影特效在网上有很多例子,比如这个,我参考着自己整合了一下,算是整合了一个比较完整且特别简单易用的出来,只需要一个脚本挂上去无需任何设定就能用。
这里只针对SkinnedMeshRenderer的网格(也就是带蒙皮的网格)残影,主要原理是根据设定的间隔时间连续的截取当前SkinnedMeshRenderer的网格数据并使用Graphics.DrawMesh画出网格。

一、首先是我们的残影类,为了能及时的Destroy,所以它最好派生至Object:
class AfterImage : Object 
{ 
    //残影网格 
    public Mesh _Mesh; 
    //残影纹理 
    public Material _Material; 
    //残影位置 
    public Matrix4x4 _Matrix; 
    //残影透明度 
    public float _Alpha; 
    //残影启动时间 
    public float _StartTime; 
    //残影保留时间 
    public float _Duration;  

    public AfterImage(Mesh mesh, Material material, Matrix4x4 matrix4x4, float alpha, float startTime, float duration) 
    { 
        _Mesh = mesh; 
        _Material = material; 
        _Matrix = matrix4x4; 
        _Alpha = alpha; 
        _StartTime = startTime; 
        _Duration = duration; 
    } 
}  

属性描述:残影从创建之时起便记录《残影启动时间》,当其生命周期达到或者超过了设定的《残影保留时间》时,该残影即被清除;《残影网格》为残影创建之时从SkinnedMeshRenderer截取而来,保留有当前SkinnedMeshRenderer的网格数据,并依据设定的《残影纹理》在《残影位置》以《残影透明度》DrawMesh。

二、我们再定义一个残影特效类来管理残影:
using UnityEngine;  
using System.Collections;  
using System.Collections.Generic;  
/// <summary>  
/// 残影特效  
/// </summary>  
public class AfterImageEffects : MonoBehaviour {  
  
    //开启残影  
    public bool _OpenAfterImage;  
  
    //残影颜色  
    public Color _AfterImageColor = Color.black;  
    //残影的生存时间  
    public float _SurvivalTime = 1;  
    //生成残影的间隔时间  
    public float _IntervalTime = 0.2f;  
    private float _Time = 0;  
    //残影初始透明度  
    [Range(0.1f, 1.0f)]  
    public float _InitialAlpha = 1.0f;  
  
    private List<AfterImage> _AfterImageList;  
    private SkinnedMeshRenderer _SkinnedMeshRenderer;  
  
    void Awake () {  
        _AfterImageList = new List<AfterImage>();  
        _SkinnedMeshRenderer = GetComponent<SkinnedMeshRenderer>();  
    }  
    void Update () {  
        if (_OpenAfterImage && _AfterImageList != null)  
        {  
            if (_SkinnedMeshRenderer == null)  
            {  
                _OpenAfterImage = false;  
                return;  
            }  
  
            _Time += Time.deltaTime;  
            //生成残影  
            CreateAfterImage();  
            //刷新残影  
            UpdateAfterImage();  
        }  
    }  
}  

属性描述:《残影的生存时间》为每个残影从创建开始到销毁经历的时间,《生成残影的间隔时间》为残影创建后到下一个残影创建的时间,每个残影都会从《初始透明度》逐渐变化到0透明度并销毁。

生成残影:
/// <summary>  
    /// 生成残影  
    /// </summary>  
    void CreateAfterImage()  
    {  
        //生成残影  
        if (_Time >= _IntervalTime)  
        {  
            _Time = 0;  
  
            Mesh mesh = new Mesh();  
            _SkinnedMeshRenderer.BakeMesh(mesh);  
  
            Material material = new Material(_SkinnedMeshRenderer.material);  
            SetMaterialRenderingMode(material, RenderingMode.Fade);  
  
            _AfterImageList.Add(new AfterImage(  
                mesh,  
                material,  
                transform.localToWorldMatrix,  
                _InitialAlpha,  
                Time.realtimeSinceStartup,  
                _SurvivalTime));  
        }  
    }  

刷新残影:
/// <summary>  
    /// 刷新残影  
    /// </summary>  
    void UpdateAfterImage()  
    {  
        //刷新残影,根据生存时间销毁已过时的残影  
        for (int i = 0; i < _AfterImageList.Count; i++)  
        {  
            float _PassingTime = Time.realtimeSinceStartup - _AfterImageList[i]._StartTime;  
  
            if (_PassingTime > _AfterImageList[i]._Duration)  
            {  
                _AfterImageList.Remove(_AfterImageList[i]);  
                Destroy(_AfterImageList[i]);  
                continue;  
            }  
  
            if (_AfterImageList[i]._Material.HasProperty("_Color"))  
            {  
                _AfterImageList[i]._Alpha *= (1 - _PassingTime / _AfterImageList[i]._Duration);  
                _AfterImageColor.a = _AfterImageList[i]._Alpha;  
                _AfterImageList[i]._Material.SetColor("_Color", _AfterImageColor);  
            }  
  
