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41
42varying vec3 position, normal;
43varying vec4 specular, ambient, diffuse, lightDirection;
44
45uniform sampler2D tex;
46uniform sampler3D noise;
47
48//const vec4 marbleColors[2] = {vec4(0.9, 0.9, 0.9, 1), vec4(0.6, 0.5, 0.5, 1)};
49uniform vec4 marbleColors[2];
50
51void main()
52{
53    float turbulence = 0.0;
54    float scale = 1.0;
55    for (int i = 0; i < 4; ++i) {
56        turbulence += scale * (texture3D(noise, 0.125 * gl_TexCoord[1].xyz / scale).x - 0.5);
57        scale *= 0.5;
58    }
59
60    vec3 N = normalize(normal);
61    // assume directional light
62
63    gl_MaterialParameters M = gl_FrontMaterial;
64
65    float NdotL = dot(N, lightDirection.xyz);
66    float RdotL = dot(reflect(normalize(position), N), lightDirection.xyz);
67
68    vec4 unlitColor = mix(marbleColors[0], marbleColors[1], exp(-4.0 * abs(turbulence)));
69    gl_FragColor = (ambient + diffuse * max(NdotL, 0.0)) * unlitColor +
70                    M.specular * specular * pow(max(RdotL, 0.0), M.shininess);
71}
72