Question

为了创造一种屏保我希望能够：

在GLFW窗口中全屏绘制内容
关闭窗口
等一会儿
在新窗口中重绘相同的内容

我可以轻松地做到这一点，但效率不高。事实上，我必须再次进行所有初始化（上下文创建，vao，vbo，编译着色器......），我不重用任何东西。如果窗口刚刚被用户隐藏，那就好了，但显然，你不能用GLFW隐藏全屏窗口。

有谁知道什么可以安全再次使用，以及如何使用？

也许代码（不重新打开新窗口）可以帮助您回答我的问题：

...

int main (int argc, char *argv[])
{   
    GLFWwindow* window;
    const GLFWvidmode *mode;
    GLenum glew_status;

    float vertices[] = {
        -1.0f,  1.0f,
         1.0f,  1.0f,
        -1.0f, -1.0f,
         1.0f, -1.0f
    };
    GLuint vao;
    GLuint vbo;
    GLuint vertexShader;
    GLuint fragmentShader;
    GLuint shaderProgram;

    GLint posAttrib;
    GLint Resolution;
    GLint Time;


    glfwSetErrorCallback(error_callback);

    if (!glfwInit())
        return 1;

    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);

    mode = glfwGetVideoMode(glfwGetPrimaryMonitor());
    window = glfwCreateWindow(mode->width, mode->height, "OpenGL", glfwGetPrimaryMonitor(), NULL); // Fullscreen

    if (!window) {
        glfwTerminate();
        return 2;
    }

    glfwMakeContextCurrent(window);

    glfwSetKeyCallback(window, key_callback);
    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
    glfwSetInputMode(window,GLFW_CURSOR,GLFW_CURSOR_HIDDEN);

    // Initialize GLEW
    glewExperimental = GL_TRUE;
    glew_status = glewInit();
    if (glew_status != GLEW_OK) {
        //Problem: glewInit failed, something is seriously wrong.
        fprintf(stderr,"glewInit failed, Error: %s\n", glewGetErrorString(glew_status));
        return 3;
    }

    // Create Vertex Array Object
    glGenVertexArrays(1, &vao);
    glBindVertexArray(vao);

    // Create a Vertex Buffer Object and copy the vertex data to it
    glGenBuffers(1, &vbo);

    glBindBuffer(GL_ARRAY_BUFFER, vbo);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

    // Create and compile the vertex shader
    vertexShader = LoadShader("/home/celestin/Documents/C/OpenGL/my_openGL/simple_shader/triangle.v.glsl",GL_VERTEX_SHADER);
    fragmentShader = LoadShader("/home/celestin/Documents/C/OpenGL/my_openGL/simple_shader/triangle.f.glsl",GL_FRAGMENT_SHADER);

    // Link the vertex and fragment shader into a shader program
    shaderProgram = glCreateProgram();
    glAttachShader(shaderProgram, vertexShader);
    glAttachShader(shaderProgram, fragmentShader);
    glBindFragDataLocation(shaderProgram, 0, "outColor");
    glLinkProgram(shaderProgram);
    glUseProgram(shaderProgram);

    // Specify the layout of the vertex data
    posAttrib = glGetAttribLocation(shaderProgram, "position");
    glEnableVertexAttribArray(posAttrib);
    glVertexAttribPointer(posAttrib, 2, GL_FLOAT, GL_FALSE, 0, 0);

    Resolution = glGetUniformLocation(shaderProgram, "resolution");
    Time = glGetUniformLocation(shaderProgram, "time");

    // Clear the screen to black
    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
    glfwSetTime(0.0);

    // Loop until the user closes the window
    while (!glfwWindowShouldClose(window))
    {

        glUniform1f(Time,glfwGetTime());
        glUniform2f(Resolution,mode->width,mode->height);

        glClear(GL_COLOR_BUFFER_BIT);

        // Draw a triangle from the 3 vertices
        glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);

        // Swap front and back buffers
        glfwSwapBuffers(window);

        // Poll for and process events
        glfwPollEvents();
    }

    glDeleteProgram(shaderProgram);
    glDeleteShader(fragmentShader);
    glDeleteShader(vertexShader);

    glDeleteBuffers(1, &vbo);
    glDeleteVertexArrays(1, &vao);

    glfwDestroyWindow(window);
    glfwTerminate();
    return 0;
}

Answer 1

确实无法创建最初隐藏的全屏GLFW窗口。但是，如果您使用的是足够现代的OpenGL，您可以假设支持framebuffer对象，则可以使用隐藏的窗口模式窗口渲染到纹理。窗口默认帧缓冲区的大小无关紧要。

如果您想在窗口之间等待，可以将此纹理的图像数据保存到RAM中并保留以供日后使用。

如果你不介意生命重叠，你可以通过上下文共享将这个纹理分享到新窗口的上下文中。这是通过glfwCreateWindow的最后一个参数完成的。上下文共享还将承载许多其他对象类型：

可以在上下文之间共享的对象包括缓冲对象，程序和着色器对象，渲染缓冲对象，采样器对象，同步对象和纹理对象（名为零的纹理对象除外）。 - OpenGL 4.5 Specification, chapter 5

关闭一个窗口并在新窗口中绘制相同的内容

1 个答案: