#include "logger.h"

#include "stb_image.h"

// I think this was for the OpenGL 4 book font file tutorial
//#define STB_IMAGE_WRITE_IMPLEMENTATION
//#include "stb_image_write.h"

#define _USE_MATH_DEFINES
#define GLM_SWIZZLE

// This is to fix a non-alignment issue when passing vec4 params.
// Check if it got fixed in a later version of GLM
#define GLM_FORCE_PURE

#include <glm/mat4x4.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>

#include "IMGUI/imgui.h"
#include "imgui_impl_glfw_gl3.h"

#include <GL/glew.h>
#include <GLFW/glfw3.h>

#include <cstdio>
#include <iostream>
#include <fstream>
#include <cmath>
#include <string>
#include <array>
#include <vector>
#include <queue>
#include <map>

using namespace std;
using namespace glm;

struct SceneObject {
   unsigned int id;
   mat4 model_mat, model_base, model_transform;
   GLuint shader_program;
   unsigned int num_points;
   GLint vertex_vbo_offset;
   GLint ubo_offset;
   vector<GLfloat> points;
   vector<GLfloat> colors;
   vector<GLfloat> texcoords;
   vector<GLfloat> normals;
   vector<GLfloat> selected_colors;
};

enum State {
   STATE_MAIN_MENU,
   STATE_GAME,
};

enum Event {
   EVENT_GO_TO_MAIN_MENU,
   EVENT_GO_TO_GAME,
   EVENT_QUIT,
};

#define NUM_KEYS (512)
#define ONE_DEG_IN_RAD ((2.0f * M_PI) / 360.0f) // 0.017444444 (maybe make this a const instead)

const int KEY_STATE_UNCHANGED = -1;
const bool FULLSCREEN = false;
const bool SHOW_FPS = false;
const bool DISABLE_VSYNC = false; // disable vsync to see real framerate
unsigned int MAX_UNIFORMS = 0; // Requires OpenGL constants only available at runtime, so it can't be const

int key_state[NUM_KEYS];
bool key_pressed[NUM_KEYS];

int width = 640;
int height = 480;

double fps;

vec3 cam_pos;

mat4 view_mat;
mat4 proj_mat;

vector<SceneObject> objects;
queue<Event> events;

SceneObject* clickedObject = NULL;
SceneObject* selectedObject = NULL;

float NEAR_CLIP = 0.1f;
float FAR_CLIP = 100.0f;

// Should really have some array or struct of UI-related variables
bool isRunning = true;

ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);

void glfw_error_callback(int error, const char* description);

void mouse_button_callback(GLFWwindow* window, int button, int action, int mods);
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods);

bool faceClicked(array<vec3, 3> points, SceneObject* obj, vec4 world_ray, vec4 cam, vec4& click_point);
bool insideTriangle(vec3 p, array<vec3, 3> triangle_points);

GLuint loadShader(GLenum type, string file);
GLuint loadShaderProgram(string vertexShaderPath, string fragmentShaderPath);
unsigned char* loadImage(string file_name, int* x, int* y);

void printVector(string label, vec3 v);
void print4DVector(string label, vec4 v);

void addObjectToScene(SceneObject& obj);
void populateBuffers(vector<SceneObject>& objects,
                     GLuint* points_vbo,
                     GLuint* colors_vbo,
                     GLuint* selected_colors_vbo,
                     GLuint* texcoords_vbo,
                     GLuint* normals_vbo,
                     GLuint* ubo,
                     GLuint* model_mat_idx_vbo,
                     map<GLuint, unsigned int>& shaderCounts,
                     map<GLuint, unsigned int>& curShaderBase);

void transformObject(SceneObject& obj, const mat4& transform, GLuint ubo);

void renderMainMenu();
void renderMainMenuGui();

