justhomework/OpenGL/hello/src/main.cpp

#include "glad/glad.h"
#include "shader.h"
#include "stb_image.h"
#include <GLFW/glfw3.h>
#include <cmath>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include <iostream>

// 四边形顶点
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
};

// 索引
unsigned int indices[] = {
    0, 1, 3, // 第一个三角形
    1, 2, 3  // 第二个三角形
};

void framebuffer_size_callback(GLFWwindow *window, int width, int height);
void processInput(GLFWwindow *window);

// settings
const unsigned int SCR_WIDTH = 600;
const unsigned int SCR_HEIGHT = 600;

int main() {

  // 设置 glfw
  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);

  // 创建窗口
  GLFWwindow *window =
      glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
  if (window == NULL) {
    std::cout << "Failed to create GLFW window" << std::endl;
    glfwTerminate();
    return -1;
  }
  glfwMakeContextCurrent(window);

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

  // 设置视口
  glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);

  // 创建着色器程序
  Shader shader = Shader("src/tex.vs", "src/tex.fs");

  unsigned int VAO, VBO, EBO;
  // 创建顶点数组对象
  glGenVertexArrays(1, &VAO);
  glBindVertexArray(VAO);

  // 创建顶点缓冲对象
  glGenBuffers(1, &VBO);
  glBindBuffer(GL_ARRAY_BUFFER, VBO);
  glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

  // 创建索引缓冲对象
  glGenBuffers(1, &EBO);
  glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
  glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices,
               GL_STATIC_DRAW);

  // 顶点属性
  glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void *)0);
  glEnableVertexAttribArray(0);
  // 颜色属性
  glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float),
                        (void *)(3 * sizeof(float)));
  glEnableVertexAttribArray(1);
  // 纹理坐标属性
  glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float),
                        (void *)(6 * sizeof(float)));
  glEnableVertexAttribArray(2);

  // 创建纹理
  unsigned int texture1, texture2;
  glGenTextures(1, &texture1);
  glBindTexture(GL_TEXTURE_2D, texture1);
  // 设置纹理环绕方式
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
  // 设置纹理过滤方式
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
                  GL_LINEAR_MIPMAP_LINEAR);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

  // 加载并生成纹理
  int width, height, nrChannels;
  // 图片翻转y轴
  stbi_set_flip_vertically_on_load(true);
  unsigned char *data =
      stbi_load("resources/container.jpg", &width, &height, &nrChannels, 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);

  glGenTextures(1, &texture2);
  glBindTexture(GL_TEXTURE_2D, texture2);
  // 设置纹理环绕方式
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
  // 设置纹理过滤方式
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
                  GL_LINEAR_MIPMAP_LINEAR);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

  // 加载并生成纹理
  // 图片翻转y轴
  stbi_set_flip_vertically_on_load(true);
  data =
      stbi_load("resources/awesomeface.png", &width, &height, &nrChannels, 0);
  if (data) {

    // note that the awesomeface.png has transparency and thus an alpha channel,
    // so make sure to tell OpenGL the data type is of GL_RGBA
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA,
                 GL_UNSIGNED_BYTE, data);
    glGenerateMipmap(GL_TEXTURE_2D);
  } else {
    std::cout << "Failed to load texture" << std::endl;
  }
  stbi_image_free(data);

  // 激活着色器
  shader.use();
  // 绑定纹理
  shader.setInt("texture1", 0);
  shader.setInt("texture2", 1);

  // create transformations
  glm::mat4 model = glm::mat4(1.0f);
  glm::mat4 view = glm::mat4(1.0f);
  glm::mat4 projection = glm::mat4(1.0f);
  model = glm::rotate(model, glm::radians(-55.0f), glm::vec3(1.0f, 0.0f, 0.0f));
  view = glm::translate(view, glm::vec3(0.0f, 0.0f, -3.0f));
  projection = glm::perspective(
      glm::radians(45.0f), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
  shader.setMat4("model", model);
  shader.setMat4("view", view);
  shader.setMat4("projection", projection);

  // 循环渲染
  while (!glfwWindowShouldClose(window)) {
    // 处理输入
    processInput(window);

    // 设置为白色
    glClearColor(1.0f, 1.0f, 1.0f, 0.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    // 绑定纹理
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, texture1);
    glActiveTexture(GL_TEXTURE1);
    glBindTexture(GL_TEXTURE_2D, texture2);

    // 绘制三角形
    shader.use();

    // 设置变换矩阵
    glm::mat4 trans(1.0f);
    trans = glm::rotate(trans, (float)glfwGetTime(), glm::vec3(0.0, 0.25,
    0.0));
    shader.setMat4("trans", trans);
    glBindVertexArray(VAO);
    glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);

    // 检查并调用事件，交换缓冲
    glfwSwapBuffers(window);
    glfwPollEvents();
  }

  // 释放资源
  glfwTerminate();
  return 0;
}

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

// 窗口大小改变时回调该函数
void framebuffer_size_callback(GLFWwindow *window, int width, int height) {
  glViewport(0, 0, width, height);
}