surface hb_plastic(

float Ks = 0.5;

float Kd = 0.5;

float Ka = 1;

float roughness = 0.2;

color specular_color = 1;

output varying color _Cambient = 0;

output varying color _Cdiffuse = 0;

output varying color _Cspecular = 0;

output varying float _roughness = 0;

output varying point _P = 0;

output varying normal _N = 0;

)

{

_Cambient = Cs*Ka;

_Cdiffuse = Cs*Kd;

_Cspecular = specular_color*Ks;

_roughness = roughness;

_P = transform("world", P);

_N = normalize(ntransform("world", N));

N = normalize(N);

 

Oi = Os;

Ci = Os * (_Cambient*ambient() +_Cdiffuse*diffuse(N)

+ _Cspecular*specular(N, -normalize(I), _roughness));

}