Unity图形学之Shader2.0 Blurning

1.屏幕后期特效：场景渲染完以后 在 添加一些特效

（1）引擎 渲染后最终的结构 是一张图片：OnRenderImage是脚本生命周期函数

Graphics.Blit(sourceTexture, desTexture, graphicsMat);

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class CameraMove : MonoBehaviour
{
    // Start is called before the first frame update
    void Start()
    {
        graphicsMat = new Material(myShader);
    }
    // Update is called once per frame
    void Update()
    {
        
    }
    public Shader myShader;
    private Material graphicsMat;
    //sourceTexture 相机在整个场景渲染完后传递给我们的图片  desTexture 更改以后得图片  存在这里，重新交给引擎重新渲染
    void OnRenderImage(RenderTexture sourceTexture, RenderTexture desTexture) {
        //指定一个Material 去渲染拦截的图片sourceTexture，最终输出新的desTexture
        Graphics.Blit(sourceTexture, desTexture, graphicsMat);
    
    }
}

（2）将图片 传递给 shader 进行 二次计算：

Shader "Hidden/GaoSi"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
        _Ambient("Ambient",float) = 0.001
    }
    SubShader
    {
        // No culling or depth
        Cull Off ZWrite Off ZTest Always
        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"
            struct appdata
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };
            struct v2f
            {
                float2 uv : TEXCOORD0;
                float4 vertex : SV_POSITION;
            };
            float _Ambient;
            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv;
                return o;
            }
            sampler2D _MainTex;
            fixed4 frag (v2f i) : SV_Target
            {
                float2 tempUV = i.uv;
                //float ambient = _Ambient;
                fixed4 col = tex2D(_MainTex, tempUV);
                fixed4 col2 = tex2D(_MainTex, tempUV+float2(-_Ambient,0));
                fixed4 col3 = tex2D(_MainTex, tempUV+float2(0,-_Ambient));
                fixed4 col4 = tex2D(_MainTex, tempUV+float2(_Ambient,0));
                fixed4 col5 = tex2D(_MainTex, tempUV+float2(0,_Ambient));
                col = (col+col2+col3+col4+col5) / 5.0;
                // just invert the colors
                //col.rgb = 1 - col.rgb;
                return col;
            }
            ENDCG
        }
    }
}