square.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 "square.h" // include first
#include "common/math/point3.h"
#include "common/math/real.h"
#include "common/math/vector3.h"
#include "context.h"
#include "hit.h"
#include "isurfaceshader.h"
#include "ray.h"
#include "scene.h"
#include "settings.h"
#include "statistics.h"
#include "utilities.h"

#include <cmath>

using namespace sheep;
using namespace std;
using namespace toxic;

Square::Square(const Matrix4 &m,
               const ISurfaceShader *surface_shader,
               IntersectionMask intersection_mask /*= INTERSECT_ALL_RAYS*/) :
    IAreaLight(m, surface_shader, intersection_mask),
    m_center(TransformToWorld(Point3(0.0))),
    m_normal(TransformNormalToWorld(Vector3(0.0, 1.0, 0.0))),
    m_basis(m_normal),
    m_ex(TransformToWorld(Vector3(1.0, 0.0, 0.0))),
    m_ez(TransformToWorld(Vector3(0.0, 0.0, 1.0)))
{
    m_aabb = AABB3(Point3(-0.5, 0.0, -0.5), Point3(0.5, 0.0, 0.5)).Transform(m);

    // Enlarge the object bounding box to avoid numerical instabilities.
    m_aabb.Extend(OBJECT_AABB_EXTENSION);
}

bool Square::Intersect(const Context &context,
                       const Ray &ray,  //!< 'ray' is expressed in world space.
                       Hit *hit /*= 0*/) const
{
    // Test whether this object intersects with this type of ray.
    if(!(m_intersection_mask & ray.GetType()))
        return false;

    // Note: rescaling of the intersection abscissa has been optimized out from this code.

    ++context.m_statistics->m_tested_intersections;

    const Ray r = TransformToLocal(ray);

    if(r.m_direction.m_y == 0.0)
        return false;   // the ray is parallel to the plane

    const Real t = - r.m_origin.m_y / r.m_direction.m_y;

    if(t < 0.0)
        return false;   // the intersection point is not on the ray

    const Real x = r.m_origin.m_x + t * r.m_direction.m_x;

    if(x < -0.5 || x > 0.5)
        return false;   // the intersection point is not on the square

    const Real z = r.m_origin.m_z + t * r.m_direction.m_z;

    if(z < -0.5 || z > 0.5)
        return false;   // the intersection point is not on the square

    ++context.m_statistics->m_intersections_found;

    if(hit) {
        hit->m_object = this;
        hit->m_abscissa = t;    // world space
        hit->m_geometric_normal = Vector3(0.0, 1.0, 0.0);   // object space
        hit->m_shading_normal = hit->m_geometric_normal;    // object space
        hit->m_u = 0.5 + x; // object space
        hit->m_v = 0.5 + z; // object space
    }

    return true;
}

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