LineSegment Class Reference

The LineSegment class is used by the LineMaterialSamplerBase class and for some ray tracing stuff. More...

#include <LineSegment.h>

Inheritance diagram for LineSegment:

Public Member Functions
	LineSegment ()=default
	LineSegment (const Point &p0, const Point &p1)
	~LineSegment () override=default
Point	closest_point (const Point &p) const
	Returns the closest point on the LineSegment to the passed in point.
bool	closest_normal_point (const Point &p, Point &closest_p) const
	Finds the closest point on the Line determined by the Line Segments.
bool	contains_point (const Point &p) const
	Determines whether a point is in a line segment or not.
bool	intersect (const libMesh::Plane &pl, Point &intersect_p) const
	Check if a line segment intersects a plane, and if so, return the intersection point.
bool	intersect (const LineSegment &l1, Point &intersect_p) const
	Check if a line segment intersects another line segment, and if so, return the intersection point.
bool	intersect (const LineSegment &line_segment) const override
	Check if a line segment intersects another line segment, without returning the intersection point.
Ball	computeBoundingBall () const override
	Compute a bounding ball for this line segment.
const Point &	start () const
	Beginning of the line segment.
const Point &	end () const
	Ending of the line segment.
void	setStart (const Point &p0)
	Sets the beginning of the line segment.
void	setEnd (const Point &p1)
	Sets the end of the line segment.
void	set (const Point &p0, const Point &p1)
	Sets the points on the line segment.
Real	length () const
	Length of segment.
Point	normal () const
	normal vector of the line segment

Private Member Functions
bool	closest_point (const Point &p, bool clamp_to_segment, Point &closest_p) const

Private Attributes
Point	_p0
Point	_p1

Detailed Description

The LineSegment class is used by the LineMaterialSamplerBase class and for some ray tracing stuff.

Definition at line 30 of file LineSegment.h.

Constructor & Destructor Documentation

LineSegment() [1/2]

LineSegment::LineSegment ( )

default

LineSegment() [2/2]

LineSegment::LineSegment	(	const Point &	p0,
		const Point &	p1
	)

Definition at line 21 of file LineSegment.C.

: _p0(p0), _p1(p1) {}

~LineSegment()

LineSegment::~LineSegment ( )

overridedefault

Member Function Documentation

closest_normal_point()

bool LineSegment::closest_normal_point	(	const Point &	p,
		Point &	closest_p
	)		const

Finds the closest point on the Line determined by the Line Segments.

Returns a boolean indicating whether that normal point is within the LineSegment or not

Definition at line 57 of file LineSegment.C.

{
  return closest_point(p, false, closest_p);
}

closest_point() [1/2]

Point LineSegment::closest_point

(

const Point &

p

)

const

Returns the closest point on the LineSegment to the passed in point.

Note that the closest point may be one of the ends of the LineSegment.

Definition at line 49 of file LineSegment.C.

{
  Point closest_p;
  closest_point(p, true, closest_p);
  return closest_p;
}

Referenced by closest_normal_point(), closest_point(), and contains_point().

closest_point() [2/2]

bool LineSegment::closest_point ( const Point &  p, bool  clamp_to_segment, Point &  closest_p  ) const

private

Definition at line 24 of file LineSegment.C.

{
  Point p0_p = p - _p0;
  Point p0_p1 = _p1 - _p0;
  Real p0_p1_2 = p0_p1.norm_sq();
  Real perp = p0_p(0) * p0_p1(0) + p0_p(1) * p0_p1(1) + p0_p(2) * p0_p1(2);
  Real t = perp / p0_p1_2;
  bool on_segment = true;
 
  if (t < 0.0 || t > 1.0)
    on_segment = false;
 
  if (clamp_to_segment)
  {
    if (t < 0.0)
      t = 0.0;
    else if (t > 1.0)
      t = 1.0;
  }
 
  closest_p = _p0 + p0_p1 * t;
  return on_segment;
}

computeBoundingBall()

Ball LineSegment::computeBoundingBall ( ) const

overridevirtual

Compute a bounding ball for this line segment.

The ball is defined by the midpoint of the segment and a radius equal to half the segment length.

Implements GeometryBase.

Definition at line 303 of file LineSegment.C.

{
  const Point center = 0.5 * (_p0 + _p1);
  const Real radius = 0.5 * (_p1 - _p0).norm();
  return Ball(center, radius);
}

contains_point()

bool LineSegment::contains_point

(

const Point &

p

)

const

Determines whether a point is in a line segment or not.

Definition at line 63 of file LineSegment.C.

