Unity Bloom更可信的实现

**Unity Bloom的效果实现网上也有蛮多例子，但它们多数都是传承与高斯模糊，用一个限定的阀值，提取出屏幕上超过阀值亮度的像素，用卷积核运算对周围像素按照一定的比例差值颜色值叠加，这种实现方式性能可以，但在配合HDR实现发光效果其实并不理想，因为太粗鲁的将高亮度像素和它们的邻居卷起来叠加，会误伤了不少应该在较暗区域的像素，较暗区域被高亮度区域过度污染了。表现为如场景上几个招牌大字霓虹灯等，灯的轮廓和周围较暗的区域混在一起，过于浑浊，丢失了霓虹灯管本应清晰的轮廓。虽然大体上看上去还可以，但并不够真实可信。
因此，这里专用箱型模糊，此模糊算法在对获取高亮度像素时获取周围像素表现得更聚集，更适合在效果中体现出曝光物体轮廓，控制泛光范围。

原场景效果：

添加Bloom，依旧能看到清晰的霓虹灯轮廓，亮光区域控制的十分自然，亮光区域并没有过度入侵较暗区域造成一片糊：

用法：
1、将Bloom.cs挂到场景上Main Camera节点。
2、打开相机HDR和项目HDR设置。
Bloom.cs

using UnityEngine;
using System.Collections;[ExecuteInEditMode]
public class Bloom : MonoBehaviour
{private Material _bloomMaterial = null;public Material bloomMaterial{get{if (_bloomMaterial == null){_bloomMaterial = new Material(Shader.Find("Custom/MBloom"));}return _bloomMaterial;}}[Tooltip("要有发光效果必须开启")]public bool HDR = true;[Tooltip("颜色")]public Color BloomColor = Color.white;[Tooltip("发光强度")][Range(0, 100)]public float intensity = 1;[Tooltip("屏幕上的高光亮度阀值")][Range(0, 10)]public float threshold = 1;[Tooltip("光线过度柔和程度")][Range(0, 1)]public float softKnee = 0.5f;[Tooltip("散射程度")][Range(0, 20)]public float diffusion = 7;[Tooltip("方框模糊采样屏幕比值")][Range(1, 8)]public int downSample = 2;RenderTexture[] rtDowns;RenderTexture[] rtUps;private void Awake(){}public static float Exp2(float x){return Mathf.Exp(x * 0.69314718055994530941723212145818f);}void OnRenderImage(RenderTexture src, RenderTexture dest){if (bloomMaterial != null){bloomMaterial.SetColor("_Bloom_Color", BloomColor);//prefilteringfloat lt = Mathf.GammaToLinearSpace(threshold);float knee = lt * softKnee + 1e-5f;Vector4 threshold4 = new Vector4(lt, lt-knee, knee*2f, 0.25f/knee);bloomMaterial.SetVector("_Threshold", threshold4);float _intensity = Exp2(intensity/10f)-1f;bloomMaterial.SetFloat("_Intensity", _intensity);int rtW = src.width / downSample;int rtH = src.height / downSample;int s = Mathf.Max(rtH, rtW);float logs = Mathf.Log(s, 2f) + Mathf.Min(diffusion, 10f) - 10f;int logs_i = Mathf.FloorToInt(logs);int k_MaxPyramidSize = 16;int iterations = Mathf.Clamp(logs_i, 1, k_MaxPyramidSize);float sampleScale = 0.5f + logs - logs_i;bloomMaterial.SetFloat("_SampleScale", sampleScale);//sheet.properties.SetFloat(ShaderIDs.SampleScale, sampleScale);rtDowns = new RenderTexture[iterations];rtUps = new RenderTexture[iterations];RenderTextureFormat textureFormat = HDR ? RenderTextureFormat.DefaultHDR : RenderTextureFormat.Default;for (int i = 0; i < iterations; i++){RenderTexture down = RenderTexture.GetTemporary(rtW, rtH, 0, textureFormat);down.filterMode = FilterMode.Bilinear;rtDowns[i] = down;RenderTexture up = RenderTexture.GetTemporary(rtW, rtH, 0, textureFormat);up.filterMode = FilterMode.Bilinear;rtUps[i] = up;if (i == 0){Graphics.Blit(src, rtDowns[i], bloomMaterial, 0);}else {Graphics.Blit(rtDowns[i-1], rtDowns[i],bloomMaterial, 1);}rtW = Mathf.Max(rtW/2, 1);rtH = Mathf.Max(rtH/2, 1);}RenderTexture lastup = rtDowns[iterations - 1];for (int i = iterations - 2; i >= 0; i--) {bloomMaterial.SetTexture("_BloomTex", rtDowns[i]);Graphics.Blit(lastup, rtUps[i], bloomMaterial, 2);lastup = rtUps[i];}bloomMaterial.SetTexture("_BloomTex", rtUps[0]);Graphics.Blit(src, dest, bloomMaterial, 3);foreach (RenderTexture rt in rtUps) {if(rt != null)RenderTexture.ReleaseTemporary(rt);}foreach (RenderTexture rt in rtDowns) {if(rt != null)RenderTexture.ReleaseTemporary(rt);}}else{Graphics.Blit(src, dest);}}
}

