OpenGL学习笔记 ---Create a Window

OpenGL是使用双缓冲的（front buffer， back buffer），front buffer用于展示，back buffer用于绘制，结束后将front buffer 与 back buffer的位置对调，此时的front buffer变成了back buffer，back buffer变成了front buffer。

glfwTerminate();函数结束window

glClearColor(R, G ,B, A);清屏后的颜色

glClear(GL_COLOR_BUFFER_BIT);清屏

glfwWindowShouldClose(window);函数可以检测window是否被关闭

glfwSwapBuffers(window);函数可以交换缓冲

GLFWwindow* window = glfwCreateWindow(窗口宽, 窗口长, 窗口名字, NULL, NULL);创建一个窗口

glfwInit();初始化glfw

glfwWindowInit(参数...);具体初始化什么样的glfw

glfwmakeContextCurrent(window);使用window这个window作为当前的窗口

glewExperimental = true;

if( glewInit() != GLEW_OK );若glewInit()初始化失败

glViewport(0, 0, 800, 600);设置可以绘制的窗口范围

glfwPollEvents(); glfwPollEvents函数检查是否触发了任何事件（如键盘输入或鼠标移动事件），更新窗口状态，并调用相应的函数（我们可以通过回调方法注册）。

if(glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS) glfwSetWindowShouldClose(window, true); 如果按了ESCAPE键的话，就关闭window

VAO：存放模型位置点数据，法线数据等信息

glGenVertexArray(1, &VAO); 获取所有模型所有VAO的信息并存在变量VAO中

glBindVertexArray(VAO); 绑定VAO

VBO：存放模型数据，并没有处理是位置点数据还是法线数据，只有没有分类的数据

#include 
#include 

void processInput(GLFWwindow* window) {
    if(glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS) {
        glfwSetWindowShouldClose(window, true);
    }
}

int main()
{
    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    //glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);//若需要在mac做操作才把这段代码启用

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

    glewExperimental = true;
    if(glewInit() != GLEW_OK){
        printf("Init GLEW failed.");
        glfwTerminate();
        return -1;
    }

    glViewport(0, 0, 800, 600);

    unsigned int VAO;
    glGenVertexArray(1, &VAO);
    glBindVertexArray(VAO);

    unsigned int VBO;
    glGenBuffers(1, &VBO);
    glBindBuffers(GL_ARRAY_BUFFER, &VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

    while(!glfwWindowShouldClose(window)) {
        glfwSwapBuffers(window);
        glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);
        glfwPollEvents();
        processInput(window);
    }

    glfwTerminate();

    return 0;
}