{
  Point closest_p;
  return closest_point(p, false, closest_p) && closest_p.absolute_fuzzy_equals(p);
}

Referenced by Moose::sideIntersectedByLine().

end()

const Point & LineSegment::end ( ) const

inline

Ending of the line segment.

Definition at line 90 of file LineSegment.h.

{ return _p1; }

Referenced by dataStore(), IntersectionPointsAlongLine::execute(), Triangle::intersect(), Ball::intersect(), Moose::recursivelyFindElementsIntersectedByLine(), and to_json().

intersect() [1/3]

bool LineSegment::intersect	(	const libMesh::Plane &	pl,
		Point &	intersect_p
	)		const

Check if a line segment intersects a plane, and if so, return the intersection point.

There are three cases in 3D for intersection of a line and a plane Case 1: The line is parallel to the plane - No intersection Numerator = non-zero Denominator = zero

Case 2: The line is within the plane - Inf intersection Numerator = zero Denominator = zero

Case 3: The line intersects the plane at a single point Denominator = non-zero

Definition at line 70 of file LineSegment.C.

{
  Point pl0 = pl.get_planar_point();
  RealVectorValue N = pl.unit_normal(_p0);
  RealVectorValue I = (_p1 - _p0).unit();
 
  Real numerator = (pl0 - _p0) * N;
  Real denominator = I * N;
 
  // The Line is parallel to the plane
  if (std::abs(denominator) < 1.e-10)
  {
    // The Line is on the plane
    if (std::abs(numerator) < 1.e-10)
    {
      // The solution is not unique so we'll just pick an end point for now
      intersect_p = _p0;
      return true;
    }
    return false;
  }
 
  Real d = numerator / denominator;
 
  // Make sure we haven't moved off the line segment!
  if (d + libMesh::TOLERANCE < 0 || d - libMesh::TOLERANCE > (_p1 - _p0).norm())
    return false;
 
  intersect_p = d * I + _p0;
 
  return true;
}

Referenced by intersect(), and Moose::sideIntersectedByLine().

intersect() [2/3]

bool LineSegment::intersect	(	const LineSegment &	l1,
		Point &	intersect_p
	)		const

Check if a line segment intersects another line segment, and if so, return the intersection point.

intersect() [3/3]

bool LineSegment::intersect ( const LineSegment &  line_segment ) const

overridevirtual

Check if a line segment intersects another line segment, without returning the intersection point.

Implements GeometryBase.

Definition at line 253 of file LineSegment.C.

{
  Point p;
  return intersect(line_segment, p);
}

length()

Real LineSegment::length ( ) const

inline

Length of segment.

Definition at line 112 of file LineSegment.h.

{ return (_p0 - _p1).norm(); }

normal()

Point LineSegment::normal

(

)

const

normal vector of the line segment

Definition at line 291 of file LineSegment.C.

{
  const auto tangent = _p1 - _p0;
 
  // Rotate 90 degrees counter-clockwise (2D)
  Point n(-tangent(1), tangent(0), 0.0);
  n /= n.norm();
 
  return n;
}

set()

void LineSegment::set	(	const Point &	p0,
		const Point &	p1
	)

Sets the points on the line segment.

Parameters

p0	The start point of the line segment
p1	The end point of the line segment

Definition at line 260 of file LineSegment.C.

{
  setStart(p0);
  setEnd(p1);
}

Referenced by dataLoad().

setEnd()

void LineSegment::setEnd ( const Point &  p1 )

inline

Sets the end of the line segment.

Definition at line 100 of file LineSegment.h.

{ _p1 = p1; }

Referenced by set().

setStart()

void LineSegment::setStart ( const Point &  p0 )

inline

Sets the beginning of the line segment.

Definition at line 95 of file LineSegment.h.

{ _p0 = p0; }

Referenced by set().

start()

const Point & LineSegment::start ( ) const

inline

Beginning of the line segment.

Definition at line 85 of file LineSegment.h.

{ return _p0; }

Referenced by dataStore(), Triangle::intersect(), Ball::intersect(), and to_json().

Member Data Documentation

_p0

Point LineSegment::_p0

private

Definition at line 122 of file LineSegment.h.

Referenced by closest_point(), computeBoundingBall(), intersect(), length(), normal(), setStart(), and start().

_p1

Point LineSegment::_p1

private

Definition at line 122 of file LineSegment.h.

Referenced by closest_point(), computeBoundingBall(), end(), intersect(), length(), normal(), and setEnd().

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The documentation for this class was generated from the following files:

• include/geometries/LineSegment.h
• src/geometries/LineSegment.C