Shader后期处理-Bloom
原理
- 对原场景图进行筛选，所有小于这个阈值的像素都被筛掉
- 对上一步操作的结果进行模糊操作，达到光溢出的效果
- 最后将处理过的图像和原图像进行叠加，得到最终效果
参考
代码
- Post_Bloom.shader
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176Shader "Post/Post_Bloom"
{
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 = UnityObjectToClipPos(v.vertex);
o.uv = v.texcoord.xy;
//dx中纹理从左上角为初始坐标，需要反向
#if UNITY_UV_STARTS_AT_TOP
if (_MainTex_TexelSize.y < 0)
o.uv.y = 1 - o.uv.y;
#endif
return o;
}
fixed luminance(fixed4 color)
{
return 0.2125 * color.r + 0.7154 * color.g + 0.0721 * color.b;
}
fixed4 frag_threshold(v2f_threshold i) : SV_Target
{
fixed4 color = tex2D(_MainTex, i.uv);
fixed val = saturate(luminance(color) - luminance(_colorThreshold));
return color * val;
// return saturate(color - _colorThreshold);
}
v2f_blur vert_blur(appdata_img v)
{
v2f_blur o;
_offsets *= _MainTex_TexelSize.xyxy;
o.pos = UnityObjectToClipPos(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 = UnityObjectToClipPos(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;
#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 0: 提取高亮部分
Pass
{
ZTest Off
Cull Off
ZWrite Off
Fog
{
Mode Off
}
CGPROGRAM
#pragma vertex vert_threshold
#pragma fragment frag_threshold
ENDCG
}
//pass 1: 高斯模糊
Pass
{
ZTest Off
Cull Off
ZWrite Off
Fog
{
Mode Off
}
CGPROGRAM
#pragma vertex vert_blur
#pragma fragment frag_blur
ENDCG
}
//pass 2: Bloom效果
Pass
{
ZTest Off
Cull Off
ZWrite Off
Fog
{
Mode Off
}
CGPROGRAM
#pragma vertex vert_bloom
#pragma fragment frag_bloom
ENDCG
}
}
} - PostBloom.cs
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57using UnityEngine;
[ExecuteInEditMode]
[ImageEffectAllowedInSceneView]
[RequireComponent(typeof(Camera))]
public class PostBloom : MonoBehaviour
{
[SerializeField] private Shader shader;
private Material m_material;
[Range(0.0f, 1.0f)] public float bloomFactor = 0.5f;
[Range(0, 4)] public int downSample = 1;
public int samplerScale = 1;
public Color colorThreshold = Color.gray;
public Color bloomColor = Color.white;
void Awake()
{
m_material = new Material(shader);
}
void OnValidate()
{
if (shader)
m_material = new Material(shader);
}
void OnRenderImage(RenderTexture source, RenderTexture destination)
{
if (m_material)
{
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);
Graphics.Blit(source, temp1);
m_material.SetVector("_colorThreshold", colorThreshold);
Graphics.Blit(temp1, temp2, m_material, 0);
m_material.SetVector("_offsets", new Vector4(0, samplerScale, 0, 0));
Graphics.Blit(temp2, temp1, m_material, 1);
m_material.SetVector("_offsets", new Vector4(samplerScale, 0, 0, 0));
Graphics.Blit(temp1, temp2, m_material, 1);
m_material.SetTexture("_BlurTex", temp2);
m_material.SetVector("_bloomColor", bloomColor);
m_material.SetFloat("_bloomFactor", bloomFactor);
Graphics.Blit(source, destination, m_material, 2);
RenderTexture.ReleaseTemporary(temp1);
RenderTexture.ReleaseTemporary(temp2);
}
}
}
Shader后期处理-Bloom
https://automask.github.io/wild/2021/06/17/lab/S_Unity_Post_Bloom/