From e3363dd3042cef16b91357162a56a8411edff165 Mon Sep 17 00:00:00 2001
From: Stephen Birarda <commit@birarda.com>
Date: Fri, 7 Mar 2014 12:22:58 -0800
Subject: [PATCH] conditionally include the OPENGL_INCLUDE_DIR since it is
 empty on windows

---
 cmake/modules/FindGLUT.cmake | 2 --
 interface/CMakeLists.txt     | 7 ++++++-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/cmake/modules/FindGLUT.cmake b/cmake/modules/FindGLUT.cmake
index ac8b66acba..21b4e958b8 100644
--- a/cmake/modules/FindGLUT.cmake
+++ b/cmake/modules/FindGLUT.cmake
@@ -73,8 +73,6 @@ else ()
   include(FindPackageHandleStandardArgs)
   find_package_handle_standard_args(GLUT DEFAULT_MSG GLUT_INCLUDE_DIR GLUT_LIBRARIES)
   
-  message(${GLUT_INCLUDE_DIR})
-  
   if (GLUT_FOUND)
     if (NOT GLUT_FIND_QUIETLY)
       message(STATUS "Found GLUT: ${GLUT_LIBRARIES}")
diff --git a/interface/CMakeLists.txt b/interface/CMakeLists.txt
index 7b4acc84ec..3e57d10645 100644
--- a/interface/CMakeLists.txt
+++ b/interface/CMakeLists.txt
@@ -215,7 +215,12 @@ else (APPLE)
     find_package(OpenGL REQUIRED)
     find_package(GLUT REQUIRED)
     
-    include_directories(SYSTEM "${GLUT_INCLUDE_DIR}" "${OPENGL_INCLUDE_DIR}")
+    include_directories(SYSTEM "${GLUT_INCLUDE_DIR}")
+    
+    if (${OPENGL_INCLUDE_DIR})
+      include_directories(SYSTEM "${OPENGL_INCLUDE_DIR}")
+    endif ()
+    
     target_link_libraries(${TARGET_NAME} "${OPENGL_LIBRARY}" "${GLUT_LIBRARIES}")
     
     # link target to external libraries