ilight.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_ILIGHT_H
#define TOXIC_RENDERER_ILIGHT_H

#include "common/math/bs.h"
#include "common/math/point3.h"
#include "common/math/vector3.h"
#include "color3.h"
#include "globals.h"
#include "isurfacesampler.h"

namespace toxic {

    class Context;
    class Ray;
    class Scene;

    class ILight {
    public:
        //! m is the object space to world space transformation matrix.
        ILight(bool cast_shadows = true);

        virtual ~ILight() {}

        //! This method returns true if the light casts shadows, false otherwise.
        bool CastShadows() const;

        //! Returns the emission power of this object, expressed in W.
        virtual const Color3 &GetPower() const = 0;

        virtual Ray GeneratePhotonRay(const Context &context) const = 0;

        struct IrradianceSample {
            Color3 m_irradiance;            //!< Differential irradiance, expressed in W.m^-2.
            sheep::Vector3 m_direction;     //!< Incoming direction, expressed in world space.

            IrradianceSample(const Color3 &irradiance, const sheep::Vector3 &direction) :
                m_irradiance(irradiance),
                m_direction(direction) {}
        };

        typedef std::vector<IrradianceSample> IrradianceSampleVector;

        //! Computes irradiance due to this light source. The point and the surface normal
        //! are both expressed in world space.
        virtual void ComputeIrradiance(
            const Context &context,
            const Scene *scene,
            const sheep::Point3 &point,
            const sheep::Vector3 &geometric_normal,
            const sheep::Vector3 &shading_normal,
            const ISurfaceSampler::SampleVector &input,
            IrradianceSampleVector *output
        ) const = 0;

    protected:
        bool m_cast_shadows;    //!< Does this light cast shadows?
    };

#include "ilight.inl"

}

#endif  // !TOXIC_RENDERER_ILIGHT_H

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