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| Shader "Unity Shaders Learn/Chapter18/CustomPBR"
{
Properties
{
_Color ("Color", Color) = (1,1,1,1)
_MainTex ("Albedo (RGB)", 2D) = "white" {}
_Glossiness ("Smoothness", Range(0,1)) = 0.5
_SpecularColor ("Specular", Color) = (0.2, 0.2, 0.2)
_SpecGlossMap ("Specular (RGB) Smoothness (A)", 2D) = "white" {}
_BumpScale ("Bump Scale", Float) = 1.0
_BumpMap ("Normal Map", 2D) = "bump" {}
_EmissionColor ("Emission Color", Color) = (0,0,0)
_EmissionMap ("Eission", 2D) = "white" {}
}
SubShader
{
Tags {"RenderType"="Opaque"}
LOD 300
CGINCLUDE
#include "UnityCG.cginc"
#include "AutoLight.cginc"
#include "Lighting.cginc"
fixed4 _Color;
sampler2D _MainTex;
float4 _MainTex_ST;
fixed _Glossiness;
fixed4 _SpecularColor;
sampler2D _SpecGlossMap;
float _BumpScale;
sampler2D _BumpMap;
fixed4 _EmissionColor;
sampler2D _EmissionMap;
// 迪士尼漫反射项
inline half3 CustomDisneyDiffuseTerm(half NdotV, half NdotL, half LdotH, half roughness, half3 baseColor)
{
half fd90 = 0.5 + 2 * LdotH * LdotH * roughness;
// Two schlick fresnel term
half lightScatter = (1 + (fd90 - 1) * pow(1 - NdotL, 5));
half viewScatter = (1 + (fd90 - 1) * pow(1 - NdotV, 5));
return baseColor * UNITY_INV_PI * lightScatter * viewScatter;
}
// 依照 Eric Heitz 提出的按 Height-Correlated Masking and Shadowing 方式组合的 Smith-Joint 阴影-遮掩函数
inline half CustomSmithJointGGXVisibilityTerm(half NdotL, half NdotV, half roughness)
{
half a2 = roughness * roughness;
// Original formulation:
// half lambda_v = (-1 + sqrt(a2 * (1 - NdotL*NdotL) / NdotL * NdotL + 1)) * 0.5f;
// half lambda_l = (-1 + sqrt(a2 * (1 - NdotV*NdotV) / NdotV * NdotV + 1)) * 0.5f;
// G = 1 / (1 + lambda_v + lambda_l);
// Approximation of the above formulation (simplify the sqrt, not mathematically correct but close enough)
half lambdaV = NdotL * (NdotV * (1 - a2) + a2);
half lambdaL = NdotV * (NdotL * (1 - a2) + a2);
return 0.5f / (lambdaL + lambdaV + 1e-5f);
}
// 法线分布项 D，CustomGGXTerm 函数的实现（依照基于 GGX 模型的法线分布函数）
inline half CustomGGXTerm(half NdotH, half roughness)
{
half a2 = roughness * roughness;
half d = (NdotH * a2 - NdotH) * NdotH + 1.0f;
return UNITY_INV_PI * a2 / (d * d + 1e-7f);
}
// 菲涅耳反射项 F，CustomFresnelTerm 函数（依照 Schlick 菲涅耳近似等式）的实现
inline half3 CustomFresnelTerm(half3 c, half cosA)
{
half t = pow(1 - cosA, 5);
return c + (1 - c) * t;
}
// 菲涅耳插值
inline half3 CustomFresnelLerp(half3 c0, half3 c1, half cosA)
{
half t = pow(1 - cosA, 5);
return lerp(c0, c1, t);
}
ENDCG
Pass
{
Tags {"LightMode" = "ForwardBase"}
CGPROGRAM
#pragma target 3.0
#pragma multi_compile_fwdbase
#pragma multi_compole_fog
#pragma vertex vert;
#pragma fragment frag;
struct a2v
{
float4 vertex : POSITION;
float4 texcoord : TEXCOORD0;
float3 normal : NORMAL;
float4 tangent : TANGENT;
};
struct v2f
{
float4 pos : SV_POSITION;
float2 uv : TEXCOORD0;
float4 TtoW0 : TEXCOORD1;
float4 TtoW1 : TEXCOORD2;
float4 TtoW2 : TEXCOORD3;
SHADOW_COORDS(4)
UNITY_FOG_COORDS(5)
};
v2f vert(a2v v)
{
v2f o;
UNITY_INITIALIZE_OUTPUT(v2f, o);
o.pos = UnityObjectToClipPos(v.vertex);
