launch cactus

1 files changed, 4 insertions, 3 deletions

diff --git a/cactus.lua b/cactus.lua
index b5624d9..7a43da8 100644
--- a/cactus.lua
+++ b/cactus.lua
@@ -36,10 +36,11 @@ end
 local function rotatev(v,nq)
 	-- rotates v by n quarters
 	nq = nq%4
-	for i = 1,nq do
-		v.x,v.z = -v.z,v.x
+	if nq == 0     then return vector.new( v.x,  v.y,  v.z)
+	elseif nq == 1 then return vector.new(-v.z,  v.y,  v.x)
+	elseif nq == 2 then return vector.new(-v.x,  v.y, -v.z)
+	elseif nq == 3 then return vector.new( v.z,  v.y, -v.x)
 	end
-	return v
 end
 
 local v = vector.new(1,0,0)