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Physically Based Rendering Algorithms: A Comprehensive Study In Unity3D ⑥

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组装你的PBRShader Part4:将所有东西组合起来

组合算法

现在我们有很多版本的NDF、GSF以及菲涅尔方程,我们需要将它们组合起来,然后我们就可以看到BRDF PBR Shader的最终效果。我们组合这些算法的方式非常简单:将这些算式相乘然后除以4 * NdotL * NdotV。

float3 specularity = (SpecularDistribution * FresnelFunction * GeometricShadow) / (4 * ( NdotL * NdotV));

当你组合了这些算法你可以将你的diffuse颜色简单做加法,然后你就得到了最终结果。

float3 lightingModel = (diffuseColor + specularity);
lightingModel *= NdotL;
float4 finalDiffuse = float4(lightingModel * attenColor,1);
return finalDiffuse;

使Unity光照信息参与计算

为了取样环境光,你需要在Unity以及你的shader中做几个比较重要的步骤。首先,添加reflection probe到你的场景中并且进行烘焙。然后你要将下面的方程放入你的shader:

UnityGI GetUnityGI(float3 lightColor, float3 lightDirection, float3 normalDirection,float3 viewDirection,
float3 viewReflectDirection, float attenuation, float roughness, float3 worldPos){
//Unity light Setup ::
UnityLight light;
light.color = lightColor;
light.dir = lightDirection;
light.ndotl = max(0.0h,dot( normalDirection, lightDirection));
UnityGIInput d;
d.light = light;
d.worldPos = worldPos;
d.worldViewDir = viewDirection;
d.atten = attenuation;
d.ambient = 0.0h;
d.boxMax[0] = unity_SpecCube0_BoxMax;
d.boxMin[0] = unity_SpecCube0_BoxMin;
d.probePosition[0] = unity_SpecCube0_ProbePosition;
d.probeHDR[0] = unity_SpecCube0_HDR;
d.boxMax[1] = unity_SpecCube1_BoxMax;
d.boxMin[1] = unity_SpecCube1_BoxMin;
d.probePosition[1] = unity_SpecCube1_ProbePosition;
d.probeHDR[1] = unity_SpecCube1_HDR;
Unity_GlossyEnvironmentData ugls_en_data;
ugls_en_data.roughness = roughness;
ugls_en_data.reflUVW = viewReflectDirection;
UnityGI gi = UnityGlobalIllumination(d, 1.0h, normalDirection, ugls_en_data );
return gi;
}

你能在你的片段程序中调用这个函数,然后它使用环境采样数据来近似环境光。

UnityGI gi = GetUnityGI(_LightColor0.rgb, lightDirection,
normalDirection, viewDirection, viewReflectDirection, attenuation, 1- _Glossiness, i.posWorld.xyz);
 
float3 indirectDiffuse = gi.indirect.diffuse.rgb ;
float3 indirectSpecular = gi.indirect.specular.rgb;

为了使用这些值,你会将他们放到我们最终的结果当中,将我们shader中diffuse相关的几行替换一下。这会允许我们采样环境光,当环境数据可用的时候我们就可以直接采样到环境数据。

float grazingTerm = saturate(roughness + _Metallic);
float3 unityIndirectSpecularity = indirectSpecular * FresnelLerp(specColor,grazingTerm,NdotV) *
max(0.15,_Metallic) * (1-roughness*roughness* roughness);
 
float3 lightingModel = (diffuseColor + specularity
+ (unityIndirectSpecularity *_UnityLightingContribution));

Debug你的算式

为了debug我们的算式,你可以通过unity的功能来开关材质的属性。

[Toggle] _ENABLE_NDF ("Normal Distribution Enabled?", Float) = 0
[Toggle] _ENABLE_G ("Geometric Shadow Enabled?", Float) = 0
[Toggle] _ENABLE_F ("Fresnel Enabled?", Float) = 0
[Toggle] _ENABLE_D ("Diffuse Enabled?", Float) = 0

这些toggle会开启或者关闭Shader的Keyword,更多信息可以在这个[页面](https://docs.unity3d.com/ScriptReference/MaterialPropertyDrawer.html)上看到,如下所示:

#ifdef _ENABLE_NDF_ON
return float4(float3(1,1,1)* SpecularDistribution,1);
#endif
#ifdef _ENABLE_G_ON
return float4(float3(1,1,1) * GeometricShadow,1) ;
#endif
#ifdef _ENABLE_F_ON
return float4(float3(1,1,1)* FresnelFunction,1);
#endif
#ifdef _ENABLE_D_ON
return float4(float3(1,1,1)* diffuseColor,1);
#endif

这种方式允许你在不同的效果之间切换你的shader,然后你就可以自己测试效果。

创建一个允许你自己选择算法的Shader

通过使用Keyword枚举,你可以让你的shader有能力自由切换你的算法,完全不需要注释来进行切换。Keyword枚举被限制在9个Keywords,所以我们必须创建我们自己的切换逻辑。

