searchableCylinder.C

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  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Copyright (C) 2011-2019 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
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#include "searchableCylinder.H"
#include "addToRunTimeSelectionTable.H"

// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //

namespace Foam
{
    defineTypeNameAndDebug(searchableCylinder, 0);
    addToRunTimeSelectionTable(searchableSurface, searchableCylinder, dict);
}


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

Foam::tmp<Foam::pointField> Foam::searchableCylinder::coordinates() const
{
    tmp<pointField> tCtrs(new pointField(1, 0.5*(point1_ + point2_)));

    return tCtrs;
}


void Foam::searchableCylinder::boundingSpheres
(
    pointField& centres,
    scalarField& radiusSqr
) const
{
    centres.setSize(1);
    centres[0] = 0.5*(point1_ + point2_);

    radiusSqr.setSize(1);
    radiusSqr[0] = Foam::magSqr(point1_-centres[0]) + Foam::sqr(radius_);

    // Add a bit to make sure all points are tested inside
    radiusSqr += Foam::sqr(small);
}


Foam::tmp<Foam::pointField> Foam::searchableCylinder::points() const
{
    tmp<pointField> tPts(new pointField(2));
    pointField& pts = tPts.ref();

    pts[0] = point1_;
    pts[1] = point2_;

    return tPts;
}


Foam::pointIndexHit Foam::searchableCylinder::findNearest
(
    const point& sample,
    const scalar nearestDistSqr
) const
{
    pointIndexHit info(false, sample, -1);

    vector v(sample - point1_);

    // Decompose sample-point1 into normal and parallel component
    scalar parallel = (v & unitDir_);

    // Remove the parallel component and normalise
    v -= parallel*unitDir_;
    scalar magV = mag(v);

    if (magV < rootVSmall)
    {
        v = Zero;
    }
    else
    {
        v /= magV;
    }

    if (parallel <= 0)
    {
        // nearest is at point1 end cap. Clip to radius.
        info.setPoint(point1_ + min(magV, radius_)*v);
    }
    else if (parallel >= magDir_)
    {
        // nearest is at point2 end cap. Clip to radius.
        info.setPoint(point2_ + min(magV, radius_)*v);
    }
    else
    {
        // in between endcaps. Might either be nearer endcaps or cylinder wall

        // distance to endpoint: parallel or parallel-magDir
        // distance to cylinder wall: magV-radius_

        // Nearest cylinder point
        point cylPt;
        if (magV < rootVSmall)
        {
            // Point exactly on centre line. Take any point on wall.
            vector e1 = point(1,0,0) ^ unitDir_;
            scalar magE1 = mag(e1);
            if (magE1 < small)
            {
                e1 = point(0,1,0) ^ unitDir_;
                magE1 = mag(e1);
            }
            e1 /= magE1;
            cylPt = sample + radius_*e1;
        }
        else
        {
            cylPt = sample + (radius_-magV)*v;
        }

        if (parallel < 0.5*magDir_)
        {
            // Project onto p1 endcap
            point end1Pt = point1_ + min(magV, radius_)*v;

            if (magSqr(sample-cylPt) < magSqr(sample-end1Pt))
            {
                info.setPoint(cylPt);
            }
            else
            {
                info.setPoint(end1Pt);
            }
        }
        else
        {
            // Project onto p2 endcap
            point end2Pt = point2_ + min(magV, radius_)*v;

            if (magSqr(sample-cylPt) < magSqr(sample-end2Pt))
            {
                info.setPoint(cylPt);
            }
            else
            {
                info.setPoint(end2Pt);
            }
        }
    }

    if (magSqr(sample - info.rawPoint()) < nearestDistSqr)
    {
        info.setHit();
        info.setIndex(0);
    }

    return info;
}


Foam::scalar Foam::searchableCylinder::radius2(const point& pt) const
{
    const vector x = (pt-point1_) ^ unitDir_;
    return x&x;
}


// From http://www.gamedev.net/community/forums/topic.asp?topic_id=467789 -
// intersection of cylinder with ray
void Foam::searchableCylinder::findLineAll
(
    const point& start,
    const point& end,
    pointIndexHit& near,
    pointIndexHit& far
) const
{
    near.setMiss();
    far.setMiss();

    vector point1Start(start-point1_);
    vector point2Start(start-point2_);
    vector point1End(end-point1_);

    // Quick rejection of complete vector outside endcaps
    scalar s1 = point1Start&unitDir_;
    scalar s2 = point1End&unitDir_;

    if ((s1 < 0 && s2 < 0) || (s1 > magDir_ && s2 > magDir_))
    {
        return;
    }

    // Line as P = start+t*V  where V is unit vector and t=[0..mag(end-start)]
    vector V(end-start);
    scalar magV = mag(V);
    if (magV < rootVSmall)
    {
        return;
    }
    V /= magV;


    // We now get the nearest intersections to start. This can either be
    // the intersection with the end plane or with the cylinder side.

