References:
https://learnopengl.com/
https://learnopengl-cn.github.io/
This section implements the coordinate transformation function and adds more vertices to display the 3D cube and more cubes.
Review graphics knowledge. OpenGL expects that after each vertex shader run, all vertices we can see are in Normalized Device Coordinate (NDC). That is, the x, y, and z coordinates of each vertex should be between -1.0 and 1.0, and vertices beyond this coordinate range will not be visible. OpenGL performs perspective division on clipping coordinates in clip space to transform them into normalized device coordinates. Therefore, our goal is to transfer the vertices to clip space first. The vertex information is initially located in the model space. It needs to be transferred to the world space through the Model matrix, then transferred to the observation space through the View matrix, and finally transferred to the clipping space through the Projection matrix, which is the MVP transformation.
First create a model matrix. This model matrix contains translation, scaling and rotation operations that are applied to all object vertices to transform them into the global world space. This is defined as a rotation of -55 degrees around the x-axis.
//Model矩阵
glm::mat4 modelMat;
modelMat = glm::rotate(modelMat, glm::radians(-55.0f), glm::vec3(1.0f, 0, 0));
Then there is the observation matrix. The goal is to transform to the camera-centered viewing space, which can be achieved by translating the scene along the negative z-axis.
//View矩阵
glm::mat4 viewMat;
viewMat = glm::translate(viewMat, glm::vec3(0, 0, -3.0f));
And finally the projection matrix. The projection matrix is generated by glm::perspective. Its first parameter defines the value of fov, which represents the field of view (Field of View), and sets the size of the viewing space. For a realistic viewing effect, its value is usually set to 45.0f, but for a doom-style result you can set it to a higher value. The second parameter sets the aspect ratio, which is obtained by dividing the viewport's width by its height. The third and fourth parameters set the near and far planes of the frustum. We usually set close range to 0.1f and far range to 100.0f. All vertices within the near and far planes and within the frustum are rendered.
//Projection矩阵
glm::mat4 projMat;
projMat = glm::perspective(glm::radians(45.0f), 1600.0f / 1200.0f, 0.1f, 100.0f);
Next, the corresponding uniform transformation matrix should be declared in the vertex shader. And multiply left to gl_Position in turn:
//顶点着色器编码
#version 330 core
layout(location = 0) in vec3 aPos;
layout(location = 1) in vec3 aColor;
layout(location = 2) in vec2 aTexCoord;
//uniform mat4 transform;
uniform mat4 modelMat;
uniform mat4 viewMat;
uniform mat4 projMat;
out vec4 vertexColor;
out vec2 TexCoord;
void main() {
gl_Position = projMat * viewMat * modelMat * vec4(aPos.x, aPos.y, aPos.z, 1.0);
vertexColor = vec4(aColor, 1.0f);
TexCoord = aTexCoord;
}
Finally pass the matrix to the shader:
glUniformMatrix4fv(glGetUniformLocation(myShader->ID, "modelMat"), 1, GL_FALSE, glm::value_ptr(modelMat)); //把矩阵数据发送给着色器
glUniformMatrix4fv(glGetUniformLocation(myShader->ID, "viewMat"), 1, GL_FALSE, glm::value_ptr(viewMat));
glUniformMatrix4fv(glGetUniformLocation(myShader->ID, "projMat"), 1, GL_FALSE, glm::value_ptr(projMat));
The following effects can be obtained:
In order to make the object show a 3D effect, more faces can be added, each face consists of two triangles with a total of 6 vertices, and six faces are 36 vertices. Add the following numerous vertex information:
float vertices[] = {
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f,
0.5f, -0.5f, -0.5f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, -0.5f, 1.0f, 1.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f
};
The code for parsing vertex data has also changed due to the abandonment of the color attribute:
//位置属性
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0); //告诉OpenGL该如何解析顶点数据（应用到逐个顶点属性上）。参数1：要配置的顶点属性（layout(location = 0)，故0），参数2：指定顶点属性的大小（vec3，故3），参数3：指定数据的类型，参数4：是否希望数据被标准化，参数5：在连续的顶点属性组之间的间隔，参数6：表示位置数据在缓冲中起始位置的偏移量(Offset)。
glEnableVertexAttribArray(0); //以顶点属性位置值作为参数，启用顶点属性，由于前面声明了layout(location = 0)，故为0
//UV属性
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(2);
At the same time, EBO is not used temporarily, so the drawing method is changed from glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0); to glDrawArrays(GL_TRIANGLES, 0, 36); After execution, the following results will be obtained:
The reason for this is the problem of the drawing order between the pixels. The pixels cover each other. The surface drawn later covers the surface drawn before, causing some surfaces that should be blocked to be drawn on the other side of the cube. on the surface. The solution is to turn on the depth buffer. We don't need to deliberately adjust the order of drawing, just turn on the depth buffer, and the minimum depth value will be recorded in the depth buffer. Only pixels smaller than this depth value, that is, "pixels that should be displayed in front" will pass the depth test. is drawn on the screen so that you don't have to worry about the drawing order.
