Merge pull request #5 from vhf/triangular-bug

Fix for triangular bounding boxes

lib/ddrt/dynamic_rtree_impl/utils.ex

@@ -89,15 +89,19 @@ defmodule DDRT.DynamicRtreeImpl.Utils do
   end
 
   # Return the area of a bounding box
-  def area([{a, b}, {c, d}]) when (b - a) * (d - c) != 0 do
-    (b - a) * (d - c)
-  end
-
-  def area([{_a, _b}, {_c, _d}]) do
-    -1
+  def area([{a, b}, {c, d}]) do
+    ab = b - a
+    cd = d - c
+
+    cond do
+      ab == 0 and cd != 0 -> cd
+      ab != 0 and cd == 0 -> ab
+      ab != 0 and cd != 0 -> ab * cd
+      ab == 0 and cd == 0 -> -1
+    end
   end
 
-  # Return de the middle bounding box value
+  # Return the middle bounding box value
   def middle_value([{a, b}, {c, d}]) do
     (a + b + c + d) / 2
   end

test/drtree_test.exs

@@ -90,6 +90,20 @@ defmodule DynamicRtreeTest do
       assert root_box == [{-50, 36}, {-10, 41}]
     end
 
+    test "MerkleMap inserts a triangular bounding box without crash" do
+      DynamicRtree.new(type: MerkleMap)
+
+      {:ok, t} = DynamicRtree.insert({1, [{9, 9}, {9, 9.1}]})
+
+      assert t == DynamicRtree.tree()
+
+      root = t |> MerkleMap.get(:root)
+      {ch, _root_ptr, root_box} = t |> MerkleMap.get(root)
+      assert t |> Enum.to_list() |> length == t |> Enum.uniq() |> length
+      assert length(ch) == 1
+      assert root_box == [{9, 9}, {9, 9.1}]
+    end
+
     test "Map delete leaf keeps tree consistency" do
       DynamicRtree.new()
 
@@ -115,7 +129,7 @@ defmodule DynamicRtreeTest do
       refute delete_id in (t[old_parent] |> elem(0))
 
       {:ok, same_t} = DynamicRtree.delete(delete_id)
-      assert t = same_t
+      assert ^t = same_t
 
       {:ok, t} = DynamicRtree.delete(1..100 |> Enum.map(fn x -> x end))
       root = t[:root]
@@ -154,7 +168,7 @@ defmodule DynamicRtreeTest do
       refute delete_id in (t |> MerkleMap.get(old_parent) |> elem(0))
 
       {:ok, same_t} = DynamicRtree.delete(delete_id)
-      assert t = same_t
+      assert ^t = same_t
 
       {:ok, t} = DynamicRtree.delete(1..100 |> Enum.map(fn x -> x end))
       root = t |> MerkleMap.get(:root)