aabb_2d_triangle_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 ***
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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.
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 *  Software distributed under the License is distributed on an "AS IS" basis, WITHOUT 
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 *  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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 */

#ifndef LASS_GUARDIAN_OF_INCLUSION_PRIM_AABB_2D_TRIANGLE_2D_H
#define LASS_GUARDIAN_OF_INCLUSION_PRIM_AABB_2D_TRIANGLE_2D_H

#include "prim_common.h"
#include "aabb_2d.h"
#include "triangle_2d.h"

namespace lass
{
namespace prim
{

/** determine axis aligned bounding box of a 2D triangle
 *  @relates lass::prim::Triangle2D
 *  @sa lass::prim::Aabb2D
 */
template <typename T> 
Aabb2D<T> aabb(const Triangle2D<T>& triangle)
{
    Aabb2D<T, AutoMinMax> result(triangle[0], triangle[1]);
    result += triangle[2];
    return result;
}



/*  @relates lass::prim::Triangle2D
 *  @sa lass::prim::Aabb2D
 */
template <typename T, typename MMP>
const bool intersects(const Triangle2D<T>& triangle, const Aabb2D<T, MMP>& box)
{
    if (!box.intersects(aabb(triangle)))
    {
        return false;
    }

    typedef typename Triangle2D<T>::TPoint TPoint;
    typedef typename Triangle2D<T>::TVector TVector;
    typedef typename Triangle2D<T>::TValue TValue;
    int k1 = 1, k2 = 2;
    for (int k0 = 0; k0 < 3; ++k0)
    {
        const TPoint& tail = triangle[k0];
        const TVector edge = triangle[k1] - tail;
        const TVector min = box.min() - tail;
        const TVector max = box.max() - tail;
        
        const TValue t[4] = {
            perpDot(edge, min),
            perpDot(edge, max),
            perpDot(edge, TVector(min.x, max.y)),
            perpDot(edge, TVector(max.x, min.y))
        };

        if (t[0] < 0 && t[1] < 0 && t[2] < 0 && t[3] < 0)
        {
            return false;
        }

        const TValue tMax = perpDot(edge, triangle[k2] - tail);
        LASS_ASSERT(tMax >= 0);
        if (t[0] > tMax && t[1] > tMax && t[2] > tMax && t[3] > tMax)
        {
            return false;
        }

        k1 = k2;
        k2 = k0;
    }

    return true;
}



/*  @relates lass::prim::Aabb2D
 *  @sa lass::prim::Triangle2D
 */
template <typename T, typename MMP>
const bool intersects(const Aabb2D<T, MMP>& box, const Triangle2D<T>& triangle)
{
    return intersects(triangle, box);
}



/*  @relates lass::prim::Triangle2D
 *  @sa lass::prim::Aabb2D
 */
template <typename T, typename MMP>
const bool collides(const Triangle2D<T>& triangle, const Aabb2D<T, MMP>& box)
{
    if (!box.collides(aabb(triangle)))
    {
        return false;
    }

    typedef typename Triangle2D<T>::TPoint TPoint;
    typedef typename Triangle2D<T>::TVector TVector;
    typedef typename Triangle2D<T>::TValue TValue;
    int k1 = 1, k2 = 2;
    for (int k0 = 0; k0 < 3; ++k0)
    {
        const TPoint& tail = triangle[k0];
        const TVector edge = triangle[k1] - tail;
        const TVector min = box.min() - tail;
        const TVector max = box.max() - tail;
        
        const TValue t[4] = {
            perpDot(edge, min),
            perpDot(edge, max),
            perpDot(edge, TVector(min.x, max.y)),
            perpDot(edge, TVector(max.x, min.y))
        };

        if (t[0] <= 0 && t[1] <= 0 && t[2] <= 0 && t[3] <= 0)
        {
            return false;
        }

        const TValue tMax = perpDot(edge, triangle[k2] - tail);
        LASS_ASSERT(tMax >= 0);
        if (t[0] >= tMax && t[1] >= tMax && t[2] >= tMax && t[3] >= tMax)
        {
            return false;
        }

        k1 = k2;
        k2 = k0;
    }

    return true;
}



/*  @relates lass::prim::Aabb2D
 *  @sa lass::prim::Triangle2D
 */
template <typename T, typename MMP>
const bool collides(const Aabb2D<T, MMP>& box, const Triangle2D<T>& triangle)
{
    return collides(triangle, box);
}

}
}

#endif

// EOF