port boolean_clockwise

lib/turf/boolean_clockwise.rb

@@ -1,8 +1,26 @@
 # frozen_string_literal: true
 
-# :nodoc:
+# Takes a ring and returns true or false whether or not the ring is clockwise or counter-clockwise.
+#
+# @param [Array<Array<Number>>] line to be evaluated
+# @return [Boolean] true/false
+# @example
+#   clockwise_ring = [[0, 0], [1, 1], [1, 0], [0, 0]]
+#   counter_clockwise_ring = [[0, 0], [1, 0], [1, 1], [0, 0]]
+#
+#   boolean_clockwise(clockwise_ring)
+#   # => true
+#   boolean_clockwise(counter_clockwise_ring)
+#   # => false
 module Turf
-  def boolean_clockwise(*args)
-    raise NotImplementedError
+  def boolean_clockwise(line)
+    ring = get_coords(line)
+    sum = 0
+
+    ring.each_cons(2) do |prev, cur|
+      sum += (cur[0] - prev[0]) * (cur[1] + prev[1])
+    end
+
+    sum > 0
   end
 end

lib/turf/length.rb

@@ -18,7 +18,7 @@ def length(geojson, options = {})
     segment_reduce(geojson, 0) do |previous_value, segment|
       previous_value ||= 0
       coords = segment.dig(:geometry, :coordinates)
-      previous_value + Turf.distance(coords[0], coords[1], options)
+      previous_value + distance(coords[0], coords[1], options)
     end
   end
 end

lib/turf/meta.rb

@@ -419,7 +419,7 @@ def segment_each(geojson)
           next
         end
 
-        segment = Turf.line_string([previous_coords, current_coord], feature[:properties])
+        segment = line_string([previous_coords, current_coord], feature[:properties])
         next unless yield(segment, feature_index, multi_feature_index, geometry_index, segment_index)
 
         segment_index += 1

test/turf_boolean_clockwise_test.rb

@@ -4,11 +4,59 @@
 
 class TurfBooleanClockwiseTest < Minitest::Test
   def test_is_clockwise_fixtures
+    # True Fixtures
+    Dir.glob(File.join(__dir__, "boolean_clockwise/true/*.geojson")).each do |filepath|
+      name = File.basename(filepath, ".geojson")
+      geojson = JSON.parse(File.read(filepath))
+      feature = geojson["features"].first
+      assert(Turf.boolean_clockwise(feature), "[true] #{name}")
+    end
+
+    # False Fixtures
+    Dir.glob(File.join(__dir__, "boolean_clockwise/false/*.geojson")).each do |filepath|
+      name = File.basename(filepath, ".geojson")
+      geojson = JSON.parse(File.read(filepath))
+      feature = geojson["features"].first
+      refute(Turf.boolean_clockwise(feature), "[false] #{name}")
+    end
   end
 
   def test_is_clockwise
+    cw_array = [
+      [0, 0],
+      [1, 1],
+      [1, 0],
+      [0, 0],
+    ]
+    ccw_array = [
+      [0, 0],
+      [1, 0],
+      [1, 1],
+      [0, 0],
+    ]
+
+    assert_equal(true, Turf.boolean_clockwise(cw_array), "[true] clockwise array input")
+    assert_equal(false, Turf.boolean_clockwise(ccw_array), "[false] counter-clockwise array input")
   end
 
   def test_is_clockwise_geometry_types
+    line = Turf.line_string([
+      [0, 0],
+      [1, 1],
+      [1, 0],
+      [0, 0],
+    ])
+
+    assert_equal(true, Turf.boolean_clockwise(line), "Feature")
+    assert_equal(true, Turf.boolean_clockwise(line[:geometry]), "Geometry Object")
   end
+
+  # Uncomment the following test if exception handling for unsupported geometry types is implemented
+  #
+  # def test_is_clockwise_throws
+  #   pt = Turf.point([-10, -33])
+  #   assert_raises do
+  #     Turf.boolean_clockwise(pt)
+  #   end
+  # end
 end