void renderScene(vector<SceneObject>& objects,
                  GLuint color_sp, GLuint texture_sp,
                  GLuint vao1, GLuint vao2,
                  GLuint points_vbo, GLuint normals_vbo,
                  GLuint colors_vbo, GLuint texcoords_vbo, GLuint selected_colors_vbo,
                  SceneObject* selectedObject,
                  map<GLuint, unsigned int>& shaderCounts,
                  map<GLuint, unsigned int>& curShaderBase);
void renderSceneGui();

void spawnAsteroid(vec3 pos, GLuint shader);

int main(int argc, char* argv[]) {
   cout << "New OpenGL Game" << endl;

   if (!restart_gl_log()) {}
   gl_log("starting GLFW\n%s\n", glfwGetVersionString());

   glfwSetErrorCallback(glfw_error_callback);
   if (!glfwInit()) {
      fprintf(stderr, "ERROR: could not start GLFW3\n");
      return 1;
   }

#ifdef __APPLE__
   glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
   glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
   glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
   glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
#endif

   glfwWindowHint(GLFW_SAMPLES, 4);

   GLFWwindow* window = NULL;
   GLFWmonitor* mon = NULL;

   if (FULLSCREEN) {
      mon = glfwGetPrimaryMonitor();
      const GLFWvidmode* vmode = glfwGetVideoMode(mon);

      width = vmode->width;
      height = vmode->height;
      cout << "Fullscreen resolution " << vmode->width << "x" << vmode->height << endl;
   }
   window = glfwCreateWindow(width, height, "New OpenGL Game", mon, NULL);

   if (!window) {
      fprintf(stderr, "ERROR: could not open window with GLFW3\n");
      glfwTerminate();
      return 1;
   }

   glfwMakeContextCurrent(window);
   glewExperimental = GL_TRUE;
   glewInit();

   /*
   * RENDERING ALGORITHM NOTES:
   *
   * Basically, I need to split my objects into groups, so that each group fits into
   * GL_MAX_UNIFORM_BLOCK_SIZE. I need to have an offset and a size for each group.
   * Getting the offset is straitforward. The size may as well be GL_MAX_UNIFORM_BLOCK_SIZE
   * for each group, since it seems that smaller sizes just round up to the nearest GL_MAX_UNIFORM_BLOCK_SIZE
   *
   * I'll need to have a loop inside my render loop that calls glBindBufferRange(GL_UNIFORM_BUFFER, ...
   * for every 1024 objects and then draws all those objects with one glDraw call.
   *
   * Since I currently have very few objects, I'll wait to implement this  until I have
   * a reasonable number of objects always using the same shader.
   */

   GLint UNIFORM_BUFFER_OFFSET_ALIGNMENT, MAX_UNIFORM_BLOCK_SIZE;
   glGetIntegerv(GL_UNIFORM_BUFFER_OFFSET_ALIGNMENT, &UNIFORM_BUFFER_OFFSET_ALIGNMENT);
   glGetIntegerv(GL_MAX_UNIFORM_BLOCK_SIZE, &MAX_UNIFORM_BLOCK_SIZE);

   MAX_UNIFORMS = MAX_UNIFORM_BLOCK_SIZE / sizeof(mat4);

   cout << "UNIFORM_BUFFER_OFFSET_ALIGNMENT: " << UNIFORM_BUFFER_OFFSET_ALIGNMENT << endl;
   cout << "MAX_UNIFORMS: " << MAX_UNIFORMS << endl;

   // Setup Dear ImGui binding
   IMGUI_CHECKVERSION();
   ImGui::CreateContext();
   ImGuiIO& io = ImGui::GetIO(); (void)io;
   //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;  // Enable Keyboard Controls
   //io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;   // Enable Gamepad Controls
   ImGui_ImplGlfwGL3_Init(window, true);

