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#include "glass.hpp"

using namespace CGLA;

glass::glass(const CGLA::Vec3f& c, float ior)
: material(ior, 0.f), color_(c)
{
}

void glass::sample(const ray& r, hit_info& hi) const
{
        hi.ior = hi.inside ? 1.f / ior_ : ior_;

        //compute fresnel
        float f;
        float cosi = dot(-r.direction, hi.shading_normal);
        cosi = clamp(cosi, -1.f, 1.f);
        float sint = 1.f / hi.ior * std::sqrt(std::max(0.f, 1.f - cosi*cosi));
        
        if (sint > 1.f)
        {
                //total internal reflection
                f = 1.f;
        }
        else if (cosi < 0.)
        {
                f = 0.f;
        }
        else
        {
                float cost = std::sqrt(std::max(0.f, 1.f - sint * sint));
                cost = clamp(cost, -1.f, 1.f);
                f = fresnel_dielectric(cosi, cost, hi.ior);

                if (f < 0.f || f > 1.f)
                        assert(false);
        }

        hi.reflection = f * color_;
        hi.refraction = (1.f - f) * color_;
}

//02566 framework, Anders Wang Kristensen, awk@imm.dtu.dk, 2007