o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);
float3 worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;
float3 worldNormal = UnityObjectToWorldNormal(v.normal);
float3 worldTangent = UnityObjectToWorldDir(v.tangent.xyz);
float3 worldBinormal = cross(worldNormal, worldTangent) * v.tangent.w;
o.TtoW0 = float4(worldTangent.x, worldBinormal.x, worldNormal.x, worldPos.x);
o.TtoW1 = float4(worldTangent.y, worldBinormal.y, worldNormal.y, worldPos.y);
o.TtoW2 = float4(worldTangent.z, worldBinormal.z, worldNormal.z, worldPos.z);
TRANSFER_SHADOW(o);
UNITY_TRANSFER_FOG(o, o.pos);
return o;
}
half4 frag(v2f i) : SV_Target
{
//// 准备好输入数据
half4 specGloss = tex2D(_SpecGlossMap, i.uv);
specGloss.a *= _Glossiness;
half3 specColor = specGloss.rgb * _SpecularColor.rgb;
half roughness = 1 - specGloss.a;
//这个变量并不是我们之前到的 BRDF 中需要的变量，它主要是为了计算掠射角的反射颜色，从而得到效果更好的菲涅耳反射效果。
half oneMinusReflectivity = 1 - max(max(specColor.r, specColor.g), specColor.b);
half3 diffColor = _Color.rgb * tex2D(_MainTex, i.uv).rgb * oneMinusReflectivity;
half3 normalTangent = UnpackNormal(tex2D(_BumpMap, i.uv));
normalTangent.xy *= _BumpScale;
normalTangent.z = sqrt(1.0 - saturate(dot(normalTangent.xy, normalTangent.xy)));
half3 worldNormal = normalize(half3(dot(i.TtoW0.xyz, normalTangent),
dot(i.TtoW1.xyz, normalTangent), dot(i.TtoW2.xyz, normalTangent)));
float3 worldPos = float3(i.TtoW0.w, i.TtoW1.w, i.TtoW2.w);
half3 lightDir = normalize(UnityWorldSpaceLightDir(worldPos));
half3 viewDir = normalize(UnityWorldSpaceViewDir(worldPos));
half3 reflDir = reflect(-viewDir, worldNormal);
UNITY_LIGHT_ATTENUATION(atten, i, worldPos);
//// 计算 BRDF 项
half3 halfDir = normalize(lightDir + viewDir);
half nv = saturate(dot(worldNormal, viewDir));
half nl = saturate(dot(worldNormal, lightDir));
half nh = saturate(dot(worldNormal, halfDir));
half lv = saturate(dot(lightDir, viewDir));
half lh = saturate(dot(lightDir, halfDir));
// diffuse term
half3 diffuseTerm = CustomDisneyDiffuseTerm(nv, nl, lh, roughness, diffColor);
// specular term
half V = CustomSmithJointGGXVisibilityTerm(nl, nv, roughness);
half D = CustomGGXTerm(nh, roughness * roughness);
half3 F = CustomFresnelTerm(specColor, lh);
half3 specularTerm = F * V * D;
// Emission term
half3 emissionTerm = tex2D(_EmissionMap, i.uv).rgb * _EmissionColor.rgb;
// IBL 使用材质粗糙度对环境贴图进行 LOD（Level Of Detail）采样
half perceptualRoughness = roughness * (1.7 - 0.7 * roughness);
//为了计算需要采样的多级渐远纹理的级数，我们将材质粗糙度乘以某个常数（在上述实现中该常数为 6），这个常数表明了整个粗糙度范围内多级渐远纹理的总级数。
half mip = perceptualRoughness * 6;
//unity_SpecCube0 包含了该物体周围当前活跃的反射探针（ReflectionProbe）中所包含的环境贴图。
half4 envMap = UNITY_SAMPLE_TEXCUBE_LOD(unity_SpecCube0, reflDir, mip);
half grazingTerm = saturate((1 - roughness) + (1 - oneMinusReflectivity));
half surfaceReduction = 1.0 / (roughness * roughness + 1.0);
//使用掠射角度进行菲涅耳插值的好处是，我们可以在掠射角得到更加真实的菲涅耳反射效果，同时还考虑了材质粗糙度的影响。
//尽管 grazingTerm 被声明为单一维数的 half 变量，在传递给 CustomFresnelLerp 时它会自动被转换成 half3 类型的变量，这在 Cg 中被称为是"Smearing" Of Scalars To Vectors。
half3 indirectSpecular = surfaceReduction * envMap.rgb * CustomFresnelLerp(specColor, grazingTerm, nv);