   // Setup style
   ImGui::StyleColorsDark();
   //ImGui::StyleColorsClassic();

   glfwSetMouseButtonCallback(window, mouse_button_callback);
   glfwSetKeyCallback(window, key_callback);

   const GLubyte* renderer = glGetString(GL_RENDERER);
   const GLubyte* version = glGetString(GL_VERSION);
   printf("Renderer: %s\n", renderer);
   printf("OpenGL version supported %s\n", version);

   glEnable(GL_DEPTH_TEST);
   glDepthFunc(GL_LESS);

   glEnable(GL_CULL_FACE);
   // glCullFace(GL_BACK);
   // glFrontFace(GL_CW);

   int x, y;
   unsigned char* texImage = loadImage("test.png", &x, &y);
   if (texImage) {
     cout << "Yay, I loaded an image!" << endl;
     cout << x << endl;
     cout << y << endl;
     printf("first 4 bytes are: %i %i %i %i\n", texImage[0], texImage[1], texImage[2], texImage[3]);
   }

   GLuint tex = 0;
   glGenTextures(1, &tex);
   glActiveTexture(GL_TEXTURE0);
   glBindTexture(GL_TEXTURE_2D, tex);
   glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, x, y, 0, GL_RGBA, GL_UNSIGNED_BYTE, texImage);

   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

   /* RENDERING ALGORITHM
    * 
    * Create a separate vbo for each of the following things:
    * - points
    * - colors
    * - texture coordinates
    * - selected colors
    * - normals
    * - indices into a ubo that stores a model matrix for each object
    *
    * Also, make a model matrix ubo, the entirety of which will be passed to the vertex shader.
    * The vbo containing the correct index into the ubo (mentioned above) will be used to select
    * the right model matrix for each point. The index in the vbo will be the saem for all points
    * of any given object.
    *
    * There will be two shader programs for now, one for draing colored objects, and another for
    * drawing textured ones. The points, normals, and model mat ubo indices will be passed to both
    * shaders, while the colors vbo will only be passed to the colors shader, and the texcoords vbo
    * only to the texture shader.
    *
    * Right now, the currently selected object is drawn using one color (specified in the selected
    * colors vbo) regardless of whether it is normally rendering using colors or a texture. The selected
    * object is rendering by binding the selected colors vbo in place of the colors vbo and using the colors
    * shader. Then, the selected object is redrawn along with all other objects, but the depth buffer test
    * prevents the unselected version of the object from appearing on the screen. This lets me render all the
    * objects that use a particular shader using one glDrawArrays() call.
    */

   GLuint color_sp = loadShaderProgram("./color.vert", "./color.frag");
   GLuint texture_sp = loadShaderProgram("./texture.vert", "./texture.frag");

   SceneObject obj;
   mat4 T_model, R_model;

   /*
   // triangle
   obj = SceneObject();
   obj.shader_program = color_sp;
   obj.points = {
       0.0f,  0.5f,  0.0f,
      -0.5f, -0.5f,  0.0f,
       0.5f, -0.5f,  0.0f,
       0.5f, -0.5f,  0.0f,
      -0.5f, -0.5f,  0.0f,
       0.0f,  0.5f,  0.0f,
   };
   obj.colors = {
      1.0f, 0.0f, 0.0f,
      0.0f, 0.0f, 1.0f,
      0.0f, 1.0f, 0.0f,
      0.0f, 1.0f, 0.0f,
      0.0f, 0.0f, 1.0f,
      1.0f, 0.0f, 0.0f,
   };
   obj.texcoords = {
      1.0f, 1.0f,
      0.0f, 1.0f,
      0.0f, 0.0f,
      1.0f, 1.0f,
      0.0f, 0.0f,
      1.0f, 0.0f
   };
   obj.selected_colors = {
      0.0f, 1.0f, 0.0f,
      0.0f, 1.0f, 0.0f,
      0.0f, 1.0f, 0.0f,
      0.0f, 1.0f, 0.0f,
      0.0f, 1.0f, 0.0f,
      0.0f, 1.0f, 0.0f,
   };

   T_model = translate(mat4(), vec3(0.45f, 0.0f, 0.0f));
   R_model = rotate(mat4(), 0.0f, vec3(0.0f, 1.0f, 0.0f));
   obj.model_base = T_model*R_model;

   addObjectToScene(obj);

