ioquatix/geospatial

# Copyright, 2018, by Samuel G. D. Williams. <http://www.codeotaku.com>
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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# THE SOFTWARE.

require_relative 'box'

module Geospatial
    class Tiles
        # Radians to degrees multiplier
        R2D = (180.0 / Math::PI)
        D2R = (Math::PI / 180.0)
        
        def initialize(box, zoom = 5)
            @box = box
            @zoom = zoom
        end
        
        attr :box
        attr :zoom
        
        def map(longitude, latitude, zoom = @zoom)
            n = 2 ** zoom
            
            x = n * ((longitude + 180.0) / 360.0)
            y = n * (1.0 - (Math::log(Math::tan(latitude * D2R) + (1.0 / Math::cos(latitude * D2R))) / Math::PI)) / 2.0
            
            return x, y
        end
        
        def unmap(x, y, zoom = @zoom)
            n = 2 ** zoom
            longitude = x / n * 360.0 - 180.0
            latitude = Math::arctan(Math::sinh(Math::PI * (1.0 - 2.0 * y / n))) * R2D
            
            return longitude, latitude
        end
        
        def each(zoom = @zoom)
            return to_enum(:each, zoom) unless block_given?
            
            min = map(*@box.min, zoom)
            max = map(*@box.max, zoom)
            
            (min[0].floor...max[0].ceil).each do |x|
                # The y axis is reversed... (i.e. the origin is in the top left)
                (max[1].floor...min[1].ceil).each do |y|
                    yield zoom, x, y
                end
            end
        end
    end
end