aabb_3d_triangle_3d.h

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/** @file
 *  @author Bram de Greve (bram@cocamware.com)
 *  @author Tom De Muer (tom@cocamware.com)
 *
 *  *** 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) 2004-2011 the Initial Developer.
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#ifndef LASS_GUARDIAN_OF_INCLUSION_PRIM_AABB_3D_TRIANGLE_3D_H
#define LASS_GUARDIAN_OF_INCLUSION_PRIM_AABB_3D_TRIANGLE_3D_H
 
#include "prim_common.h"
#include "aabb_3d.h"
#include "triangle_3d.h"
 
namespace lass
{
namespace prim
{
 
/** determine axis aligned bounding box of a 3D triangle
 *  @relates Aabb3D
 */
template <typename T> 
Aabb3D<T> aabb(const Triangle3D<T>& triangle)
{
    Aabb3D<T, AutoMinMax> result(triangle[0], triangle[1]);
    result += triangle[2];
    return result;
}
 
namespace impl
{
 
template <typename T>
void inpminmax(T& a, T& b)
{
    if (a > b)
    {
        std::swap(a, b);
    }
}
 
template <typename P>
bool intersectsHelperTriangleAabb3D(const P& v0, const P& v1, const P& v2, const P& a, const P& b)
{
    typedef typename P::TVector TVector;
    typedef typename P::TValue TValue;
 
    // this should move somedday to some place more appropriate.
    class Range
    {
    public:
        Range(TValue min, TValue max): min_(min), max_(max)
        {
            inpminmax(min_, max_);
        }
        Range& operator+=(const Range& other)
        {
            min_ += other.min_;
            max_ += other.max_;
            return *this;
        }
        bool seperated(const Range& other) const
        {
            return other.max_ < min_ || other.min_ > max_;
        }
    private:
        TValue min_;
        TValue max_;
    };
 
    const TVector f = v1 - v0; // triangleEdge
 
    {
        // const V aabbEdge(1, 0, 0);
        // const V axis = cross(aabbEdge, triangleEdge);
        const Range triangleRange(
            v0.z * v1.y - v0.y * v1.z, // == dot(v0, axis) == dot(v1, axis)
            f.y * v2.z - f.z * v2.y  // == dot(v2, axis)
            );
        Range boxRange(a.y * -f.z, b.y * -f.z);
        boxRange += Range(a.z * f.y, b.z * f.y);
        if (triangleRange.seperated(boxRange)) return false;
    }
 
    {
        // const V aabbEdge(0, 1, 0);
        const Range triangleRange(
            v0.x * v1.z - v0.z * v1.x,
            f.z * v2.x - f.x * v2.z
            );
        Range boxRange(a.z * -f.x, b.z * -f.x);
        boxRange += Range(a.x * f.z, b.x * f.z);
        if (triangleRange.seperated(boxRange)) return false;
    }
 
    {
        // const V aabbEdge(0, 0, 1);
        const Range triangleRange(
            v0.y * v1.x - v0.x * v1.y,
            f.x * v2.y - f.y * v2.x
            );
        Range boxRange(a.x * -f.y, b.x * -f.y);
        boxRange += Range(a.y * f.x, b.y * f.x);
        if (triangleRange.seperated(boxRange)) return false;
    }
 
    return true;
}
 
}
 
/*  @relates lass::prim::Triangle3D
 *  @sa lass::prim::Aabb3D
 *
 *  Using the Tomas Akenine-Moller algorithm from "Fast 3D Triangle-Box Overlap Testing"
 */
template <typename T, typename MMP>
bool intersects(const Triangle3D<T>& triangle, const Aabb3D<T, MMP>& box)
{
    // bullet 3
    if (!impl::intersectsHelperTriangleAabb3D(triangle[0], triangle[1], triangle[2], box.min(), box.max())) return false;
    if (!impl::intersectsHelperTriangleAabb3D(triangle[1], triangle[2], triangle[0], box.min(), box.max())) return false;
    if (!impl::intersectsHelperTriangleAabb3D(triangle[2], triangle[0], triangle[1], box.min(), box.max())) return false;
 
    // bullet 1
    if (!box.intersects(aabb(triangle)))
    {
        return false;
    }
 
    // bullet 2
    return intersects(triangle.plane(), box);
}
 
 
}
}
 
#endif
 
// EOF