Class: Geometry::Transformation

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

Overview

Transformation represents a relationship between two coordinate frames

To create a pure translation relationship:

translate = Geometry::Transformation.new(:translate => Point[4, 2])

To create a transformation with an origin and an X-axis aligned with the parent coordinate system’s Y-axis (the Y and Z axes will be chosen arbitrarily):

translate = Geometry::Transformation.new(:origin => [4, 2], :x => [0,1,0])

To create a transformation with an origin, an X-axis aligned with the parent coordinate system’s Y-axis, and a Y-axis aligned with the parent coordinate system’s X-axis:

translate = Geometry::Transformation.new(:origin => [4, 2], :x => [0,1,0], :y => [1,0,0])

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(*args) ⇒ Transformation

Returns a new instance of Transformation.

Parameters:

  • options (Hash) —

    a customizable set of options



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# File 'lib/geometry/transformation.rb', line 46

def initialize(*args)
    options, args = args.partition {|a| a.is_a? Hash}
    translate, rotate, scale = args
    options = options.reduce({}, :merge)

    @dimensions = options[:dimensions] || nil

    @rotation = options[:rotate] || rotate || Geometry::Rotation.new(options)
    @scale = options[:scale] || scale

    case options.count {|k,v| [:move, :origin, :translate].include? k }
	when 0
	    @translation = translate
	when 1
	    @translation = (options[:translate] ||= options.delete(:move) || options.delete(:origin))
	else
	    raise ArgumentError, "Too many translation parameters in #{options}"
    end

    @translation = Point[*@translation]
    if @translation
	@translation = nil if @translation.all? {|v| v == 0}
	raise ArgumentError, ":translate must be a Point or a Vector" if @translation and not @translation.is_a?(Vector)
    end

    if @dimensions
	biggest = [@translation, @scale].select {|a| a}.map {|a| a.size}.max

	if biggest and (biggest != 0) and (((biggest != @dimensions)) or (@rotation and (@rotation.dimensions != biggest)))
	    raise ArgumentError, "Dimensionality mismatch"
	end
    end
end

Instance Attribute Details

#dimensions ⇒ Object (readonly)

Returns the value of attribute dimensions.



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# File 'lib/geometry/transformation.rb', line 24

def dimensions
  @dimensions
end

#rotation ⇒ Object (readonly)

Returns the value of attribute rotation.



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# File 'lib/geometry/transformation.rb', line 25

def rotation
  @rotation
end

#scale ⇒ Object (readonly)

Returns the value of attribute scale.



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# File 'lib/geometry/transformation.rb', line 26

def scale
  @scale
end

#translation ⇒ Object (readonly)

Returns the value of attribute translation.



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# File 'lib/geometry/transformation.rb', line 27

def translation
  @translation
end

#x_axis ⇒ Object (readonly)

Returns the value of attribute x_axis.



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# File 'lib/geometry/transformation.rb', line 29

def x_axis
  @x_axis
end

#y_axis ⇒ Object (readonly)

Returns the value of attribute y_axis.



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# File 'lib/geometry/transformation.rb', line 29

def y_axis
  @y_axis
end

#z_axis ⇒ Object (readonly)

Returns the value of attribute z_axis.



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# File 'lib/geometry/transformation.rb', line 29

def z_axis
  @z_axis
end

Instance Method Details

#+(other) ⇒ Object

Compose the current Geometry::Transformation with another one



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# File 'lib/geometry/transformation.rb', line 91

def +(other)
    if other.is_a?(Array) or other.is_a?(Vector)
	if @translation
	    Transformation.new(@translation+other, @rotation, @scale)
	else
	    Transformation.new(other, @rotation, @scale)
	end
    end
end

#-(other) ⇒ Object 



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

def -(other)
    if other.is_a?(Array) or other.is_a?(Vector)
	if @translation
	    Transformation.new(@translation-other, @rotation, @scale)
	else
	    Transformation.new(other.map {|e| -e}, @rotation, @scale)
	end
    end
end

#eql?(other) ⇒ Boolean Also known as: ==

Returns:

  • (Boolean) 


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# File 'lib/geometry/transformation.rb', line 85

def eql?(other)
    (self.rotation.eql? other.rotation) && (self.scale.eql? other.scale) && (self.translation.eql? other.translation)
end

#identity? ⇒ Boolean

Returns true if the Geometry::Transformation is the identity transformation

Returns:

  • (Boolean) 


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# File 'lib/geometry/transformation.rb', line 81

def identity?
    @rotation.identity? && !(@scale || @translation)
end

#transform(point) ⇒ Point

Transform and return a new Point

Parameters:

Returns:



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# File 'lib/geometry/transformation.rb', line 114

def transform(point)
    @translation + point
end