光照方程
lightResult= ambientLight * diffuseColor + lightColor * diffuseColor * defficusefactor + lightColor * specularColor*(specularFactor)glossvalue
+ lightColor2 * diffuseColor * defficusefactor + lightColor2 * specularColor*(specularFactor)glossvalue
texture 是反射率 diffuseColor也是
AO的半球和brdf的半球都是所有入射光组成的球面
ao只考虑环境光 并且各个方向相同。
shadow*(diffuse+specular)