如何将OpenGL正交投影设置为旋转时用矩形填充屏幕

#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <iostream>

// 顶点着色器代码
const char* vertexShaderSource = R"(
    #version 330 core
    layout (location = 0) in vec3 aPos;
    void main()
    {
        gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);
    }
)";

// 片段着色器代码
const char* fragmentShaderSource = R"(
    #version 330 core
    out vec4 FragColor;
    void main()
    {
        FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);
    }
)";

int main()
{
    // 初始化GLFW
    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    // 创建窗口
    GLFWwindow* window = glfwCreateWindow(800, 600, "OpenGL", NULL, NULL);
    if (window == NULL)
    {
        std::cout << "Failed to create GLFW window" << std::endl;
        glfwTerminate();
        return -1;
    }
    glfwMakeContextCurrent(window);

    // 初始化GLEW
    if (glewInit() != GLEW_OK)
    {
        std::cout << "Failed to initialize GLEW" << std::endl;
        return -1;
    }

    // 创建顶点着色器对象
    GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
    glCompileShader(vertexShader);

    // 创建片段着色器对象
    GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
    glCompileShader(fragmentShader);

    // 创建着色器程序
    GLuint shaderProgram = glCreateProgram();
    glAttachShader(shaderProgram, vertexShader);
    glAttachShader(shaderProgram, fragmentShader);
    glLinkProgram(shaderProgram);

    // 删除着色器对象
    glDeleteShader(vertexShader);
    glDeleteShader(fragmentShader);

    // 定义矩形的顶点数据
    float vertices[] = {
        -0.5f, -0.5f, 0.0f,
         0.5f, -0.5f, 0.0f,
         0.5f,  0.5f, 0.0f,
        -0.5f,  0.5f, 0.0f
    };

    // 定义矩形的索引数据
    unsigned int indices[] = {
        0, 1, 2,
        2, 3, 0
    };

    // 创建顶点缓冲对象和索引缓冲对象
    GLuint VBO, EBO;
    glGenBuffers(1, &VBO);
    glGenBuffers(1, &EBO);

    // 绑定顶点缓冲对象和索引缓冲对象
    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);

    // 设置顶点属性指针
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);

    // 渲染循环
    while (!glfwWindowShouldClose(window))
    {
        // 清空屏幕
        glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);

        // 更新模型矩阵
        float angle = (float)glfwGetTime() * 50.0f;
        glm::mat4 model = glm::rotate(glm::mat4(1.0f), glm::radians(angle), glm::vec3(0.0f, 0.0f, 1.0f));

        // 设置模型矩阵
        GLuint modelLoc = glGetUniformLocation(shaderProgram, "model");
        glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));

        // 使用着色器程序
        glUseProgram(shaderProgram);

        // 绘制矩形
        glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);

        // 交换缓冲区和轮询事件
        glfwSwapBuffers(window);
        glfwPollEvents();
    }

    // 删除缓冲对象和着色器程序
    glDeleteBuffers(1, &VBO);
    glDeleteBuffers(1, &EBO);
    glDeleteProgram(shaderProgram);

    // 终止GLFW
    glfwTerminate();
    return 0;
}