Avoid full random

lib/algorithms/point_in_polygon.rb

@@ -1,7 +1,9 @@
 module Geometry
   class PointInPolygon < Struct.new(:point, :polygon)
     extend Memoist
-
+
+    MAX_SEED = 1000000.0
+
     def inside?
       point_location == :inside
     end
@@ -36,23 +38,25 @@ def point_on_edge?
 
     def choose_good_ray
       ray = random_ray
-      while ! good_ray?(ray) do
-        ray = random_ray
+      seed = 1.0
+      while (seed < MAX_SEED) && (! good_ray?(ray)) do
+        seed += 1.0
+        ray = random_ray(seed)
       end
       ray
     end
 
     def good_ray?(ray)
       edges.none? { |edge| !edge.length.zero? && edge.parallel_to?(ray) } && vertices.none? { |vertex| ray.contains_point?(vertex) }
     end
-    
+
     def intersection_count(ray)
       edges.select { |edge| edge.intersects_with?(ray) }.size
     end
-    
-    def random_ray
-      random_direction = rand * (2 * Math::PI)
-      
+
+    def random_ray(seed = 1.0)
+      random_direction = (Math::PI / 2.0 * seed + Math::PI / (seed + 1.0)) % (Math::PI * 2.0)
+
       ray_endpoint = Point sufficient_ray_radius * Math.cos(random_direction), sufficient_ray_radius * Math.sin(random_direction)
       Segment point, ray_endpoint
     end

test/polygon/contains_point_test.rb

@@ -70,4 +70,21 @@ def test_nonconvex
       assert ! nonconvex_polygon.contains?(outer_point)
     end
   end
+
+  def test_closed_polygon
+    coordinates_raw = "114.146011,22.284090 114.145050,22.282860 114.146240,22.279619 114.151176,22.277014 114.151833,22.276251 114.151443,22.275000 114.151550,22.273470 114.153198,22.272249 114.156143,22.272970 114.161690,22.271900 114.162521,22.274820 114.162697,22.276211 114.160957,22.275850 114.159927,22.276190 114.158340,22.276270 114.157082,22.276661 114.155312,22.276310 114.153732,22.278000 114.154312,22.278870 114.153992,22.279900 114.152321,22.280890 114.150261,22.282721 114.146011,22.284090"
+    coordinates = coordinates_raw.split(/\s+/).map do |raw_coor|
+      # latitude and longitude are reversed since they are from KML
+      # most important point : the last point is the same as the first one
+      raw_coor.split(',').map(&:to_f).reverse
+    end
+
+    vertices = coordinates.map do |coordinate_array|
+      Point.new_by_array(coordinate_array)
+    end
+    rectangle = Polygon.new(vertices)
+
+    inner = Point(22.2817, 114.14932)
+    assert rectangle.contains?(inner)
+  end
 end