sb.Append("\n");
			sb.Append("usemtl ").Append(mats.name).Append("\n");
			sb.Append("usemap ").Append(mats.name).Append("\n");

			//See if this material is already in the materiallist.
			try {
				ObjMaterial objMaterial = new ObjMaterial();

				objMaterial.name = mats.name;

				if (mats.mainTexture)
					objMaterial.textureName = AssetDatabase.GetAssetPath(mats.mainTexture);
				else
					objMaterial.textureName = null;

				materialList.Add(objMaterial.name, objMaterial);
			} catch (ArgumentException) {
				//Already in the dictionary
			}


			int[] triangles = m.GetTriangles(0);
			for (int i = 0; i < triangles.Length; i += 3) {
				//Because we inverted the x-component, we also needed to alter the triangle winding.
				sb.Append(string.Format("f {1}/{1}/{1} {0}/{0}/{0} {2}/{2}/{2}\n",
					triangles[i] + 1 + vertexOffset, triangles[i + 1] + 1 + normalOffset, triangles[i + 2] + 1 + uvOffset));
			}

		vertexOffset += m.vertices.Length;
		normalOffset += m.normals.Length;
		uvOffset += m.uv.Length;

		return sb.ToString();
	}

	private static void Clear() {
		vertexOffset = 0;
		normalOffset = 0;
		uvOffset = 0;
	}

	private static Dictionary<string, ObjMaterial> PrepareFileWrite() {
		Clear();

		return new Dictionary<string, ObjMaterial>();
	}

	private static void MaterialsToFile(Dictionary<string, ObjMaterial> materialList, string folder, string filename) {
		using (StreamWriter sw = new StreamWriter(folder + Path.PathSeparator + filename + ".mtl")) {
			foreach (KeyValuePair<string, ObjMaterial> kvp in materialList) {
				sw.Write("\n");
				sw.Write("newmtl {0}\n", kvp.Key);
				sw.Write("Ka  0.6 0.6 0.6\n");
				sw.Write("Kd  0.6 0.6 0.6\n");
				sw.Write("Ks  0.9 0.9 0.9\n");
				sw.Write("d  1.0\n");
				sw.Write("Ns  0.0\n");
				sw.Write("illum 2\n");

				if (kvp.Value.textureName != null) {
					string destinationFile = kvp.Value.textureName;


					int stripIndex = destinationFile.LastIndexOf(Path.PathSeparator);

					if (stripIndex >= 0)
						destinationFile = destinationFile.Substring(stripIndex + 1).Trim();


					string relativeFile = destinationFile;

					destinationFile = folder + Path.PathSeparator + destinationFile;

					Debug.Log("Copying texture from " + kvp.Value.textureName + " to " + destinationFile);

					try {
						//Copy the source file
						File.Copy(kvp.Value.textureName, destinationFile);
					} catch {

					}


					sw.Write("map_Kd {0}", relativeFile);
				}

				sw.Write("\n\n\n");
			}
		}
	}

	private static void MeshToFile(MeshFilter mf, string folder, string filename) {
		Dictionary<string, ObjMaterial> materialList = PrepareFileWrite();

		using (StreamWriter sw = new StreamWriter(folder + Path.PathSeparator + filename + ".obj")) {
			sw.Write("mtllib ./" + filename + ".mtl\n");

			sw.Write(MeshToString(mf, materialList));
		}

		MaterialsToFile(materialList, folder, filename);
	}

	private static void MeshesToFile(MeshFilter[] mf, string folder, string filename) {
		Dictionary<string, ObjMaterial> materialList = PrepareFileWrite();

		using (StreamWriter sw = new StreamWriter(folder + Path.PathSeparator + filename + ".obj")) {
			sw.Write("mtllib ./" + filename + ".mtl\n");

			for (int i = 0; i < mf.Length; i++) {
				sw.Write(MeshToString(mf[i], materialList));
			}
		}

