uMaterial, uLight pagalba

Sveiki, gal kas galite padėti išsiaiškinti šį kodo gabalą? T.y kaip gaunama galutinė formulė? Ką reiškia uMaterial, uLight?

Ačiū

void main(void)

{

float att = 0.0; // Attenuationv

vec3 L = normalize(vLightDir);

vec3 N = normalize(vNormal);

//Lambert's cosine law

float lambertTerm = dot(N,-L);

//Ambient Term

vec4 Ia = uLightAmbient;

//Diffuse Term

vec4 Id = vec4(0.0,0.0,0.0,1.0);

//Specular Term

vec4 Is = vec4(0.0,0.0,0.0,1.0);

if(lambertTerm > 0.0) //only if lambertTerm is positive

{

float distance = length(vec3(vLightPositionEye3 - vPositionEye3));

att = 1.0/(constantAtt+linearAtt * distance +

quadraticAtt * distance * distance);

Id = att * uMaterialDiffuse * uLightDiffuse * lambertTerm; //add diffuse term

vec3 E = normalize(vEyeVec);

vec3 R = reflect(L, N);

float specular = pow( max(dot(R, E), 0.0), uShininess);

Is = att * uMaterialSpecular * uLightSpecular * specular; //add specular term

}

//}

//Final color

vec4 finalColor = Ia + Id + Is;

Paprasta matematika :D Eik mokykis vektorius, matricas..