/*
* 当需要给图形赋予真实颜色的时候，不太可能为没一个顶点指定一个颜色，通常会采用纹理贴图
* 每个顶点关联一个纹理坐标 (Texture Coordinate) 其它片段上进行片段插值
* 
*/#include <iostream>
#define STBI_NO_SIMD
#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"#include <glad/glad.h>   // 把这个头文件放在最上面
#include <GLFW/glfw3.h>
#include <string>
#include <fstream>
#include <sstream>#include "glm/glm.hpp"class MyShader {
public:unsigned int ID;	// 着色器程序 ID// 构造函数读取并构建 shaderMyShader(const char* vertexPath, const char* fragmentPath);// 使用激活 Shadervoid use();// 设置 uniform 的工具函数void setBool(const std::string& name, bool value) const;void setInt(const std::string& name, int value) const;void setFloat(const std::string& name, float value) const;void setVec4(const std::string& name, const glm::vec4& value) const;};MyShader::MyShader(const char* vertexPath, const char* fragmentPath)
{// 从文件加载 shader 的源码// 1.0 从文件路径加载顶点 / 片段源代码std::string vertexCode, fragmentCode;std::ifstream vShaderFile, fShaderFile;// 确保 ifstream 对象可以引发异常vShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);fShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);try{// 打开文件vShaderFile.open(vertexPath);fShaderFile.open(fragmentPath);std::stringstream vShaderStream, fShaderStream;// 将文件的缓冲区内容读入流vShaderStream << vShaderFile.rdbuf();fShaderStream << fShaderFile.rdbuf();// 关闭文件处理程序vShaderFile.close();fShaderFile.close();// 将流转换为字符串vertexCode = vShaderStream.str();fragmentCode = fShaderStream.str();}catch (const std::ifstream::failure e){std::cout << "ERROR::SHADER::FILE_NOT_SUCCESSFULLY_READ" << std::endl;}const char* vShaderCode = vertexCode.c_str();const char* fShaderCode = fragmentCode.c_str();// 编译着色器unsigned int vertexShader, fragmentShader;int success;char infoLog[512];// 顶点着色器vertexShader = glCreateShader(GL_VERTEX_SHADER);glShaderSource(vertexShader, 1, &vShaderCode, nullptr);glCompileShader(vertexShader);glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);if (!success)	// 打印错误提示信息{glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;}//片元着色器fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);glShaderSource(fragmentShader, 1, &fShaderCode, nullptr);glCompileShader(fragmentShader);glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);if (!success){glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << std::endl;}//着色器程序ID = glCreateProgram();glAttachShader(ID, vertexShader);glAttachShader(ID, fragmentShader);glLinkProgram(ID);glGetProgramiv(ID, GL_LINK_STATUS, &success);if (!success){glGetProgramInfoLog(ID, 512, nullptr, infoLog);std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << std::endl;}//删除着色器glDeleteShader(vertexShader);glDeleteShader(fragmentShader);}void MyShader::use()
{glUseProgram(ID);
}void MyShader::setBool(const std::string& name, bool value) const
{glUniform1i(glGetUniformLocation(ID, name.c_str()), (int)value);
}void MyShader::setInt(const std::string& name, int value) const
{glUniform1i(glGetUniformLocation(ID, name.c_str()), value);
}void MyShader::setFloat(const std::string& name, float value) const
{glUniform1i(glGetUniformLocation(ID, name.c_str()), value);
}void MyShader::setVec4(const std::string& name, const glm::vec4& value) const
{glUniform4fv(glGetUniformLocation(ID, name.c_str()), 1, &value[0]);
}//响应键盘输入事件
//ESC推出窗口
void processInput(GLFWwindow* window)
{if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS){glfwSetWindowShouldClose(window, true);}
}//当用户改变窗口的大小的时候，视口也应该被调整。
//对窗口注册一个回调函数(Callback Function)，它会在每次窗口大小被调整的时候被调用
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{//glViewport函数前两个参数控制窗口左下角的位置。第三个和第四个参数控制渲染窗口的宽度和高度（像素）glViewport(0, 0, width, height);
}int main()
{float vertices[] = {// 位置             // 颜色	         // 纹理坐标 0.5f,  0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f,	// 右上0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f,	// 右下-0.5f, -0.5f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f,	// 左下-0.5f,  0.5f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 0.0f	// 左上};unsigned int indices[] = {0, 1, 3,1, 2, 3,};/*******************************************定义常量************************************************///设置窗口的宽和高const unsigned int SCR_WIDTH = 800;const unsigned int SCR_HEIGHT = 600;/*******************************************函数***************************************************///初始化GLFWglfwInit();// 初始化GLFWif (!glfwInit()){std::cerr << "Failed to initialize GLFW" << std::endl;return -1;}//声明版本与核心glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4); //主版本号glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 6); //次版本号glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);//创建窗口并设置其大小，名称，与检测是否创建成功GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", nullptr, nullptr);if (window == nullptr){std::cout << "Failed to create GLFW window" << std::endl;glfwTerminate();return -1;}//创建完毕之后，需要让当前窗口的环境在当前线程上成为当前环境，就是接下来的画图都会画在我们刚刚创建的窗口上glfwMakeContextCurrent(window);//告诉GLFW我们希望每当窗口调整大小的时候调用这个函数glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);//glad寻找opengl的函数地址，调用opengl的函数前需要初始化gladif (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)){std::cout << "Failed to initialize GLAD" << std::endl;return -1;}// 创建一个 shader 的类MyShader shader("shader/shader.vs", "shader/shader.fs");unsigned int VBO, VAO, EBO;glGenVertexArrays(1, &VAO);glBindVertexArray(VAO);         //绑定VAO对象glGenBuffers(1, &VBO);glGenBuffers(1, &EBO);glBindBuffer(GL_ARRAY_BUFFER, VBO);glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);glEnableVertexAttribArray(0);glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));glEnableVertexAttribArray(1);glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));glEnableVertexAttribArray(2);// 绑定 EBOglBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);//链接顶点属性，设置顶点属性指针glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);//以顶点属性位置值作为参数，启用顶点属性；顶点属性默认是禁用的。glBindBuffer(GL_ARRAY_BUFFER, 0);//glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);glBindVertexArray(0);// 读一张纹理图像int width, height, channels;unsigned char* data = stbi_load("lena.jpg", &width, &height, &channels, 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 << "Failed to load texture" << std::endl;}stbi_image_free(data);//glfwWindowShouldClose()检查窗口是否需要关闭。如果是，游戏循环就结束了，接下来我们将会清理资源，结束程序while (!glfwWindowShouldClose(window)){//响应键盘输入processInput(window);//设置清除颜色glClearColor(0.2f, 0.3f, 0.3f, 1.0f);//清除当前窗口，把颜色设置为清除颜色glClear(GL_COLOR_BUFFER_BIT);shader.use();		// 选择流水线// 设置unifor 值float timeValue = glfwGetTime();float greenValue = sin(timeValue) / 2.0f + 0.5f;glm::vec4 color = glm::vec4(0.0f, greenValue, 0.0f, 1.0f);shader.setVec4("ourColor", color);//绑定VAOglBindVertexArray(VAO);glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);//glDrawArrays(GL_TRIANGLES, 0, 3);glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);//线框绘制//glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);//交换颜色缓冲 glfwSwapBuffers(window);//处理事件glfwPollEvents();}//释放前面所申请的资源glfwTerminate(); 清理资源glDeleteVertexArrays(1, &VAO);glDeleteBuffers(1, &VBO);glDeleteBuffers(1, &EBO);glDeleteProgram(shader.ID);return 0;}