[KeywordEnum(BlinnPhong,Phong,Beckmann,Gaussian,GGX,TrowbridgeReitz,TrowbridgeReitzAnisotropic, Ward)] _NormalDistModel("Normal Distribution Model;", Float) = 0
[KeywordEnum(AshikhminShirley,AshikhminPremoze,Duer,Neumann,Kelemen,ModifiedKelemen,Cook,Ward,Kurt)]_GeoShadowModel("Geometric Shadow Model;", Float) = 0
 
[KeywordEnum(None,Walter,Beckman,GGX,Schlick,SchlickBeckman,SchlickGGX, Implicit)]_SmithGeoShadowModel("Smith Geometric Shadow Model; None if above is Used;", Float) = 0
 
[KeywordEnum(Schlick,SchlickIOR, SphericalGaussian)]_FresnelModel("Normal Distribution Model;", Float) = 0
//Normal Distribution Function/Specular Distribution-----------------------------------------------------
#ifdef _NORMALDISTMODEL_BLINNPHONG
SpecularDistribution *= BlinnPhongNormalDistribution(NdotH, _Glossiness, max(1,_Glossiness * 40));
#elif _NORMALDISTMODEL_PHONG
SpecularDistribution *= PhongNormalDistribution(RdotV, _Glossiness, max(1,_Glossiness * 40));
#elif _NORMALDISTMODEL_BECKMANN
SpecularDistribution *= BeckmannNormalDistribution(roughness, NdotH);
#elif _NORMALDISTMODEL_GAUSSIAN
SpecularDistribution *= GaussianNormalDistribution(roughness, NdotH);
#elif _NORMALDISTMODEL_GGX
SpecularDistribution *= GGXNormalDistribution(roughness, NdotH);
#elif _NORMALDISTMODEL_TROWBRIDGEREITZ
SpecularDistribution *= TrowbridgeReitzNormalDistribution(NdotH, roughness);
#elif _NORMALDISTMODEL_TROWBRIDGEREITZANISOTROPIC
SpecularDistribution *= TrowbridgeReitzAnisotropicNormalDistribution(_Anisotropic,NdotH, dot(halfDirection, i.tangentDir), dot(halfDirection, i.bitangentDir));
#elif _NORMALDISTMODEL_WARD
SpecularDistribution *= WardAnisotropicNormalDistribution(_Anisotropic,NdotL, NdotV, NdotH, dot(halfDirection, i.tangentDir), dot(halfDirection, i.bitangentDir));
#else
SpecularDistribution *= GGXNormalDistribution(roughness, NdotH);
#endif
//Geometric Shadowing term----------------------------------------------------------------------------------
#ifdef _SMITHGEOSHADOWMODEL_NONE
#ifdef _GEOSHADOWMODEL_ASHIKHMINSHIRLEY
GeometricShadow *= AshikhminShirleyGeometricShadowingFunction (NdotL, NdotV, LdotH);
#elif _GEOSHADOWMODEL_ASHIKHMINPREMOZE
GeometricShadow *= AshikhminPremozeGeometricShadowingFunction (NdotL, NdotV);
#elif _GEOSHADOWMODEL_DUER
GeometricShadow *= DuerGeometricShadowingFunction (lightDirection, viewDirection, normalDirection, NdotL, NdotV);
#elif _GEOSHADOWMODEL_NEUMANN
GeometricShadow *= NeumannGeometricShadowingFunction (NdotL, NdotV);
#elif _GEOSHADOWMODEL_KELEMAN
GeometricShadow *= KelemenGeometricShadowingFunction (NdotL, NdotV, LdotH, VdotH);
#elif _GEOSHADOWMODEL_MODIFIEDKELEMEN
GeometricShadow *= ModifiedKelemenGeometricShadowingFunction (NdotV, NdotL, roughness);
#elif _GEOSHADOWMODEL_COOK
GeometricShadow *= CookTorrenceGeometricShadowingFunction (NdotL, NdotV, VdotH, NdotH);
#elif _GEOSHADOWMODEL_WARD
GeometricShadow *= WardGeometricShadowingFunction (NdotL, NdotV, VdotH, NdotH);
#elif _GEOSHADOWMODEL_KURT
GeometricShadow *= KurtGeometricShadowingFunction (NdotL, NdotV, VdotH, roughness);
#else
GeometricShadow *= ImplicitGeometricShadowingFunction (NdotL, NdotV);
#endif
////SmithModelsBelow
////Gs = F(NdotL) * F(NdotV);
#elif _SMITHGEOSHADOWMODEL_WALTER
GeometricShadow *= WalterEtAlGeometricShadowingFunction (NdotL, NdotV, roughness);
#elif _SMITHGEOSHADOWMODEL_BECKMAN
GeometricShadow *= BeckmanGeometricShadowingFunction (NdotL, NdotV, roughness);
#elif _SMITHGEOSHADOWMODEL_GGX
GeometricShadow *= GGXGeometricShadowingFunction (NdotL, NdotV, roughness);
#elif _SMITHGEOSHADOWMODEL_SCHLICK
GeometricShadow *= SchlickGeometricShadowingFunction (NdotL, NdotV, roughness);
#elif _SMITHGEOSHADOWMODEL_SCHLICKBECKMAN
GeometricShadow *= SchlickBeckmanGeometricShadowingFunction (NdotL, NdotV, roughness);
#elif _SMITHGEOSHADOWMODEL_SCHLICKGGX
GeometricShadow *= SchlickGGXGeometricShadowingFunction (NdotL, NdotV, roughness);
#elif _SMITHGEOSHADOWMODEL_IMPLICIT
GeometricShadow *= ImplicitGeometricShadowingFunction (NdotL, NdotV);
#else
GeometricShadow *= ImplicitGeometricShadowingFunction (NdotL, NdotV);
#endif
//Fresnel Function-------------------------------------------------------------------------------------------------
 
