parallelogram_3d_ray_3d.h

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/** @file
 *  @author Bram de Greve (bramz@users.sourceforge.net)
 *  @author Tom De Muer (tomdemuer@users.sourceforge.net)
 *
 *  *** BEGIN LICENSE INFORMATION ***
 *  
 *  The contents of this file are subject to the Common Public Attribution License 
 *  Version 1.0 (the "License"); you may not use this file except in compliance with 
 *  the License. You may obtain a copy of the License at 
 *  http://lass.sourceforge.net/cpal-license. The License is based on the 
 *  Mozilla Public License Version 1.1 but Sections 14 and 15 have been added to cover 
 *  use of software over a computer network and provide for limited attribution for 
 *  the Original Developer. In addition, Exhibit A has been modified to be consistent 
 *  with Exhibit B.
 *  
 *  Software distributed under the License is distributed on an "AS IS" basis, WITHOUT 
 *  WARRANTY OF ANY KIND, either express or implied. See the License for the specific 
 *  language governing rights and limitations under the License.
 *  
 *  The Original Code is LASS - Library of Assembled Shared Sources.
 *  
 *  The Initial Developer of the Original Code is Bram de Greve and Tom De Muer.
 *  The Original Developer is the Initial Developer.
 *  
 *  All portions of the code written by the Initial Developer are:
 *  Copyright (C) 2004-2007 the Initial Developer.
 *  All Rights Reserved.
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 *  Contributor(s):
 *
 *  Alternatively, the contents of this file may be used under the terms of the 
 *  GNU General Public License Version 2 or later (the GPL), in which case the 
 *  provisions of GPL are applicable instead of those above.  If you wish to allow use
 *  of your version of this file only under the terms of the GPL and not to allow 
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 *  deleting the provisions above and replace them with the notice and other 
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 *  *** END LICENSE INFORMATION ***
 */

#ifndef LASS_GUARDIAN_OF_INCLUSION_PRIM_PARALLELOGRAM_3D_RAY_3D_H
#define LASS_GUARDIAN_OF_INCLUSION_PRIM_PARALLELOGRAM_3D_RAY_3D_H

#include "prim_common.h"
#include "parallelogram_3d.h"
#include "ray_3d.h"
#include "../num/floating_point_consistency.h"

namespace lass
{
namespace prim
{

/** Find the intersection of a ray and a parallelogram by their parameter t on the ray
 *  and it's coordinates (u,v) on the parallelogram.
 *  @relates lass::prim::Ray3D
 *  @relates lass::prim::Parallelogram3D
 *
 *  A maximum of two possible intersections with @a t > 0.
 *
 *  @param parallelogram [in] the parallelogram
 *  @param ray [in] the ray
 *  @param oU [out] the parameter of the intersection point on the parallelogram.
 *  @param oV [out] the parameter of the intersection point on the parallelogram.
 *  @param t [out] the parameter of the intersection point > @a tMin.
 *  @param tMin [in] the minimum t that may be returned as valid intersection.
 *  @return @arg rNone: no intersections with @a t > @a tMin found. @a t is not assigned.
 *          @arg rOne: a intersection with @a t > @a tMin is found. @a t is assigned.
 *  
 *  @par Algorithm, based on ray/triangle intersection from:
 *  @arg Tomas Möller and Ben Trumbore.
 *  "Fast, minimum storage ray-triangle intersection."
 *  Journal of Graphics Tools, 2(1):21--28, 1997.
 *  http://www.graphics.cornell.edu/pubs/1997/MT97.html
 */
template <typename T, class NP, class PP>
Result intersect(
        const Parallelogram3D<T>& parallelogram, const Ray3D<T, NP, PP>& ray, 
        T& u, T& v, T& t, const T& tMin = T())
{
    typedef typename Parallelogram3D<T>::TVector TVector;
    typedef typename Parallelogram3D<T>::TValue TValue;
    typedef typename Parallelogram3D<T>::TNumTraits TNumTraits;
    typedef num::Consistent<T> TConsistent;

    const TVector pvec = cross(ray.direction(), parallelogram.sizeV());
    
    const TValue det = dot(pvec, parallelogram.sizeU());
    if (det == TNumTraits::zero)
    {
        return rNone;
    }
    const TValue invDet = num::inv(det);

    const TVector tvec = ray.support() - parallelogram.support();
    const TValue uCandidate = dot(tvec, pvec) * invDet;
    if (uCandidate < TNumTraits::zero || uCandidate > TNumTraits::one)
    {
        return rNone;
    }

    const TVector qvec = cross(tvec, parallelogram.sizeU());
    const TValue vCandidate = dot(ray.direction(), qvec) * invDet;
    if (vCandidate < TNumTraits::zero || vCandidate > TNumTraits::one)
    {
        return rNone;
    }

    const TConsistent tCandidate = dot(parallelogram.sizeV(), qvec) * invDet;
    if (tCandidate <= tMin)
    {
        return rNone;
    }

    u = uCandidate;
    v = vCandidate;
    t = tCandidate.value();
    return rOne;
}



/** Find the intersection of a ray and a parallelogram by their parameter t on the ray.
 *  @relates lass::prim::Ray3D
 *  @relates lass::prim::Parallelogram3D
 *
 *  A maximum of two possible intersections with t > 0.
 *
 *  @param parallelogram [in] the parallelogram
 *  @param ray [in] the ray
 *  @param t [out] the parameter of the intersection point > @a tMin.
 *  @param tMin [in] the minimum t that may be returned as valid intersection.
 *  @return @arg rNone      no intersections with @a t > @a tMin found
 *                          @a t is not assigned.
 *          @arg rOne       a intersection with @a t > @a tMin is found
 *                          @a t is assigned.
 */
template <typename T, class NP, class PP> inline
Result intersect(
        const Parallelogram3D<T>& parallelogram, const Ray3D<T, NP, PP>& ray, 
        T& t, const T& tMin = T())
{
    T u;
    T v;
    return intersect(parallelogram, ray, u, v, t, tMin);
}

}

}

#endif

// EOF