UnityShader 学习笔记 25 屏幕后期之Bloom效果

• Shader:

Shader "_MyShader/9_PostScreenEffect/3_MyBloom"{

    Properties {

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

            _Bloom ("Bloom (RGB)", 2D) = "black" {}

            _LuminanceThreshold ("Luminance Threshold", Float) = 0.5

            _BlurSize ("Blur Size", Float) = 1.0

    }

    SubShader {

        CGINCLUDE



        #include "UnityCG.cginc"



        sampler2D _MainTex;

        half4 _MainTex_TexelSize;

        sampler2D _Bloom;

        float _LuminanceThreshold;

        float _BlurSize;



        struct v2f {

            float4 pos : SV_POSITION; 

            half2 uv : TEXCOORD0;

        };    



        v2f vertExtractBright(appdata_img v) {

            v2f o;



            o.pos = mul(UNITY_MATRIX_MVP, v.vertex);



            o.uv = v.texcoord;



            return o;

        }



        fixed luminance(fixed4 color) {

            return  0.2125 * color.r + 0.7154 * color.g + 0.0721 * color.b; 

        }



        fixed4 fragExtractBright(v2f i) : SV_Target {

            fixed4 c = tex2D(_MainTex, i.uv);

            fixed val = clamp(luminance(c) - _LuminanceThreshold, 0.0, 1.0);



            return c * val;

        }



        struct v2fBloom {

            float4 pos : SV_POSITION; 

            half4 uv : TEXCOORD0;

        };



        v2fBloom vertBloom(appdata_img v) {

            v2fBloom o;



            o.pos = mul (UNITY_MATRIX_MVP, v.vertex);

            o.uv.xy = v.texcoord;        

            o.uv.zw = v.texcoord;



            #if UNITY_UV_STARTS_AT_TOP            

            if (_MainTex_TexelSize.y < 0.0)

            o.uv.w = 1.0 - o.uv.w;

            #endif



            return o; 

        }



        fixed4 fragBloom(v2fBloom i) : SV_Target {

            return tex2D(_MainTex, i.uv.xy) + tex2D(_Bloom, i.uv.zw);

        } 



        ENDCG



        ZTest Always Cull Off ZWrite Off



        Pass {  

            CGPROGRAM  

            #pragma vertex vertExtractBright  

            #pragma fragment fragExtractBright  



            ENDCG  

        }



        UsePass "_MyShader/9_PostScreenEffect/2_MyGausianBlur/GAUSSIAN_BLUR_VERTICAL"



        UsePass "_MyShader/9_PostScreenEffect/2_MyGausianBlur/GAUSSIAN_BLUR_HORIZONTAL"



        Pass {  

            CGPROGRAM  

            #pragma vertex vertBloom  

            #pragma fragment fragBloom  



            ENDCG  

        }

    }

    FallBack Off

}

• C#:

using UnityEngine;

using System.Collections;



public class MyBloom : ScreenEffectBase {



    public Shader bloomShader;

    private Material bloomMaterial = null;

    public Material material {  

        get {

            bloomMaterial = CheckShaderAndCreateMaterial(bloomShader, bloomMaterial);

            return bloomMaterial;

        }  

    }



    // Blur iterations - larger number means more blur.

    [Range(0, 4)]

    public int iterations = 3;



    // Blur spread for each iteration - larger value means more blur

    [Range(0.2f, 3.0f)]

    public float blurSpread = 0.6f;



    [Range(1, 8)]

    public int downSample = 2;



    [Range(0.0f, 4.0f)]

    public float luminanceThreshold = 0.6f;



    void OnRenderImage (RenderTexture src, RenderTexture dest) {

        if (material != null) {

            material.SetFloat("_LuminanceThreshold", luminanceThreshold);



            int rtW = src.width/downSample;

            int rtH = src.height/downSample;



            RenderTexture buffer0 = RenderTexture.GetTemporary(rtW, rtH, 0);

            buffer0.filterMode = FilterMode.Bilinear;



            Graphics.Blit(src, buffer0, material, 0);



            for (int i = 0; i < iterations; i++) {

                material.SetFloat("_BlurSize", 1.0f + i * blurSpread);



                RenderTexture buffer1 = RenderTexture.GetTemporary(rtW, rtH, 0);



                // Render the vertical pass

                Graphics.Blit(buffer0, buffer1, material, 1);



                RenderTexture.ReleaseTemporary(buffer0);

                buffer0 = buffer1;

                buffer1 = RenderTexture.GetTemporary(rtW, rtH, 0);



                // Render the horizontal pass

                Graphics.Blit(buffer0, buffer1, material, 2);



                RenderTexture.ReleaseTemporary(buffer0);

                buffer0 = buffer1;

            }



            material.SetTexture ("_Bloom", buffer0);  

            Graphics.Blit (src, dest, material, 3);  



            RenderTexture.ReleaseTemporary(buffer0);

        } else {

            Graphics.Blit(src, dest);

        }

    }

}