aabb_3d_simple_polygon_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.
 *  
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 *  Copyright (C) 2004-2007 the Initial Developer.
 *  All Rights Reserved.
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 *  GNU General Public License Version 2 or later (the GPL), in which case the 
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 */

#ifndef LASS_GUARDIAN_OF_INCLUSION_PRIM_AABB_3D_SIMPLE_POLYGON_3D_H
#define LASS_GUARDIAN_OF_INCLUSION_PRIM_AABB_3D_SIMPLE_POLYGON_3D_H

#include "prim_common.h"
#include "aabb_3d.h"
#include "simple_polygon_3d.h"

namespace lass
{
namespace prim
{

/** determine axis aligned bounding box of a 3D simple polygon
 *  @relates Aabb3D
 */
template <typename T, class EP, class NP> 
Aabb3D<T> aabb(const SimplePolygon3D<T, EP, NP>& polygon)
{
    Aabb3D<T> result;
    const size_t n = polygon.size();
    for (size_t i = 0; i < n; ++i)
    {
        result += polygon[i];
    }
    return result;
}

/** Clip a plane to an AABB and get a polygon.
 *  @relates lass::prim::Aabb3D
 *  @relates lass::prim::Plane3D
 *  @relates lass::prim::SimplePolygon3D
 *
 *  @param iAabb [in] the Aabb to clip to
 *  @param iPlane [in] the plane to be clipped
 *  @return the clipped polygon.
 */
template <typename T, class EP, class NP, class MMP>
SimplePolygon3D<T, EP, NP> clip(const Aabb3D<T, MMP>& iAabb, 
        const Plane3D<T, EP, NP>& iPlane)
{
    typedef Plane3D<T, EP, NP> TPlane;
    typedef SimplePolygon3D<T, EP, NP> TPolygon;
    typedef Point3D<T> TPoint;
    typedef typename TPoint::TVector TVector;
    typedef typename TPoint::TValue TValue;
    TPolygon poly(iPlane);

    const TPoint& min = iAabb.min();
    const TPoint& max = iAabb.max();
    
    TVector normal;
    TValue d;
    iPlane.getCartesian(normal, d);

    TVector m;
    switch (iPlane.majorAxis())
    {
        case 0: // x
        {
                TPoint p[4] = 
            {
                TPoint(0.0, min.y, min.z), TPoint(0.0, max.y, min.z),
                TPoint(0.0, max.y, max.z), TPoint(0.0, min.y, max.z)
            };
            if (iPlane.normal().x < 0)
            {
                std::reverse(p, p + 4);
            }
            for (size_t i = 0; i < 4; ++i)
            {
                p[i].x = -(dot(normal, p[i].position()) + d) / normal.x;
                poly.add(p[i]);
            }
            m = TVector(1.0, 0.0, 0.0);
            break;
        }
        case 1: // y
        {
            TPoint p[4] = 
            {
                TPoint(min.x, 0.0, min.z), TPoint(min.x, 0.0, max.z),
                TPoint(max.x, 0.0, max.z), TPoint(max.x, 0.0, min.z)
            };
            if (iPlane.normal().y < 0)
            {
                std::reverse(p, p + 4);
            }
            for (size_t i = 0; i < 4; ++i)
            {
                p[i].y = -(dot(normal, p[i].position()) + d) / normal.y;
                poly.add(p[i]);
            }
            m = TVector(0.0, 1.0, 0.0);
            break;
        }
        case 2: // z
        {
            TPoint p[4] = 
            {
                TPoint(min.x, min.y, 0.0), TPoint(max.x, min.y, 0.0),
                TPoint(max.x, max.y, 0.0), TPoint(min.x, max.y, 0.0)
            };
            if (iPlane.normal().z < 0)
            {
                std::reverse(p, p + 4);
            }
            for (size_t i = 0; i < 4; ++i)
            {
                p[i].z = -(dot(normal, p[i].position()) + d) / normal.z;
                poly.add(p[i]);
            }
            m = TVector(0.0, 0.0, 1.0);
        }
        default:
            LASS_ENFORCE_UNREACHABLE;
    };

    // clip against those 'm' borders
    return clip(TPlane(m, min), clip(TPlane(-m, max), poly));
}       

}
}

#endif

// EOF