Class: Geometry::ThreePointArc

Inherits:
Arc
  • Object
show all
Defined in:
lib/geometry/arc.rb

Instance Attribute Summary collapse

Attributes collapse

Instance Method Summary collapse

Methods inherited from Arc

new

Methods included from ClusterFactory

included

Constructor Details

#initialize(center_point, start_point, end_point) ⇒ ThreePointArc

Contruct a new Arc given center, start and end Points

Always assumes that the {Arc} is counter-clockwise. Reverse the order
of the start and end points to get an {Arc} that goes around the other way.

Parameters:

Raises:

  • (ArgumentError) 


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# File 'lib/geometry/arc.rb', line 88

def initialize(center_point, start_point, end_point)
    @center, @start, @end = [center_point, start_point, end_point].map {|p| Point[p]}
    raise ArgumentError unless [@center, @start, @end].all? {|p| p.is_a?(Point)}
end

Instance Attribute Details

#center ⇒ Object (readonly)

Returns the value of attribute center.



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# File 'lib/geometry/arc.rb', line 78

def center
  @center
end

#end ⇒ Object (readonly) Also known as: last

Returns the value of attribute end.



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# File 'lib/geometry/arc.rb', line 79

def end
  @end
end

#start ⇒ Object (readonly) Also known as: first

Returns the value of attribute start.



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# File 'lib/geometry/arc.rb', line 79

def start
  @start
end

Instance Method Details

#==(other) ⇒ Object 



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# File 'lib/geometry/arc.rb', line 101

def ==(other)
    if other.is_a?(ThreePointArc)
	(self.center == other.center) && (self.end == other.end) && (self.start == other.start)
    else
	super other
    end
end

#end_angle ⇒ Object 



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# File 'lib/geometry/arc.rb', line 149

def end_angle
    a = (self.end - self.center)
    Math.atan2(a.y, a.x)
end

#max ⇒ Point

Returns The upper-right corner of the bounding rectangle that encloses the Path.

Returns:

  • (Point) —

    The upper-right corner of the bounding rectangle that encloses the Path



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# File 'lib/geometry/arc.rb', line 112

def max
    minmax.last
end

#min ⇒ Point

Returns The lower-left corner of the bounding rectangle that encloses the Path.

Returns:

  • (Point) —

    The lower-left corner of the bounding rectangle that encloses the Path



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# File 'lib/geometry/arc.rb', line 117

def min
    minmax.first
end

#minmax ⇒ Array<Point>

Returns The lower-left and upper-right corners of the enclosing bounding rectangle.

Returns:

  • (Array<Point>) —

    The lower-left and upper-right corners of the enclosing bounding rectangle



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# File 'lib/geometry/arc.rb', line 122

def minmax
    a = [self.start, self.end]
    quadrants = a.map(&:quadrant)

    # If the Arc spans more than one quadrant, then it must cross at
    #  least one axis. Each axis-crossing is a potential extrema.
    if quadrants.first != quadrants.last
	range = (quadrants.first...quadrants.last)
	# If the Arc crosses the X axis...
	if quadrants.first > quadrants.last
	    range = (quadrants.first..4).to_a + (1...quadrants.last).to_a
	end

	a = range.map do |q|
	    case q
		when 1 then self.center + Point[0,radius]
		when 2 then self.center + Point[-radius, 0]
		when 3 then self.center + Point[0,-radius]
		when 4 then self.center + Point[radius,0]
	    end
	end.push(*a)
	a.reduce([a.first, a.first]) {|memo, e| [memo.first.min(e), memo.last.max(e)] }
    else
	[a.first.min(a.last), a.first.max(a.last)]
    end
end

#radius ⇒ Object 



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# File 'lib/geometry/arc.rb', line 154

def radius
    (self.start - self.center).magnitude
end

#start_angle ⇒ Object 



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# File 'lib/geometry/arc.rb', line 158

def start_angle
    a = (self.start - self.center)
    Math.atan2(a.y, a.x)
end