using UnityEngine;

using System.Collections;

using System.Collections.Generic;

//残影特效，支持Mesh和SkinedMesh以及他俩组合

public class GhostEffect : MonoBehaviour

{

	//如果让Mesh也带残影请保证Mesh的Read/Write是开启的

	public bool IncludeMeshFilter = true;

	//残影

	public class GhostImange

	{

		public Mesh mesh;

		public Material material;

		public Matrix4x4 matrix;

		public float duration;

		public float time;

	}

	//材质

	public Material EffectMaterial;

	//总时长

	public float Duration = 5;

	//产生残影的间隔

	public float Interval = 0.2f;

	//残影淡出时间

	public float FadeoutTime = 1;

	private float mTime = 5;

	private List<GhostImange> mImageList = new List<GhostImange>();

	void Start()

	{

	}

	[ContextMenu("Play")]

	public void Play()

	{

		mTime = Duration;

		StartCoroutine(AddImage());

	}

	IEnumerator AddImage()

	{

		while (mTime > 0)

		{

			CreateImage();

			yield return new WaitForSeconds(Interval);

			mTime -= Interval;

		}

	}

	void CreateImage()

	{

		SkinnedMeshRenderer[] skinRenderers = GetComponentsInChildren<SkinnedMeshRenderer>();

		MeshFilter[] filters = null;

		int filtersCount = 0;

		if (IncludeMeshFilter)

		{

			filters = GetComponentsInChildren<MeshFilter>();

			filtersCount = filters.Length;

		}

		if (skinRenderers.Length+filtersCount <= 0)

		{

			return;

		}

		CombineInstance[] combineInstances = new CombineInstance[skinRenderers.Length + filtersCount];

		int idx = 0;

		for (int i = 0; i < skinRenderers.Length; i++)

		{

			var render = skinRenderers[i];

			var mesh = new Mesh();

			render.BakeMesh(mesh);

			combineInstances[idx] = new CombineInstance

			{

				mesh = mesh,

				transform = render.gameObject.transform.localToWorldMatrix,

				subMeshIndex = 0

			};

			idx++;

		}

		for (int i = 0; i < filtersCount; i++)

		{

			var render = filters[i];

			var temp = (null != render.sharedMesh) ? render.sharedMesh : render.mesh;

			var mesh = (Mesh)Object.Instantiate(temp);

			combineInstances[idx] = new CombineInstance

			{

				mesh = mesh,

				transform = render.gameObject.transform.localToWorldMatrix,

				subMeshIndex = 0

			};

			idx++;

		}

		Mesh combinedMesh = new Mesh();

		combinedMesh.CombineMeshes(combineInstances, true, true);

		mImageList.Add(new GhostImange

		{

			mesh = combinedMesh,

			material = new Material(EffectMaterial),

			time = FadeoutTime,

			duration = FadeoutTime,

		});

	}

	void LateUpdate()

	{

		bool needRemove = false;

		foreach (var image in mImageList)

		{

			image.time -= Time.deltaTime;

			if (image.material.HasProperty("_Color"))

			{

				Color color = Color.white;

				color.a = Mathf.Max(0, image.time / image.duration);

				image.material.SetColor("_Color", color);

			}

			Graphics.DrawMesh(image.mesh, Matrix4x4.identity, image.material, gameObject.layer);

			if(image.time<=0)

			{

				needRemove = true;

			}

		}

		if (needRemove)

		{

			mImageList.RemoveAll(x => x.time <= 0);

		}

	}

}