GteIntrLine2Segment2.h

Go to the documentation of this file.

// David Eberly, Geometric Tools, Redmond WA 98052
// Copyright (c) 1998-2017
// Distributed under the Boost Software License, Version 1.0.
// http://www.boost.org/LICENSE_1_0.txt
// http://www.geometrictools.com/License/Boost/LICENSE_1_0.txt
// File Version: 3.0.0 (2016/06/19)

#pragma once

#include <Mathematics/GteSegment.h>
#include <Mathematics/GteIntrLine2Line2.h>

namespace gte
{

template <typename Real>
class TIQuery<Real, Line2<Real>, Segment2<Real>>
{
public:
    struct Result
    {
        bool intersect;

        // The number is 0 (no intersection), 1 (line and segment intersect in
        // a single point) or std::numeric_limits<int>::max() (line and
        // segment are collinear).
        int numIntersections;
    };

    Result operator()(Line2<Real> const& line, Segment2<Real> const& segment);
};

template <typename Real>
class FIQuery<Real, Line2<Real>, Segment2<Real>>
{
public:
    struct Result
    {
        bool intersect;

        // The number is 0 (no intersection), 1 (line and segment intersect in
        // a single point) or std::numeric_limits<int>::max() (line and
        // segment are collinear).
        int numIntersections;

        // If numIntersections is 1, the intersection is
        //   point = line.origin + lineParameter[0] * line.direction
        //         = segment.origin + segmentParameter[0] * segment.direction
        // If numIntersections is maxInt, point is not valid but the
        // intervals are
        //   lineParameter[] = { -maxReal, +maxReal }
        //   segmentParameter[] = { -segmentExtent, segmentExtent }
        Real lineParameter[2], segmentParameter[2];
        Vector2<Real> point;
    };

    Result operator()(Line2<Real> const& line, Segment2<Real> const& segment);
};


template <typename Real>
typename TIQuery<Real, Line2<Real>, Segment2<Real>>::Result
TIQuery<Real, Line2<Real>, Segment2<Real>>::operator()(
    Line2<Real> const& line, Segment2<Real> const& segment)
{
    Result result;
    Vector2<Real> segOrigin, segDirection;
    Real segExtent;
    segment.GetCenteredForm(segOrigin, segDirection, segExtent);

    FIQuery<Real, Line2<Real>, Line2<Real>> llQuery;
    auto llResult = llQuery(line, Line2<Real>(segOrigin, segDirection));
    if (llResult.numIntersections == 1)
    {
        // Test whether the line-line intersection is on the segment.
        if (std::abs(llResult.line1Parameter[0]) <= segExtent)
        {
            result.intersect = true;
            result.numIntersections = 1;
        }
        else
        {
            result.intersect = false;
            result.numIntersections = 0;
        }
    }
    else
    {
        result.intersect = llResult.intersect;
        result.numIntersections = llResult.numIntersections;
    }
    return result;
}

template <typename Real>
typename FIQuery<Real, Line2<Real>, Segment2<Real>>::Result
FIQuery<Real, Line2<Real>, Segment2<Real>>::operator()(
    Line2<Real> const& line, Segment2<Real> const& segment)
{
    Result result;
    Vector2<Real> segOrigin, segDirection;
    Real segExtent;
    segment.GetCenteredForm(segOrigin, segDirection, segExtent);

    FIQuery<Real, Line2<Real>, Line2<Real>> llQuery;
    auto llResult = llQuery(line, Line2<Real>(segOrigin, segDirection));
    if (llResult.numIntersections == 1)
    {
        // Test whether the line-line intersection is on the ray.
        if (std::abs(llResult.line1Parameter[0]) <= segExtent)
        {
            result.intersect = true;
            result.numIntersections = 1;
            result.lineParameter[0] = llResult.line0Parameter[0];
            result.segmentParameter[0] = llResult.line1Parameter[0];
            result.point = llResult.point;
        }
        else
        {
            result.intersect = false;
            result.numIntersections = 0;
        }
    }
    else if (llResult.numIntersections == std::numeric_limits<int>::max())
    {
        result.intersect = true;
        result.numIntersections = std::numeric_limits<int>::max();
        Real maxReal = std::numeric_limits<Real>::max();
        result.lineParameter[0] = -maxReal;
        result.lineParameter[1] = +maxReal;
        result.segmentParameter[0] = -segExtent;
        result.segmentParameter[1] = +segExtent;
    }
    else
    {
        result.intersect = false;
        result.numIntersections = 0;
    }
    return result;
}


}