#ifdef _FRESNELMODEL_SCHLICK
FresnelFunction *= SchlickFresnelFunction(specColor, LdotH);
#elif _FRESNELMODEL_SCHLICKIOR
FresnelFunction *= SchlickIORFresnelFunction(_Ior, LdotH);
#elif _FRESNELMODEL_SPHERICALGAUSSIAN
FresnelFunction *= SphericalGaussianFresnelFunction(LdotH, specColor);
#else
FresnelFunction *= SchlickIORFresnelFunction(_Ior, LdotH);
#endif

现在我们选择Keyword的时候我们可以实时地切换效果。通过这个你的shader应该可以完美运行了。我推荐拷贝一下下面的代码,你就可以得到完整shader的效果了,自己写的话有可能会有些凌乱。

完整代码

Shader "Physically-Based-Lighting" {
Properties {
_Color ("Main Color", Color) = (1,1,1,1)
_SpecularColor ("Specular Color", Color) = (1,1,1,1)
_SpecularPower("Specular Power", Range(0,1)) = 1
_SpecularRange("Specular Gloss", Range(1,40)) = 0
_Glossiness("Smoothness",Range(0,1)) = 1
_Metallic("Metallicness",Range(0,1)) = 0
_Anisotropic("Anisotropic", Range(-20,1)) = 0
_Ior("Ior", Range(1,4)) = 1.5
_UnityLightingContribution("Unity Reflection Contribution", Range(0,1)) = 1
[KeywordEnum(BlinnPhong,Phong,Beckmann,Gaussian,GGX,TrowbridgeReitz,TrowbridgeReitzAnisotropic, Ward)] _NormalDistModel("Normal Distribution Model;", Float) = 0
[KeywordEnum(AshikhminShirley,AshikhminPremoze,Duer,Neumann,Kelemen,ModifiedKelemen,Cook,Ward,Kurt)]_GeoShadowModel("Geometric Shadow Model;", Float) = 0
[KeywordEnum(None,Walter,Beckman,GGX,Schlick,SchlickBeckman,SchlickGGX, Implicit)]_SmithGeoShadowModel("Smith Geometric Shadow Model; None if above is Used;", Float) = 0
[KeywordEnum(Schlick,SchlickIOR, SphericalGaussian)]_FresnelModel("Normal Distribution Model;", Float) = 0
[Toggle] _ENABLE_NDF ("Normal Distribution Enabled?", Float) = 0
[Toggle] _ENABLE_G ("Geometric Shadow Enabled?", Float) = 0
[Toggle] _ENABLE_F ("Fresnel Enabled?", Float) = 0
[Toggle] _ENABLE_D ("Diffuse Enabled?", Float) = 0
}
SubShader {
Tags {
"RenderType"="Opaque" "Queue"="Geometry"
}
Pass {
Name "FORWARD"
Tags {
"LightMode"="ForwardBase"
}
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#define UNITY_PASS_FORWARDBASE
#include "UnityCG.cginc"
#include "AutoLight.cginc"
#include "Lighting.cginc"
#pragma multi_compile_fwdbase_fullshadows
#pragma multi_compile _NORMALDISTMODEL_BLINNPHONG _NORMALDISTMODEL_PHONG _NORMALDISTMODEL_BECKMANN _NORMALDISTMODEL_GAUSSIAN _NORMALDISTMODEL_GGX _NORMALDISTMODEL_TROWBRIDGEREITZ _NORMALDISTMODEL_TROWBRIDGEREITZANISOTROPIC _NORMALDISTMODEL_WARD
#pragma multi_compile _GEOSHADOWMODEL_ASHIKHMINSHIRLEY _GEOSHADOWMODEL_ASHIKHMINPREMOZE _GEOSHADOWMODEL_DUER_GEOSHADOWMODEL_NEUMANN _GEOSHADOWMODEL_KELEMAN _GEOSHADOWMODEL_MODIFIEDKELEMEN _GEOSHADOWMODEL_COOK _GEOSHADOWMODEL_WARD _GEOSHADOWMODEL_KURT
#pragma multi_compile _SMITHGEOSHADOWMODEL_NONE _SMITHGEOSHADOWMODEL_WALTER _SMITHGEOSHADOWMODEL_BECKMAN _SMITHGEOSHADOWMODEL_GGX _SMITHGEOSHADOWMODEL_SCHLICK _SMITHGEOSHADOWMODEL_SCHLICKBECKMAN _SMITHGEOSHADOWMODEL_SCHLICKGGX _SMITHGEOSHADOWMODEL_IMPLICIT
#pragma multi_compile _FRESNELMODEL_SCHLICK _FRESNELMODEL_SCHLICKIOR _FRESNELMODEL_SPHERICALGAUSSIAN
#pragma multi_compile _ENABLE_NDF_OFF _ENABLE_NDF_ON
#pragma multi_compile _ENABLE_G_OFF _ENABLE_G_ON
#pragma multi_compile _ENABLE_F_OFF _ENABLE_F_ON
#pragma multi_compile _ENABLE_D_OFF _ENABLE_D_ON
#pragma target 3.0
 
