diff --git a/Cura/gui/opengl.py b/Cura/gui/opengl.py
index 7b2b676..4cf9740 100644
--- a/Cura/gui/opengl.py
+++ b/Cura/gui/opengl.py
@@ -1,4 +1,4 @@
-import math
+import math, time
 
 from util import util3d
 from util import profile
@@ -205,20 +205,20 @@ def DrawBox(vMin, vMax):
 
 def DrawSTL(mesh):
 	glEnable(GL_CULL_FACE)
-	for i in xrange(0, mesh.vertexCount, 3):
-		glBegin(GL_TRIANGLES)
-		v1 = mesh.vertexes[i]
-		v2 = mesh.vertexes[i+1]
-		v3 = mesh.vertexes[i+2]
-		glNormal3f(mesh.normal[i/3][0], mesh.normal[i/3][1], mesh.normal[i/3][2])
-		glVertex3f(v1[0], v1[1], v1[2])
-		glVertex3f(v2[0], v2[1], v2[2])
-		glVertex3f(v3[0], v3[1], v3[2])
-		glNormal3f(-mesh.normal[i/3][0], -mesh.normal[i/3][1], -mesh.normal[i/3][2])
-		glVertex3f(v1[0], v1[1], v1[2])
-		glVertex3f(v3[0], v3[1], v3[2])
-		glVertex3f(v2[0], v2[1], v2[2])
-		glEnd()
+	glEnableClientState(GL_VERTEX_ARRAY);
+	glEnableClientState(GL_NORMAL_ARRAY);
+	glVertexPointer(3, GL_FLOAT, 0, mesh.vertexes)
+	glNormalPointer(GL_FLOAT, 0, mesh.normal)
+	
+	glCullFace(GL_BACK)
+	glDrawArrays(GL_TRIANGLES, 0, mesh.vertexCount)
+	
+	glCullFace(GL_FRONT)
+	glNormalPointer(GL_FLOAT, 0, mesh.invNormal)
+	glDrawArrays(GL_TRIANGLES, 0, mesh.vertexCount)
+	
+	glDisableClientState(GL_VERTEX_ARRAY)
+	glDisableClientState(GL_NORMAL_ARRAY);
 
 def DrawGCodeLayer(layer):
 	filamentRadius = profile.getProfileSettingFloat('filament_diameter') / 2
diff --git a/Cura/util/mesh.py b/Cura/util/mesh.py
index dc01198..799551f 100644
--- a/Cura/util/mesh.py
+++ b/Cura/util/mesh.py
@@ -20,7 +20,7 @@ class mesh(object):
 	def _prepareVertexCount(self, vertexNumber):
 		#Set the amount of faces before loading data in them. This way we can create the numpy arrays before we fill them.
 		self.origonalVertexes = numpy.zeros((vertexNumber, 3), float)
-		self.normal = numpy.zeros((vertexNumber / 3, 3))
+		self.normal = numpy.zeros((vertexNumber, 3), float)
 		self.vertexCount = 0
 
 	def _postProcessAfterLoad(self):
@@ -56,11 +56,11 @@ class mesh(object):
 		mat10 = math.sin(rotate) * scaleX
 		mat11 = math.cos(rotate) * scaleY
 		
-		mat = numpy.array([[mat00,mat10,0],[mat01,mat11,0],[0,0,scaleZ]])
+		mat = numpy.array([[mat00,mat10,0],[mat01,mat11,0],[0,0,scaleZ]], float)
 		if swapXZ:
-			mat = numpy.array([mat[2],mat[1],mat[0]])
+			mat = numpy.array([mat[2],mat[1],mat[0]], float)
 		if swapYZ:
-			mat = numpy.array([mat[0],mat[2],mat[1]])
+			mat = numpy.array([mat[0],mat[2],mat[1]], float)
 		self.vertexes = (numpy.matrix(self.origonalVertexes, copy = False) * numpy.matrix(mat)).getA()
 
 		tris = self.vertexes.reshape(self.vertexCount / 3, 3, 3)
@@ -69,7 +69,13 @@ class mesh(object):
 		normals[:,0] /= lens
 		normals[:,1] /= lens
 		normals[:,2] /= lens
-		self.normal = normals
+		
+		n = numpy.zeros((self.vertexCount / 3, 9), float)
+		n[:,0:3] = normals
+		n[:,3:6] = normals
+		n[:,6:9] = normals
+		self.normal = n.reshape(self.vertexCount, 3)
+		self.invNormal = -self.normal
 		
 		self.getMinimumZ()