face.C

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License
    This file is part of OpenFOAM.
 
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    the Free Software Foundation, either version 3 of the License, or
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    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    for more details.
 
    You should have received a copy of the GNU General Public License
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#include "face.H"
#include "triFace.H"
#include "triPointRef.H"
#include "mathematicalConstants.H"
#include "Swap.H"
#include "ConstCirculator.H"
 
// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
const char* const Foam::face::typeName = "face";
 
 
// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
Foam::face::face(const triFace& f)
:
    labelList(f)
{}
 
 
// * * * * * * * * * * * * * Static Member Functions * * * * * * * * * * * * //
 
int Foam::face::compare(const face& a, const face& b)
{
    // Basic rule: we assume that the sequence of labels in each list
    // will be circular in the same order (but not necessarily in the
    // same direction or from the same starting point).
 
    // Trivial reject: faces are different size
    label sizeA = a.size();
    label sizeB = b.size();
 
    if (sizeA != sizeB || sizeA == 0)
    {
        return 0;
    }
    else if (sizeA == 1)
    {
        if (a[0] == b[0])
        {
            return 1;
        }
        else
        {
            return 0;
        }
    }
 
    ConstCirculator<face> aCirc(a);
    ConstCirculator<face> bCirc(b);
 
    // Rotate face b until its element matches the starting element of face a.
    do
    {
        if (aCirc() == bCirc())
        {
            // Set bCirc fulcrum to its iterator and increment the iterators
            bCirc.setFulcrumToIterator();
            ++aCirc;
            ++bCirc;
 
            break;
        }
    } while (bCirc.circulate(CirculatorBase::direction::clockwise));
 
    // If the circulator has stopped then faces a and b do not share a matching
    // point. Doesn't work on matching, single element face.
    if (!bCirc.circulate())
    {
        return 0;
    }
 
    // Look forwards around the faces for a match
    do
    {
        if (aCirc() != bCirc())
        {
            break;
        }
    }
    while
    (
        aCirc.circulate(CirculatorBase::direction::clockwise),
        bCirc.circulate(CirculatorBase::direction::clockwise)
    );
 
    // If the circulator has stopped then faces a and b matched.
    if (!aCirc.circulate())
    {
        return 1;
    }
    else
    {
        // Reset the circulators back to their fulcrum
        aCirc.setIteratorToFulcrum();
        bCirc.setIteratorToFulcrum();
        ++aCirc;
        --bCirc;
    }
 
    // Look backwards around the faces for a match
    do
    {
        if (aCirc() != bCirc())
        {
            break;
        }
    }
    while
    (
        aCirc.circulate(CirculatorBase::direction::clockwise),
        bCirc.circulate(CirculatorBase::direction::anticlockwise)
    );
 
    // If the circulator has stopped then faces a and b matched.
    if (!aCirc.circulate())
    {
        return -1;
    }
 
    return 0;
}
 
 
bool Foam::face::sameVertices(const face& a, const face& b)
{
    label sizeA = a.size();
    label sizeB = b.size();
 
    // Trivial reject: faces are different size
    if (sizeA != sizeB)
    {
        return false;
    }
    // Check faces with a single vertex
    else if (sizeA == 1)
    {
        if (a[0] == b[0])
        {
            return true;
        }
        else
        {
            return false;
        }
    }
 
    forAll(a, i)
    {
        // Count occurrences of a[i] in a
        label aOcc = 0;
        forAll(a, j)
        {
            if (a[i] == a[j]) aOcc++;
        }
 
        // Count occurrences of a[i] in b
        label bOcc = 0;
        forAll(b, j)
        {
            if (a[i] == b[j]) bOcc++;
        }
 
        // Check if occurrences of a[i] in a and b are the same
        if (aOcc != bOcc) return false;
    }
 
    return true;
}
 
 
// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
Foam::label Foam::face::collapse()
{
    if (size() > 1)
    {
        label ci = 0;
        for (label i=1; i<size(); i++)
        {
            if (operator[](i) != operator[](ci))
            {
                operator[](++ci) = operator[](i);
            }
        }
 
        if (operator[](ci) != operator[](0))
        {
            ci++;
        }
 
        setSize(ci);
    }
 
    return size();
}
 
 
void Foam::face::flip()
{
    const label n = size();
 
    if (n > 2)
    {
        for (label i=1; i < (n+1)/2; ++i)
        {
            Swap(operator[](i), operator[](n-i));
        }
    }
}
 
 
Foam::point Foam::face::centre(const pointField& ps) const
{
    return centre(UIndirectList<point>(ps, *this));
}
 
 
Foam::vector Foam::face::area(const pointField& ps) const
{
    return area(UIndirectList<point>(ps, *this));
}
 
 
Foam::vector Foam::face::normal(const pointField& points) const
{
    return normalised(area(points));
}
 