float4 _Color;
float4 _SpecularColor;
float _SpecularPower;
float _SpecularRange;
float _Glossiness;
float _Metallic;
float _Anisotropic;
float _Ior;
float _NormalDistModel;
float _GeoShadowModel;
float _FresnelModel;
float _UnityLightingContribution;
 
struct VertexInput {
float4 vertex : POSITION; //local vertex position
float3 normal : NORMAL; //normal direction
float4 tangent : TANGENT; //tangent direction
float2 texcoord0 : TEXCOORD0; //uv coordinates
float2 texcoord1 : TEXCOORD1; //lightmap uv coordinates
};
 
struct VertexOutput {
float4 pos : SV_POSITION; //screen clip space position and depth
float2 uv0 : TEXCOORD0; //uv coordinates
float2 uv1 : TEXCOORD1; //lightmap uv coordinates
 
//below we create our own variables with the texcoord semantic.
float3 normalDir : TEXCOORD3; //normal direction
float3 posWorld : TEXCOORD4; //normal direction
float3 tangentDir : TEXCOORD5;
float3 bitangentDir : TEXCOORD6;
LIGHTING_COORDS(7,8) //this initializes the unity lighting and shadow
UNITY_FOG_COORDS(9) //this initializes the unity fog
};
 
VertexOutput vert (VertexInput v) {
VertexOutput o = (VertexOutput)0;
o.uv0 = v.texcoord0;
o.uv1 = v.texcoord1;
o.normalDir = UnityObjectToWorldNormal(v.normal);
o.tangentDir = normalize( mul( _Object2World, float4( v.tangent.xyz, 0.0 ) ).xyz );
o.bitangentDir = normalize(cross(o.normalDir, o.tangentDir) * v.tangent.w);
o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
o.posWorld = mul(_Object2World, v.vertex);
UNITY_TRANSFER_FOG(o,o.pos);
TRANSFER_VERTEX_TO_FRAGMENT(o)
return o;
}
 
UnityGI GetUnityGI(float3 lightColor, float3 lightDirection, float3 normalDirection,float3 viewDirection, float3 viewReflectDirection, float attenuation, float roughness, float3 worldPos){
//Unity light Setup ::
UnityLight light;
light.color = lightColor;
light.dir = lightDirection;
light.ndotl = max(0.0h,dot( normalDirection, lightDirection));
UnityGIInput d;
d.light = light;
d.worldPos = worldPos;
d.worldViewDir = viewDirection;
d.atten = attenuation;
d.ambient = 0.0h;
d.boxMax[0] = unity_SpecCube0_BoxMax;
d.boxMin[0] = unity_SpecCube0_BoxMin;
d.probePosition[0] = unity_SpecCube0_ProbePosition;
d.probeHDR[0] = unity_SpecCube0_HDR;
d.boxMax[1] = unity_SpecCube1_BoxMax;
d.boxMin[1] = unity_SpecCube1_BoxMin;
d.probePosition[1] = unity_SpecCube1_ProbePosition;
d.probeHDR[1] = unity_SpecCube1_HDR;
Unity_GlossyEnvironmentData ugls_en_data;
ugls_en_data.roughness = roughness;
ugls_en_data.reflUVW = viewReflectDirection;
UnityGI gi = UnityGlobalIllumination(d, 1.0h, normalDirection, ugls_en_data );
return gi;
}
//---------------------------
//helper functions
float MixFunction(float i, float j, float x) {
return j * x + i * (1.0 - x);
}
float2 MixFunction(float2 i, float2 j, float x){
return j * x + i * (1.0h - x);
}
float3 MixFunction(float3 i, float3 j, float x){
return j * x + i * (1.0h - x);
}
float MixFunction(float4 i, float4 j, float x){
return j * x + i * (1.0h - x);
}
float sqr(float x){
return x*x;
}
//------------------------------
//------------------------------------------------
//schlick functions
float SchlickFresnel(float i){
float x = clamp(1.0-i, 0.0, 1.0);
float x2 = x*x;
return x2*x2*x;
}
float3 FresnelLerp (float3 x, float3 y, float d)
{
float t = SchlickFresnel(d);
return lerp (x, y, t);
}
 
