CLion Not Finding GLUT with CMake - c++

Question

I have a problem that I can't seem to find the settings to modify.
When attempting to find the GLUT package using CLion's CMake utilities on Ubuntu, it does not find GLUT. Using command-line CMake and Makefile commands, however, finds the dependencies perfectly and allows the following to generate and compile:
# CMakeLists.txt
cmake_minimum_required(VERSION 3.16)
project(mre)
set(CMAKE_CXX_STANDARD 20)
find_package(OpenGL REQUIRED) # Works in CLion and terminal
find_package(GLUT REQUIRED) # Works only in terminal
include_directories(GL)
add_executable(mre mre.cpp)
target_link_libraries(mre -lglut -lGLU -lGL)
// mre.cpp
#include <GL/gl.h>
#include <GL/glut.h>
int main()
{
return 0;
}
Whereas attempting to use these files in a CLion project would cause errors (first unable to find GLUT, mitigated by manually setting library and include variables; then GL/glut.h: No such file or directory, which I am unable to fix).
Does anyone have any suggestions? I'm assuming it's something to do with a working directory or prefixes, but CMAKE_PREFIX_PATH is unset in CLion, and setting it to various values does nothing to solve the problem.
Thanks!

Answer 1

You know something has gone wrong when you write include_directories or -l flags by hand. You should absolutely always link to libraries via their imported targets.
See the documentation:
OpenGL package: https://cmake.org/cmake/help/latest/module/FindOpenGL.html
GLUT package: https://cmake.org/cmake/help/latest/module/FindGLUT.html
Try this revision:
cmake_minimum_required(VERSION 3.16)
project(mre)
find_package(OpenGL REQUIRED)
find_package(GLUT REQUIRED)
add_executable(mre mre.cpp)
target_link_libraries(mre PRIVATE OpenGL::GL OpenGL::GLU GLUT::GLUT)
target_compile_features(mre PRIVATE cxx_std_20)
As for not being able to find GLUT... just set CMAKE_PREFIX_PATH in CLion's settings to whichever directory on your system contains include/GL/glut.h.

Answer 2

Alternative solution
CLion was installed through the Software Center via Flatpak, which uses some kind of filesystem sandboxing that may be interfering with paths. I tried explicitly allowing /usr and related paths, but had no effect.
I have reinstalled via JetBrains's official archive, which correctly detects GLUT and OpenGL. Their official snap also works properly.