/*
 * Adapted from Open Shading Language with this license:
 *
 * Copyright (c) 2009-2010 Sony Pictures Imageworks Inc., et al.
 * All Rights Reserved.
 *
 * Modifications Copyright 2011, Blender Foundation.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * * Neither the name of Sony Pictures Imageworks nor the names of its
 *   contributors may be used to endorse or promote products derived from
 *   this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <OpenImageIO/fmath.h>

#include <OSL/genclosure.h>

#include "osl_closures.h"

CCL_NAMESPACE_BEGIN

using namespace OSL;

class RefractionClosure : public BSDFClosure {
public:
	Vec3 m_N;      // shading normal
	float m_eta;   // ratio of indices of refraction (inside / outside)
	RefractionClosure() : BSDFClosure(Labels::SINGULAR, Back) {}

	void setup() {}

	bool mergeable(const ClosurePrimitive *other) const {
		const RefractionClosure *comp = (const RefractionClosure *)other;
		return m_N == comp->m_N && m_eta == comp->m_eta &&
		       BSDFClosure::mergeable(other);
	}

	size_t memsize() const { return sizeof(*this); }

	const char *name() const { return "refraction"; }

	void print_on(std::ostream &out) const {
		out << name() << " (";
		out << "(" << m_N[0] << ", " << m_N[1] << ", " << m_N[2] << "), ";
		out << m_eta;
		out << ")";
	}

	Color3 eval_reflect(const Vec3 &omega_out, const Vec3 &omega_in, float& pdf) const
	{
		return Color3(0, 0, 0);
	}

	Color3 eval_transmit(const Vec3 &omega_out, const Vec3 &omega_in, float& pdf) const
	{
		return Color3(0, 0, 0);
	}

	float albedo(const Vec3 &omega_out) const
	{
		return 1.0f;
	}

	ustring sample(const Vec3 &Ng,
	               const Vec3 &omega_out, const Vec3 &domega_out_dx, const Vec3 &domega_out_dy,
	               float randu, float randv,
	               Vec3 &omega_in, Vec3 &domega_in_dx, Vec3 &domega_in_dy,
	               float &pdf, Color3 &eval) const
	{
		Vec3 R, dRdx, dRdy;
		Vec3 T, dTdx, dTdy;
		bool inside;

		fresnel_dielectric(m_eta, m_N,
		                   omega_out, domega_out_dx, domega_out_dy,
		                   R, dRdx, dRdy,
		                   T, dTdx, dTdy,
		                   inside);

		if (!inside) {
			pdf = 1;
			eval.setValue(1.0f, 1.0f, 1.0f);
			omega_in = T;
			domega_in_dx = dTdx;
			domega_in_dy = dTdy;
		}

		return Labels::TRANSMIT;
	}
};

ClosureParam bsdf_refraction_params[] = {
	CLOSURE_VECTOR_PARAM(RefractionClosure, m_N),
	CLOSURE_FLOAT_PARAM(RefractionClosure, m_eta),
	CLOSURE_STRING_KEYPARAM("label"),
	CLOSURE_FINISH_PARAM(RefractionClosure)
};

CLOSURE_PREPARE(bsdf_refraction_prepare, RefractionClosure)

CCL_NAMESPACE_END