diff --git a/sys/apis/point.lua b/sys/apis/point.lua
index 1d83eab..f36933b 100644
--- a/sys/apis/point.lua
+++ b/sys/apis/point.lua
@@ -189,6 +189,8 @@ function Point.closest(reference, pts)
 end
 
 function Point.eachClosest(spt, ipts, fn)
+	if not ipts then error('Point.eachClosest: invalid points', 2) end
+
 	local pts = Util.shallowCopy(ipts)
 	while #pts > 0 do
 		local pt = Point.closest(spt, pts)
@@ -200,6 +202,17 @@ function Point.eachClosest(spt, ipts, fn)
 	end
 end
 
+function Point.iterateClosest(spt, ipts)
+	local pts = Util.shallowCopy(ipts)
+	return function()
+		local pt = Point.closest(spt, pts)
+		if pt then
+			Util.removeByValue(pts, pt)
+			return pt
+		end
+	end
+end
+
 function Point.adjacentPoints(pt)
 	local pts = { }