bsdf.h

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/*
    toxic - A Global Illumination Renderer
    Copyright (C) 2003-2004 Francois Beaune
    Contact: http://toxicengine.sourceforge.net/

    This file is part of toxic.

    toxic is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    toxic is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with toxic; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#ifndef TOXIC_RENDERER_BSDF_H
#define TOXIC_RENDERER_BSDF_H

#include "common/math/real.h"
#include "common/math/vector3.h"
#include "globals.h"
#include "ibdf.h"

#include <utility>  // std::pair<>, std::make_pair<>()
#include <vector>

namespace toxic {

    class Context;

    //! Bidirectional Scattering Distribution Function (BSDF).
    class BSDF : public IBDF {
    public:
        BSDF();

        virtual ~BSDF() {}

        virtual bool IsDiffuse() const;
        virtual bool IsSpecular() const;

        void Insert(const IBRDF *brdf, sheep::Real weight);
        void Insert(const IBTDF *btdf, sheep::Real weight);

        //! Evaluates the function. Both the incoming and outgoing directions are
        //! expressed in local space.
        virtual sheep::Real Evaluate(
            const Context &context,
            const sheep::Vector3 &incoming,
            const sheep::Vector3 &outgoing) const;

        virtual sheep::Real EvaluateSpecular(
            const Context &context,
            const sheep::Vector3 &incoming,
            sheep::Vector3 *outgoing) const;

        //! Samples the function in order to obtain an outgoing direction, given
        //! an incoming direction. The probability with which the direction has
        //! been chosen is also computed. Both incoming and outgoing directions
        //! are expressed in local space.
        virtual void Sample(
            const Context &context,
            const sheep::Vector3 &incoming,
            sheep::Vector3 *outgoing,
            sheep::Real *prob,
            sheep::Real *value) const;

        //! Computes the probability of scattering from 'incoming' direction to
        //! 'outgoing' direction. Both incoming and outgoing directions are
        //! expressed in local space.
        virtual sheep::Real ComputeScatteringProbability(
            const sheep::Vector3 &incoming,
            const sheep::Vector3 &outgoing) const;

        //! Computes and returns the hemispherical hemispherical reflectance.
        virtual sheep::Real ComputeReflectance(const Context &context) const;

        //! Computes and returns the directional hemispherical reflectance. The
        //! incoming direction is expressed in local space.
        virtual sheep::Real ComputeReflectance(
            const Context &context,
            const sheep::Vector3 &incoming) const;

    private:
        typedef std::pair<const IBRDF *, sheep::Real> weighted_brdf;
        typedef std::pair<const IBTDF *, sheep::Real> weighted_btdf;

        typedef std::vector<weighted_brdf> brdf_vector;
        typedef std::vector<weighted_btdf> btdf_vector;

        typedef brdf_vector::const_iterator brdf_vector_const_it;
        typedef btdf_vector::const_iterator btdf_vector_const_it;

        brdf_vector m_brdfs;            //!< Vector of all BRDFs.
        btdf_vector m_btdfs;            //!< Vector of all BTDFs.
        brdf_vector m_specular_brdfs;   //!< Vector of specular BRDFs.
        btdf_vector m_specular_btdfs;   //!< Vector of specular BTDFs.

        sheep::Real m_total_weight;     //!< The total weight of all components (BRDFs and BTDFs).
    };

#include "bsdf.inl"

}

#endif  // !TOXIC_RENDERER_BSDF_H

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