ray_2d_simple_polygon_2d.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_RAY_2D_SIMPLE_POLYGON_2D_H
#define LASS_GUARDIAN_OF_INCLUSION_PRIM_RAY_2D_SIMPLE_POLYGON_2D_H

#include "prim_common.h"
#include "ray_2d.h"
#include "simple_polygon_2d.h"
#include "impl/intersect_edge_2d.h"

namespace lass
{
namespace prim
{


/** Find the intersection of a ray and a triangle by their parameter t on the ray.
 *  @relates lass::prim::Ray2D
 *  @relates lass::prim::SimplePolygon2D
 *
 *  @param polygon [in] the simple polygon
 *  @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 DP, class NP, class PP>
Result intersect(
        const SimplePolygon2D<T, DP>& polygon, const Ray2D<T, NP, PP>& ray, 
        T& t, const T& tMin = T())
{
    typedef Point2D<T> TPoint;
    typedef Vector2D<T> TVector;
    typedef typename TVector::TValue TValue;
    typedef typename TVector::TNumTraits TNumTraits;

    const TPoint& support = ray.support();
    const TVector& direction = ray.direction();

    TValue tNear = TNumTraits::infinity;
    bool good = false;
    size_t size = polygon.size();
    size_t iPrev = size - 1;
    for (size_t i = 0; i < size; ++i)
    {
        good |= impl::intersectEdge2D(
            support, direction, polygon[iPrev], polygon[i], tNear, tMin);
        iPrev = i;
    }
    if (good)
    {
        t = tNear;
        return rOne;
    }
    return rNone;
}

}
}

#endif

// EOF