Unity角色殘影特效

殘影特效在網上有很多例子，比如這個，我參考着自己整合了一下，算是整合了一個比較完整且特別簡單易用的出來，只需要一個腳本掛上去無需任何設定就能用。

這裏只針對SkinnedMeshRenderer的網格（也就是帶蒙皮的網格）殘影，主要原理是根據設定的間隔時間連續的截取當前SkinnedMeshRenderer的網格數據並使用Graphics.DrawMesh畫出網格。

一、首先是我們的殘影類，爲了能及時的Destroy，所以它最好派生至Object：

class AfterImage : Object
{
    //殘影網格
    public Mesh _Mesh;
    //殘影紋理
    public Material _Material;
    //殘影位置
    public Matrix4x4 _Matrix;
    //殘影透明度
    public float _Alpha;
    //殘影啓動時間
    public float _StartTime;
    //殘影保留時間
    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;
    }
}

屬性描述：殘影從創建之時起便記錄《殘影啓動時間》，當其生命週期達到或者超過了設定的《殘影保留時間》時，該殘影即被清除；《殘影網格》爲殘影創建之時從SkinnedMeshRenderer截取而來，保留有當前SkinnedMeshRenderer的網格數據，並依據設定的《殘影紋理》在《殘影位置》以《殘影透明度》DrawMesh。

二、我們再定義一個殘影特效類來管理殘影：

using UnityEngine;
using System.Collections;
using System.Collections.Generic;
/// <summary>
/// 殘影特效
/// </summary>
public class AfterImageEffects : MonoBehaviour {
 
    //開啓殘影
    public bool _OpenAfterImage;
 
    //殘影顏色
    public Color _AfterImageColor = Color.black;
    //殘影的生存時間
    public float _SurvivalTime = 1;
    //生成殘影的間隔時間
    public float _IntervalTime = 0.2f;
    private float _Time = 0;
    //殘影初始透明度
    [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;
            //生成殘影
            CreateAfterImage();
            //刷新殘影
            UpdateAfterImage();
        }
    }
}

屬性描述：《殘影的生存時間》爲每個殘影從創建開始到銷燬經歷的時間，《生成殘影的間隔時間》爲殘影創建後到下一個殘影創建的時間，每個殘影都會從《初始透明度》逐漸變化到0透明度並銷燬。

生成殘影：

/// <summary>
    /// 生成殘影
    /// </summary>
    void CreateAfterImage()
    {
        //生成殘影
        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));
        }
    }

刷新殘影：

/// <summary>
    /// 刷新殘影
    /// </summary>
    void UpdateAfterImage()
    {
        //刷新殘影，根據生存時間銷燬已過時的殘影
        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);
        }
    }

殘影存在透明通道，所以必須要設置紋理的渲染模式爲fade模式：

/// <summary>
    /// 設置紋理渲染模式
    /// </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、效果圖如下：

四、我將完整的源碼貼一遍，只需要新建一個腳本AfterImageEffects，複製以下源碼到其中，然後掛在有SkinnedMeshRenderer組件的模型上，並勾選OpenAfterImage，運行便可以看到效果：

using UnityEngine;
using System.Collections;
using System.Collections.Generic;
/// <summary>
/// 殘影特效
/// </summary>
public class AfterImageEffects : MonoBehaviour {
 
    //開啓殘影
    public bool _OpenAfterImage;
 
    //殘影顏色
    public Color _AfterImageColor = Color.black;
    //殘影的生存時間
    public float _SurvivalTime = 1;
    //生成殘影的間隔時間
    public float _IntervalTime = 0.2f;
    private float _Time = 0;
    //殘影初始透明度
    [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;
            //生成殘影
            CreateAfterImage();
            //刷新殘影
            UpdateAfterImage();
        }
	}
    /// <summary>
    /// 生成殘影
    /// </summary>
    void CreateAfterImage()
    {
        //生成殘影
        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>
    /// 刷新殘影
    /// </summary>
    void UpdateAfterImage()
    {
        //刷新殘影，根據生存時間銷燬已過時的殘影
        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>
    /// 設置紋理渲染模式
    /// </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
{
    //殘影網格
    public Mesh _Mesh;
    //殘影紋理
    public Material _Material;
    //殘影位置
    public Matrix4x4 _Matrix;
    //殘影透明度
    public float _Alpha;
    //殘影啓動時間
    public float _StartTime;
    //殘影保留時間
    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;
    }
}