		MaterialsToFile(materialList, folder, filename);
	}

	private static bool CreateTargetFolder() {
		try {
			System.IO.Directory.CreateDirectory(targetFolder);
		} catch {
			EditorUtility.DisplayDialog("Error!", "Failed to create target folder!", "");
			return false;
		}

		return true;
	}

	[MenuItem("Custom/Export/Export all MeshFilters in selection to separate OBJs")]
	static void ExportSelectionToSeparate() {
		if (!CreateTargetFolder())
			return;

		Transform[] selection = Selection.GetTransforms(SelectionMode.Editable | SelectionMode.ExcludePrefab);

		if (selection.Length == 0) {
			EditorUtility.DisplayDialog("No source object selected!", "Please select one or more target objects", "");
			return;
		}

		int exportedObjects = 0;

		for (int i = 0; i < selection.Length; i++) {
			Component[] meshfilter = selection[i].GetComponentsInChildren(typeof(MeshFilter));

			for (int m = 0; m < meshfilter.Length; m++) {
				exportedObjects++;
				MeshToFile((MeshFilter)meshfilter[m], targetFolder, selection[i].name + "_" + i + "_" + m);
			}
		}

		if (exportedObjects > 0)
			EditorUtility.DisplayDialog("Objects exported", "Exported " + exportedObjects + " objects", "");
		else
			EditorUtility.DisplayDialog("Objects not exported", "Make sure at least some of your selected objects have mesh filters!", "");
	}

	[MenuItem("Custom/Export/Export whole selection to single OBJ")]
	static void ExportWholeSelectionToSingle() {
		if (!CreateTargetFolder())
			return;


		Transform[] selection = Selection.GetTransforms(SelectionMode.Editable | SelectionMode.ExcludePrefab);

		if (selection.Length == 0) {
			EditorUtility.DisplayDialog("No source object selected!", "Please select one or more target objects", "");
			return;
		}

		int exportedObjects = 0;

		ArrayList mfList = new ArrayList();

		for (int i = 0; i < selection.Length; i++) {
			Component[] meshfilter = selection[i].GetComponentsInChildren(typeof(MeshFilter));

			for (int m = 0; m < meshfilter.Length; m++) {
				exportedObjects++;
				mfList.Add(meshfilter[m]);
			}
		}

		if (exportedObjects > 0) {
			MeshFilter[] mf = new MeshFilter[mfList.Count];

			for (int i = 0; i < mfList.Count; i++) {
				mf[i] = (MeshFilter)mfList[i];
			}

			string filename = EditorSceneManager.GetActiveScene().name + "_" + exportedObjects;

			int stripIndex = filename.LastIndexOf(Path.PathSeparator);

			if (stripIndex >= 0)
				filename = filename.Substring(stripIndex + 1).Trim();

			MeshesToFile(mf, targetFolder, filename);


			EditorUtility.DisplayDialog("Objects exported", "Exported " + exportedObjects + " objects to " + filename, "");
		} else
			EditorUtility.DisplayDialog("Objects not exported", "Make sure at least some of your selected objects have mesh filters!", "");
	}



	[MenuItem("Custom/Export/Export each selected to single OBJ")]
	static void ExportEachSelectionToSingle() {
		if (!CreateTargetFolder())
			return;

		Transform[] selection = Selection.GetTransforms(SelectionMode.Editable | SelectionMode.ExcludePrefab);

		if (selection.Length == 0) {
			EditorUtility.DisplayDialog("No source object selected!", "Please select one or more target objects", "");
			return;
		}

		int exportedObjects = 0;


		for (int i = 0; i < selection.Length; i++) {
			Component[] meshfilter = selection[i].GetComponentsInChildren(typeof(MeshFilter));

			MeshFilter[] mf = new MeshFilter[meshfilter.Length];

			for (int m = 0; m < meshfilter.Length; m++) {
				exportedObjects++;
				mf[m] = (MeshFilter)meshfilter[m];
			}

			MeshesToFile(mf, targetFolder, selection[i].name + "_" + i);
		}

		if (exportedObjects > 0) {
			EditorUtility.DisplayDialog("Objects exported", "Exported " + exportedObjects + " objects", "");
		} else
			EditorUtility.DisplayDialog("Objects not exported", "Make sure at least some of your selected objects have mesh filters!", "");
	}

}