float3 SchlickFresnelFunction(float3 SpecularColor,float LdotH){
return SpecularColor + (1 - SpecularColor)* SchlickFresnel(LdotH);
}
 
float SchlickIORFresnelFunction(float ior,float LdotH){
float f0 = pow((ior-1)/(ior+1),2);
return f0 + (1 - f0) * SchlickFresnel(LdotH);
}
float SphericalGaussianFresnelFunction(float LdotH,float SpecularColor)
{
float power = ((-5.55473 * LdotH) - 6.98316) * LdotH;
return SpecularColor + (1 - SpecularColor) * pow(2,power);
}
 
//-----------------------------------------------
 
//-----------------------------------------------
//normal incidence reflection calculation
float F0 (float NdotL, float NdotV, float LdotH, float roughness){
// Diffuse fresnel
float FresnelLight = SchlickFresnel(NdotL);
float FresnelView = SchlickFresnel(NdotV);
float FresnelDiffuse90 = 0.5 + 2.0 * LdotH*LdotH * roughness;
return MixFunction(1, FresnelDiffuse90, FresnelLight) * MixFunction(1, FresnelDiffuse90, FresnelView);
}
 
//-----------------------------------------------
//-----------------------------------------------
//Normal Distribution Functions
 
float BlinnPhongNormalDistribution(float NdotH, float specularpower, float speculargloss){
float Distribution = pow(NdotH,speculargloss) * specularpower;
Distribution *= (2+specularpower) / (2*3.1415926535);
return Distribution;
}
float PhongNormalDistribution(float RdotV, float specularpower, float speculargloss){
float Distribution = pow(RdotV,speculargloss) * specularpower;
Distribution *= (2+specularpower) / (2*3.1415926535);
return Distribution;
}
 
float BeckmannNormalDistribution(float roughness, float NdotH)
{
float roughnessSqr = roughness*roughness;
float NdotHSqr = NdotH*NdotH;
return max(0.000001,(1.0 / (3.1415926535*roughnessSqr*NdotHSqr*NdotHSqr))* exp((NdotHSqr-1)/(roughnessSqr*NdotHSqr)));
}
 
float GaussianNormalDistribution(float roughness, float NdotH)
{
float roughnessSqr = roughness*roughness;
float thetaH = acos(NdotH);
return exp(-thetaH*thetaH/roughnessSqr);
}
 
float GGXNormalDistribution(float roughness, float NdotH)
{
float roughnessSqr = roughness*roughness;
float NdotHSqr = NdotH*NdotH;
float TanNdotHSqr = (1-NdotHSqr)/NdotHSqr;
return (1.0/3.1415926535) * sqr(roughness/(NdotHSqr * (roughnessSqr + TanNdotHSqr)));
// float denom = NdotHSqr * (roughnessSqr-1)
 
}
 
float TrowbridgeReitzNormalDistribution(float NdotH, float roughness){
float roughnessSqr = roughness*roughness;
float Distribution = NdotH*NdotH * (roughnessSqr-1.0) + 1.0;
return roughnessSqr / (3.1415926535 * Distribution*Distribution);
}
 
float TrowbridgeReitzAnisotropicNormalDistribution(float anisotropic, float NdotH, float HdotX, float HdotY){
float aspect = sqrt(1.0h-anisotropic * 0.9h);
float X = max(.001, sqr(1.0-_Glossiness)/aspect) * 5;
float Y = max(.001, sqr(1.0-_Glossiness)*aspect) * 5;
return 1.0 / (3.1415926535 * X*Y * sqr(sqr(HdotX/X) + sqr(HdotY/Y) + NdotH*NdotH));
}
 
float WardAnisotropicNormalDistribution(float anisotropic, float NdotL, float NdotV, float NdotH, float HdotX, float HdotY){
float aspect = sqrt(1.0h-anisotropic * 0.9h);
float X = max(.001, sqr(1.0-_Glossiness)/aspect) * 5;
float Y = max(.001, sqr(1.0-_Glossiness)*aspect) * 5;
float exponent = -(sqr(HdotX/X) + sqr(HdotY/Y)) / sqr(NdotH);
float Distribution = 1.0 / ( 3.14159265 * X * Y * sqrt(NdotL * NdotV));
Distribution *= exp(exponent);
return Distribution;
}
//--------------------------
 