Use glEnable(GL_DEPTH_TEST) to enable depth testing. At the same time, because the depth test is used, the depth buffer needs to be cleared before each rendering iteration, otherwise the depth information of the previous frame is still saved in the buffer. Just like clearing the color buffer, we can clear the depth buffer by specifying the DEPTH_BUFFER_BIT bit in the glClear function: glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); so that the object will be drawn with the correct context:
Next draw more objects, each cube looks the same, the difference is their position in the world and the rotation angle. The graphics layout of the cube is already defined, so we don't need to change our buffer arrays and property arrays when rendering more objects, the only thing we need to do is change the model matrix of each object to transform the cube to the world coordinate system middle.
First, let's define a displacement vector for each cube specifying its position in world space. We will define 10 cube positions in a glm::vec3 array:
glm::vec3 cubePositions[] = {
glm::vec3( 0.0f, 0.0f, 0.0f),
glm::vec3( 2.0f, 5.0f, -15.0f),
glm::vec3(-1.5f, -2.2f, -2.5f),
glm::vec3(-3.8f, -2.0f, -12.3f),
glm::vec3( 2.4f, -0.4f, -3.5f),
glm::vec3(-1.7f, 3.0f, -7.5f),
glm::vec3( 1.3f, -2.0f, -2.5f),
glm::vec3( 1.5f, 2.0f, -2.5f),
glm::vec3( 1.5f, 0.2f, -1.5f),
glm::vec3(-1.3f, 1.0f, -1.5f)
};
In each rendering cycle, the glDrawArrays method is called to draw, the difference is that we pass in a different model matrix to the vertex shader before each rendering. When using the translate method to build a model matrix, pass in the preset cube position value in cubePositions, and give each object a different rotation angle based on the number of renderings, so that their displayed position and rotation information are different:
//循环绘制10个物体
for (int i = 0; i < 10; i++)
{
//每个物体的模型矩阵
glm::mat4 modelMat2;
modelMat2 = glm::translate(modelMat2, cubePositions[i]);
float angle = 20.0f * i;
modelMat2 = glm::rotate(modelMat2, glm::radians(angle), glm::vec3(1.0f, 0.3f, 0.5f));
//告诉OpenGL每个着色器采样器属于哪个纹理单元
glUniform1i(glGetUniformLocation(myShader->ID, "ourTexture"), 0);
glUniform1i(glGetUniformLocation(myShader->ID, "ourFace"), 3);
//glUniformMatrix4fv(glGetUniformLocation(myShader->ID, "transform"), 1, GL_FALSE, glm::value_ptr(trans)); //把矩阵数据发送给着色器
glUniformMatrix4fv(glGetUniformLocation(myShader->ID, "modelMat"), 1, GL_FALSE, glm::value_ptr(modelMat2)); //把矩阵数据发送给着色器
glUniformMatrix4fv(glGetUniformLocation(myShader->ID, "viewMat"), 1, GL_FALSE, glm::value_ptr(viewMat));
glUniformMatrix4fv(glGetUniformLocation(myShader->ID, "projMat"), 1, GL_FALSE, glm::value_ptr(projMat));
glDrawArrays(GL_TRIANGLES, 0, 36);
//glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0); //绘制，参数1：绘制模式（三角形），参数2：绘制顶点数（两个三角形6个顶点），参数3：索引的类型，参数4：指定EBO中的偏移量。
}
Run it to get the following result:
The current code of the main program is as follows:
#define GLEW_STATIC
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <iostream>
#include "Shader.h"
#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
//顶点数据
//float vertices[] = {
// // ---- 位置 ---- ---- 颜色 ---- - 纹理坐标 -
// 0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, // 右上
// 0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, // 右下
// -0.5f, -0.5f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, // 左下
// -0.5f, 0.5f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f // 左上
//};
float vertices[] = {
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f,
0.5f, -0.5f, -0.5f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
0.5f, -0.5f, -0.5f, 1.0f, 1.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f
};
//顶点索引
unsigned int indices[] = {
0, 1, 2, //第一个三角形使用的顶点
2, 3, 0 //第二个三角形使用的顶点
};
//立方体位置
glm::vec3 cubePositions[] = {
glm::vec3(0.0f, 0.0f, 0.0f),
glm::vec3(2.0f, 5.0f, -15.0f),
glm::vec3(-1.5f, -2.2f, -2.5f),
glm::vec3(-3.8f, -2.0f, -12.3f),
glm::vec3(2.4f, -0.4f, -3.5f),
glm::vec3(-1.7f, 3.0f, -7.5f),
glm::vec3(1.3f, -2.0f, -2.5f),
glm::vec3(1.5f, 2.0f, -2.5f),
glm::vec3(1.5f, 0.2f, -1.5f),
glm::vec3(-1.3f, 1.0f, -1.5f)
};
//检查输入函数
void processInput(GLFWwindow* window)
{
//按下ESC键时，将WindowShouldClose设为true，循环绘制将停止
if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
{
glfwSetWindowShouldClose(window, true);
}
}
//视口改变时的回调函数
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
glViewport(0, 0, width, height); //OpenGL渲染窗口的尺寸大小
}
int main()
{
glfwInit(); //初始化GLFW
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); //告诉GLFW要使用OpenGL的版本号
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3); //主版本号、次版本号都为3，即3.3版本
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); //告诉GLFW使用核心模式(Core-profile)
//打开 GLFW Window
GLFWwindow* window = glfwCreateWindow(1600, 1200, "My OpenGL Game", nullptr, nullptr);
if (window == nullptr) //若窗口创建失败，打印错误信息，终止GLFW并return -1
{
printf("Open window failed.");
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window); //创建OpenGL上下文
glfwSetFramebufferSizeCallback(window, framebuffer_size_callback); //用户改变窗口大小的时候，视口调用回调函数
//初始化GLEW
glewExperimental = true;
if (glewInit() != GLEW_OK) //若GLEW初始化失败，打印错误信息并终止GLFW窗口
{
printf("Init GLEW failed.");
glfwTerminate();
return -1;
}
glEnable(GL_DEPTH_TEST);
Shader* myShader = new Shader("vertexSource.txt", "fragmentSource.txt");
//创建VAO（顶点数组对象）
unsigned int VAO;
glGenVertexArrays(1, &VAO); //生成一个顶点数组对象
glBindVertexArray(VAO); //绑定VAO
//创建VBO（顶点缓冲对象）
unsigned int VBO;
glGenBuffers(1, &VBO); //生成缓冲区对象。第一个参数是要生成的缓冲对象的数量，第二个是要输入用来存储缓冲对象名称的数组，由于只需创建一个VBO，因此不需要用数组形式
glBindBuffer(GL_ARRAY_BUFFER, VBO); //把新创建的缓冲绑定到GL_ARRAY_BUFFER目标上，GL_ARRAY_BUFFER是一种顶点缓冲对象的缓冲类型。OpenGL允许同时绑定多个缓冲，只要它们是不同的缓冲类型。
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW); //把定义的数据复制到当前绑定缓冲的函数。参数1：目标缓冲类型，参数2：指定传输数据的大小(以字节为单位)，参数3：我们希望发送的实际数据，参数4：指定显卡如何管理给定的数据，GL_STATIC_DRAW表示数据不会或几乎不会改变。
//创建EBO（元素缓冲对象/索引缓冲对象）
unsigned int EBO;
glGenBuffers(1, &EBO);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
//位置属性
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0); //告诉OpenGL该如何解析顶点数据（应用到逐个顶点属性上）。参数1：要配置的顶点属性（layout(location = 0)，故0），参数2：指定顶点属性的大小（vec3，故3），参数3：指定数据的类型，参数4：是否希望数据被标准化，参数5：在连续的顶点属性组之间的间隔，参数6：表示位置数据在缓冲中起始位置的偏移量(Offset)。
glEnableVertexAttribArray(0); //以顶点属性位置值作为参数，启用顶点属性，由于前面声明了layout(location = 0)，故为0
//颜色属性
//glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
//glEnableVertexAttribArray(1);
//UV属性
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(2);
