diff --git a/init.lua b/init.lua
index 45ccfe2..eca3de2 100644
--- a/init.lua
+++ b/init.lua
@@ -41,11 +41,12 @@ local files = {
 	"vec3",
 	"quat",
 	"simplex",
-	"intersect"
+	"intersect",
+  "mesh"
 }
 
 for _, v in ipairs(files) do
-	cpml[v] = require(current_folder .. "cpml." .. v)
+	cpml[v] = require(current_folder .. "modules." .. v)
 end
 
 return cpml
diff --git a/cpml/constants.lua b/modules/constants.lua
similarity index 100%
rename from cpml/constants.lua
rename to modules/constants.lua
diff --git a/cpml/intersect.lua b/modules/intersect.lua
similarity index 100%
rename from cpml/intersect.lua
rename to modules/intersect.lua
diff --git a/cpml/mat4.lua b/modules/mat4.lua
similarity index 100%
rename from cpml/mat4.lua
rename to modules/mat4.lua
diff --git a/modules/mesh.lua b/modules/mesh.lua
new file mode 100644
index 0000000..e883a04
--- /dev/null
+++ b/modules/mesh.lua
@@ -0,0 +1,18 @@
+local current_folder = (...):gsub('%.[^%.]+$', '') .. "."
+local vec3 = require(current_folder .. "vec3")
+
+local mesh = {}
+
+function mesh.compute_normal(a, b, c)
+	return (c - a):cross(b - a):normalize()
+end
+
+function mesh.average(vertices)
+	local avg = vec3(0,0,0)
+	for _, v in ipairs(vertices) do
+		avg = avg + v
+	end
+	return avg / #vertices
+end
+
+return mesh
diff --git a/cpml/quat.lua b/modules/quat.lua
similarity index 94%
rename from cpml/quat.lua
rename to modules/quat.lua
index 4ca377f..015dcda 100644
--- a/cpml/quat.lua
+++ b/modules/quat.lua
@@ -8,8 +8,8 @@ This is a class for handling quaternion numbers.  It was originally
 designed as a way of encoding rotations of 3 dimensional space.
 --]]
 
-local Class = require "libs.hump.class"
-local quaternion = Class {}
+local quaternion = {}
+quaternion.__index = quaternion
 local FLT_EPSILON = 1.19209290e-07
 
 --[[
@@ -17,32 +17,33 @@ A quaternion can either be specified by giving the four coordinates as
 real numbers or by giving the scalar part and the vector part.
 --]]
 
-
-function quaternion:init(...)
+local function new(...)
+	local a, b, c, d
 	-- copy
 	local arg = {...}
 	if #arg == 1 and type(arg[1]) == "table" then
-		self.a = arg[1].a
-		self.b = arg[1].b
-		self.c = arg[1].c
-		self.d = arg[1].d
+		a = arg[1].a
+		b = arg[1].b
+		c = arg[1].c
+		d = arg[1].d
 	-- four numbers
 	elseif #arg == 4 then
-		self.a = arg[1]
-		self.b = arg[2]
-		self.c = arg[3]
-		self.d = arg[4]
+		a = arg[1]
+		b = arg[2]
+		c = arg[3]
+		d = arg[4]
 	-- real number plus vector
 	elseif #arg == 2 then
-		self.a = arg[1]
-		self.b = arg[2].x
-		self.c = arg[2].y
-		self.d = arg[2].z
+		a = arg[1]
+		b = arg[2].x
+		c = arg[2].y
+		d = arg[2].z
 	else
 		error("Incorrect number of arguments to quaternion")
 	end
-end
 
+	return setmetatable({ a = a or 0, b = b or 0, c = c or 0, d = d or 0 }, quaternion)
+end
 
 function quaternion:to_axis_angle()
 	local tmp = self
@@ -64,7 +65,6 @@ function quaternion:to_axis_angle()
 	return angle, { x, y, z }
 end
 
-
 --[[
 Test if we are zero.
 --]]
@@ -497,4 +497,7 @@ function quaternion.unit()
 	return quaternion(1,0,0,0)
 end
 
-return quaternion
+--return quaternion
+-- the module
+return setmetatable({ new = new },
+{ __call = function(_, ...) return new(...) end })
diff --git a/cpml/simplex.lua b/modules/simplex.lua
similarity index 100%
rename from cpml/simplex.lua
rename to modules/simplex.lua
diff --git a/cpml/vec3.lua b/modules/vec3.lua
similarity index 100%
rename from cpml/vec3.lua
rename to modules/vec3.lua