class Proj::PrimeMeridian
Public Class Methods
Returns a list of Prime Meridians that are built into Proj
. A more comprehensive list is stored in the Proj
database and can be queried via PjObject#create_from_database
# File lib/proj/prime_meridian.rb, line 5 def self.built_in pointer_to_array = FFI::Pointer.new(Api::PJ_PRIME_MERIDIANS, Api.proj_list_prime_meridians) result = Array.new 0.step do |i| prime_meridian_info = Api::PJ_PRIME_MERIDIANS.new(pointer_to_array[i]) break result if prime_meridian_info[:id].nil? result << prime_meridian_info end result end
Public Instance Methods
Returns the longitude of the prime meridian in its native unit
@see proj.org/development/reference/functions.html#c.proj_prime_meridian_get_parameters
@return [Float]
# File lib/proj/prime_meridian.rb, line 44 def longitude self.parameters[:longitude] end
Returns prime meridian parameters
@see proj.org/development/reference/functions.html#c.proj_prime_meridian_get_parameters
@return [Hash] Hash of ellipsoid parameters. Axes are in meters
# File lib/proj/prime_meridian.rb, line 21 def parameters @parameters ||= begin out_longitude = FFI::MemoryPointer.new(:double) out_unit_conv_factor = FFI::MemoryPointer.new(:double) out_unit_name = FFI::MemoryPointer.new(:string) result = Api.proj_prime_meridian_get_parameters(self.context, self, out_longitude, out_unit_conv_factor, out_unit_name) if result != 1 Error.check_object(self) end {longitude: out_longitude.read_double, unit_conv_factor: out_unit_conv_factor.read_double, unit_name: out_unit_name.read_pointer.read_string_to_null} end end
Returns the conversion factor of the prime meridian longitude unit to radians
@see proj.org/development/reference/functions.html#c.proj_prime_meridian_get_parameters
@return [Float]
# File lib/proj/prime_meridian.rb, line 53 def unit_conv_factor self.parameters[:unit_conv_factor] end
Returns the unit name
@see proj.org/development/reference/functions.html#c.proj_prime_meridian_get_parameters
@return [String ]
# File lib/proj/prime_meridian.rb, line 62 def unit_name self.parameters[:unit_name] end