光照计算公式

  color.xyz = emissive + ambient + diffuse + specular;

 

The Basic Lighting Model

 The Emissive Term   自发光

 emissive=ke    ；  Ke is the material's emissive color.

The Ambient  Term

 Ambient=Ka*globalAmbient

 Ka is the material's ambient reflectance and

 globalAmbient is the color of incomming ambient light. 传入的环境光

The Diffuse Term

diffuse=Kd*lightcolor*max(N点乘L,0)

Kd is the material's diffuse color 材质的散射颜色

lightcolor is the color of the incomming diffuse light 传入的散射光

N is the normalized suface normal  归一化表面正常

L is normalized vector toward the light source ,and  归一化向量向光源

P is the point being shaded. 被着色点

The Specular Term

specular = K_s x lightColor x facing x (max(N · H, 0)) ^shininess

where:

• K_s is the material's specular color,
• lightColor is the color of the incoming specular light,
• N is the normalized surface normal,
• V is the normalized vector toward the viewpoint,
• L is the normalized vector toward the light source,
• H is the normalized vector that is halfway between V and L,
• P is the point being shaded, and
• facing is 1 if N · L is greater than 0, and 0 otherwise.