   // square
   obj = SceneObject();
   obj.shader_program = texture_sp;
   obj.points = {
       0.5f,  0.5f,  0.0f,
      -0.5f,  0.5f,  0.0f,
      -0.5f, -0.5f,  0.0f,
       0.5f,  0.5f,  0.0f,
      -0.5f, -0.5f,  0.0f,
       0.5f, -0.5f,  0.0f,
   };
   obj.colors = {
      1.0f, 0.0f, 0.0f,
      0.0f, 0.0f, 1.0f,
      0.0f, 1.0f, 0.0f,
      0.0f, 1.0f, 0.0f,
      0.0f, 0.0f, 1.0f,
      1.0f, 0.0f, 0.0f,
   };
   obj.texcoords = {
      1.0f, 1.0f,
      0.0f, 1.0f,
      0.0f, 0.0f,
      1.0f, 1.0f,
      0.0f, 0.0f,
      1.0f, 0.0f
   };
   obj.selected_colors = {
      0.0f, 0.6f, 0.9f,
      0.0f, 0.6f, 0.9f,
      0.0f, 0.6f, 0.9f,
      0.0f, 0.6f, 0.9f,
      0.0f, 0.6f, 0.9f,
      0.0f, 0.6f, 0.9f,
   };

   T_model = translate(mat4(), vec3(-0.5f, 0.0f, -1.00f));
   R_model = rotate(mat4(), 0.5f, vec3(0.0f, 1.0f, 0.0f));
   obj.model_base = T_model*R_model;

   addObjectToScene(obj);
   */

   // player ship
   obj = SceneObject();
   obj.shader_program = color_sp;
   obj.points = {
      //back
      -0.5f,  0.3f,  0.0f,
      -0.5f,  0.0f,  0.0f,
       0.5f,  0.0f,  0.0f,
      -0.5f,  0.3f,  0.0f,
       0.5f,  0.0f,  0.0f,
       0.5f,  0.3f,  0.0f,

      // left back
      -0.5f,  0.3f, -2.0f,
      -0.5f,  0.0f, -2.0f,
      -0.5f,  0.0f,  0.0f,
      -0.5f,  0.3f, -2.0f,
      -0.5f,  0.0f,  0.0f,
      -0.5f,  0.3f,  0.0f,

      // right back
       0.5f,  0.3f,  0.0f,
       0.5f,  0.0f,  0.0f,
       0.5f,  0.0f, -2.0f,
       0.5f,  0.3f,  0.0f,
       0.5f,  0.0f, -2.0f,
       0.5f,  0.3f, -2.0f,

      // left mid
      -0.25f,  0.3f, -3.0f,
      -0.25f,  0.0f, -3.0f,
      -0.5f,  0.0f, -2.0f,
      -0.25f,  0.3f, -3.0f,
      -0.5f,  0.0f, -2.0f,
      -0.5f,  0.3f, -2.0f,

      // right mid
       0.5f,  0.3f, -2.0f,
       0.5f,  0.0f, -2.0f,
       0.25f,  0.0f, -3.0f,
       0.5f,  0.3f, -2.0f,
       0.25f,  0.0f, -3.0f,
       0.25f,  0.3f, -3.0f,

      // left front
       0.0f,  0.0f, -3.5f,
      -0.25f,  0.0f, -3.0f,
      -0.25f,  0.3f, -3.0f,

      // right front
       0.25f,  0.3f, -3.0f,
       0.25f,  0.0f, -3.0f,
       0.0f,  0.0f, -3.5f,

      // top back
      -0.5f,  0.3f, -2.0f,
      -0.5f,  0.3f,  0.0f,
       0.5f,  0.3f,  0.0f,
      -0.5f,  0.3f, -2.0f,
       0.5f,  0.3f,  0.0f,
       0.5f,  0.3f, -2.0f,

      // bottom back
      -0.5f,  0.0f,  0.0f,
      -0.5f,  0.0f, -2.0f,
       0.5f,  0.0f,  0.0f,
       0.5f,  0.0f,  0.0f,
      -0.5f,  0.0f, -2.0f,
       0.5f,  0.0f, -2.0f,

