Class: Rubyvis::SvgScene::PathBasis

Inherits:
Object
  • Object
show all
Defined in:
lib/rubyvis/scene/svg_curve.rb

Overview

:nodoc:

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(p0, p1, p2, p3) ⇒ PathBasis

Returns a new instance of PathBasis.



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# File 'lib/rubyvis/scene/svg_curve.rb', line 3

def initialize(p0,p1,p2,p3)
  @p0=p0
  @p1=p1
  @p2=p2
  @p3=p3
end

Instance Attribute Details

#p0 ⇒ Object

Returns the value of attribute p0.



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# File 'lib/rubyvis/scene/svg_curve.rb', line 9

def p0
  @p0
end

#p1 ⇒ Object

Returns the value of attribute p1.



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# File 'lib/rubyvis/scene/svg_curve.rb', line 9

def p1
  @p1
end

#p2 ⇒ Object

Returns the value of attribute p2.



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# File 'lib/rubyvis/scene/svg_curve.rb', line 9

def p2
  @p2
end

#p3 ⇒ Object

Returns the value of attribute p3.



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# File 'lib/rubyvis/scene/svg_curve.rb', line 9

def p3
  @p3
end

Instance Method Details

#basis ⇒ Object

Matrix to transform basis (b-spline) control points to bezier control points. Derived from FvD 11.2.8.



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# File 'lib/rubyvis/scene/svg_curve.rb', line 16

def basis
  [
  [ 1/6.0, 2/3.0, 1/6.0,   0 ],
  [   0, 2/3.0, 1/3.0,   0 ],
  [   0, 1/3.0, 2/3.0,   0 ],
  [   0, 1/6.0, 2/3.0, 1/6.0 ]
  ]
end

#convert ⇒ Object 



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# File 'lib/rubyvis/scene/svg_curve.rb', line 33

def convert
  b1 = weight(basis[1])
  b2 = weight(basis[2])
  b3 = weight(basis[3])
  "C#{b1.x},#{b1.y},#{b2.x},#{b2.y },#{b3.x},#{b3.y}"
end

#segment ⇒ Object 



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# File 'lib/rubyvis/scene/svg_curve.rb', line 42

def segment
  b0 = weight(basis[0])
  b1 = weight(basis[1])
  b2 = weight(basis[2])
  b3 = weight(basis[3])
  "M#{b0.x},#{b0.y}C#{b1.x},#{b1.y},#{b2.x},#{b2.y},#{b3.x},#{b3.y}"
end

#to_s ⇒ Object 



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# File 'lib/rubyvis/scene/svg_curve.rb', line 39

def to_s
  convert
end

#weight(w) ⇒ Object

Returns the point that is the weighted sum of the specified control points, using the specified weights. This method requires that there are four weights and four control points.



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# File 'lib/rubyvis/scene/svg_curve.rb', line 27

def weight(w)
  OpenStruct.new({
  :x=> w[0] * p0.left + w[1] * p1.left + w[2] * p2.left + w[3] * p3.left,
  :y=> w[0] * p0.top  + w[1] * p1.top  + w[2] * p2.top  + w[3] * p3.top
  })
end