【OpenGL】代码记录01创建窗口

创建空窗口：

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

//set key_callback
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode)
{
    // When a user presses the escape key, we set the WindowShouldClose property to true, 
    // closing the application
    if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
        glfwSetWindowShouldClose(window, GL_TRUE);
}

int main()
{
//instantiate the GLFW window
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);//3为版本号
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);//设置为GL_TRUE就可以调整窗口大小


//initial GLFW window
GLFWwindow* window = glfwCreateWindow(800, 600, "LLapuras", nullptr, nullptr);
if (window == nullptr)
{
    std::cout << "Failed to create GLFW window" << std::endl;
    glfwTerminate();
    return -1;
}
//通知GLFW将window的上下文设置为当前线程的主上下文
glfwMakeContextCurrent(window);

//initial GLEW
//GLEW用来管理OpenGL的函数指针，在调用任何OpenGL的函数之要先初始化GLEW

//设置glewExperimental为TRUE可以让GLEW在管理OpenGL的函数指针时更多地使用现代化的技术，
//如果把它设置为GL_FALSE的话可能会在使用OpenGL的核心模式时出现一些问题。
glewExperimental = GL_TRUE;
if (glewInit() != GLEW_OK)
{
    std::cout << "Failed to initialize GLEW" << std::endl;
    return -1;
}

//viewpoint
//告诉opengl需要渲染窗口的尺寸
int width, height;

//获取窗口的width和height in pixels，要以屏幕坐标衡量用glfwGetWindowSize() 
glfwGetFramebufferSize(window, &width, &height);

//OpenGL坐标范围为（-1，1），需要映射为屏幕坐标，
//OpenGL幕后使用glViewport中定义的位置和宽高进行2D坐标的转换
glViewport(0, 0, width, height);

//这句去掉也没事？？是个输入回馈函数
glfwSetKeyCallback(window, key_callback);

// Program loop
//在退出前保持循环
while (!glfwWindowShouldClose(window))
{
    // Check and call events
    glfwPollEvents();

    // Rendering commands here
    glClearColor(0.9f, 0.3f, 0.3f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    // Swap the buffers
    glfwSwapBuffers(window);
}


//释放GLFW分配的内存
glfwTerminate();
return 0;
}

运行：