[CMake] CMake Tutorial and Error: undefined symbols

[Bill Hoffman]

David Morris wrote:
> I'm new to cmake, and I have been trying to find a good comprehensive 
> tutorial to get myself started, but have had no luck. Does anyone know 
> a good one besides the cmake.org <http://cmake.org> site and the 
> linuxjournal one?
>
> I will try to describe one problem i'm having, but I'm not really sure 
> where to begin. I'm trying to compile a C++ project and I get this error:
>
> /usr/bin/ld: Undefined symbols:
> _glBegin
> _glBindTexture
> _glColor3d
> _glColor3f
> _glCullFace
> ...
> ...
>
> and so on...
>
> I read somewhere this might have to do with cmake trying to compile 
> C++ code using gcc instead of g++, and that you can override this 
> setting in the CMakeCache file, but this is the line in the 
> CMakeCache.txt file:
>
> CMAKE_CXX_COMPILER:FILEPATH=/usr/bin/c++
>
> I tried changing it to g++, but it didn't seem to do anything. I don't 
> think this has much to do with the actual code of the project, so I 
> didn't bother explaining anything about it here. Any help would be 
> greatly appreciated. I'm thinking it's a really simple error, but who 
> knows. Here is the text of my main CMakeLists.txt file:
>
> ---
>
> #Change PROJECT_NAME to the name of your project
> PROJECT(TopMod)
> #include some macros from another file...
> INCLUDE(${TopMod_SOURCE_DIR}/CMakeMacros.txt)
> #Declare any external dependencies that your project may have here.
> #examples include: ITK, VTK, JPEG, PNG, OpenGL, ZLIB, Perl, Java
> #If you're not sure what name to use, look in the Modules directory of 
> your
> #cmake install and check that a file named Find(Package).cmake exists
> SET(Required_Packages
> FLTK JPEG PNG OpenGL ZLIB GLUT
> )
> FOREACH(Package ${Required_Packages})
>   LOADPACKAGE(${Package})
> ENDFOREACH(Package)
>
> #run through these sub directories to build these two libraries
> SUBDIRS(vecmat)
> SUBDIRS(arcball)
>
> INCLUDE_DIRECTORIES(${TopMod_SOURCE_DIR}/arcball 
> ${TopMod_SOURCE_DIR}/vecmat ${TopMod_SOURCE_DIR}/include /opt/local/lib)
> LINK_DIRECTORIES(${TopMod_BINARY_DIR}/arcball 
> ${TopMod_BINARY_DIR}/vecmat ${TopMod_BINARY_DIR}/include /opt/local/lib)
>
> SET(Libraries fltk_images fltk_gl fltk arcball vecmat)
>
> SET(CurrentExe "TopMod")
> FILE(GLOB SRC *.cc)
> ADD_EXECUTABLE(${CurrentExe} ${SRC})
> TARGET_LINK_LIBRARIES(${CurrentExe} ${Libraries})
You need to link in the opengl library.

-Bill