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346 awk 1 
#include "glass.hpp"
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using namespace CGLA;
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glass::glass(const CGLA::Vec3f& c, float ior)
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: material(ior, 0.f), color_(c)
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{
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}
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void glass::sample(const ray& r, hit_info& hi) const
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{
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	hi.ior = hi.inside ? 1.f / ior_ : ior_;
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	//compute fresnel
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	float f;
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	float cosi = dot(-r.direction, hi.shading_normal);
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	cosi = clamp(cosi, -1.f, 1.f);
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	float sint = 1.f / hi.ior * std::sqrt(std::max(0.f, 1.f - cosi*cosi));
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	if (sint > 1.f)
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	{
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		//total internal reflection
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		f = 1.f;
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	}
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	else if (cosi < 0.)
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	{
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		f = 0.f;
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	}
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	else
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	{
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		float cost = std::sqrt(std::max(0.f, 1.f - sint * sint));
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		cost = clamp(cost, -1.f, 1.f);
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		f = fresnel_dielectric(cosi, cost, hi.ior);
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		if (f < 0.f || f > 1.f)
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			assert(false);
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	}
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	hi.reflection = f * color_;
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	hi.refraction = (1.f - f) * color_;
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}
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//02566 framework, Anders Wang Kristensen, awk@imm.dtu.dk, 2007