CatmullRomSpline.C

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#include "CatmullRomSpline.H"

// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //

Foam::CatmullRomSpline::CatmullRomSpline
(
    const pointField& knots,
    const bool closed
)
:
    polyLine(knots, closed)
{}


// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //

Foam::point Foam::CatmullRomSpline::position(const scalar mu) const
{
    // endpoints
    if (mu < small)
    {
        return points().first();
    }
    else if (mu > 1 - small)
    {
        return points().last();
    }

    scalar lambda = mu;
    label segment = localParameter(lambda);
    return position(segment, lambda);
}


Foam::point Foam::CatmullRomSpline::position
(
    const label segment,
    const scalar mu
) const
{
    // out-of-bounds
    if (segment < 0)
    {
        return points().first();
    }
    else if (segment > nSegments())
    {
        return points().last();
    }

    const point& p0 = points()[segment];
    const point& p1 = points()[segment+1];

    // special cases - no calculation needed
    if (mu <= 0.0)
    {
        return p0;
    }
    else if (mu >= 1.0)
    {
        return p1;
    }


    // determine the end points
    point e0;
    point e1;

    if (segment == 0)
    {
        // end: simple reflection
        e0 = 2*p0 - p1;
    }
    else
    {
        e0 = points()[segment-1];
    }

    if (segment+1 == nSegments())
    {
        // end: simple reflection
        e1 = 2*p1 - p0;
    }
    else
    {
        e1 = points()[segment+2];
    }


    return 0.5 *
    (
        ( 2*p0 )
      + mu *
        (
            ( -e0 + p1 )
          + mu *
            (
                ( 2*e0 - 5*p0 + 4*p1 - e1 )
              + mu *
                ( -e0 + 3*p0 - 3*p1 + e1 )
            )
        )
    );
}


Foam::scalar Foam::CatmullRomSpline::length() const
{
    NotImplemented;
    return 1.0;
}


// ************************************************************************* //