icamera.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_ICAMERA_H
#define TOXIC_RENDERER_ICAMERA_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 "basis.h"
#include "globals.h"

namespace toxic {

    class Context;
    class Ray;
    class Scene;

    //! Normalized Device Coordinates (NDC) are normalized pixel coordinates so
    //! that x and y both run from -0.5 to +0.5 across the entire (uncropped)
    //! image, with (-0.5, -0.5) being at the lower left corner of the image plane
    //! and (0.5, 0.5) being at the upper right corner, regardless of the image
    //! resolution.

    //! The camera is located at the origin and looks toward Z-.
    class ICamera : public Basis {
    public:
        //! 'm' is the object space to world space transformation matrix.
        //! 'hfov' is the horizontal field of view, expressed in radians.
        ICamera(
            const sheep::Matrix4 &m,
            sheep::Real hfov,
            sheep::Real aspect_ratio
        );

        virtual ~ICamera() {}

        //! This method must be called only once, after the camera is completely
        //! configured, and before it is used for the first time.
        virtual void Finalize(
            const Context &context,
            const Scene *scene
        ) {}

        //! Returns a ray whose origin is at camera location, and which
        //! is directed toward the point 'p'. 'p' is a point on the film
        //! plane. It is expressed in NDC. The returned ray is expressed
        //! in world space. The direction of the returned ray IS unit-length.
        virtual Ray ComputeRay(
            const Context &context,
            const sheep::Point2 &p
        ) const = 0;

        //! Projects a point in the scene to the image plane.
        virtual sheep::Point2 Project(
            const sheep::Point3 &p
        ) const = 0;

    protected:
        sheep::Point3 m_location;           //!< Location of the camera, expressed in world space.
        sheep::Vector3 m_ex, m_ey, m_ez;    //!< Basis vectors, expressed in world space. m_ex is scaled by the aspect ratio.
        sheep::Vector3 m_u, m_w;            //!< m_u = m_ex * m_aspect_ratio, m_w = m_ez * (-m_focal_length).

        //! Frustum parameters.
        sheep::Real m_hfov;                 //!< User defined horizontal field of view, expressed in radians.
        sheep::Real m_aspect_ratio;         //!< User defined aspect ratio.
        sheep::Real m_focal_length;         //!< Lens focal length (computed from m_hfov and m_aspect_ratio values).
    };

#include "icamera.inl"

}

#endif  // !TOXIC_RENDERER_ICAMERA_H

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