1.描述了入射光线在非透明物体表面如何进行反射,也就是说多少光发生了漫反射,多少光发生了镜面反射
BRDF 函数计算的是“特定反射方向的光强与入射光强的比例”
2.各向异性 与 均向性 相反,是指在不同方向具有不同行为的性质,也就是其行为与方向有关,如在物理上,沿着材料做不同方向的量测,若会出现不同行为,通常称该材料具有某种“各向异性”,这样的材料表面称为各向异性表面
3.分布函数:光在表面是怎么分布的
灯光的遮挡:
Shader "Custom/BRDF"
{Properties{_SpeColor ("SpecColor", Color) = (1,1,1,1)_MainTex ("Albedo (RGB)", 2D) = "white" {}_SpecPower("SpecPower",float) = 1}SubShader{Tags { "RenderType"="Opaque" }LOD 200CGPROGRAM// Physically based Standard lighting model, and enable shadows on all light types#pragma surface surf BRDFLighting// Use shader model 3.0 target, to get nicer looking lighting#pragma target 3.0sampler2D _MainTex;struct Input{float2 uv_MainTex;};fixed4 _SpeColor;float _SpecPower;#define PI 3.1415926half4 LightingBRDFLighting (SurfaceOutput s, half3 lightDir, half3 viewDir, half atten){float3 H = normalize(lightDir+viewDir);float3 N = normalize(s.Normal);float d = (_SpecPower+2)*pow(dot(N,H),_SpecPower)/8.0;float f = _SpeColor + (1-_SpeColor)*pow(1-dot(H,N),5);float k = 2.0 /(sqrt(PI * (_SpecPower + 2)));float v = 1/((dot(N,lightDir)*(1-k)+k)*(dot(N,viewDir)*(1-k)+k));float all = d*f*v;float diff = dot(lightDir,N);float tmpResult = all+(1-all)*diff;half4 finalColor = 0;finalColor.rgb = tmpResult * s.Albedo * _LightColor0.rgb;finalColor.a = s.Alpha;return finalColor;}void surf (Input IN, inout SurfaceOutput o){// Albedo comes from a texture tinted by colorfixed4 c = tex2D (_MainTex, IN.uv_MainTex);o.Albedo = c.rgb;o.Alpha = c.a;}ENDCG}FallBack "Diffuse"
}