            Graphics.DrawMesh(_AfterImageList[i]._Mesh, _AfterImageList[i]._Matrix, _AfterImageList[i]._Material, gameObject.layer);  
        }  
    }  

残影存在透明通道,所以必须要设置纹理的渲染模式为fade模式:
/// <summary>  
    /// 设置纹理渲染模式  
    /// </summary>  
    void SetMaterialRenderingMode(Material material, RenderingMode renderingMode)  
    {  
        switch (renderingMode)  
        {  
            case RenderingMode.Opaque:  
                material.SetInt("_SrcBlend", (int)UnityEngine.Rendering.BlendMode.One);  
                material.SetInt("_DstBlend", (int)UnityEngine.Rendering.BlendMode.Zero);  
                material.SetInt("_ZWrite", 1);  
                material.DisableKeyword("_ALPHATEST_ON");  
                material.DisableKeyword("_ALPHABLEND_ON");  
                material.DisableKeyword("_ALPHAPREMULTIPLY_ON");  
                material.renderQueue = -1;  
                break;  
            case RenderingMode.Cutout:  
                material.SetInt("_SrcBlend", (int)UnityEngine.Rendering.BlendMode.One);  
                material.SetInt("_DstBlend", (int)UnityEngine.Rendering.BlendMode.Zero);  
                material.SetInt("_ZWrite", 1);  
                material.EnableKeyword("_ALPHATEST_ON");  
                material.DisableKeyword("_ALPHABLEND_ON");  
                material.DisableKeyword("_ALPHAPREMULTIPLY_ON");  
                material.renderQueue = 2450;  
                break;  
            case RenderingMode.Fade:  
                material.SetInt("_SrcBlend", (int)UnityEngine.Rendering.BlendMode.SrcAlpha);  
                material.SetInt("_DstBlend", (int)UnityEngine.Rendering.BlendMode.OneMinusSrcAlpha);  
                material.SetInt("_ZWrite", 0);  
                material.DisableKeyword("_ALPHATEST_ON");  
                material.EnableKeyword("_ALPHABLEND_ON");  
                material.DisableKeyword("_ALPHAPREMULTIPLY_ON");  
                material.renderQueue = 3000;  
                break;  
            case RenderingMode.Transparent:  
                material.SetInt("_SrcBlend", (int)UnityEngine.Rendering.BlendMode.One);  
                material.SetInt("_DstBlend", (int)UnityEngine.Rendering.BlendMode.OneMinusSrcAlpha);  
                material.SetInt("_ZWrite", 0);  
                material.DisableKeyword("_ALPHATEST_ON");  
                material.DisableKeyword("_ALPHABLEND_ON");  
                material.EnableKeyword("_ALPHAPREMULTIPLY_ON");  
                material.renderQueue = 3000;  
                break;  
        }  
    }  

三、效果图如下:

泰课在线

泰课在线

泰课在线

四、我将完整的源码贴一遍,只需要新建一个脚本AfterImageEffects,复制以下源码到其中,然后挂在有SkinnedMeshRenderer组件的模型上,并勾选OpenAfterImage,运行便可以看到效果:
using UnityEngine;  
using System.Collections;  
using System.Collections.Generic;  
/// <summary>  
/// 残影特效  
/// </summary>  
public class AfterImageEffects : MonoBehaviour {  
  
    //开启残影  
    public bool _OpenAfterImage;  
  
    //残影颜色  
    public Color _AfterImageColor = Color.black;  
    //残影的生存时间  
    public float _SurvivalTime = 1;  
    //生成残影的间隔时间  
    public float _IntervalTime = 0.2f;  
    private float _Time = 0;  
    //残影初始透明度  
    [Range(0.1f, 1.0f)]  
    public float _InitialAlpha = 1.0f;  
  
    private List<AfterImage> _AfterImageList;  
    private SkinnedMeshRenderer _SkinnedMeshRenderer;  
  
    void Awake () {  
        _AfterImageList = new List<AfterImage>();  
        _SkinnedMeshRenderer = GetComponent<SkinnedMeshRenderer>();  
    }  
    void Update () {  
        if (_OpenAfterImage && _AfterImageList != null)  
        {  
            if (_SkinnedMeshRenderer == null)  
            {  
                _OpenAfterImage = false;  
                return;  
            }  
  
            _Time += Time.deltaTime;  
            //生成残影  
            CreateAfterImage();  
            //刷新残影  
            UpdateAfterImage();  
        }  
    }  
    /// <summary>  
    /// 生成残影  
    /// </summary>  
    void CreateAfterImage()  
    {  
        //生成残影  
        if (_Time >= _IntervalTime)  
        {  
            _Time = 0;  
  
            Mesh mesh = new Mesh();  
            _SkinnedMeshRenderer.BakeMesh(mesh);  
  
