mx_conductor_bsdf.osl

#include "lib/mx_microfacet_specular.osl"

void mx_conductor_bsdf(float weight, color ior_n, color ior_k, vector2 roughness, normal N, vector U, string distribution, output BSDF bsdf)
{
    bsdf.throughput = color(0.0);

    if (weight < M_FLOAT_EPS)
    {
        bsdf.response = 0;
        return;
    }

    // Calculate conductor fresnel
    //
    // Fresnel should be based on microfacet normal
    // but we have no access to that from here, so just use
    // view direction and surface normal instead
    //
    float NdotV = fabs(dot(N,-I));
    color F = mx_fresnel_conductor(NdotV, ior_n, ior_k);

    // Calculate compensation for multiple scattering.
    // This should normally be done inside the closure
    // but since vanilla OSL doesen't support this we
    // add it here in shader code instead.
    vector2 safeAlpha = clamp(roughness, M_FLOAT_EPS, 1.0);
    float avgAlpha = mx_average_alpha(safeAlpha);
    color comp = mx_ggx_energy_compensation(NdotV, avgAlpha, F);

    // Set ior to 0.0 to disable the internal dielectric fresnel
    bsdf.response = F * comp * weight * microfacet(distribution, N, U, safeAlpha.x, safeAlpha.y, 0.0, false);
}