我無法使用 sdl2 在 opengl 中創建兩個上下文

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越野車，一旦我創建了第二個上下文，並且好像第一個似乎存在，從而破壞了 windows 之一的渲染，是否可以使用 sdl2 使用多個 opengl 上下文？

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

下面是兩個具有不同上下文的 windows 的示例：

#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;
}

但是每個 window 的單獨上下文不是必需的。