using System;

using System.Collections;

using UnityEngine;

using System.Collections.Generic;

public class CharacterCombine : MonoBehaviour

{

    // 目标物体（必须是骨骼的父物体，不然蒙皮失效）

    public GameObject target;

    // 最终材质（合并所有模型后使用的材质）

    public Material material;

    // 物体所有的部分

    private GameObject[] targetParts = new GameObject[];

    private string[] defaultEquipPartPaths = new string[];

    void Start()

    {

        // 把FBX的模型按部件分别放入Resources下对应的文件夹里，可以留空，模型需要蒙皮，而且所有模型使用同一骨骼

        // 最后的M是Fbx的模型，需要的Unity3D里设置好材质和贴图，部件贴图要勾选Read/Write Enabled

        defaultEquipPartPaths[] = "Model/Player/GirlPlayer/Head/Head0000/M";

        defaultEquipPartPaths[] = "Model/Player/GirlPlayer/Face/Face0000/M";

        defaultEquipPartPaths[] = "Model/Player/GirlPlayer/Hair/Hair0000/M";

        defaultEquipPartPaths[] = "";

        defaultEquipPartPaths[] = "Model/Player/GirlPlayer/Body/Body0000/M";

        defaultEquipPartPaths[] = "Model/Player/GirlPlayer/Leg/Leg0000/M";

        defaultEquipPartPaths[] = "Model/Player/GirlPlayer/Hand/Hand0000/M";

        defaultEquipPartPaths[] = "Model/Player/GirlPlayer/Foot/Foot0000/M";

        defaultEquipPartPaths[] = "Model/Player/GirlPlayer/Wing/Wing0001/M";

        Destroy(target.GetComponent<SkinnedMeshRenderer>());

        for (int i = ; i < defaultEquipPartPaths.Length; i++)

        {

            UnityEngine.Object o = Resources.Load(defaultEquipPartPaths[i]);

            if (o)

            {

                GameObject go = Instantiate(o) as GameObject;

                go.transform.parent = target.transform;

                go.transform.localPosition = new Vector3(, -, );

                go.transform.localRotation = new Quaternion();

                targetParts[i] = go;

            }

        }

        StartCoroutine(DoCombine());

    }

    /// <summary>

    /// 使用延时，不然某些GameObject还没有创建

    /// </summary>

    /// <returns></returns>

    IEnumerator DoCombine()

    {

        yield return null;

        Combine(target.transform);

    }

    /// <summary>

    /// 合并蒙皮网格，刷新骨骼

    /// 注意：合并后的网格会使用同一个Material

    /// </summary>

    /// <param name="root">角色根物体</param>

    private void Combine(Transform root)

    {

        float startTime = Time.realtimeSinceStartup;

        List<CombineInstance> combineInstances = new List<CombineInstance>();

        List<Transform> boneList = new List<Transform>();

        Transform[] transforms = root.GetComponentsInChildren<Transform>();

        List<Texture2D> textures = new List<Texture2D>();

        int width = ;

        int height = ;

        int uvCount = ;

        List<Vector2[]> uvList = new List<Vector2[]>();

        // 遍历所有蒙皮网格渲染器，以计算出所有需要合并的网格、UV、骨骼的信息

        foreach (SkinnedMeshRenderer smr in root.GetComponentsInChildren<SkinnedMeshRenderer>())

        {

            for (int sub = ; sub < smr.sharedMesh.subMeshCount; sub++)

            {

                CombineInstance ci = new CombineInstance();

                ci.mesh = smr.sharedMesh;

                ci.subMeshIndex = sub;

                combineInstances.Add(ci);

            }

            uvList.Add(smr.sharedMesh.uv);

            uvCount += smr.sharedMesh.uv.Length;

            if (smr.material.mainTexture != null)

            {

                textures.Add(smr.GetComponent<Renderer>().material.mainTexture as Texture2D);

                width += smr.GetComponent<Renderer>().material.mainTexture.width;

                height += smr.GetComponent<Renderer>().material.mainTexture.height;

            }

            foreach (Transform bone in smr.bones)

            {

                foreach (Transform item in transforms)

                {

                    if (item.name != bone.name) continue;

                    boneList.Add(item);

                    break;

                }

            }

        }

        // 获取并配置角色所有的SkinnedMeshRenderer

        SkinnedMeshRenderer tempRenderer = root.gameObject.GetComponent<SkinnedMeshRenderer>();

        if (!tempRenderer)

        {

            tempRenderer = root.gameObject.AddComponent<SkinnedMeshRenderer>();

        }

        tempRenderer.sharedMesh = new Mesh();

        // 合并网格，刷新骨骼，附加材质

        tempRenderer.sharedMesh.CombineMeshes(combineInstances.ToArray(), true, false);

        tempRenderer.bones = boneList.ToArray();

        tempRenderer.material = material;

        Texture2D skinnedMeshAtlas = new Texture2D(get2Pow(width), get2Pow(height));

        Rect[] packingResult = skinnedMeshAtlas.PackTextures(textures.ToArray(), );

        Vector2[] atlasUVs = new Vector2[uvCount];

        // 因为将贴图都整合到了一张图片上，所以需要重新计算UV

        int j = ;

        for (int i = ; i < uvList.Count; i++)

        {

            foreach (Vector2 uv in uvList[i])

            {

                atlasUVs[j].x = Mathf.Lerp(packingResult[i].xMin, packingResult[i].xMax, uv.x);

                atlasUVs[j].y = Mathf.Lerp(packingResult[i].yMin, packingResult[i].yMax, uv.y);

                j++;

            }

        }

        // 设置贴图和UV

        tempRenderer.material.mainTexture = skinnedMeshAtlas;

        tempRenderer.sharedMesh.uv = atlasUVs;

        // 销毁所有部件

        foreach (GameObject goTemp in targetParts)

        {

            if (goTemp)

            {

                Destroy(goTemp);

            }

        }

        Debug.Log("合并耗时 : " + (Time.realtimeSinceStartup - startTime) *  + " ms");

    }

    /// <summary>

    /// 获取最接近输入值的2的N次方的数，最大不会超过1024，例如输入320会得到512

    /// </summary>

    private int get2Pow(int into)

    {

        int outo = ;

        for (int i = ; i < ; i++)

        {

            outo *= ;

            if (outo > into)

            {

                break;

            }

        }

        return outo;

    }

}