废话不多上代码
C# （肯定是绑定在摄像机上面的，你懂的）

public class MobileBloom : MonoBehaviour
{
    //分辨率  
    public int downSample = 1;
    //采样率  
    public int samplerScale = 1;
    //高亮部分提取阈值  
    public Color colorThreshold = Color.gray;
    //Bloom泛光颜色  
    public Color bloomColor = Color.white;
    //Bloom权值  
    [Range(0.0f, 1.0f)]
    public float bloomFactor = 0.5f;

    public Material material = null;
    void Awake()
    {
#if UNITY_EDITOR
        material = new Material(Shader.Find("Custom/MobileBloom"));

#else
//获取ab包里面的shader
#endif
    }
    public void SetAttribute(int _downSample, int _samplerScale, Color _colorThreshold, Color _bloomColor,float _bloomFactor)
    {
        downSample = _downSample;
        samplerScale = _samplerScale;
        colorThreshold = _colorThreshold;
        bloomColor = _bloomColor;
        bloomFactor = _bloomFactor;
    }
    void OnRenderImage(RenderTexture source, RenderTexture destination)
    {
        if (material)
        {
            //申请两块RT，并且分辨率按照downSameple降低  
            RenderTexture temp1 = RenderTexture.GetTemporary(source.width >> downSample, source.height >> downSample, 0, source.format);
            RenderTexture temp2 = RenderTexture.GetTemporary(source.width >> downSample, source.height >> downSample, 0, source.format);

            //直接将场景图拷贝到低分辨率的RT上达到降分辨率的效果  
            Graphics.Blit(source, temp1);


            //根据阈值提取高亮部分,使用pass0进行高亮提取  
            material.SetVector("_colorThreshold", colorThreshold);
            Graphics.Blit(temp1, temp2, material, 0);

            //高斯模糊，两次模糊，横向纵向，使用pass1进行高斯模糊  
            material.SetVector("_offsets", new Vector4(0, samplerScale, 0, 0));
            Graphics.Blit(temp2, temp1, material, 1);
            material.SetVector("_offsets", new Vector4(samplerScale, 0, 0, 0));
            Graphics.Blit(temp1, temp2, material, 1);

            //Bloom，将模糊后的图作为Material的Blur图参数  
            material.SetTexture("_BlurTex", temp2);
            material.SetVector("_bloomColor", bloomColor);
            material.SetFloat("_bloomFactor", bloomFactor);

            //使用pass2进行景深效果计算，清晰场景图直接从source输入到shader的_MainTex中  
            Graphics.Blit(source, destination, material, 2);

            //释放申请的RT  
            RenderTexture.ReleaseTemporary(temp1);
            RenderTexture.ReleaseTemporary(temp2);
        }
    }

shader

Shader "Custom/MobileBloom" {

    Properties{  
        _MainTex("Base (RGB)", 2D) = "white" {}  
        _BlurTex("Blur", 2D) = "white"{}  
    }  

    CGINCLUDE  
    #include "UnityCG.cginc"  

    struct v2f_threshold  
    {  
        float4 pos : SV_POSITION;  
        float2 uv : TEXCOORD0;  
    };  

    struct v2f_blur  
    {  
        float4 pos : SV_POSITION;  
        float2 uv  : TEXCOORD0;  
        float4 uv01 : TEXCOORD1;  
        float4 uv23 : TEXCOORD2;  
        float4 uv45 : TEXCOORD3;  
    };  

    struct v2f_bloom  
    {  
        float4 pos : SV_POSITION;  
        float2 uv  : TEXCOORD0;  
        float2 uv1 : TEXCOORD1;  
    };  

    sampler2D _MainTex;  
    float4 _MainTex_TexelSize;  
    sampler2D _BlurTex;  
    float4 _BlurTex_TexelSize;  
    float4 _offsets;  
    float4 _colorThreshold;  
    float4 _bloomColor;  
    float _bloomFactor;  

    v2f_threshold vert_threshold(appdata_img v)  
    {  
        v2f_threshold o;  
        o.pos = mul(UNITY_MATRIX_MVP, v.vertex);  
        o.uv = v.texcoord.xy;  
#if UNITY_UV_STARTS_AT_TOP  
        if (_MainTex_TexelSize.y < 0)  
            o.uv.y =1- o.uv.y;  
        else
            o.uv.y = o.uv.y;  
#endif    
        return o;  
    }  

    fixed4 frag_threshold(v2f_threshold i) : SV_Target  
    {  
        fixed4 color = tex2D(_MainTex, i.uv);  
        return saturate(color - _colorThreshold);  
    }  

    v2f_blur vert_blur(appdata_img v)  
    {  
        v2f_blur o;  
        _offsets *= _MainTex_TexelSize.xyxy;  
        o.pos = mul(UNITY_MATRIX_MVP, v.vertex);  
        o.uv = v.texcoord.xy;  

        o.uv01 = v.texcoord.xyxy + _offsets.xyxy * float4(1, 1, -1, -1);  
        o.uv23 = v.texcoord.xyxy + _offsets.xyxy * float4(1, 1, -1, -1) * 2.0;  
        o.uv45 = v.texcoord.xyxy + _offsets.xyxy * float4(1, 1, -1, -1) * 3.0;  

        return o;  
    }  

    fixed4 frag_blur(v2f_blur i) : SV_Target  
    {  
        fixed4 color = fixed4(0,0,0,0);  
        color += 0.40 * tex2D(_MainTex, i.uv);  
        color += 0.15 * tex2D(_MainTex, i.uv01.xy);  
        color += 0.15 * tex2D(_MainTex, i.uv01.zw);  
        color += 0.10 * tex2D(_MainTex, i.uv23.xy);  
        color += 0.10 * tex2D(_MainTex, i.uv23.zw);  
        color += 0.05 * tex2D(_MainTex, i.uv45.xy);  
        color += 0.05 * tex2D(_MainTex, i.uv45.zw);  
        return color;  
    }  

    v2f_bloom vert_bloom(appdata_img v)  
    {  
        v2f_bloom o;  
        o.pos = mul(UNITY_MATRIX_MVP, v.vertex);  
        o.uv.xy = v.texcoord.xy;  
        o.uv1.xy = o.uv.xy;  
#if UNITY_UV_STARTS_AT_TOP  
        if (_MainTex_TexelSize.y < 0)  
            o.uv.y =1- o.uv.y;  
        else
            o.uv.y = o.uv.y;  
#endif    
        return o;  
    }  

    fixed4 frag_bloom(v2f_bloom i) : SV_Target  
    {  
        fixed4 ori = tex2D(_MainTex, i.uv1);  
        fixed4 blur = tex2D(_BlurTex, i.uv);  
        fixed4 final = ori + _bloomFactor * blur * _bloomColor;  
        return final;  
    }  

        ENDCG  

    SubShader  
    {  
        Pass  
        {  
            ZTest Off  
            Cull Off  
            ZWrite Off  
            Fog{ Mode Off }  

            CGPROGRAM  
            #pragma vertex vert_threshold  
            #pragma fragment frag_threshold  
            ENDCG  
        }  

        Pass  
        {  
            ZTest Off  
            Cull Off  
            ZWrite Off  
            Fog{ Mode Off }  

            CGPROGRAM  
            #pragma vertex vert_blur  
            #pragma fragment frag_blur  
            ENDCG  
        }  

        Pass  
        {  

            ZTest Off  
            Cull Off  
            ZWrite Off  
            Fog{ Mode Off }  

            CGPROGRAM  
            #pragma vertex vert_bloom  
            #pragma fragment frag_bloom  
            ENDCG  
        }  

    }  
}