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# Various mathematical calculations extracted from the PDF::Writer for Ruby gem.

# - http://rubyforge.org/projects/ruby-pdf

# - Copyright 2003 - 2005 Austin Ziegler.

# - Licensed under a MIT-style licence.

#

module RFPDF::Math

  PI2   = ::Math::PI * 2.0

  # One degree of arc measured in terms of radians.

  DR  = PI2 / 360.0

  # One radian of arc, measured in terms of degrees.

  RD  = 360 / PI2

  # One degree of arc, measured in terms of gradians.

  DG  = 400 / 360.0

  # One gradian of arc, measured in terms of degrees.

  GD  = 360 / 400.0

  # One radian of arc, measured in terms of gradians.

  RG  = 400 / PI2

  # One gradian of arc, measured in terms of radians.

  GR  = PI2 / 400.0

  # Truncate the remainder.

  def remt(num, den)

    num - den * (num / den.to_f).to_i

  end

  # Wrap radian values within the range of radians (0..PI2).

  def rad2rad(rad)

    remt(rad, PI2)

  end

  # Wrap degree values within the range of degrees (0..360).

  def deg2deg(deg)

    remt(deg, 360)

  end

  # Wrap gradian values within the range of gradians (0..400).

  def grad2grad(grad)

    remt(grad, 400)

  end

  # Convert degrees to radians. The value will be constrained to the

  # range of radians (0..PI2) unless +wrap+ is false.

  def deg2rad(deg, wrap = true)

    rad = DR * deg

    rad = rad2rad(rad) if wrap

    rad

  end

  # Convert degrees to gradians. The value will be constrained to the

  # range of gradians (0..400) unless +wrap+ is false.

  def deg2grad(deg, wrap = true)

    grad = DG * deg

    grad = grad2grad(grad) if wrap

    grad

  end

  # Convert radians to degrees. The value will be constrained to the

  # range of degrees (0..360) unless +wrap+ is false.

  def rad2deg(rad, wrap = true)

    deg = RD * rad

    deg = deg2deg(deg) if wrap

    deg

  end

  # Convert radians to gradians. The value will be constrained to the

  # range of gradians (0..400) unless +wrap+ is false.

  def rad2grad(rad, wrap = true)

    grad = RG * rad

    grad = grad2grad(grad) if wrap

    grad

  end

  # Convert gradians to degrees. The value will be constrained to the

  # range of degrees (0..360) unless +wrap+ is false.

  def grad2deg(grad, wrap = true)

    deg = GD * grad

    deg = deg2deg(deg) if wrap

    deg

  end

  # Convert gradians to radians. The value will be constrained to the

  # range of radians (0..PI2) unless +wrap+ is false.

  def grad2rad(grad, wrap = true)

    rad = GR * grad

    rad = rad2rad(rad) if wrap

    rad

  end

end