sampling.h

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/*
    Sheep - A Rigid Body Dynamics Engine
    Copyright (C) 2001-2004 Francois Beaune
    Contact: http://toxicengine.sourceforge.net/

    This file is part of Sheep.

    Sheep 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 2 of the License, or
    (at your option) any later version.

    Sheep 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 Sheep; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#ifndef SHEEP_MATH_SAMPLING_H
#define SHEEP_MATH_SAMPLING_H

#include "common/math/point2.h"
#include "common/math/point3.h"
#include "common/math/real.h"

#include <cassert>
#include <cmath>

namespace sheep {

    //! Returns a point chosen uniformly on the surface of the unit disk.
    sheep::Point2 UniformDiskSampling(sheep::Real xi1, sheep::Real xi2);

    //! Returns a point chosen uniformly on the surface of the unit sphere.
    //! The vector from the origin to the returned point is unit-length.
    sheep::Point3 UniformSphereSampling(sheep::Real xi1, sheep::Real xi2);

    //! Returns a point chosen uniformly on the surface of the unit hemisphere (the y >= 0 part
    //! of the unit sphere). The vector from the origin to the returned point is unit-length.
    //! Note: when doing stratified sampling, there should be 4 times more samples
    //! for xi2 than for xi1, since xi2 is used to compute the Phi angle.
    sheep::Point3 UniformHemisphereSampling(sheep::Real xi1, sheep::Real xi2);

    //! Returns a point chosen with a cosine-weighted distribution on the surface of the
    //! unit hemisphere (see above for definition). The vector from the origin to the
    //! returned point is unit-length.
    //! Note: when doing stratified sampling, there should be 4 times more samples
    //! for xi2 than for xi1, since xi2 is used to compute the Phi angle.
    sheep::Point3 CosineHemisphereSampling(sheep::Real xi1, sheep::Real xi2);

#include "sampling.inl"

}

#endif  // !SHEEP_MATH_SAMPLING_H

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