Clion (cmake) won't link the libraries [closed] - c++

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I'm having a problem when trying to link SDL2 and GL libraries to Clion (cmake). Despite changing the cmakelists.txt and adding the target-link-libraries() function. So the cmake file looked like this:
cmake_minimum_required(VERSION 3.9)
project(OpenGL1)
set(CMAKE_CXX_STANDARD 17)
target_link_libraries(OpenGL1 SDL2 GL)
add_executable(OpenGL1 main.cpp Display1.cpp Display1.h)
But with no luck. Clion would not link the libraries with errors such as undifined refference to functions of the libraries.
Then a friend suggested it that I would wite that into cmakelists file:
cmake_minimum_required(VERSION 3.9)
project(OpenGL1)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -lGL -lSDL2 -lOpenGL")
add_executable(OpenGL1 main.cpp Display1.cpp Display1.h)
And it kinda worked... But it would not find the -lOpenGL.
Last but not least, my project will not compile with the traditional way in the terminal with g++. And it will compile fine with one .cpp file.
My project consists of 2 cpp files and a header file. Like that:
main.cpp
Display1.cpp
Display.h
And code of the files is the following:
main.cpp
#include <iostream>
#include "Display.h"
using namespace std;
int main() {
Display d1(800,600,"Hello");
while (!d1.m_isClosed()){
d1.Clear(0.0f, 0.15f, 0.3f, 1.0f);
d1.Update();
}
return 0;
}
Display1.cpp
#include "Display.h"
#include <GL/glew.h>
using namespace std;
Display::Display(int width, int height, const string title) {
SDL_Init(SDL_INIT_EVERYTHING);
SDL_GL_SetAttribute(SDL_GL_RED_SIZE,8);
SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE,8);
SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE,8);
SDL_GL_SetAttribute(SDL_GL_ALPHA_SIZE,8);
SDL_GL_SetAttribute(SDL_GL_BUFFER_SIZE,32);
SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER,1);
m_window = SDL_CreateWindow(title.c_str(),SDL_WINDOWPOS_CENTERED,SDL_WINDOWPOS_CENTERED,width,height,SDL_WINDOW_OPENGL);
m_glContext = SDL_GL_CreateContext(m_window);
GLenum status = glewInit();
if (status != GLEW_OK)
cerr << "Glew failed!" << endl;
isClosed = false;
}
Display::~Display() {
SDL_GL_DeleteContext(m_glContext);
SDL_DestroyWindow(m_window);
SDL_Quit();
}
void Display::Clear(float r, float g, float b, float a) {
glClearColor(r,g,b,a);
glClear(GL_COLOR_BUFFER_BIT);
}
bool Display::m_isClosed() {
return isClosed;
}
void Display::Update() {
SDL_GL_SwapWindow(m_window);
SDL_Event e;
while (SDL_PollEvent(&e)){
if (e.type == SDL_QUIT)
isClosed = true;
}
}
Display1.h
#ifndef OPENGL_DISPLAY_H
#define OPENGL_DISPLAY_H
#include <iostream>
#include <SDL2/SDL.h>
using namespace std;
class Display {
SDL_Window* m_window;
SDL_GLContext m_glContext;
bool isClosed;
public:
Display(int width, int height, string title);
virtual ~Display();
void Update();
bool m_isClosed();
void Clear(float r, float g, float b, float a);
};
#endif //OPENGL_DISPLAY_H
Now, i know that others have asked the same, but nothing could help me so that's why I'm asking. I'm running Ubuntu 17.10 (64-bit). Thanks in advance!

Answer 1

You have to fix your CMakeLists.txt:
cmake_minimum_required(VERSION 3.9)
project(OpenGL1)
set(CMAKE_CXX_STANDARD 17)
find_package(OpenGL REQUIRED)
find_package(GLEW REQUIRED)
set(SDL2_INCLUDE_DIRS /usr/include/SDL2)
set(SDL2_LIBRARIES /usr/lib/x86_64-linux-gnu/libSDL2.so)
include_directories(${OPENGL_INCLUDE_DIRS} ${GLEW_INCLUDE_DIRS} ${SDL2_INCLUDE_DIRS})
add_executable(OpenGL1 main.cpp Display1.cpp Display1.h)
target_link_libraries(OpenGL1 ${OPENGL_LIBRARIES} ${GLEW_LIBRARIES} ${SDL2_LIBRARIES})
First find the OpenGL files with find_package(OpenGL REQUIRED). Then set the paths for SDL2. Set the include directories for your target (OpenGL1). Add your target. Link libraries to your target.
A better way to use SDL2 is to use FindSDL2.cmake and add find_package(SDL2) to your CMakeLists.txt:
cmake_minimum_required(VERSION 3.9)
project(OpenGL1)
set(CMAKE_CXX_STANDARD 17)
find_package(OpenGL REQUIRED)
find_package(GLEW REQUIRED)
find_package(SDL2 REQUIRED)
include_directories(${OPENGL_INCLUDE_DIRS} ${GLEW_INCLUDE_DIRS} ${SDL2_INCLUDE_DIRS})
add_executable(OpenGL1 main.cpp Display1.cpp Display1.h)
target_link_libraries(OpenGL1 ${OPENGL_LIBRARIES} ${GLEW_LIBRARIES} ${SDL2_LIBRARIES})
SDL2 installs its own cmake configuration file called sdl2-config.cmake, so you don't need to download it from github.