[LearnOpenGL]OpenGL绘制一个简单三角形

实现效果：

代码：

// System Headers
#include <glad/glad.h>
#include <GLFW/glfw3.h>

// Standard Headers
#include <cstdio>
#include <cstdlib>
#include <iostream>

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

// 片段着色器源码
const char *fragmentShaderSource = "#version 330 core\n"
    "out vec4 FragColor;"
    "void main()\n"
    "{\n"
        "FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);\n"
    "}\n\0";

// 调整窗口大小
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
    glViewport(0, 0, width, height);
}
// 键入Esc退出处理
void processInput(GLFWwindow *window)
{
    if(glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
        glfwSetWindowShouldClose(window, true);
}

int main()
{
//---Part1.准备窗口工作------------
    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
#ifdef __APPLE__
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
#endif

    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);

    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
    {
        std::cout << "Failed to initialize GLAD" << std::endl;
        return -1;
    }

    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
//---End Part1.准备窗口工作------------

//---Part2.编译链接形成着色器程序------------
    unsigned int vertexShader;
    vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
    glCompileShader(vertexShader);
    int  success;
    char infoLog[512];
    glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
    if(!success)
    {
        glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
    }
    unsigned int fragmentShader;
    fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
    glCompileShader(fragmentShader);
    glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
    if(!success)
    {
        glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
    }
    unsigned int shaderProgram;
    shaderProgram = glCreateProgram();
    glAttachShader(shaderProgram, vertexShader);
    glAttachShader(shaderProgram, fragmentShader);
    glLinkProgram(shaderProgram);
    glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);
    if(!success) {
        glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
        std::cout << "ERROR::PROGRAM::CREATE::LINK_FAILED\n" << infoLog << std::endl;
    }
    glDeleteShader(vertexShader);
    glDeleteShader(fragmentShader);
//---End Part2.编译链接形成着色器程序------------

//---Part3.准备及绑定顶点数组对象和顶点缓存对象------------
    float vertices[] = {
        -0.5f, -0.5f, 0.0f, // left
        0.5f, -0.5f, 0.0f, // right
        0.0f,  0.5f, 0.0f  // top
    };
    unsigned int VAO;
    glGenVertexArrays(1, &VAO);
    unsigned int VBO;
    glGenBuffers(1, &VBO);
    glBindVertexArray(VAO);
    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glBindVertexArray(0);
//---End Part3.准备及绑定顶点数组对象和顶点缓存对象------------

//---Part4.循环渲染------------
    while(!glfwWindowShouldClose(window))
    {
        processInput(window);

        glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);

        glUseProgram(shaderProgram);
        glBindVertexArray(VAO);
        glDrawArrays(GL_TRIANGLES, 0, 3);

        glfwSwapBuffers(window);
        glfwPollEvents();
    }
//---End Part4.循环渲染------------

//---Part5.收尾工作------------
    glDeleteVertexArrays(1, &VAO);
    glDeleteBuffers(1, &VBO);
    glfwTerminate();
//---End Part5.收尾工作------------

    return 0;
}