/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Copyright (C) 2017-2024 OpenFOAM Foundation
     \\/     M anipulation  |
-------------------------------------------------------------------------------
License
    This file is part of OpenFOAM.

    OpenFOAM is free software: you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    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
    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.

\*---------------------------------------------------------------------------*/

#include "barycentric.H"
#include "randomGenerator.H"

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

Foam::barycentric Foam::barycentric01(randomGenerator& rndGen)
{
    scalar s = rndGen.scalar01();
    scalar t = rndGen.scalar01();
    scalar u = rndGen.scalar01();

    // Transform the random point in the unit cube to a random point in the
    // unit tet by means of a series of reflections. See
    // <http://vcg.isti.cnr.it/jgt/tetra.htm> for details.

    if (s + t > 1)
    {
        s = 1 - s;
        t = 1 - t;
    }

    if (s + t + u > 1)
    {
        Foam::scalar temp = u;

        if (t + u > 1)
        {
            u = 1 - s - t;
            t = 1 - temp;
        }
        else
        {
            u = s + t + u - 1;
            s = 1 - t - temp;
        }
    }

    return Foam::barycentric(1 - s - t - u, s, t, u);
}


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