//-----------------------------------------------
//Geometric Shadowing Functions
 
float ImplicitGeometricShadowingFunction (float NdotL, float NdotV){
float Gs = (NdotL*NdotV);
return Gs;
}
 
float AshikhminShirleyGeometricShadowingFunction (float NdotL, float NdotV, float LdotH){
float Gs = NdotL*NdotV/(LdotH*max(NdotL,NdotV));
return (Gs);
}
 
float AshikhminPremozeGeometricShadowingFunction (float NdotL, float NdotV){
float Gs = NdotL*NdotV/(NdotL+NdotV - NdotL*NdotV);
return (Gs);
}
 
float DuerGeometricShadowingFunction (float3 lightDirection,float3 viewDirection, float3 normalDirection,float NdotL, float NdotV){
float3 LpV = lightDirection + viewDirection;
float Gs = dot(LpV,LpV) * pow(dot(LpV,normalDirection),-4);
return (Gs);
}
 
float NeumannGeometricShadowingFunction (float NdotL, float NdotV){
float Gs = (NdotL*NdotV)/max(NdotL, NdotV);
return (Gs);
}
 
float KelemenGeometricShadowingFunction (float NdotL, float NdotV, float LdotH, float VdotH){
// float Gs = (NdotL*NdotV)/ (LdotH * LdotH); //this
float Gs = (NdotL*NdotV)/(VdotH * VdotH); //or this?
return (Gs);
}
 
float ModifiedKelemenGeometricShadowingFunction (float NdotV, float NdotL, float roughness)
{
float c = 0.797884560802865; // c = sqrt(2 / Pi)
float k = roughness * roughness * c;
float gH = NdotV * k +(1-k);
return (gH * gH * NdotL);
}
 
float CookTorrenceGeometricShadowingFunction (float NdotL, float NdotV, float VdotH, float NdotH){
float Gs = min(1.0, min(2*NdotH*NdotV / VdotH, 2*NdotH*NdotL / VdotH));
return (Gs);
}
 
float WardGeometricShadowingFunction (float NdotL, float NdotV, float VdotH, float NdotH){
float Gs = pow( NdotL * NdotV, 0.5);
return (Gs);
}
 
float KurtGeometricShadowingFunction (float NdotL, float NdotV, float VdotH, float alpha){
float Gs = (VdotH*pow(NdotL*NdotV, alpha))/ NdotL * NdotV;
return (Gs);
}
 
//SmithModelsBelow
//Gs = F(NdotL) * F(NdotV);
 
float WalterEtAlGeometricShadowingFunction (float NdotL, float NdotV, float alpha){
float alphaSqr = alpha*alpha;
float NdotLSqr = NdotL*NdotL;
float NdotVSqr = NdotV*NdotV;
float SmithL = 2/(1 + sqrt(1 + alphaSqr * (1-NdotLSqr)/(NdotLSqr)));
float SmithV = 2/(1 + sqrt(1 + alphaSqr * (1-NdotVSqr)/(NdotVSqr)));
float Gs = (SmithL * SmithV);
return Gs;
}
 
float BeckmanGeometricShadowingFunction (float NdotL, float NdotV, float roughness){
float roughnessSqr = roughness*roughness;
float NdotLSqr = NdotL*NdotL;
float NdotVSqr = NdotV*NdotV;
float calulationL = (NdotL)/(roughnessSqr * sqrt(1- NdotLSqr));
float calulationV = (NdotV)/(roughnessSqr * sqrt(1- NdotVSqr));
float SmithL = calulationL < 1.6 ? (((3.535 * calulationL) + (2.181 * calulationL * calulationL))/(1 + (2.276 * calulationL) + (2.577 * calulationL * calulationL))) : 1.0;
float SmithV = calulationV < 1.6 ? (((3.535 * calulationV) + (2.181 * calulationV * calulationV))/(1 + (2.276 * calulationV) + (2.577 * calulationV * calulationV))) : 1.0;
float Gs = (SmithL * SmithV);
return Gs;
}
 
float GGXGeometricShadowingFunction (float NdotL, float NdotV, float roughness){
float roughnessSqr = roughness*roughness;
float NdotLSqr = NdotL*NdotL;
float NdotVSqr = NdotV*NdotV;
float SmithL = (2 * NdotL)/ (NdotL + sqrt(roughnessSqr + ( 1-roughnessSqr) * NdotLSqr));
float SmithV = (2 * NdotV)/ (NdotV + sqrt(roughnessSqr + ( 1-roughnessSqr) * NdotVSqr));
float Gs = (SmithL * SmithV) ;
return Gs;
}
 
float SchlickGeometricShadowingFunction (float NdotL, float NdotV, float roughness)
{
float roughnessSqr = roughness*roughness;
float SmithL = (NdotL)/(NdotL * (1-roughnessSqr) + roughnessSqr);
float SmithV = (NdotV)/(NdotV * (1-roughnessSqr) + roughnessSqr);
return (SmithL * SmithV);
}
float SchlickBeckmanGeometricShadowingFunction (float NdotL, float NdotV, float roughness){
float roughnessSqr = roughness*roughness;
float k = roughnessSqr * 0.797884560802865;
float SmithL = (NdotL)/ (NdotL * (1- k) + k);
float SmithV = (NdotV)/ (NdotV * (1- k) + k);
float Gs = (SmithL * SmithV);
return Gs;
}
 
float SchlickGGXGeometricShadowingFunction (float NdotL, float NdotV, float roughness){
float k = roughness / 2;
float SmithL = (NdotL)/ (NdotL * (1- k) + k);
float SmithV = (NdotV)/ (NdotV * (1- k) + k);
float Gs = (SmithL * SmithV);
return Gs;
}
 
