Linking error in OpenGL using freeglut in CLion

Question

So, I am using freeglut to try to do some openGL stuff, but I keep getting errors saying that references are undefined:

CMakeFiles\texture_mapping.dir/objects.a(TextureMapper.cpp.obj): In function `ZN13TextureMapper4initEv':
.../TextureMapper.cpp:20: undefined reference to `glClearColor@16'
.../TextureMapper.cpp:23: undefined reference to `glMatrixMode@4'
.../TextureMapper.cpp:24: undefined reference to `glLoadIdentity@0'
.../TextureMapper.cpp:25: undefined reference to `glOrtho@48'
CMakeFiles\texture_mapping.dir/objects.a(TextureMapper.cpp.obj): In function `ZN13TextureMapper7displayEv':
.../TextureMapper.cpp:45: undefined reference to `glClear@4'
...TextureMapper.cpp:48: undefined reference to `glColor3f@12'
...TextureMapper.cpp:49: undefined reference to `glBegin@4'
...TextureMapper.cpp:52: undefined reference to `glVertex3f@12'
...TextureMapper.cpp:53: undefined reference to `glVertex3f@12'
...TextureMapper.cpp:54: undefined reference to `glVertex3f@12'
...TextureMapper.cpp:55: undefined reference to `glVertex3f@12'
...TextureMapper.cpp:58: undefined reference to `glEnd@0'
...TextureMapper.cpp:61: undefined reference to `glFlush@0'

I am using MinGW with CLion to do this project. I thought that I got everything correctly. I moved the appropriate files into the include folder in MinGW, as well as the bin folder, and also the lib folder. Then, I have this in my CMakeLists.txt:

cmake_minimum_required(VERSION 3.3)
project(texture_mapping)
find_package(OpenGL REQUIRED)
find_package(GLUT REQUIRED)

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")

set(SOURCE_FILES main.cpp TextureMapper.cpp TextureMapper.h Vertex.h ObjParser.cpp ObjParser.h)

add_executable(texture_mapping ${SOURCE_FILES})
target_link_libraries(texture_mapping libfreeglut.a libfreeglut_static.a)

The libraries I linked were the only library files that freeglut came with.

So, what am I missing? CLion doesn't show any errors before it is compiled. I can even go into the functions in the header files provided by freeglut. Why then, are these functions not defined in my program?

Sundin

Your issue has nothing to do with CLion. It's just about CMake and your environment. – Unsheathe

Answer 1

You did not actually link OpenGL to your project, so you get undefined references to OpenGL functions. Try to replace

target_link_libraries(texture_mapping libfreeglut.a libfreeglut_static.a)

with

target_link_libraries(texture_mapping libfreeglut.a libfreeglut_static.a GL)

I reproduced your issue with your CMakeLists.txt and the following program:

#include <GL/gl.h>

int main() {
        glClear(GL_COLOR_BUFFER_BIT);
        return 0;
}

and solved it with the above replacement. The solution automatically links GL library from my library path:

$ ls -1 /usr/lib64/libGL.*
/usr/lib64/libGL.la
/usr/lib64/libGL.so
/usr/lib64/libGL.so.1
/usr/lib64/libGL.so.1.0.0

UPDATE

According to this, you have some variables to access your actual OpenGL libraries. For example, you may point to OpenGL library file(s) directly like this:

target_link_libraries(texture_mapping libfreeglut.a libfreeglut_static.a ${OPENGL_gl_LIBRARY})

Also you may add OpenGL library directory to the library search path (do it before target_link_libraries):

link_directories(${OPENGL_gl_LIBRARY})

Unsheathe

I get c:/mingw/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe: cannot find -lGL as a result of that. – Sundin

@CacheStaheli I updated my answer. That should work as it takes your actual environment into account. – Unsheathe

As soon as I added the link_directories call, along with the extra library (${OPENGL_gl_LIBRARY}) in target_link_libraries, it worked splendidly. Thanks! – Sundin

Answer 2

I have struggled with the same problem and solved it by appending following lines to CMakeLists.txt:

find_package(OpenGL REQUIRED)
find_package(GLUT REQUIRED)
include_directories(${OPENGL_INCLUDE_DIRS} ${GLUT_INCLUDE_DIRS})
target_link_libraries(${PROJECT_NAME} ${OPENGL_LIBRARIES} ${GLUT_LIBRARY})

Sumba

Answer 3

Reordering the CMakeLists.txt helped me (<name> should be replaced accordingly):

cmake_minimum_required(VERSION 3.10)
project(<name>)

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -lGL -lGLU -lglut")
set(CMAKE_CXX_STANDARD 17)

add_executable(<name> main.cpp)

find_package(OpenGL REQUIRED)
find_package(GLUT REQUIRED)
include_directories(${OPENGL_INCLUDE_DIRS} ${GLUT_INCLUDE_DIRS})
target_link_libraries(${PROJECT_NAME} ${OPENGL_LIBRARIES} ${GLUT_LIBRARY})

Calkins