1 files changed, 10 insertions, 4 deletions
diff --git a/builtin/common/vector.lua b/builtin/common/vector.lua
index 581d014e0..a08472e32 100644
--- a/builtin/common/vector.lua
+++ b/builtin/common/vector.lua
@@ -6,10 +6,8 @@ Note: The vector.*-functions must be able to accept old vectors that had no meta
 -- localize functions
 local setmetatable = setmetatable
 
-vector = {}
-
-local metatable = {}
-vector.metatable = metatable
+-- vector.metatable is set by C++.
+local metatable = vector.metatable
 
 local xyz = {"x", "y", "z"}
 
@@ -112,6 +110,14 @@ function vector.apply(v, func)
 	)
 end
 
+function vector.combine(a, b, func)
+	return fast_new(
+		func(a.x, b.x),
+		func(a.y, b.y),
+		func(a.z, b.z)
+	)
+end
+
 function vector.distance(a, b)
 	local x = a.x - b.x
 	local y = a.y - b.y