half3 col = emissionTerm + UNITY_PI * (diffuseTerm + specularTerm) * _LightColor0.rgb * nl * atten + indirectSpecular;
UNITY_APPLY_FOG(i.fogCpprd, c.rgb);
return half4(col, 1);
}
ENDCG
}
Pass
{
Tags {"LightMode" = "ForwardAdd"}
Blend One One
CGPROGRAM
#pragma target 3.0
#pragma multi_compile_fwdadd
#pragma vertex vert;
#pragma fragment frag;
struct a2v
{
float4 vertex : POSITION;
float4 texcoord : TEXCOORD0;
float3 normal : NORMAL;
float4 tangent : TANGENT;
};
struct v2f
{
float4 pos : SV_POSITION;
float2 uv : TEXCOORD0;
float4 TtoW0 : TEXCOORD1;
float4 TtoW1 : TEXCOORD2;
float4 TtoW2 : TEXCOORD3;
SHADOW_COORDS(4)
};
v2f vert(a2v v)
{
v2f o;
UNITY_INITIALIZE_OUTPUT(v2f, o);
o.pos = UnityObjectToClipPos(v.vertex);
o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);
float3 worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;
float3 worldNormal = UnityObjectToWorldNormal(v.normal);
float3 worldTangent = UnityObjectToWorldDir(v.tangent.xyz);
float3 worldBinormal = cross(worldNormal, worldTangent) * v.tangent.w;
o.TtoW0 = float4(worldTangent.x, worldBinormal.x, worldNormal.x, worldPos.x);
o.TtoW1 = float4(worldTangent.y, worldBinormal.y, worldNormal.y, worldPos.y);
o.TtoW2 = float4(worldTangent.z, worldBinormal.z, worldNormal.z, worldPos.z);
TRANSFER_SHADOW(o);
return o;
}
half4 frag(v2f i) : SV_Target
{
//// 准备好输入数据
half4 specGloss = tex2D(_SpecGlossMap, i.uv);
specGloss.a *= _Glossiness;
half3 specColor = specGloss.rgb * _SpecularColor.rgb;
half roughness = 1 - specGloss.a;
//这个变量并不是我们之前到的 BRDF 中需要的变量，它主要是为了计算掠射角的反射颜色，从而得到效果更好的菲涅耳反射效果。
half oneMinusReflectivity = 1 - max(max(specColor.r, specColor.g), specColor.b);
half3 diffColor = _Color.rgb * tex2D(_MainTex, i.uv).rgb * oneMinusReflectivity;
half3 normalTangent = UnpackNormal(tex2D(_BumpMap, i.uv));
normalTangent.xy *= _BumpScale;
normalTangent.z = sqrt(1.0 - saturate(dot(normalTangent.xy, normalTangent.xy)));
half3 worldNormal = normalize(half3(dot(i.TtoW0.xyz, normalTangent),
dot(i.TtoW1.xyz, normalTangent), dot(i.TtoW2.xyz, normalTangent)));
float3 worldPos = float3(i.TtoW0.w, i.TtoW1.w, i.TtoW2.w);
half3 lightDir = normalize(UnityWorldSpaceLightDir(worldPos));
half3 viewDir = normalize(UnityWorldSpaceViewDir(worldPos));
half3 reflDir = reflect(-viewDir, worldNormal);
UNITY_LIGHT_ATTENUATION(atten, i, worldPos);
//// 计算 BRDF 项
half3 halfDir = normalize(lightDir + viewDir);
half nv = saturate(dot(worldNormal, viewDir));
half nl = saturate(dot(worldNormal, lightDir));
half nh = saturate(dot(worldNormal, halfDir));
half lv = saturate(dot(lightDir, viewDir));
half lh = saturate(dot(lightDir, halfDir));
// diffuse term
half3 diffuseTerm = CustomDisneyDiffuseTerm(nv, nl, lh, roughness, diffColor);
// specular term
half V = CustomSmithJointGGXVisibilityTerm(nl, nv, roughness);
half D = CustomGGXTerm(nh, roughness * roughness);
half3 F = CustomFresnelTerm(specColor, lh);
half3 specularTerm = F * V * D;
half3 col = UNITY_PI * (diffuseTerm + specularTerm) * _LightColor0.rgb * nl * atten;
return half4(col, 1);
}
ENDCG
}
}
FallBack "VertexLit"
}
|
