EasyGeometry::D2::LinearEntity

A base class for all linear entities (Line, Ray and Segment) in 2-dimensional Euclidean space.

#direction

Description

The direction vector of the LinearEntity.

Signature

Parameters:

Returns:
    Easy::Geometry::Vector
    
Errors:

Example

l1 = EasyGeometry::D2::Line.new([0, 0], [1, 1])
s2 = EasyGeometry::D2::Segment.new([0, 0], [-1, 1])

l1.direction  # Vector(1, 1)
s2.direction  # Vector(-1, 1)

#angle_between(other)

Description

Return the non-reflex angle formed by rays emanating from the origin with directions the same as the direction vectors of the linear entities.

From the dot product of vectors v1 and v2 it is known that:

dot(v1, v2) = |v1|*|v2|*cos(A)

where A is the angle formed between the two vectors. We can get the directional vectors of the two lines and readily find the angle between the two using the above formula.

Signature

Parameters:
    other - EasyGeometry::D2::LinearEntity
    
Returns:
    Numeric (angle in radians)
    
Errors:

Example

l1 = EasyGeometry::D2::Line.new([0, 0], [1, 1])
s2 = EasyGeometry::D2::Segment.new([0, 0], [-1, 1])

l1.angle_between(s2)  # 90 * Math::PI / 180

#parallel_to?(other)

Description

Are two LinearEntity parallel?

return true if self and other LinearEntity are parallel, false otherwise.

Signature

Parameters:
    other - EasyGeometry::D2::LinearEntity
    
Returns:
    boolean (true or false)
    
Errors:
    raise TypeError if other is not LinearEntity

Example

l1 = EasyGeometry::D2::Line.new([0, 0], [1, 1])
s2 = EasyGeometry::D2::Segment.new([0, 0], [-1, 1])

l1.parallel_to?(l1)  # true
l1.parallel_to?(s2)  # false

#perpendicular_to?(other)

Description

Are two LinearEntity perpendicular?

return true if self and other LinearEntity are perpendicular, false otherwise.

Signature

Parameters:
    other - EasyGeometry::D2::LinearEntity
    
Returns:
    boolean (true or false)
    
Errors:
    raise TypeError if other is not LinearEntity

Example

l1 = EasyGeometry::D2::Line.new([0, 0], [1, 1])
s2 = EasyGeometry::D2::Segment.new([0, 0], [-1, 1])

l1.perpendicular_to?(l1)  # false
l1.perpendicular_to?(s2)  # true

#similar_to?(other)

Description

Are two linear entities similar?

Return true if self and other are contained in the same line.

Signature

Parameters:
    other - EasyGeometry::D2::LinearEntity
    
Returns:
    boolean (true or false)
    
Errors:
    raise TypeError if other is not LinearEntity

Example

l1 = EasyGeometry::D2::Line.new([0, 0], [1, 1])
s2 = EasyGeometry::D2::Segment.new([0, 0], [-1, 1])

l1.similar_to?(s2)  # false
l1.similar_to?(EasyGeometry::D2::Segment.new([2, 2], [4, 4]))  # true

#intersection(entity)

Description

The intersection with another geometrical entity.

Signature

Parameters:
    entity - GeometryEntity(Point, Line etc.)
    
Returns:
    Array of geometrical entities
    
Errors:
    raise TypeError if intersection method is not defined for entity 

Example

l1 = EasyGeometry::D2::Line.new([0, 0], [1, 1])
s2 = EasyGeometry::D2::Segment.new([0, 0], [-1, 1])

l1.intersection(l1)  # [l1]
l1.intersection(s2)  # [Point(0, 0)]
l1.intersection(EasyGeometry::D2::Segment.new([1, 0], [2, 1])) # []

#parallel_line(point)

Description

Create a new Line parallel to this linear entity which passes through the point p.

Signature

Parameters:
    point - EasyGeometry::D2::Point or Array of Numeric(coordinates)
    
Returns:
    EasyGeometry::D2::Line
    
Errors:
    raise TypeError if point is not Point or valid Array

Example

l1 = EasyGeometry::D2::Line.new([0, 0], [1, 0])

l1.parallel_line([1, 1])  # Line(Point(1, 1), Point(2, 1))

#perpendicular_line(point)

Description

Create a new Line perpendicular to this linear entity which passes through the point.

Signature

Parameters:
    point - EasyGeometry::D2::Point or Array of Numeric(coordinates)
    
Returns:
     EasyGeometry::D2::Line
    
Errors:
    raise TypeError if point is not Point or valid Array

Example

l1 = EasyGeometry::D2::Line.new([0, 0], [1, 0])

l1.perpendicular_line([1, 1])  # Line(Point(1, 1), Point(1, 2))

#perpendicular_segment(point)

Description

Create a perpendicular line segment from point to this line. The enpoints of the segment are point and the closest point in the line containing self. (If self is not a line, the point might not be in self.)

Signature

Parameters:
    point - EasyGeometry::D2::Point or Array of Numeric(coordinates)
    
Returns:
    Segment or Point (if `point` is on this linear entity.)
    
Errors:
    raise TypeError if point is not Point or valid Array

Example

l1 = EasyGeometry::D2::Line.new([0, 0], [1, 0])

l1.perpendicular_segment([0, 0])  # Point(0, 0)
l1.perpendicular_segment([1, 1])  # Segment(Point(1, 1), Point(1, 0))

#slope

Description

The slope of this linear entity, or infinity if vertical.

Signature

Parameters:
    
Returns:
    Numeric or BigDecimal('Infinity')
    
Errors:

Example

l1 = EasyGeometry::D2::Line.new([0, 0], [1, 1])

l1.slope  # 1

#span_test(point)

Description

Test whether the point lies in the positive span of self. A point x is 'in front' of a point y if x.dot(y) >= 0.

Returns:

• -1 if other is behind self.p1

• 0 if other is self.p1

• 1 if other is in front of self.p1.

Signature

Parameters:
    point - EasyGeometry::D2::Point or Array of Numeric(coordinates)
    
Returns:
    Numeric
    
Errors:
    raise TypeError if point is not Point or valid Array

Example

l1 = EasyGeometry::D2::Line.new([0, 0], [1, 1])

l1.span_test([0, 0])  # 0
l1.span_test([1, 1])  # 1