pinholecamera.cpp

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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
*/

#include "pinholecamera.h"  // include first
#include "context.h"
#include "ray.h"

#include <cassert>
#include <cmath>

using namespace sheep;
using namespace toxic;

PinholeCamera::PinholeCamera(const Matrix4 &m, Real hfov, Real aspect_ratio) :
    ICamera(m, hfov, aspect_ratio)
{
}

Ray PinholeCamera::ComputeRay(const Context &context,
                              const Point2 &p) const
{
    assert(p.m_x >= -0.5 && p.m_x <= 0.5);
    assert(p.m_y >= -0.5 && p.m_y <= 0.5);

    // Create a ray with origin at the camera position and directed toward
    // the specified location on the film plane.
    Ray ray(Ray::PRIMARY_RAY);
    ray.m_origin = m_location;
    ray.m_direction =
        p.m_x * m_u +   // m_u = m_ex * m_aspect_ratio
        p.m_y * m_ey +
        m_w;            // m_w = m_ez * (-m_focal_length)
    ray.m_direction.Normalize();

    return ray;
}

Point2 PinholeCamera::Project(const Point3 &p) const {
    Vector3 xi = p - m_location;
    assert(xi * m_ez != 0.0);

    xi *= -m_focal_length / (xi * m_ez);

    return Point2(xi * m_ex / m_aspect_ratio, xi * m_ey);
}

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