Bloom.shader

Shader "Custom/MBloom"
{Properties{_MainTex ("Texture", 2D) = "white" {}}SubShader{CGINCLUDE#define HALF_MAX        65504.0#define EPSILON         1.0e-4#include "UnityCG.cginc"struct appdata{float4 vertex : POSITION;float4 uv : TEXCOORD0;};struct v2f{float4 uv : TEXCOORD0;float4 vertex : SV_POSITION;};sampler2D _MainTex;sampler2D _BloomTex;float4 _BloomTex_ST;float4 _BloomTex_TexelSize;half3 _Bloom_Color;float4 _MainTex_ST;float4 _MainTex_TexelSize;float4 _Threshold;float _SampleScale;float _Intensity;float Max3(float a, float b, float c){return max(max(a, b), c);}// Standard box filteringhalf4 DownsampleBox4Tap(sampler2D tex, float2 uv, float2 texelSize){float4 d = texelSize.xyxy * float4(-1.0, -1.0, 1.0, 1.0);half4 s;s =  tex2D(tex,  uv + d.xy);s += tex2D(tex,  uv + d.zy);s += tex2D(tex,  uv + d.xw);s += tex2D(tex,  uv + d.zw);return s * (1.0 / 4.0);}// Standard box filteringhalf4 UpsampleBox(sampler2D tex, float2 uv, float2 texelSize, float4 sampleScale){float4 d = texelSize.xyxy * float4(-1.0, -1.0, 1.0, 1.0) * (sampleScale * 0.5);half4 s;s =  tex2D(tex,  uv + d.xy);s += tex2D(tex,  uv + d.zy);s += tex2D(tex,  uv + d.xw);s += tex2D(tex,  uv + d.zw);return s * (1.0 / 4.0);}//// Quadratic color thresholding// curve = (threshold - knee, knee * 2, 0.25 / knee)//half4 QuadraticThreshold(half4 color, half threshold, half3 curve){// Pixel brightnesshalf br = Max3(color.r, color.g, color.b);// Under-threshold part: quadratic curvehalf rq = clamp(br - curve.x, 0.0, curve.y);rq = curve.z * rq * rq;// Combine and apply the brightness response curve.color *= max(rq, br - threshold) / max(br, 1.0e-4);return color;}half4 Prefilter(half4 color){color = QuadraticThreshold(color, _Threshold.x, _Threshold.yzw);return color;}half4 farg_Prefilter(v2f i):SV_Target{half4 color = DownsampleBox4Tap(_MainTex, i.uv.xy, _MainTex_TexelSize.xy);return Prefilter(color);}v2f vert(appdata v){v2f o;o.vertex = UnityObjectToClipPos(v.vertex);o.uv.xy = TRANSFORM_TEX(v.uv, _MainTex);o.uv.zw = TRANSFORM_TEX(v.uv, _BloomTex);return o;}fixed4 frag_downsample(v2f i) : SV_Target{// sample the texturefixed4 col = DownsampleBox4Tap(_MainTex, i.uv.xy, _MainTex_TexelSize.xy);return col;}half4 frag_upsample(v2f i) : SV_Target{half4 color = UpsampleBox(_MainTex, i.uv.xy, _MainTex_TexelSize.xy, _SampleScale);half4 bloom = tex2D(_BloomTex, i.uv.zw);return color + bloom;}fixed4 frag(v2f i) : SV_Target {return tex2D(_MainTex, i.uv.xy) + tex2D(_BloomTex, i.uv.zw);} fixed4 frag_uber(v2f i) : SV_Target{half4 color = tex2D(_MainTex, i.uv.xy);half4 bloom = UpsampleBox(_BloomTex, i.uv.xy, _BloomTex_TexelSize.xy, _SampleScale);bloom *= _Intensity;color += bloom * half4(_Bloom_Color, 1.0);return color;}ENDCGZTest Always Cull Off ZWrite OffPass {CGPROGRAM  #pragma vertex vert  #pragma fragment farg_Prefilter ENDCG  }Pass {CGPROGRAM  #pragma vertex vert  #pragma fragment frag_downsampleENDCG  }Pass {CGPROGRAM  #pragma vertex vert  #pragma fragment frag_upsampleENDCG  }Pass {CGPROGRAM  #pragma vertex vert#pragma fragment frag_uberENDCG  }Pass {CGPROGRAM  #pragma vertex vert  #pragma fragment fragENDCG  }}
}

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Unity Bloom更可信的实现

原场景效果：

添加Bloom，依旧能看到清晰的霓虹灯轮廓，亮光区域控制的十分自然，亮光区域并没有过度入侵较暗区域造成一片糊：

Unity Bloom更可信的实现相关推荐

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