//使用纹理单元0绑定TexBufferA
unsigned int TexBufferA;
glGenTextures(1, &TexBufferA);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, TexBufferA);
int width, height, nrChannel;
stbi_set_flip_vertically_on_load(true); //翻转图像y轴
//加载并生成第一张纹理
unsigned char* data = stbi_load("container.jpg", &width, &height, &nrChannel, 0);
if (data)
{
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
glGenerateMipmap(GL_TEXTURE_2D);
}
else
{
std::cout << "图片加载失败" << std::endl;
}
stbi_image_free(data); //释放
//使用纹理单元3绑定TexBufferB
unsigned int TexBufferB;
glGenTextures(1, &TexBufferB);
glActiveTexture(GL_TEXTURE3);
glBindTexture(GL_TEXTURE_2D, TexBufferB);
//加载并生成第二张纹理
unsigned char* data2 = stbi_load("awesomeface1.png", &width, &height, &nrChannel, 0);
if (data2)
{
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data2);
glGenerateMipmap(GL_TEXTURE_2D);
}
else
{
std::cout << "图片加载失败" << std::endl;
}
stbi_image_free(data2);
//变换矩阵
glm::mat4 trans;
//trans = glm::translate(trans, glm::vec3(0.3f, 0.3f, 0.2f)); //位移
//trans = glm::rotate(trans, glm::radians(45.0f), glm::vec3(0, 0, 1.0f)); //旋转
//trans = glm::scale(trans, glm::vec3(0.5f, 0.5f, 0.5f)); //缩放
//Model矩阵
glm::mat4 modelMat;
modelMat = glm::rotate(modelMat, glm::radians(-55.0f), glm::vec3(1.0f, 0, 0));
//View矩阵
glm::mat4 viewMat;
viewMat = glm::translate(viewMat, glm::vec3(0, 0, -3.0f));
//Projection矩阵
glm::mat4 projMat;
projMat = glm::perspective(glm::radians(45.0f), 1600.0f / 1200.0f, 0.1f, 100.0f);
//让程序在手动关闭之前不断绘制图像
while (!glfwWindowShouldClose(window))
{
//检测输入
processInput(window);
//渲染指令
glClearColor(0.f, 0.5f, 0.5f, 1.0f); //设置清空屏幕所用的颜色
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); //清空屏幕的颜色缓冲区和深度缓冲区
//绑定纹理到对应的纹理单元
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, TexBufferA);
glActiveTexture(GL_TEXTURE3);
glBindTexture(GL_TEXTURE_2D, TexBufferB);
glBindVertexArray(VAO); //绘制物体的时候就拿出相应的VAO，绑定它
//glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO); //绑定EBO
myShader->use();
//循环绘制10个物体
for (int i = 0; i < 10; i++)
{
//每个物体的模型矩阵
glm::mat4 modelMat2;
modelMat2 = glm::translate(modelMat2, cubePositions[i]);
float angle = 20.0f * i;
modelMat2 = glm::rotate(modelMat2, glm::radians(angle), glm::vec3(1.0f, 0.3f, 0.5f));
//告诉OpenGL每个着色器采样器属于哪个纹理单元
glUniform1i(glGetUniformLocation(myShader->ID, "ourTexture"), 0);
glUniform1i(glGetUniformLocation(myShader->ID, "ourFace"), 3);
//glUniformMatrix4fv(glGetUniformLocation(myShader->ID, "transform"), 1, GL_FALSE, glm::value_ptr(trans)); //把矩阵数据发送给着色器
glUniformMatrix4fv(glGetUniformLocation(myShader->ID, "modelMat"), 1, GL_FALSE, glm::value_ptr(modelMat2)); //把矩阵数据发送给着色器
glUniformMatrix4fv(glGetUniformLocation(myShader->ID, "viewMat"), 1, GL_FALSE, glm::value_ptr(viewMat));
glUniformMatrix4fv(glGetUniformLocation(myShader->ID, "projMat"), 1, GL_FALSE, glm::value_ptr(projMat));
glDrawArrays(GL_TRIANGLES, 0, 36);
//glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0); //绘制，参数1：绘制模式（三角形），参数2：绘制顶点数（两个三角形6个顶点），参数3：索引的类型，参数4：指定EBO中的偏移量。
}
//检查并调用事件，交换缓冲区
glfwSwapBuffers(window); //交换颜色缓冲区，前缓冲区保存最终输出的图像，后缓冲区负责绘制渲染指令，当渲染指令执行完毕后，交换前后缓冲区，使完整图像呈现出来，避免逐像素绘制图案时的割裂感
glfwPollEvents(); //检查触发事件，如键盘输入、鼠标移动等
}
glfwTerminate(); //关闭GLFW并退出
return 0;
}