      // top mid
      -0.25f,  0.3f, -3.0f,
      -0.5f,  0.3f, -2.0f,
       0.5f,  0.3f, -2.0f,
      -0.25f,  0.3f, -3.0f,
       0.5f,  0.3f, -2.0f,
       0.25f,  0.3f, -3.0f,

      // bottom mid
      -0.5f,  0.0f, -2.0f,
      -0.25f,  0.0f, -3.0f,
       0.5f,  0.0f, -2.0f,
       0.5f,  0.0f, -2.0f,
      -0.25f,  0.0f, -3.0f,
       0.25f,  0.0f, -3.0f,

      // top front
      -0.25f,  0.3f, -3.0f,
       0.25f,  0.3f, -3.0f,
       0.0f,  0.0f, -3.5f,

      // bottom front
       0.25f,  0.0f, -3.0f,
      -0.25f,  0.0f, -3.0f,
       0.0f,  0.0f, -3.5f,

      // left wing start back
      -1.5f,  0.3f,  0.0f,
      -1.5f,  0.0f,  0.0f,
      -0.5f,  0.0f,  0.0f,
      -1.5f,  0.3f,  0.0f,
      -0.5f,  0.0f,  0.0f,
      -0.5f,  0.3f,  0.0f,

      // left wing start top
      -0.5f,  0.3f, -0.3f,
      -1.3f,  0.3f, -0.3f,
      -1.5f,  0.3f,  0.0f,
      -0.5f,  0.3f, -0.3f,
      -1.5f,  0.3f,  0.0f,
      -0.5f,  0.3f,  0.0f,

      // left wing start front
      -0.5f,  0.3f, -0.3f,
      -0.5f,  0.0f, -0.3f,
      -1.3f,  0.0f, -0.3f,
      -0.5f,  0.3f, -0.3f,
      -1.3f,  0.0f, -0.3f,
      -1.3f,  0.3f, -0.3f,

      // left wing start bottom
      -0.5f, 0.0f, 0.0f,
      -1.5f, 0.0f, 0.0f,
      -1.3f, 0.0f, -0.3f,
      -0.5f, 0.0f, 0.0f,
      -1.3f, 0.0f, -0.3f,
      -0.5f, 0.0f, -0.3f,

      // left wing end outside
      -1.5f,  0.3f,  0.0f,
      -2.2f,  0.15f, -0.8f,
      -1.5f,  0.0f,  0.0f,

      // left wing end top
      -1.3f,  0.3f, -0.3f,
      -2.2f,  0.15f, -0.8f,
      -1.5f,  0.3f,  0.0f,

      // left wing end front
      -1.3f, 0.0f, -0.3f,
      -2.2f, 0.15f, -0.8f,
      -1.3f, 0.3f, -0.3f,

      // left wing end bottom
      -1.5f, 0.0f, 0.0f,
      -2.2f,  0.15f, -0.8f,
      -1.3f, 0.0f, -0.3f,

      // right wing start back
       1.5f, 0.0f, 0.0f,
       1.5f, 0.3f, 0.0f,
       0.5f, 0.0f, 0.0f,
       0.5f, 0.0f, 0.0f,
       1.5f, 0.3f, 0.0f,
       0.5f, 0.3f, 0.0f,

      // right wing start top
       1.3f, 0.3f, -0.3f,
       0.5f, 0.3f, -0.3f,
       1.5f, 0.3f, 0.0f,
       1.5f, 0.3f, 0.0f,
       0.5f, 0.3f, -0.3f,
       0.5f, 0.3f, 0.0f,

      // right wing start front
       0.5f,  0.0f, -0.3f,
       0.5f,  0.3f, -0.3f,
       1.3f,  0.0f, -0.3f,
       1.3f,  0.0f, -0.3f,
       0.5f,  0.3f, -0.3f,
       1.3f,  0.3f, -0.3f,

