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Unity3d 基于物理渲染Physically-Based Rendering之最终篇

前情提要：

讲求基本算法

Unity3d 基于物理渲染Physically-Based Rendering之specular BRDF

plus篇

Unity3d 基于物理渲染Physically-Based Rendering之实现

最后我们用fragment shader 实现，加上diffuse漫反射，代码和之前的surface差不多，只是多了reflect方向的计算，reflect方向的计算方法为用CG函数库中函数reflect，

float3 reflect(float3 i, float3 n);
i为in入射方向，n为normal发现方向，此处入射方向为view direction。

float3 refDir = reflect(-viewDir,N);

参考了下SIGGRAPH 2013中虚幻引擎的diffuse

他们的方法为new diffuse = diffuse color/π。

把π改为可控参数就好，调成我们想要的效果。

建立了一个外部变量_ReflAmount为cubeMap和diffuse的比重，_ReflAmount越高反射周围景物越明显

这是本文实现效果

Unity3d 基于物理渲染Physically-Based Rendering之最终篇

_ReflAmount = 0.5

_ReflAmount = 0

有没有要滴出血的感觉？

_ReflAmount = 1

高大上的丝袜黑

Unity3d 基于物理渲染Physically-Based Rendering之最终篇

_ReflAmount = 1
Unity3d 基于物理渲染Physically-Based Rendering之最终篇
_ReflAmount = 0

_ReflAmount = 0.5

与unity作比较：

diffuse：

Unity3d 基于物理渲染Physically-Based Rendering之最终篇

specular：

Unity3d 基于物理渲染Physically-Based Rendering之最终篇

这是虚幻引擎在 SIGGRAPH 2013 发表的效果：

Unity3d 基于物理渲染Physically-Based Rendering之最终篇

Unity3d 基于物理渲染Physically-Based Rendering之最终篇
可惜我没有那么高大上的模型做实验，可惜了，就用人脸做代替

代码如下：

Shader "Custom/reflect new ops3" {  Properties{  _MainTex("Base (RGB)", 2D) = "white" {}  _Maintint("Main Color", Color) = (1, 1, 1, 1)   _Cubemap("CubeMap", CUBE) = ""{}  _SC("Specular Color", Color) = (1, 1, 1, 1)   _GL("gloss", Range(0, 1)) = 0.5   _nMips("nMipsF", Range(0, 5)) = 0.5   _ReflAmount("Reflection Amount", Range(0.01, 1)) = 0.5 }  SubShader{   pass{//平行光的的pass渲染   Tags{ "LightMode" = "ForwardBase" }   Cull Back    CGPROGRAM #pragma vertex vert #pragma fragment frag #include "UnityCG.cginc"     float4 _LightColor0;   samplerCUBE _Cubemap;   float4 _SC;   float _GL;   float4 _Maintint;   float _nMips;   float _ReflAmount;   uniform sampler2D _MainTex;   float4 _MainTex_ST;   struct v2f {    float4 pos : SV_POSITION;    float2 uv_MainTex : TEXCOORD0;    float3 lightDir : TEXCOORD1;    float3 viewDir : TEXCOORD2;    float3 normal : TEXCOORD3;    };    v2f vert(appdata_full v) {    v2f o;    o.pos = mul(UNITY_MATRIX_MVP, v.vertex);//切换到世界坐标    o.normal = v.normal;    o.lightDir = ObjSpaceLightDir(v.vertex);    o.viewDir = ObjSpaceViewDir(v.vertex);    o.uv_MainTex = TRANSFORM_TEX(v.texcoord, _MainTex);    return o;   } #define PIE 3.1415926535      float4 frag(v2f i) :COLOR   {    float3 viewDir = normalize(i.viewDir);    float3 lightDir = normalize(i.lightDir);    float3 H = normalize(lightDir + viewDir);    float3 N = normalize(i.normal);    float _SP = pow(8192, _GL);    float d = (_SP + 2) / (8 * PIE) * pow(dot(N, H), _SP);    // float f = _SC + (1 - _SC)*pow((1 - dot(H, lightDir)), 5);    float f = _SC + (1 - _SC)*pow(2, -10 * dot(H, lightDir));    float k = min(1, _GL + 0.545);    float v = 1 / (k* dot(viewDir, H)*dot(viewDir, H) + (1 - k));      float all = d*f*v;    // float3 refDir = N - lightDir / 2;//H     float3 refDir = reflect(-viewDir,N);     float3 ref = texCUBElod(_Cubemap, float4(refDir, _nMips - _GL*_nMips)).rgb;//* _ReflAmount;    float3 c = tex2D(_MainTex, i.uv_MainTex);    float3 diff = dot(lightDir, N);   // diff /= PIE;    diff = (1 - all)*diff;    // return float4(c *(diff + all), 1)  * _LightColor0;    return float4(lerp(c, ref, _ReflAmount) *(diff*_Maintint + all), 1)*_LightColor0;   // return float4(ref*((_Maintint+0.2) * (1 - dot(lightDir, N))) + c *(diff*_Maintint + all), 1)*_LightColor0;   // return float4(lerp(c, ref, _ReflAmount) *(diff*(_Maintint + 0.2)* (1 - dot(lightDir, N)) + all), 1)*_LightColor0;   }   ENDCG  }  } }

----- by wolf96

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