From 05d1dcd331fafd5de3c171a8feb2db7da05ea51e Mon Sep 17 00:00:00 2001
From: Michael Sloan <mgsloan@gmail.com>
Date: Tue, 30 Oct 2012 02:03:09 -0700
Subject: [PATCH] Add NullBackend for Ellipsoid

---
 src/Diagrams/ThreeD/Shapes.hs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/Diagrams/ThreeD/Shapes.hs b/src/Diagrams/ThreeD/Shapes.hs
index 70c21fee..8042f237 100644
--- a/src/Diagrams/ThreeD/Shapes.hs
+++ b/src/Diagrams/ThreeD/Shapes.hs
@@ -1,5 +1,6 @@
 {-# LANGUAGE TypeFamilies
            , FlexibleContexts
+           , MultiParamTypeClasses
            , ViewPatterns
   #-}
 -----------------------------------------------------------------------------
@@ -38,6 +39,9 @@ type instance V Ellipsoid = R3
 instance Transformable Ellipsoid where
   transform t1 (Ellipsoid t2) = Ellipsoid (t1 <> t2)
 
+instance Renderable Ellipsoid NullBackend where
+  render _ _ = mempty
+
 sphere :: (Backend b R3, Renderable Ellipsoid b) => Diagram b R3
 sphere = mkQD (Prim $ Ellipsoid mempty)
               (mkEnvelope sphereEnv)