Class: Geo3d::Triangle

Inherits:
Object
  • Object
show all
Defined in:
lib/geo3d/triangle.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(*args) ⇒ Triangle

Returns a new instance of Triangle.


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# File 'lib/geo3d/triangle.rb', line 9

def initialize *args
  @a = args.size > 0 ? args[0] : Vector.new
  @b = args.size > 1 ? args[1] : Vector.new
  @c = args.size > 2 ? args[2] : Vector.new
end

Instance Attribute Details

#a ⇒ Object

Returns the value of attribute a.


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# File 'lib/geo3d/triangle.rb', line 3

def a
  @a
end

#b ⇒ Object

Returns the value of attribute b.


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# File 'lib/geo3d/triangle.rb', line 3

def b
  @b
end

#c ⇒ Object

Returns the value of attribute c.


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# File 'lib/geo3d/triangle.rb', line 3

def c
  @c
end

Instance Method Details

#clockwise?(reference_normal = Vector.new(0,0,-1)) ⇒ Boolean Also known as: cw?

Returns:

  • (Boolean) 

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# File 'lib/geo3d/triangle.rb', line 38

def clockwise? reference_normal = Vector.new(0,0,-1)
  signed_area( reference_normal ) > 0
end

#counter_clockwise?(reference_normal = Vector.new(0,0,-1)) ⇒ Boolean Also known as: ccw?

Returns:

  • (Boolean) 

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# File 'lib/geo3d/triangle.rb', line 42

def counter_clockwise? reference_normal = Vector.new(0,0,-1)
  signed_area( reference_normal ) < 0
end

#flip ⇒ Object 


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# File 'lib/geo3d/triangle.rb', line 19

def flip
  f = clone
  f.flip!
  f
end

#flip! ⇒ Object 


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# File 'lib/geo3d/triangle.rb', line 15

def flip!
  @b, @c = @c, @b
end

#normal ⇒ Object 


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# File 'lib/geo3d/triangle.rb', line 25

def normal
  (b - a).cross(c - a).normalize
end

#points ⇒ Object 


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# File 'lib/geo3d/triangle.rb', line 5

def points
  [a, b, c]
end

#signed_area(reference_normal = Vector.new(0,0,-1)) ⇒ Object 


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# File 'lib/geo3d/triangle.rb', line 29

def signed_area reference_normal = Vector.new(0,0,-1)
  sum = Vector.new 0, 0, 0, 0
  points.each_with_index do |current_point, i|
    next_point = points[(i == points.size - 1) ? 0 : i+1]
    sum += current_point.cross next_point
  end
  reference_normal.dot(sum) / 2.0
end