    // Get the two points (expressed in t) on the end planes. This is to
    // clip any cylinder intersection against.
    scalar tPoint1;
    scalar tPoint2;

    // Maintain the two intersections with the endcaps
    scalar tNear = vGreat;
    scalar tFar = vGreat;

    {
        scalar s = (V&unitDir_);
        if (mag(s) > vSmall)
        {
            tPoint1 = -s1/s;
            tPoint2 = -(point2Start&unitDir_)/s;
            if (tPoint2 < tPoint1)
            {
                Swap(tPoint1, tPoint2);
            }
            if (tPoint1 > magV || tPoint2 < 0)
            {
                return;
            }

            // See if the points on the endcaps are actually inside the cylinder
            if (tPoint1 >= 0 && tPoint1 <= magV)
            {
                if (radius2(start+tPoint1*V) <= sqr(radius_))
                {
                    tNear = tPoint1;
                }
            }
            if (tPoint2 >= 0 && tPoint2 <= magV)
            {
                if (radius2(start+tPoint2*V) <= sqr(radius_))
                {
                    // Check if already have a near hit from point1
                    if (tNear <= 1)
                    {
                        tFar = tPoint2;
                    }
                    else
                    {
                        tNear = tPoint2;
                    }
                }
            }
        }
        else
        {
            // Vector perpendicular to cylinder. Check for outside already done
            // above so just set tpoint to allow all.
            tPoint1 = -vGreat;
            tPoint2 = vGreat;
        }
    }


    const vector x = point1Start ^ unitDir_;
    const vector y = V ^ unitDir_;
    const scalar d = sqr(radius_);

    // Second order equation of the form a*t^2 + b*t + c
    const scalar a = (y&y);
    const scalar b = 2*(x&y);
    const scalar c = (x&x)-d;

    const scalar disc = b*b-4*a*c;

    scalar t1 = -vGreat;
    scalar t2 = vGreat;

    if (disc < 0)
    {
        // Fully outside
        return;
    }
    else if (disc < rootVSmall)
    {
        // Single solution
        if (mag(a) > rootVSmall)
        {
            t1 = -b/(2*a);

            // Pout<< "single solution t:" << t1
            //    << " for start:" << start << " end:" << end
            //    << " c:" << c << endl;

            if (t1 >= 0 && t1 <= magV && t1 >= tPoint1 && t1 <= tPoint2)
            {
                // valid. Insert sorted.
                if (t1 < tNear)
                {
                    tFar = tNear;
                    tNear = t1;
                }
                else if (t1 < tFar)
                {
                    tFar = t1;
                }
            }
            else
            {
                return;
            }
        }
        else
        {
            // Aligned with axis. Check if outside radius
            // Pout<< "small discriminant:" << disc
            //    << " for start:" << start << " end:" << end
            //    << " magV:" << magV
            //    << " c:" << c << endl;
            if (c > 0)
            {
                return;
            }
        }
    }
    else
    {
        if (mag(a) > rootVSmall)
        {
            scalar sqrtDisc = sqrt(disc);

            t1 = (-b - sqrtDisc)/(2*a);
            t2 = (-b + sqrtDisc)/(2*a);
            if (t2 < t1)
            {
                Swap(t1, t2);
            }

            if (t1 >= 0 && t1 <= magV && t1 >= tPoint1 && t1 <= tPoint2)
            {
                // valid. Insert sorted.
                if (t1 < tNear)
                {
                    tFar = tNear;
                    tNear = t1;
                }
                else if (t1 < tFar)
                {
                    tFar = t1;
                }
            }
            if (t2 >= 0 && t2 <= magV && t2 >= tPoint1 && t2 <= tPoint2)
            {
                // valid. Insert sorted.
                if (t2 < tNear)
                {
                    tFar = tNear;
                    tNear = t2;
                }
                else if (t2 < tFar)
                {
                    tFar = t2;
                }
            }
            // Pout<< "two solutions t1:" << t1 << " t2:" << t2
            //    << " for start:" << start << " end:" << end
            //    << " magV:" << magV
            //    << " c:" << c << endl;
        }
        else
        {
            // Aligned with axis. Check if outside radius
            // Pout<< "large discriminant:" << disc
            //    << " small a:" << a
            //    << " for start:" << start << " end:" << end
            //    << " magV:" << magV
            //    << " c:" << c << endl;
            if (c > 0)
            {
                return;
            }
        }
    }