      // right wing start bottom
       1.5f, 0.0f, 0.0f,
       0.5f, 0.0f, 0.0f,
       1.3f, 0.0f, -0.3f,
       1.3f, 0.0f, -0.3f,
       0.5f, 0.0f, 0.0f,
       0.5f, 0.0f, -0.3f,

      // right wing end outside
       2.2f,  0.15f, -0.8f,
       1.5f,  0.3f,  0.0f,
       1.5f,  0.0f,  0.0f,

      // right wing end top
       2.2f,  0.15f, -0.8f,
       1.3f,  0.3f, -0.3f,
       1.5f,  0.3f,  0.0f,

      // right wing end front
       2.2f, 0.15f, -0.8f,
       1.3f, 0.0f, -0.3f,
       1.3f, 0.3f, -0.3f,

      // right wing end bottom
       2.2f,  0.15f, -0.8f,
       1.5f, 0.0f, 0.0f,
       1.3f, 0.0f, -0.3f,
   };
   obj.colors = {
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,

      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,

      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,

      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,

      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,

      0.0f, 0.0f, 1.0f,
      0.0f, 0.0f, 1.0f,
      0.0f, 0.0f, 1.0f,

      0.0f, 0.0f, 1.0f,
      0.0f, 0.0f, 1.0f,
      0.0f, 0.0f, 1.0f,

      0.0f, 0.0f, 1.0f,
      0.0f, 0.0f, 1.0f,
      0.0f, 0.0f, 1.0f,
      0.0f, 0.0f, 1.0f,
      0.0f, 0.0f, 1.0f,
      0.0f, 0.0f, 1.0f,

      0.0f, 0.0f, 1.0f,
      0.0f, 0.0f, 1.0f,
      0.0f, 0.0f, 1.0f,
      0.0f, 0.0f, 1.0f,
      0.0f, 0.0f, 1.0f,
      0.0f, 0.0f, 1.0f,

      0.0f, 0.0f, 1.0f,
      0.0f, 0.0f, 1.0f,
      0.0f, 0.0f, 1.0f,
      0.0f, 0.0f, 1.0f,
      0.0f, 0.0f, 1.0f,
      0.0f, 0.0f, 1.0f,

      0.0f, 0.0f, 1.0f,
      0.0f, 0.0f, 1.0f,
      0.0f, 0.0f, 1.0f,
      0.0f, 0.0f, 1.0f,
      0.0f, 0.0f, 1.0f,
      0.0f, 0.0f, 1.0f,

      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,

      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,

      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,

      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,

      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,

      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,

      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,

      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,

      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,

      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,

      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,

      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,

      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,

      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,

      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,

      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,

      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,

      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
      0.0f, 0.0f, 0.3f,
   };
   obj.texcoords = { 0.0f };
   obj.selected_colors = { 0.0f };

   T_model = translate(mat4(), vec3(0.0f, -1.2f, 0.0f));
   R_model = rotate(mat4(), 20.0f * (float)ONE_DEG_IN_RAD, vec3(1.0f, 0.0f, 0.0f));
   R_model = mat4();
   obj.model_base = T_model * R_model * scale(mat4(), vec3(0.3f, 0.3f, 0.3f));

   addObjectToScene(obj);

   spawnAsteroid(vec3(0.0f, -1.2f, -11.5f), color_sp);
   spawnAsteroid(vec3(1.0f, -1.2f, -11.5f), color_sp);
   spawnAsteroid(vec3(-0.5f, -0.7f, -10.8f), color_sp);

   vector<SceneObject>::iterator obj_it;
   GLsizeiptr offset;

   GLuint points_vbo, colors_vbo, selected_colors_vbo, texcoords_vbo,
      normals_vbo, ubo, model_mat_idx_vbo;

   map<GLuint, unsigned int> shaderCounts, curShaderBase;

   populateBuffers(objects,
                  &points_vbo,
                  &colors_vbo,
                  &selected_colors_vbo,
                  &texcoords_vbo,
                  &normals_vbo,
                  &ubo,
                  &model_mat_idx_vbo,
                  shaderCounts,
                  curShaderBase);