            Material material = new Material(_SkinnedMeshRenderer.material);  
            SetMaterialRenderingMode(material, RenderingMode.Fade);  
  
            _AfterImageList.Add(new AfterImage(  
                mesh,  
                material,  
                transform.localToWorldMatrix,  
                _InitialAlpha,  
                Time.realtimeSinceStartup,  
                _SurvivalTime));  
        }  
    }  
    /// <summary>  
    /// 刷新残影  
    /// </summary>  
    void UpdateAfterImage()  
    {  
        //刷新残影,根据生存时间销毁已过时的残影  
        for (int i = 0; i < _AfterImageList.Count; i++)  
        {  
            float _PassingTime = Time.realtimeSinceStartup - _AfterImageList[i]._StartTime;  
  
            if (_PassingTime > _AfterImageList[i]._Duration)  
            {  
                _AfterImageList.Remove(_AfterImageList[i]);  
                Destroy(_AfterImageList[i]);  
                continue;  
            }  
  
            if (_AfterImageList[i]._Material.HasProperty("_Color"))  
            {  
                _AfterImageList[i]._Alpha *= (1 - _PassingTime / _AfterImageList[i]._Duration);  
                _AfterImageColor.a = _AfterImageList[i]._Alpha;  
                _AfterImageList[i]._Material.SetColor("_Color", _AfterImageColor);  
            }  
  
            Graphics.DrawMesh(_AfterImageList[i]._Mesh, _AfterImageList[i]._Matrix, _AfterImageList[i]._Material, gameObject.layer);  
        }  
    }  
    /// <summary>  
    /// 设置纹理渲染模式  
    /// </summary>  
    void SetMaterialRenderingMode(Material material, RenderingMode renderingMode)  
    {  
        switch (renderingMode)  
        {  
            case RenderingMode.Opaque:  
                material.SetInt("_SrcBlend", (int)UnityEngine.Rendering.BlendMode.One);  
                material.SetInt("_DstBlend", (int)UnityEngine.Rendering.BlendMode.Zero);  
                material.SetInt("_ZWrite", 1);  
                material.DisableKeyword("_ALPHATEST_ON");  
                material.DisableKeyword("_ALPHABLEND_ON");  
                material.DisableKeyword("_ALPHAPREMULTIPLY_ON");  
                material.renderQueue = -1;  
                break;  
            case RenderingMode.Cutout:  
                material.SetInt("_SrcBlend", (int)UnityEngine.Rendering.BlendMode.One);  
                material.SetInt("_DstBlend", (int)UnityEngine.Rendering.BlendMode.Zero);  
                material.SetInt("_ZWrite", 1);  
                material.EnableKeyword("_ALPHATEST_ON");  
                material.DisableKeyword("_ALPHABLEND_ON");  
                material.DisableKeyword("_ALPHAPREMULTIPLY_ON");  
                material.renderQueue = 2450;  
                break;  
            case RenderingMode.Fade:  
                material.SetInt("_SrcBlend", (int)UnityEngine.Rendering.BlendMode.SrcAlpha);  
                material.SetInt("_DstBlend", (int)UnityEngine.Rendering.BlendMode.OneMinusSrcAlpha);  
                material.SetInt("_ZWrite", 0);  
                material.DisableKeyword("_ALPHATEST_ON");  
                material.EnableKeyword("_ALPHABLEND_ON");  
                material.DisableKeyword("_ALPHAPREMULTIPLY_ON");  
                material.renderQueue = 3000;  
                break;  
            case RenderingMode.Transparent:  
                material.SetInt("_SrcBlend", (int)UnityEngine.Rendering.BlendMode.One);  
                material.SetInt("_DstBlend", (int)UnityEngine.Rendering.BlendMode.OneMinusSrcAlpha);  
                material.SetInt("_ZWrite", 0);  
                material.DisableKeyword("_ALPHATEST_ON");  
                material.DisableKeyword("_ALPHABLEND_ON");  
                material.EnableKeyword("_ALPHAPREMULTIPLY_ON");  
                material.renderQueue = 3000;  
                break;  
        }  
    }  
}  
public enum RenderingMode  
{  
    Opaque,  
    Cutout,  
    Fade,  
    Transparent,  
}  
class AfterImage : Object  
{  
    //残影网格  
    public Mesh _Mesh;  
    //残影纹理  
    public Material _Material;  
    //残影位置  
    public Matrix4x4 _Matrix;  
    //残影透明度  
    public float _Alpha;  
    //残影启动时间  
    public float _StartTime;  
    //残影保留时间  
    public float _Duration;  
  
    public AfterImage(Mesh mesh, Material material, Matrix4x4 matrix4x4, float alpha, float startTime, float duration)  
    {  
        _Mesh = mesh;  
        _Material = material;  
        _Matrix = matrix4x4;  
        _Alpha = alpha;  
        _StartTime = startTime;  
        _Duration = duration;  
    }  
}