Chris@909: # Various mathematical calculations extracted from the PDF::Writer for Ruby gem.
Chris@909: # - http://rubyforge.org/projects/ruby-pdf
Chris@909: # - Copyright 2003 - 2005 Austin Ziegler.
Chris@909: # - Licensed under a MIT-style licence.
Chris@909: #
Chris@909: 
Chris@909: module RFPDF::Math
Chris@909:   PI2   = ::Math::PI * 2.0
Chris@909: 
Chris@909:   # One degree of arc measured in terms of radians.
Chris@909:   DR  = PI2 / 360.0
Chris@909:   # One radian of arc, measured in terms of degrees.
Chris@909:   RD  = 360 / PI2
Chris@909:   # One degree of arc, measured in terms of gradians.
Chris@909:   DG  = 400 / 360.0
Chris@909:   # One gradian of arc, measured in terms of degrees.
Chris@909:   GD  = 360 / 400.0
Chris@909:   # One radian of arc, measured in terms of gradians.
Chris@909:   RG  = 400 / PI2
Chris@909:   # One gradian of arc, measured in terms of radians.
Chris@909:   GR  = PI2 / 400.0
Chris@909: 
Chris@909:   # Truncate the remainder.
Chris@909:   def remt(num, den)
Chris@909:     num - den * (num / den.to_f).to_i
Chris@909:   end
Chris@909: 
Chris@909:   # Wrap radian values within the range of radians (0..PI2).
Chris@909:   def rad2rad(rad)
Chris@909:     remt(rad, PI2)
Chris@909:   end
Chris@909: 
Chris@909:   # Wrap degree values within the range of degrees (0..360).
Chris@909:   def deg2deg(deg)
Chris@909:     remt(deg, 360)
Chris@909:   end
Chris@909: 
Chris@909:   # Wrap gradian values within the range of gradians (0..400).
Chris@909:   def grad2grad(grad)
Chris@909:     remt(grad, 400)
Chris@909:   end
Chris@909: 
Chris@909:   # Convert degrees to radians. The value will be constrained to the
Chris@909:   # range of radians (0..PI2) unless +wrap+ is false.
Chris@909:   def deg2rad(deg, wrap = true)
Chris@909:     rad = DR * deg
Chris@909:     rad = rad2rad(rad) if wrap
Chris@909:     rad
Chris@909:   end
Chris@909: 
Chris@909:   # Convert degrees to gradians. The value will be constrained to the
Chris@909:   # range of gradians (0..400) unless +wrap+ is false.
Chris@909:   def deg2grad(deg, wrap = true)
Chris@909:     grad = DG * deg
Chris@909:     grad = grad2grad(grad) if wrap
Chris@909:     grad
Chris@909:   end
Chris@909: 
Chris@909:   # Convert radians to degrees. The value will be constrained to the
Chris@909:   # range of degrees (0..360) unless +wrap+ is false.
Chris@909:   def rad2deg(rad, wrap = true)
Chris@909:     deg = RD * rad
Chris@909:     deg = deg2deg(deg) if wrap
Chris@909:     deg
Chris@909:   end
Chris@909: 
Chris@909:   # Convert radians to gradians. The value will be constrained to the
Chris@909:   # range of gradians (0..400) unless +wrap+ is false.
Chris@909:   def rad2grad(rad, wrap = true)
Chris@909:     grad = RG * rad
Chris@909:     grad = grad2grad(grad) if wrap
Chris@909:     grad
Chris@909:   end
Chris@909: 
Chris@909:   # Convert gradians to degrees. The value will be constrained to the
Chris@909:   # range of degrees (0..360) unless +wrap+ is false.
Chris@909:   def grad2deg(grad, wrap = true)
Chris@909:     deg = GD * grad
Chris@909:     deg = deg2deg(deg) if wrap
Chris@909:     deg
Chris@909:   end
Chris@909: 
Chris@909:   # Convert gradians to radians. The value will be constrained to the
Chris@909:   # range of radians (0..PI2) unless +wrap+ is false.
Chris@909:   def grad2rad(grad, wrap = true)
Chris@909:     rad = GR * grad
Chris@909:     rad = rad2rad(rad) if wrap
Chris@909:     rad
Chris@909:   end
Chris@909: end