   GLuint vao = 0;
   glGenVertexArrays(1, &vao);
   glBindVertexArray(vao);

   glEnableVertexAttribArray(0);
   glEnableVertexAttribArray(1);
   glEnableVertexAttribArray(2);
   glEnableVertexAttribArray(3);

   glBindBuffer(GL_ARRAY_BUFFER, points_vbo);
   glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);

   glBindBuffer(GL_ARRAY_BUFFER, normals_vbo);
   glVertexAttribPointer(2, 3, GL_FLOAT, GL_FALSE, 0, 0);

   glBindBuffer(GL_ARRAY_BUFFER, model_mat_idx_vbo);
   glVertexAttribIPointer(3, 1, GL_UNSIGNED_INT, 0, 0);

   GLuint vao2 = 0;
   glGenVertexArrays(1, &vao2);
   glBindVertexArray(vao2);

   glEnableVertexAttribArray(0);
   glEnableVertexAttribArray(1);
   glEnableVertexAttribArray(2);
   glEnableVertexAttribArray(3);

   glBindBuffer(GL_ARRAY_BUFFER, points_vbo);
   glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);

   glBindBuffer(GL_ARRAY_BUFFER, texcoords_vbo);
   glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 0, 0);

   glBindBuffer(GL_ARRAY_BUFFER, normals_vbo);
   glVertexAttribPointer(2, 3, GL_FLOAT, GL_FALSE, 0, 0);

   glBindBuffer(GL_ARRAY_BUFFER, model_mat_idx_vbo);
   glVertexAttribIPointer(3, 1, GL_UNSIGNED_INT, 0, 0);

   float cam_speed = 1.0f;
   float cam_yaw_speed = 60.0f*ONE_DEG_IN_RAD;
   float cam_pitch_speed = 60.0f*ONE_DEG_IN_RAD;

   // glm::lookAt can create the view matrix
   // glm::perspective can create the projection matrix

   cam_pos = vec3(0.0f, 0.0f, 2.0f);
   //cam_pos = vec3(-2.1f, -1.5f, -1.5f); // Good position for checking ship faces
   float cam_yaw = 0.0f * 2.0f * 3.14159f / 360.0f;
   float cam_pitch = 0.0f * 2.0f * 3.14159f / 360.0f;

   mat4 T = translate(mat4(), vec3(-cam_pos.x, -cam_pos.y, -cam_pos.z));
   mat4 R = mat4();
   view_mat = R*T;

   float fov = 67.0f * ONE_DEG_IN_RAD;
   float aspect = (float)width / (float)height;

   float range = tan(fov * 0.5f) * NEAR_CLIP;
   float Sx = NEAR_CLIP / (range * aspect);
   float Sy = NEAR_CLIP / range;
   float Sz = -(FAR_CLIP + NEAR_CLIP) / (FAR_CLIP - NEAR_CLIP);
   float Pz = -(2.0f * FAR_CLIP * NEAR_CLIP) / (FAR_CLIP - NEAR_CLIP);

   float proj_arr[] = {
     Sx, 0.0f, 0.0f, 0.0f,
     0.0f, Sy, 0.0f, 0.0f,
     0.0f, 0.0f, Sz, -1.0f,
     0.0f, 0.0f, Pz, 0.0f,
   };
   proj_mat = make_mat4(proj_arr);

   GLuint ub_binding_point = 0;

   GLuint view_test_loc = glGetUniformLocation(color_sp, "view");
   GLuint proj_test_loc = glGetUniformLocation(color_sp, "proj");
   GLuint color_sp_ub_index = glGetUniformBlockIndex(color_sp, "models");

