I can't create two contexts in opengl using sdl2

Question

i need a debug window, in which i could better observe the scenario the possible changes, and change in real time, using sdl2 and opengl 3.3 i created the second window, changed the event system to close the window using multiple windows, but glContext is buggy, once I create a second context, and as if the first one seems to exist, thus breaking the rendering of one of the windows, would it be possible to use multiple opengl contexts using sdl2?

this->window=SDL_CreateWindow(title, SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, width, height, SDL_WINDOW_OPENGL | (resize ? SDL_WINDOW_RESIZABLE : SDL_WINDOW_SHOWN));
SDL_GLContext windowContext=SDL_GL_CreateContext(this->window);
this->debug=SDL_CreateWindow("debug", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 600, 600, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);
SDL_GLContext debugContext=SDL_GL_CreateContext(this->debug);

Answer 1

Here's an example of two windows with separate contexts:

#include <SDL2/SDL.h>
#include <SDL2/SDL_opengl.h>
#include <stdio.h>

int main(int argc, char **argv) {
    (void)argc, (void)argv;
    if(SDL_Init(SDL_INIT_VIDEO) < 0) {
        fprintf(stderr, "SDL_Init error: %s\n", SDL_GetError());
        return 1;
    }
    SDL_Window *windows[2];
    SDL_GLContext contexts[2];
    for(int i = 0; i != sizeof(windows)/sizeof(windows[0]); ++i) {
        char title[32];
        snprintf(title, sizeof(title), "window%d", i);
        windows[i] = SDL_CreateWindow(title, SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
                640, 480, SDL_WINDOW_OPENGL);
        if(!windows[i]) {
            fprintf(stderr, "SDL_CreateWindow error: %s\n", SDL_GetError());
            return 1;
        }
        contexts[i] = SDL_GL_CreateContext(windows[i]);
        if(!contexts[i]) {
            fprintf(stderr, "SDL_GL_CreateContext error: %s\n", SDL_GetError());
            return 1;
        }
    }

    int running = 1;
    while(running) {
        SDL_Event ev;
        while(SDL_PollEvent(&ev)) {
            if(ev.type == SDL_KEYDOWN && ev.key.keysym.sym == SDLK_q) {
                running = 0;
                break;
            }
        }

        SDL_GL_MakeCurrent(windows[0], contexts[0]);
        glClearColor(1, 0, 0, 1);
        glClear(GL_COLOR_BUFFER_BIT);
        SDL_GL_SwapWindow(windows[0]);

        SDL_GL_MakeCurrent(windows[1], contexts[1]);
        glClearColor(0, 1, 0, 1);
        glClear(GL_COLOR_BUFFER_BIT);
        SDL_GL_SwapWindow(windows[1]);
    }

    return 0;
}

But separate context for each window is not a requirement.