add square:divide() function

1 files changed, 37 insertions, 0 deletions

diff --git a/city/geometry-test.lua b/city/geometry-test.lua
index f85bec0..74ddb3a 100644
--- a/city/geometry-test.lua
+++ b/city/geometry-test.lua
@@ -93,3 +93,40 @@ test(
       end
    end
 )
+
+test(
+   'subdivide a square',
+   function()
+      local center = geom.point(2, 2)
+      local square = geom.square(center, 4)
+
+      local children = square:divide()
+      assert(
+	 #children == 4,
+	 string.format(
+	    'incorrect number of children: %d',
+	    #children
+	 )
+      )
+
+      local aa = children[1]
+      assert(aa.center.x == 1)
+      assert(aa.center.y == 1)
+      assert(aa.span == 2)
+
+      local ba = children[2]
+      assert(ba.center.x == 3)
+      assert(ba.center.y == 1)
+      assert(ba.span == 2)
+
+      local ab = children[3]
+      assert(ab.center.x == 1)
+      assert(ab.center.y == 3)
+      assert(ab.span == 2)
+
+      local bb = children[4]
+      assert(bb.center.x == 3)
+      assert(bb.center.y == 3)
+      assert(bb.span == 2)
+   end
+)