1varying vec3 Normal;
2
3void main(void)
4{
5    const vec4 LightSourceAmbient = vec4(0.1, 0.1, 0.1, 1.0);
6    const vec4 LightSourceDiffuse = vec4(0.8, 0.8, 0.8, 1.0);
7    const vec4 LightSourceSpecular = vec4(0.8, 0.8, 0.8, 1.0);
8    const vec4 MaterialAmbient = vec4(1.0, 1.0, 1.0, 1.0);
9    const vec4 MaterialDiffuse = vec4(1.0, 1.0, 1.0, 1.0);
10    const vec4 MaterialSpecular = vec4(0.2, 0.2, 0.2, 1.0);
11    const float MaterialShininess = 100.0;
12
13    vec3 N = normalize(Normal);
14
15    // In the lighting model we are using here (Blinn-Phong with light at
16    // infinity, viewer at infinity), the light position/direction and the
17    // half vector is constant for the all the fragments.
18    vec3 L = normalize(LightSourcePosition.xyz);
19    vec3 H = normalize(LightSourceHalfVector);
20
21    // Calculate the diffuse color according to Lambertian reflectance
22    vec4 diffuse = MaterialDiffuse * LightSourceDiffuse * max(dot(N, L), 0.0);
23
24    // Calculate the ambient color
25    vec4 ambient = MaterialAmbient * LightSourceAmbient;
26
27    // Calculate the specular color according to the Blinn-Phong model
28    vec4 specular = MaterialSpecular * LightSourceSpecular *
29                    pow(max(dot(N,H), 0.0), MaterialShininess);
30
31    // Calculate the final color
32    gl_FragColor = ambient + specular + diffuse;
33}
34