Unity shader学习之屏幕后期处理效果之运动模糊

运动模糊，代码如下：

using UnityEngine;

public class MotionBlurRenderer : PostEffectRenderer
{
    [Range(0.1f, 0.9f)]
    [SerializeField]
    float m_blurAmount = 0.1f;

    RenderTexture m_accumulationTexture;

    void OnDisable()
    {
        DestroyImmediate(m_accumulationTexture);
    }

    protected override void OnRenderImage(RenderTexture src, RenderTexture dest)
    {
        if (!m_accumulationTexture || m_accumulationTexture.width != src.width || m_accumulationTexture.height != src.height)
        {
            DestroyImmediate(m_accumulationTexture);
            m_accumulationTexture = new RenderTexture(src.width, src.height, 0);
            //m_accumulationTexture.hideFlags = HideFlags.HideAndDontSave;
            Graphics.Blit(src, m_accumulationTexture);
        }

        //m_accumulationTexture.MarkRestoreExpected();

        Mat.SetFloat("_BlurAmount", m_blurAmount);

        Graphics.Blit(src, m_accumulationTexture, Mat);
        Graphics.Blit(m_accumulationTexture, dest);

        base.OnRenderImage(src, dest);
    }

    protected override string ShaderName
    {
        get { return "Custom/Study/Motion Shader"; }
    }
}

对应shader如下：

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

Shader "Custom/Study/Motion Shader"
{
    Properties
    {
        _MainTex ("Main Texture", 2D) = "white" {}
        _BlurAmount ("Blur Amount", Range(0,1)) = 0.5
    }

    SubShader
    {
        ZWrite Off
        ZTest Always
        Cull Off

        Pass
        {
            Blend SrcAlpha OneMinusSrcAlpha

            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            sampler2D _MainTex;
            fixed _BlurAmount;

            struct appdata
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

            struct v2f
            {
                float4 pos : SV_POSITION;
                float2 uv : TEXCOORD0;
            };

            v2f vert(appdata v)
            {
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv;
                return o;
            }

            fixed4 frag(v2f i) : SV_TARGET
            {
                fixed4 tex = tex2D(_MainTex, i.uv);
                return fixed4(tex.rgb, _BlurAmount);
            }

            ENDCG
        }
    }

    Fallback Off
}

效果如下：