using UnityEngine;
using System.Collections;
 
public class Translating : MonoBehaviour {
 
 public float speed = 10.0f;
 public Vector3 startPoint = Vector3.zero;
 public Vector3 endPoint = Vector3.zero;
 public Vector3 lookAt = Vector3.zero;
 public bool pingpong = true;
 
 private Vector3 curEndPoint = Vector3.zero;
 
 // Use this for initialization
 void Start () {
 transform.position = startPoint;
 curEndPoint = endPoint;
 }
 
 // Update is called once per frame
 void Update () {
 transform.position = Vector3.Slerp(transform.position, curEndPoint, Time.deltaTime * speed);
 transform.LookAt(lookAt);
 if (pingpong) {
 if (Vector3.Distance(transform.position, curEndPoint) < 0.001f) {
 curEndPoint = Vector3.Distance(curEndPoint, endPoint) < Vector3.Distance(curEndPoint, startPoint) ? startPoint : endPoint;
 }
 }
 }
}

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
 
public class MotionBlur : PostEffectsBase
{
 
 public Shader MotionBlurShader;
 private Material _motionBlurMaterial = null;
 
 public Material Material
 {
  get
  {
   _motionBlurMaterial = CheckShaderAndCreateMaterial(MotionBlurShader, _motionBlurMaterial);
   return _motionBlurMaterial;
  }
 } 
 
 //定義運動模糊在混合圖像時使用的模糊參數(shù),值越大，拖尾越明顯，但過大會完全替代當(dāng)前幀的渲染結(jié)果，所以最大為0.9
 [Range(0.0f, 0.9f)] public float BlurAmount = 0.5f;
 
 //定義一個RenderTexture類型的變量，保存之前圖像疊加的結(jié)果
 private RenderTexture _accumulationTexture;
 //當(dāng)腳本不運行時，立即銷毀，這樣在下一次開始運行時會重新疊加圖像
 void OnDisable()
 {
  DestroyImmediate(_accumulationTexture);
 }
 
 void OnRenderImage(RenderTexture src, RenderTexture dest)
 {
  if (Material != null)
  {
   //判斷用于混合圖像的_accumulationTexture是否為空，或者是否與當(dāng)前屏幕分辨率相等
   //如果不滿足，需要重新創(chuàng)建
   if (_accumulationTexture == null || _accumulationTexture.width != src.width ||
    _accumulationTexture.height != src.height)
   {
    //立即銷毀當(dāng)前_accumulationTexture
    DestroyImmediate(_accumulationTexture);
    //創(chuàng)建一個與當(dāng)前屏幕分辨率相等的
    _accumulationTexture = new RenderTexture(src.width, src.height, 0);
    //由于我們自己控制這個變量的銷毀，所以不需要他顯示在Hierarchy中，也不需要保存在場景中
    _accumulationTexture.hideFlags = HideFlags.HideAndDontSave;
    //使用當(dāng)前的幀圖像初始化_accumulationTexture
    Graphics.Blit(src, _accumulationTexture);
   }
 
   //對渲染紋理進(jìn)行恢復(fù)操作，發(fā)生在渲染的紋理而該紋理又沒有被提前清空或銷毀的情況下
   //運動模糊每次調(diào)用OnRenderImage函數(shù)，都需要把當(dāng)前紋理與_accumulationTexture中的圖像混合，所以_accumulationTexture不需要被提前清空
   _accumulationTexture.MarkRestoreExpected();
 
   //將參數(shù)傳給材質(zhì)
   Material.SetFloat("_BlurAmount", 1.0f - BlurAmount);
 
   //把當(dāng)前的屏幕圖像疊加到_accumulationTexture
   Graphics.Blit(src, _accumulationTexture, Material);
   //把疊加后的圖像輸出到屏幕
   Graphics.Blit(_accumulationTexture, dest);
  }
  else
  {
   Graphics.Blit(src, dest);
  }
 }
}

Shader "Unity Shaders Book/Chapter 12/MotionBlur"
{
 Properties
 {
 _MainTex ("Base (RGB)", 2D) = "white" {}
  //混合系數(shù)
 _BlurAmount("Blur Amount", Float) = 1.0
 }
 SubShader
 {
 CGINCLUDE
 #include "UnityCG.cginc"
 
 sampler2D _MainTex;
 fixed _BlurAmount;
 
 //定義頂點著色器
 struct v2f {
 float4 pos : SV_POSITION;
 half2 uv : TEXCOORD0;
 };
 
 v2f vert(appdata_img v) {
 v2f o;
 o.pos = UnityObjectToClipPos(v.vertex);
 o.uv = v.texcoord;
 return o;
 }
 
 //定義第一個片元著色器，用于更新渲染紋理的RGB通道部分
 fixed4 fragRGB(v2f i) : SV_Target{
 //將A通道的值設(shè)為_BlurAmount,這樣在后面混合時可直接使用透明通道進(jìn)行混合
 return fixed4(tex2D(_MainTex, i.uv).rgb, _BlurAmount);
 }
 
 //定義第二個片元著色器，用于更新渲染紋理的A通道部分
 half4 fragA(v2f i) : SV_Target{
 //直接返回采樣結(jié)果，為了維護(hù)渲染紋理的透明通道值，不讓其受到混合時使用的透明度值的影響
 return tex2D(_MainTex, i.uv);
 }
 
 ENDCG
 
 ZTest Always Cull Off Zwrite Off
 //第一個Pass,用于更新渲染紋理的RGB通道
 Pass
 {
 Blend SrcAlpha OneMinusSrcAlpha
 ColorMask RGB
 CGPROGRAM
 #pragma vertex vert
 #pragma fragment fragRGB
 ENDCG
 }
 
 //第二個Pass,用于更新渲染紋理的A通道
 Pass
 {
 Blend One Zero
 ColorMask A
 CGPROGRAM
 #pragma vertex vert
 #pragma fragment fragA
 ENDCG
 }
 }
 Fallback Off
}