    // Check tNear, tFar
    if (tNear >= 0 && tNear <= magV)
    {
        near.setPoint(start+tNear*V);
        near.setHit();
        near.setIndex(0);

        if (tFar <= magV)
        {
            far.setPoint(start+tFar*V);
            far.setHit();
            far.setIndex(0);
        }
    }
    else if (tFar >= 0 && tFar <= magV)
    {
        near.setPoint(start+tFar*V);
        near.setHit();
        near.setIndex(0);
    }
}


Foam::boundBox Foam::searchableCylinder::calcBounds() const
{

    // Adapted from
    // http://www.gamedev.net/community/forums
    //       /topic.asp?topic_id=338522&forum_id=20&gforum_id=0

    // Let cylinder have end points A,B and radius r,

    // Bounds in direction X (same for Y and Z) can be found as:
    // Let A.X<B.X (otherwise swap points)
    // Good approximate lowest bound is A.X-r and highest is B.X+r (precise for
    // capsule). At worst, in one direction it can be larger than needed by 2*r.

    // Accurate bounds for cylinder is
    // A.X-kx*r, B.X+kx*r
    // where
    // kx=sqrt(((A.Y-B.Y)^2+(A.Z-B.Z)^2)/((A.X-B.X)^2+(A.Y-B.Y)^2+(A.Z-B.Z)^2))

    // similar thing for Y and Z
    // (i.e.
    // ky=sqrt(((A.X-B.X)^2+(A.Z-B.Z)^2)/((A.X-B.X)^2+(A.Y-B.Y)^2+(A.Z-B.Z)^2))
    // kz=sqrt(((A.X-B.X)^2+(A.Y-B.Y)^2)/((A.X-B.X)^2+(A.Y-B.Y)^2+(A.Z-B.Z)^2))
    // )

    // How derived: geometric reasoning. Bounds of cylinder is same as for 2
    // circles centered on A and B. This sqrt thingy gives sine of angle between
    // axis and direction, used to find projection of radius.

    vector kr
    (
        sqrt(sqr(unitDir_.y()) + sqr(unitDir_.z())),
        sqrt(sqr(unitDir_.x()) + sqr(unitDir_.z())),
        sqrt(sqr(unitDir_.x()) + sqr(unitDir_.y()))
    );

    kr *= radius_;

    point min = point1_ - kr;
    point max = point1_ + kr;

    min = ::Foam::min(min, point2_ - kr);
    max = ::Foam::max(max, point2_ + kr);

    return boundBox(min, max);
}


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

Foam::searchableCylinder::searchableCylinder
(
    const IOobject& io,
    const point& point1,
    const point& point2,
    const scalar radius
)
:
    searchableSurface(io),
    point1_(point1),
    point2_(point2),
    magDir_(mag(point2_-point1_)),
    unitDir_((point2_-point1_)/magDir_),
    radius_(radius)
{
    bounds() = calcBounds();
}


Foam::searchableCylinder::searchableCylinder
(
    const IOobject& io,
    const dictionary& dict
)
:
    searchableSurface(io),
    point1_(dict.lookup("point1")),
    point2_(dict.lookup("point2")),
    magDir_(mag(point2_-point1_)),
    unitDir_((point2_-point1_)/magDir_),
    radius_(dict.lookup<scalar>("radius"))
{
    bounds() = calcBounds();
}


// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //

Foam::searchableCylinder::~searchableCylinder()
{}


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

const Foam::wordList& Foam::searchableCylinder::regions() const
{
    if (regions_.empty())
    {
        regions_.setSize(1);
        regions_[0] = "region0";
    }
    return regions_;
}


void Foam::searchableCylinder::findNearest
(
    const pointField& samples,
    const scalarField& nearestDistSqr,
    List<pointIndexHit>& info
) const
{
    info.setSize(samples.size());

    forAll(samples, i)
    {
        info[i] = findNearest(samples[i], nearestDistSqr[i]);
    }
}


void Foam::searchableCylinder::findLine
(
    const pointField& start,
    const pointField& end,
    List<pointIndexHit>& info
) const
{
    info.setSize(start.size());

    forAll(start, i)
    {
        // Pick nearest intersection. If none intersected take second one.
        pointIndexHit b;
        findLineAll(start[i], end[i], info[i], b);
        if (!info[i].hit() && b.hit())
        {
            info[i] = b;
        }
    }
}


void Foam::searchableCylinder::findLineAny
(
    const pointField& start,
    const pointField& end,
    List<pointIndexHit>& info
) const
{
    info.setSize(start.size());

    forAll(start, i)
    {
        // Discard far intersection
        pointIndexHit b;
        findLineAll(start[i], end[i], info[i], b);
        if (!info[i].hit() && b.hit())
        {
            info[i] = b;
        }
    }
}


void Foam::searchableCylinder::findLineAll
(
    const pointField& start,
    const pointField& end,
    List<List<pointIndexHit>>& info
) const
{
    info.setSize(start.size());

    forAll(start, i)
    {
        pointIndexHit near, far;
        findLineAll(start[i], end[i], near, far);

        if (near.hit())
        {
            if (far.hit())
            {
                info[i].setSize(2);
                info[i][0] = near;
                info[i][1] = far;
            }
            else
            {
                info[i].setSize(1);
                info[i][0] = near;
            }
        }
        else
        {
            if (far.hit())
            {
                info[i].setSize(1);
                info[i][0] = far;
            }
            else
            {
                info[i].clear();
            }
        }
    }
}


void Foam::searchableCylinder::getRegion
(
    const List<pointIndexHit>& info,
    labelList& region
) const
{
    region.setSize(info.size());
    region = 0;
}


void Foam::searchableCylinder::getNormal
(
    const List<pointIndexHit>& info,
    vectorField& normal
) const
{
    normal.setSize(info.size());
    normal = Zero;

    forAll(info, i)
    {
        if (info[i].hit())
        {
            vector v(info[i].hitPoint() - point1_);

            // Decompose sample-point1 into normal and parallel component
            scalar parallel = (v & unitDir_);

            // Remove the parallel component and normalise
            v -= parallel*unitDir_;
            scalar magV = mag(v);

            if (parallel <= 0)
            {
                if ((magV-radius_) < mag(parallel))
                {
                    // either above endcap (magV<radius) or outside but closer
                    normal[i] = -unitDir_;
                }
                else
                {
                    normal[i] = v/magV;
                }
            }
            else if (parallel <= 0.5*magDir_)
            {
                // See if endcap closer or sidewall
                if (magV >= radius_ || (radius_-magV) < parallel)
                {
                    normal[i] = v/magV;
                }
                else
                {
                    // closer to endcap
                    normal[i] = -unitDir_;
                }
            }
            else if (parallel <= magDir_)
            {
                // See if endcap closer or sidewall
                if (magV >= radius_ || (radius_-magV) < (magDir_-parallel))
                {
                    normal[i] = v/magV;
                }
                else
                {
                    // closer to endcap
                    normal[i] = unitDir_;
                }
            }
            else    // beyond cylinder
            {
                if ((magV-radius_) < (parallel-magDir_))
                {
                    // above endcap
                    normal[i] = unitDir_;
                }
                else
                {
                    normal[i] = v/magV;
                }
            }
        }
    }
}


void Foam::searchableCylinder::getVolumeType
(
    const pointField& points,
    List<volumeType>& volType
) const
{
    volType.setSize(points.size());
    volType = volumeType::inside;

    forAll(points, pointi)
    {
        const point& pt = points[pointi];

        vector v(pt - point1_);

        // Decompose sample-point1 into normal and parallel component
        scalar parallel = v & unitDir_;

        if (parallel < 0)
        {
            // left of point1 endcap
            volType[pointi] = volumeType::outside;
        }
        else if (parallel > magDir_)
        {
            // right of point2 endcap
            volType[pointi] = volumeType::outside;
        }
        else
        {
            // Remove the parallel component
            v -= parallel*unitDir_;

            if (mag(v) > radius_)
            {
                volType[pointi] = volumeType::outside;
            }
            else
            {
                volType[pointi] = volumeType::inside;
            }
        }
    }
}


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