learn-opengl/05-coordinate_systems/src/main.cpp

#define _USE_MATH_DEFINES
#include <math.h>
#include "dbc.hpp"
#include <print>
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <vector>
#include <functional>
#include "shader.hpp"
#include <stb_image.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include "data.hpp"
#include "physics.hpp"

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

const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;

struct Config {
  Shader shader;
  unsigned int VAO = 0;
  unsigned int VBO = 0;
  unsigned int texture1 = 0;
  unsigned int texture2 = 0;
};

void init_glfw() {
  glfwInit();
  glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
  glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
  glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
}

void framebuffer_size_callback(GLFWwindow *, int width, int height) {
  glViewport(0, 0, width, height);
}

GLFWwindow* create_window() {
  GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
  dbc::check(window != NULL, "failed to open window");

  glfwMakeContextCurrent(window);

  glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);

  auto good = gladLoadGLLoader((GLADloadproc)glfwGetProcAddress);
  dbc::check(good, "failed to load GLAD");

  return window;
}

void processInput(GLFWwindow *window, BoxTest &box) {
  if(glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS) {
    glfwSetWindowShouldClose(window, true);
  }

  if(glfwGetKey(window, GLFW_KEY_SPACE) == GLFW_PRESS) {
    b2Vec2 force(0.0f, 0.5f);
    for(size_t i = 0; i < BODY_COUNT; i++) {
      box.bodies[i]->ApplyForceToCenter(force, true);
      box.bodies[i]->ApplyTorque(0.1f, true);
    }
  }
}

unsigned int load_texture(const std::string& image_file) {
  unsigned int texture_id;
  glGenTextures(1, &texture_id);
  glBindTexture(GL_TEXTURE_2D, texture_id);

  // set the texture wrapping parameters
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

  // set texture filtering parameters
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

  int width = 0;
  int height = 0;
  int nrChannels = 0;
  stbi_set_flip_vertically_on_load(true);

  unsigned char *data = stbi_load(image_file.c_str(), &width, &height, &nrChannels, 0);

  dbc::check(data != nullptr, std::format("Failed to load texture: {}", image_file));

  dbc::check(nrChannels == 3 || nrChannels == 4,
      std::format("Image {} has invalid channels {} should be 3 or 4.", image_file, nrChannels));

  auto rgb_or_a = nrChannels == 3 ? GL_RGB : GL_RGBA;

  glTexImage2D(GL_TEXTURE_2D, 0, rgb_or_a, width, height, 0, rgb_or_a, GL_UNSIGNED_BYTE, data);
  glGenerateMipmap(GL_TEXTURE_2D);

  stbi_image_free(data);

  return texture_id;
}

Config setup() {
  glEnable(GL_DEPTH_TEST);

  Config config{{"shaders/4.2.texture.vs", "shaders/4.2.texture.fs"}};

  unsigned int VBO = 0;
  unsigned int VAO = 0;

  glGenVertexArrays(1, &VAO);
  glGenBuffers(1, &VBO);

  glBindVertexArray(VAO);

  glBindBuffer(GL_ARRAY_BUFFER, VBO);
  glBufferData(GL_ARRAY_BUFFER, sizeof(vertices_3d), vertices_3d, GL_STATIC_DRAW);

  glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
  glEnableVertexAttribArray(0);

  glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
  glEnableVertexAttribArray(1);

  config.texture1 = load_texture("resources/textures/container.jpg");
  config.texture2 = load_texture("resources/textures/awesomeface.png");

  config.shader.use();
  config.shader.setInt("texture1", 0);
  config.shader.setInt("texture2", 1);

  config.VAO = VAO;
  config.VBO = VBO;

  return config;
}

void render(GLFWwindow* window, const Config& config, BoxTest& box, b2World& world) {
  glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

  glActiveTexture(GL_TEXTURE0);
  glBindTexture(GL_TEXTURE_2D, config.texture1);
  glActiveTexture(GL_TEXTURE1);
  glBindTexture(GL_TEXTURE_2D, config.texture2);

  config.shader.use();

  // this is position
  float time = glfwGetTime();
  Box2d_step_world(world);


  glm::mat4 view = glm::mat4(1.0f);
  view = glm::translate(view, glm::vec3(0.0f, 0.0f, -3.0f));
  config.shader.setMat4("view", view);

  glm::mat4 projection = glm::mat4(1.0f);
  projection = glm::perspective(glm::radians(45.0f), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
  config.shader.setMat4("projection", projection);

  glBindVertexArray(config.VAO);

  for(unsigned int i = 0; i < BODY_COUNT; i++) {
    glm::mat4 model = glm::mat4(1.0f);

    // get position from box
    b2Vec2 position = box.bodies[i]->GetPosition();
    float angle = box.bodies[i]->GetAngle();

    model = glm::translate(model, glm::vec3(position.x, position.y, 0.0f));
    model = glm::rotate(model, angle / 5.0f, glm::vec3(1.0f, 0.0f, 0.0f));
    model = glm::rotate(model, glm::radians(time * 10.0f), glm::vec3(0.0f, 1.0f, 1.0f));

    config.shader.setMat4("model", model);

    glDrawArrays(GL_TRIANGLES, 0, 36);
  }

  glfwSwapBuffers(window);
  glfwPollEvents();
}

void cleanup(Config& config) {
  glDeleteVertexArrays(1, &config.VAO);
  glDeleteBuffers(1, &config.VAO);
  glDeleteBuffers(1, &config.VBO);
  config.shader.cleanup();
}

int main() {
  init_glfw();

  b2Vec2 gravity(0.0f, -10.0f);
  b2World world(gravity);
  BoxTest box = Box2d_setup(world);

  auto window = create_window();

  auto config = setup();

  while(!glfwWindowShouldClose(window)) {
    processInput(window, box);
    render(window, config, box, world);
  }

  cleanup(config);

  glfwTerminate();

  return 0;
}