intersect_triangle_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 ***
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 *  The contents of this file are subject to the Common Public Attribution License 
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 *  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.
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 *  Copyright (C) 2004-2007 the Initial Developer.
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 */

#ifndef LASS_GUARDIAN_OF_INCLUSION_PRIM_IMPL_INTERSECT_TRIANGLE_3D_H
#define LASS_GUARDIAN_OF_INCLUSION_PRIM_IMPL_INTERSECT_TRIANGLE_3D_H

#include "../../num/floating_point_consistency.h"

namespace lass
{
namespace prim
{
namespace impl
{

/** @internal
 *
 *  @par Algorithm:
 *  @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
 *  
 *  @arg comp.graphics.algorithms Frequently Asked Questions: 
 *  Subject 5.06: "How do I determine the intersection between a ray and a triangle?"
 *  http://www.faqs.org/faqs/graphics/algorithms-faq/ *
 */
template <typename Point, typename Vector, typename T> inline
Result intersectTriangle3D(const Point& iVertex0, const Vector& iEdge1, const Vector& iEdge2,
                           const Point& iSupport, const Vector& iDirection,
                           T& oU, T& oV, T& oT, const T& iMinT)
{
    typedef typename Vector::TNumTraits TNumTraits;
    typedef num::Consistent<T> TConsistent;

    const Vector pvec = cross(iDirection, iEdge2);
    const T det = dot(pvec, iEdge1);

    if (det == TNumTraits::zero)
    {
        return rNone;
    }

    const T invDet = num::inv(det);

    const Vector tvec = iSupport - iVertex0;
    const T u = dot(tvec, pvec) * invDet;
    if (u < TNumTraits::zero || u > TNumTraits::one)
    {
        return rNone;
    }

    const Vector qvec = cross(tvec, iEdge1);
    const T v = dot(iDirection, qvec) * invDet;
    if (v < TNumTraits::zero || (u + v) > TNumTraits::one)
    {
        return rNone;
    }

    const TConsistent t = dot(iEdge2, qvec) * invDet;
    if (t <= iMinT)
    {
        return rNone;
    }

    oU = u;
    oV = v;
    oT = t.value();
    return rOne;
}

}
}
}

#endif

// EOF