square.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_SQUARE_H
#define TOXIC_RENDERER_SQUARE_H

#include "common/math/aabb3.h"
#include "common/math/matrix4.h"
#include "common/math/point2.h"
#include "common/math/point3.h"
#include "common/math/real.h"
#include "common/math/vector3.h"
#include "color3.h"
#include "globals.h"
#include "iarealight.h"
#include "surfacebasis.h"

#include <cassert>

namespace toxic {

    class Context;
    class Hit;
    class ISurfaceShader;
    class Ray;
    class Scene;

    class Square : public IAreaLight {
    public:
        // The square is contained in the XZ plane and extends from (-0.5, 0, -0.5) to (0.5, 0, 0.5)
        // (borders are included). Surface normal is pointing toward Y+ (it goes away from the square
        // plane toward increasing Y).

        //! m is the object space to world space transformation matrix.
        Square(
            const sheep::Matrix4 &m,
            const ISurfaceShader *surface_shader,
            IntersectionMask intersection_mask = INTERSECT_ALL_RAYS);

        //! Returns the Axis Aligned Bounding Box of this object. The AABB is
        //! expressed in world space.
        virtual const sheep::AABB3 &GetAABB() const;

        //! Computes the surface area of this object.
        virtual sheep::Real ComputeSurfaceArea() const;

        //! Given a point in the unit square (the set of points in [0..1]^2),
        //! this method computes the corresponding surface point and normal
        //! (both are expressed in world space).
        virtual void EvaluateSurface(
            const sheep::Point2 &input,
            sheep::Point3 *point,
            sheep::Vector3 *geometric_normal
        ) const;

        //! This method returns true if the ray intersect the object, or false otherwise.
        //! If 'hit' is not null, intersection data are reported through the 'hit' parameter
        //! (only if an intersection has been found; if no intersection has been found, the
        //! 'hit' parameter is left unchanged). The ray is expressed in world space.
        virtual bool Intersect(
            const Context &context,
            const Ray &ray,
            Hit *hit = 0
        ) const;

    private:
        sheep::Point3 m_center;     //!< Center of the object, expressed in world space.
        sheep::Vector3 m_normal;    //!< Normal to the plane supporting the square, expressed in world space.
        const SurfaceBasis m_basis;
        sheep::Vector3 m_ex, m_ez;  //!< X (1,0,0) and Z (0,0,1) basis vectors, expressed in world space.
        sheep::AABB3 m_aabb;        //!< Bounding box of the object, expressed in world space.
    };

#include "square.inl"

}

#endif  // !TOXIC_RENDERER_SQUARE_H

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