//--------------------------
float4 frag(VertexOutput i) : COLOR {
 
//normal direction calculations
float3 normalDirection = normalize(i.normalDir);
float3 viewDirection = normalize(_WorldSpaceCameraPos.xyz - i.posWorld.xyz);
float shiftAmount = dot(i.normalDir, viewDirection);
normalDirection = shiftAmount < 0.0f ? normalDirection + viewDirection * (-shiftAmount + 1e-5f) : normalDirection;
 
//light calculations
float3 lightDirection = normalize(lerp(_WorldSpaceLightPos0.xyz, _WorldSpaceLightPos0.xyz - i.posWorld.xyz,_WorldSpaceLightPos0.w));
float3 lightReflectDirection = reflect( -lightDirection, normalDirection );
float3 viewReflectDirection = normalize(reflect( -viewDirection, normalDirection ));
float NdotL = max(0.0, dot( normalDirection, lightDirection ));
float3 halfDirection = normalize(viewDirection+lightDirection);
float NdotH = max(0.0,dot( normalDirection, halfDirection));
float NdotV = max(0.0,dot( normalDirection, viewDirection));
float VdotH = max(0.0,dot( viewDirection, halfDirection));
float LdotH = max(0.0,dot(lightDirection, halfDirection));
float LdotV = max(0.0,dot(lightDirection, viewDirection));
float RdotV = max(0.0, dot( lightReflectDirection, viewDirection ));
float attenuation = LIGHT_ATTENUATION(i);
float3 attenColor = attenuation * _LightColor0.rgb;
 
//get Unity Scene lighting data
UnityGI gi = GetUnityGI(_LightColor0.rgb, lightDirection, normalDirection, viewDirection, viewReflectDirection, attenuation, 1- _Glossiness, i.posWorld.xyz);
float3 indirectDiffuse = gi.indirect.diffuse.rgb ;
float3 indirectSpecular = gi.indirect.specular.rgb;
 
//diffuse color calculations
float roughness = 1-(_Glossiness * _Glossiness);
roughness = roughness * roughness;
float3 diffuseColor = _Color.rgb * (1.0 - _Metallic) ;
float f0 = F0(NdotL, NdotV, LdotH, roughness);
diffuseColor *= f0;
diffuseColor+=indirectDiffuse;
//Specular calculations
float3 specColor = lerp(_SpecularColor.rgb, _Color.rgb, _Metallic * 0.5);
 
float3 SpecularDistribution = specColor;
float GeometricShadow = 1;
float3 FresnelFunction = specColor;
 
