/*
 * 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