Class: EasyGeometry::D2::Line

Inherits:
LinearEntity show all
Defined in:
lib/easy_geometry/d2/line.rb

Overview

An infinite line in 2-dimensional Euclidean space.

Instance Attribute Summary

Attributes inherited from LinearEntity

#p1, #p2

Instance Method Summary collapse

Methods inherited from LinearEntity

#angle_between, #direction, #initialize, #intersection, #parallel_line, #parallel_to?, #perpendicular_line, #perpendicular_segment, #perpendicular_to?, #projection_point, #similar_to?, #slope, #span_test

Constructor Details

This class inherits a constructor from EasyGeometry::D2::LinearEntity

Instance Method Details

#==(other) ⇒ Object

Returns True if self and other are the same mathematical entities.

Parameters:

GeometryEntity



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# File 'lib/easy_geometry/d2/line.rb', line 47

def ==(other)
  return false unless other.is_a?(Line)
  Point.is_collinear?(self.p1, other.p1, self.p2, other.p2)
end

#a ⇒ Object

The coefficients ‘a’ for ax + by + c = 0.



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# File 'lib/easy_geometry/d2/line.rb', line 64

def a
  @a ||= self.p1.y - self.p2.y
end

#b ⇒ Object

The coefficients ‘b’ for ax + by + c = 0.



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# File 'lib/easy_geometry/d2/line.rb', line 69

def b
  @b ||= self.p2.x - self.p1.x
end

#c ⇒ Object

The coefficients ‘c’ for ax + by + c = 0.



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# File 'lib/easy_geometry/d2/line.rb', line 74

def c
  @c ||= self.p1.x * self.p2.y - self.p1.y * self.p2.x
end

#contains?(other) ⇒ Boolean

Is other GeometryEntity contained in this Line?

Parameters:

GeometryEntity or Array of Numeric(coordinates)

Returns:

true if `other` is on this Line.
false otherwise.

Returns:

  • (Boolean) 


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# File 'lib/easy_geometry/d2/line.rb', line 15

def contains?(other)
  other = Point.new(other[0], other[1]) if other.is_a?(Array)
  
  if other.is_a?(Point)
    return Point.is_collinear?(other, self.p1, self.p2)    
  end

  if other.is_a?(LinearEntity)
    return Point.is_collinear?(other.p1, other.p2, self.p1, self.p2)
  end

  return false
end

#distance(other) ⇒ Object

Finds the shortest distance between a line and a point.

Parameters:

Point or Array of Numeric(coordinates)

Raises:

  • (TypeError) 


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# File 'lib/easy_geometry/d2/line.rb', line 34

def distance(other)
  other = Point.new(other[0], other[1]) if other.is_a?(Array)
  raise TypeError, "Distance between Line and #{ other.class } is not defined" unless other.is_a?(Point)

  return 0 if self.contains?(other)
  self.perpendicular_segment(other).length
end

#equation ⇒ Object

The equation of the line: ax + by + c.



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# File 'lib/easy_geometry/d2/line.rb', line 53

def equation
  if p1.x == p2.x
    return "x - #{p1.x}"
  elsif p1.y == p2.y
    return "#{p2.y} - p1.y"
  end

  "#{a}*x + #{b}*y + #{c} = 0"
end