 
Foam::face Foam::face::reverseFace() const
{
    // Reverse the label list and return
    // The starting points of the original and reverse face are identical.
 
    const labelList& f = *this;
    labelList newList(size());
 
    newList[0] = f[0];
 
    for (label pointi = 1; pointi < newList.size(); pointi++)
    {
        newList[pointi] = f[size() - pointi];
    }
 
    return face(move(newList));
}
 
 
Foam::label Foam::face::which(const label globalIndex) const
{
    const labelList& f = *this;
 
    forAll(f, localIdx)
    {
        if (f[localIdx] == globalIndex)
        {
            return localIdx;
        }
    }
 
    return -1;
}
 
 
Foam::scalar Foam::face::sweptVol
(
    const pointField& oldPoints,
    const pointField& newPoints
) const
{
    // This Optimisation causes a small discrepancy between the swept-volume of
    // opposite faces of complex cells with triangular faces opposing polygons.
    // It could be used without problem for tetrahedral cells
    // if (size() == 3)
    // {
    //     return
    //     (
    //         triPointRef
    //         (
    //             oldPoints[operator[](0)],
    //             oldPoints[operator[](1)],
    //             oldPoints[operator[](2)]
    //         ).sweptVol
    //         (
    //             triPointRef
    //             (
    //                 newPoints[operator[](0)],
    //                 newPoints[operator[](1)],
    //                 newPoints[operator[](2)]
    //             )
    //         )
    //     );
    // }
 
    scalar sv = 0;
 
    // Calculate the swept volume by breaking the face into triangles and
    // summing their swept volumes.
    // Changed to deal with small concavity by using a central decomposition
 
    point centreOldPoint = centre(oldPoints);
    point centreNewPoint = centre(newPoints);
 
    label nPoints = size();
 
    for (label pi=0; pi<nPoints-1; ++pi)
    {
        // Note: for best accuracy, centre point always comes last
        sv += triPointRef
        (
            centreOldPoint,
            oldPoints[operator[](pi)],
            oldPoints[operator[](pi + 1)]
        ).sweptVol
        (
            triPointRef
            (
                centreNewPoint,
                newPoints[operator[](pi)],
                newPoints[operator[](pi + 1)]
            )
        );
    }
 
    sv += triPointRef
    (
        centreOldPoint,
        oldPoints[operator[](nPoints-1)],
        oldPoints[operator[](0)]
    ).sweptVol
    (
        triPointRef
        (
            centreNewPoint,
            newPoints[operator[](nPoints-1)],
            newPoints[operator[](0)]
        )
    );
 
    return sv;
}
 
 
Foam::tensor Foam::face::inertia
(
    const pointField& p,
    const point& refPt,
    scalar density
) const
{
    // If the face is a triangle, do a direct calculation
    if (size() == 3)
    {
        return triPointRef
        (
            p[operator[](0)],
            p[operator[](1)],
            p[operator[](2)]
        ).inertia(refPt, density);
    }
 
    const point ctr = centre(p);
 
    tensor J = Zero;
 
    forAll(*this, i)
    {
        J += triPointRef
        (
            p[operator[](i)],
            p[operator[](fcIndex(i))],
            ctr
        ).inertia(refPt, density);
    }
 
    return J;
}
 
 
Foam::edgeList Foam::face::edges() const
{
    const labelList& points = *this;
 
    edgeList e(points.size());
 
    for (label pointi = 0; pointi < points.size() - 1; ++pointi)
    {
        e[pointi] = edge(points[pointi], points[pointi + 1]);
    }
 
    // Add last edge
    e.last() = edge(points.last(), points[0]);
 
    return e;
}
 
 
int Foam::face::edgeDirection(const edge& e) const
{
    forAll(*this, i)
    {
        if (operator[](i) == e.start())
        {
            if (operator[](rcIndex(i)) == e.end())
            {
                // Reverse direction
                return -1;
            }
            else if (operator[](fcIndex(i)) == e.end())
            {
                // Forward direction
                return 1;
            }
 
            // No match
            return 0;
        }
        else if (operator[](i) == e.end())
        {
            if (operator[](rcIndex(i)) == e.start())
            {
                // Forward direction
                return 1;
            }
            else if (operator[](fcIndex(i)) == e.start())
            {
                // Reverse direction
                return -1;
            }
 
            // No match
            return 0;
        }
    }
 
    // Not found
    return 0;
}
 
 
Foam::label Foam::longestEdge(const face& f, const pointField& pts)
{
    const edgeList& eds = f.edges();
 
    label longestEdgeI = -1;
    scalar longestEdgeLength = -small;
 
    forAll(eds, edI)
    {
        scalar edgeLength = eds[edI].mag(pts);
 
        if (edgeLength > longestEdgeLength)
        {
            longestEdgeI = edI;
            longestEdgeLength = edgeLength;
        }
    }
 
    return longestEdgeI;
}
 
 
// ************************************************************************* //