卷积/球谐函数

这篇的球谐部分还需要完善下 目前是咩有的

正好light probe里面有

https://www.jianshu.com/p/cbd1a1f86d1b

https://blog.csdn.net/bitcarmanlee/article/details/54729807

blur是个卷积 每个点采样高斯分布

照着做了一下 还真是

float a=1.0;

s = a*(SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, UnityStereoTransformScreenSpaceTex(uv + _MainTex_TexelSize.xy*float2(-1,1))));
// s += a * (SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, UnityStereoTransformScreenSpaceTex(uv + _MainTex_TexelSize.xy*float2(0,1))));
// s += a * (SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, UnityStereoTransformScreenSpaceTex(uv + _MainTex_TexelSize.xy*float2(1,1))));

// s += a * (SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, UnityStereoTransformScreenSpaceTex(uv + _MainTex_TexelSize.xy*float2(-1,0))));
s += a*(SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, UnityStereoTransformScreenSpaceTex(uv + _MainTex_TexelSize.xy*float2(0,0))));
//s += -a * (SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, UnityStereoTransformScreenSpaceTex(uv + _MainTex_TexelSize.xy*float2(1,0))));

//s += a * (SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, UnityStereoTransformScreenSpaceTex(uv + _MainTex_TexelSize.xy*float2(-1,-1))));
//s += -a * (SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, UnityStereoTransformScreenSpaceTex(uv + _MainTex_TexelSize.xy*float2(0,-1))));
s += a * (SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, UnityStereoTransformScreenSpaceTex(uv + _MainTex_TexelSize.xy*float2(-1,-1))));
//s += 0.5;
//s *=(1.0 / 9.0);

a组成的3X3的矩阵就是kernel了

浮雕的kernel是

-1,-1,-1

-1, 0, 1

 1, 1, 1

结果再-0.5

gause的kernel

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球谐

正弦函数 傅里叶展开

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是时候填这个很多年前的坑了

球谐函数是一组基函数 二维的 参数是theta 和phi（参数定义三维空间方向）

定义在球面上

有一些性质适合 记录低频信息 L和T都可以

http://bgrawi.com/Fourier-Visualizations/