fixed python build on linux with opengl enabled

Former-commit-id: f528c4d63af5abb305e59e00c489fb3ab8cb3915

.travis.yml

@@ -11,13 +11,13 @@ matrix:
         - cd python
         - mkdir build
         - cd build
-        - cmake -DCMAKE_CXX_COMPILER=g++-4.8 ../
+        - cmake -DCMAKE_CXX_COMPILER=g++-4.8 -DCMAKE_C_COMPILER=gcc-4.8 ../
         - make -j 2
         - cd ../../
         - cd tutorial
         - mkdir build
         - cd build
-        - cmake -DLIBIGL_USE_STATIC_LIBRARY=ON -DCMAKE_CXX_COMPILER=g++-4.8 ../
+        - cmake -DLIBIGL_USE_STATIC_LIBRARY=ON -DCMAKE_CXX_COMPILER=g++-4.8 -DCMAKE_C_COMPILER=gcc-4.8 ../
         - make -j 2
       addons:
         apt:

python/CMakeLists.txt

@@ -19,7 +19,7 @@ if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
     "MinSizeRel" "RelWithDebInfo")
 endif()
 
-find_package(OPENGL QUIET)
+find_package(OpenGL QUIET)
 
 if (OPENGL_FOUND)
   add_definitions(-DPY_VIEWER)
@@ -39,7 +39,8 @@ find_package(PythonInterp REQUIRED)
 
 string(TOUPPER "${CMAKE_BUILD_TYPE}" U_CMAKE_BUILD_TYPE)
 if (UNIX)
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -fPIC")
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fPIC")
   if (NOT ${U_CMAKE_BUILD_TYPE} MATCHES DEBUG)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fvisibility=hidden -flto")
   endif()