CODEWITHSUNDEEP
c++openglcmakeglutglu
chasekosborne
chasekosborne

Reputation: 1

Undefined reference to gluPerspective() when building GLUT project with CMake?

I am currently working on rendering 3D objects using the GLUT utilities in OpenGL. I am doing this on a Linux operating system, and are using CMake to compile the code. Every time I go to compile the code I get an 'undefined reference' error, but only for particular functions within the glad library.

My include directory in my main.cpp looks like;

#include <GL/glut.h>

And in my CMakeLists.txt file I have;

cmake_minimum-required(VERSION 3.17)

project(proj03)
add_executable({PROJECT_NAME} main.cpp glad.c)

find_package(OpenGL REQUIRED COMPONENTS OpenGL)
find_package(GLUT REQUIRED)

add_dependencies(${PROJECT_NAME} OpenGL::OpenGL GLUT::GLUT)

target_link_libraries(${PROJECT_NAME} OpenGL::OpenGL GLUT::GLUT)

Everything looks good at least for what I need, but when I run the make command within my build file in the bash terminal. I get the error;

[ 33%] Linking CXX executable proj03
/usr/bin/ld: CMakeFiles/proj03.dir/main.cpp.o: in function `reshape(int, int)':
main.cpp:(.text+0x790): undefined reference to `gluPerspective'
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/proj03.dir/build.make:114: proj03] Error 1
make[1]: *** [CMakeFiles/Makefile2:83: CMakeFiles/proj03.dir/all] Error 2
make: *** [Makefile:91: all] Error 2

I've tried adding different libraries to see if the error would just go away that way, but it seems to only have this error for these particular functions within GLUT.

Upvotes: 0

Views: 652

Answers (1)

genpfault
genpfault

Reputation: 52084

GLU != GLUT.

FindOpenGL defines several IMPORTED targets, including OpenGL::GLU. Add that to target_link_libraries():

target_link_libraries(${PROJECT_NAME} OpenGL::OpenGL OpenGL:GLU GLUT::GLUT)

Though if you're using GLAD there's no reason to use the OpenGL::OpenGL target since GLAD handles linking against the system OpenGL shared library at run-time via dlsym() as well as providing all the OpenGL declarations itself. You will however have to use include_directories() to point CMake at the GLAD include directory. All together:

cmake_minimum-required(VERSION 3.17)

project(proj03)

find_package(OpenGL REQUIRED COMPONENTS GLU)
find_package(GLUT REQUIRED)

include_directories(SYSTEM "path/to/glad/include")

add_executable({PROJECT_NAME} main.cpp glad.c)
target_link_libraries(${PROJECT_NAME} OpenGL::GLU GLUT::GLUT)

Upvotes: 1

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