//Normal Distribution Function/Specular Distribution-----------------------------------------------------
#ifdef _NORMALDISTMODEL_BLINNPHONG
SpecularDistribution *= BlinnPhongNormalDistribution(NdotH, _Glossiness, max(1,_Glossiness * 40));
#elif _NORMALDISTMODEL_PHONG
SpecularDistribution *= PhongNormalDistribution(RdotV, _Glossiness, max(1,_Glossiness * 40));
#elif _NORMALDISTMODEL_BECKMANN
SpecularDistribution *= BeckmannNormalDistribution(roughness, NdotH);
#elif _NORMALDISTMODEL_GAUSSIAN
SpecularDistribution *= GaussianNormalDistribution(roughness, NdotH);
#elif _NORMALDISTMODEL_GGX
SpecularDistribution *= GGXNormalDistribution(roughness, NdotH);
#elif _NORMALDISTMODEL_TROWBRIDGEREITZ
SpecularDistribution *= TrowbridgeReitzNormalDistribution(NdotH, roughness);
#elif _NORMALDISTMODEL_TROWBRIDGEREITZANISOTROPIC
SpecularDistribution *= TrowbridgeReitzAnisotropicNormalDistribution(_Anisotropic,NdotH, dot(halfDirection, i.tangentDir), dot(halfDirection, i.bitangentDir));
#elif _NORMALDISTMODEL_WARD
SpecularDistribution *= WardAnisotropicNormalDistribution(_Anisotropic,NdotL, NdotV, NdotH, dot(halfDirection, i.tangentDir), dot(halfDirection, i.bitangentDir));
#else
SpecularDistribution *= GGXNormalDistribution(roughness, NdotH);
#endif
//Geometric Shadowing term----------------------------------------------------------------------------------
#ifdef _SMITHGEOSHADOWMODEL_NONE
#ifdef _GEOSHADOWMODEL_ASHIKHMINSHIRLEY
GeometricShadow *= AshikhminShirleyGeometricShadowingFunction (NdotL, NdotV, LdotH);
#elif _GEOSHADOWMODEL_ASHIKHMINPREMOZE
GeometricShadow *= AshikhminPremozeGeometricShadowingFunction (NdotL, NdotV);
#elif _GEOSHADOWMODEL_DUER
GeometricShadow *= DuerGeometricShadowingFunction (lightDirection, viewDirection, normalDirection, NdotL, NdotV);
#elif _GEOSHADOWMODEL_NEUMANN
GeometricShadow *= NeumannGeometricShadowingFunction (NdotL, NdotV);
#elif _GEOSHADOWMODEL_KELEMAN
GeometricShadow *= KelemenGeometricShadowingFunction (NdotL, NdotV, LdotH, VdotH);
#elif _GEOSHADOWMODEL_MODIFIEDKELEMEN
GeometricShadow *= ModifiedKelemenGeometricShadowingFunction (NdotV, NdotL, roughness);
#elif _GEOSHADOWMODEL_COOK
GeometricShadow *= CookTorrenceGeometricShadowingFunction (NdotL, NdotV, VdotH, NdotH);
#elif _GEOSHADOWMODEL_WARD
GeometricShadow *= WardGeometricShadowingFunction (NdotL, NdotV, VdotH, NdotH);
#elif _GEOSHADOWMODEL_KURT
GeometricShadow *= KurtGeometricShadowingFunction (NdotL, NdotV, VdotH, roughness);
#else
GeometricShadow *= ImplicitGeometricShadowingFunction (NdotL, NdotV);
#endif
////SmithModelsBelow
////Gs = F(NdotL) * F(NdotV);
#elif _SMITHGEOSHADOWMODEL_WALTER
GeometricShadow *= WalterEtAlGeometricShadowingFunction (NdotL, NdotV, roughness);
#elif _SMITHGEOSHADOWMODEL_BECKMAN
GeometricShadow *= BeckmanGeometricShadowingFunction (NdotL, NdotV, roughness);
#elif _SMITHGEOSHADOWMODEL_GGX
GeometricShadow *= GGXGeometricShadowingFunction (NdotL, NdotV, roughness);
#elif _SMITHGEOSHADOWMODEL_SCHLICK
GeometricShadow *= SchlickGeometricShadowingFunction (NdotL, NdotV, roughness);
#elif _SMITHGEOSHADOWMODEL_SCHLICKBECKMAN
GeometricShadow *= SchlickBeckmanGeometricShadowingFunction (NdotL, NdotV, roughness);
#elif _SMITHGEOSHADOWMODEL_SCHLICKGGX
GeometricShadow *= SchlickGGXGeometricShadowingFunction (NdotL, NdotV, roughness);
#elif _SMITHGEOSHADOWMODEL_IMPLICIT
GeometricShadow *= ImplicitGeometricShadowingFunction (NdotL, NdotV);
#else
GeometricShadow *= ImplicitGeometricShadowingFunction (NdotL, NdotV);
#endif
//Fresnel Function-------------------------------------------------------------------------------------------------
 
#ifdef _FRESNELMODEL_SCHLICK
FresnelFunction *= SchlickFresnelFunction(specColor, LdotH);
#elif _FRESNELMODEL_SCHLICKIOR
FresnelFunction *= SchlickIORFresnelFunction(_Ior, LdotH);
#elif _FRESNELMODEL_SPHERICALGAUSSIAN
FresnelFunction *= SphericalGaussianFresnelFunction(LdotH, specColor);
#else
FresnelFunction *= SchlickIORFresnelFunction(_Ior, LdotH);
#endif
#ifdef _ENABLE_NDF_ON
return float4(float3(1,1,1)* SpecularDistribution,1);
#endif
#ifdef _ENABLE_G_ON
return float4(float3(1,1,1) * GeometricShadow,1) ;
#endif
#ifdef _ENABLE_F_ON
return float4(float3(1,1,1)* FresnelFunction,1);
#endif
#ifdef _ENABLE_D_ON
return float4(float3(1,1,1)* diffuseColor,1);
#endif
 
//PBR
float3 specularity = (SpecularDistribution * FresnelFunction * GeometricShadow) / (4 * ( NdotL * NdotV));
float grazingTerm = saturate(roughness + _Metallic);
float3 unityIndirectSpecularity = indirectSpecular * FresnelLerp(specColor,grazingTerm,NdotV) * max(0.15,_Metallic) * (1-roughness*roughness* roughness);
 
float3 lightingModel = ((diffuseColor) + specularity + (unityIndirectSpecularity *_UnityLightingContribution));
lightingModel *= NdotL;
float4 finalDiffuse = float4(lightingModel * attenColor,1);
UNITY_APPLY_FOG(i.fogCoord, finalDiffuse);
return finalDiffuse;
}
ENDCG
}
}
FallBack "Legacy Shaders/Diffuse"
}

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