   GLuint view_mat_loc = glGetUniformLocation(texture_sp, "view");
   GLuint proj_mat_loc = glGetUniformLocation(texture_sp, "proj");
   GLuint texture_sp_ub_index = glGetUniformBlockIndex(texture_sp, "models");

   glUseProgram(color_sp);
   glUniformMatrix4fv(view_test_loc, 1, GL_FALSE, value_ptr(view_mat));
   glUniformMatrix4fv(proj_test_loc, 1, GL_FALSE, value_ptr(proj_mat));

   glUniformBlockBinding(color_sp, color_sp_ub_index, ub_binding_point);
   glBindBufferRange(GL_UNIFORM_BUFFER, ub_binding_point, ubo, 0, GL_MAX_UNIFORM_BLOCK_SIZE);

   glUseProgram(texture_sp);
   glUniformMatrix4fv(view_mat_loc, 1, GL_FALSE, value_ptr(view_mat));
   glUniformMatrix4fv(proj_mat_loc, 1, GL_FALSE, value_ptr(proj_mat));

   glUniformBlockBinding(texture_sp, texture_sp_ub_index, ub_binding_point);
   glBindBufferRange(GL_UNIFORM_BUFFER, ub_binding_point, ubo, 0, GL_MAX_UNIFORM_BLOCK_SIZE);

   bool cam_moved = false;

   int frame_count = 0;
   double elapsed_seconds_fps = 0.0f;
   double previous_seconds = glfwGetTime();

   // This draws wireframes. Useful for seeing separate faces and occluded objects.
   //glPolygonMode(GL_FRONT, GL_LINE);

   if (DISABLE_VSYNC && SHOW_FPS) {
      glfwSwapInterval(0);
   }

   State curState = STATE_MAIN_MENU;

   while (!glfwWindowShouldClose(window) && isRunning) {
      double current_seconds = glfwGetTime();
      double elapsed_seconds = current_seconds - previous_seconds;
      previous_seconds = current_seconds;

      if (SHOW_FPS) {
         elapsed_seconds_fps += elapsed_seconds;
         if (elapsed_seconds_fps > 0.25f) {
            fps = (double)frame_count / elapsed_seconds_fps;
            cout << "FPS: " << fps << endl;

            frame_count = 0;
            elapsed_seconds_fps = 0.0f;
         }

         frame_count++;
      }

      // Handle events

      clickedObject = NULL;

      // reset the all key states to KEY_STATE_UNCHANGED (something the GLFW key callback can never return)
      // so that GLFW_PRESS and GLFW_RELEASE are only detected once
      // TODO: Change this if we ever need to act on GLFW_REPEAT (which is when a key is held down
      //  continuously for a period of time)
      fill(key_state, key_state + NUM_KEYS, KEY_STATE_UNCHANGED);

      glfwPollEvents();

      while (!events.empty()) {
         switch (events.front()) {
            case EVENT_GO_TO_MAIN_MENU:
               curState = STATE_MAIN_MENU;
               break;
            case EVENT_GO_TO_GAME:
               curState = STATE_GAME;
               break;
            case EVENT_QUIT:
               isRunning = false;
               break;
         }
         events.pop();
      }

      if (curState == STATE_GAME) {
         /*
         if (clickedObject == &objects[0]) {
            selectedObject = &objects[0];
         }
         if (clickedObject == &objects[1]) {
            selectedObject = &objects[1];
         }
         */

         /*
         if (key_state[GLFW_KEY_SPACE] == GLFW_PRESS) {
            transformObject(objects[1], translate(mat4(), vec3(0.3f, 0.0f, 0.0f)), ubo);
         }
         if (key_pressed[GLFW_KEY_RIGHT]) {
            transformObject(objects[2], translate(mat4(), vec3(0.01f, 0.0f, 0.0f)), ubo);
         }
         if (key_pressed[GLFW_KEY_LEFT]) {
            transformObject(objects[2], translate(mat4(), vec3(-0.01f, 0.0f, 0.0f)), ubo);
         }
         */

         if (key_pressed[GLFW_KEY_RIGHT]) {
            transformObject(objects[0], translate(mat4(), vec3(0.01f, 0.0f, 0.0f)), ubo);
         }
         if (key_pressed[GLFW_KEY_LEFT]) {
            transformObject(objects[0], translate(mat4(), vec3(-0.01f, 0.0f, 0.0f)), ubo);
         }

         if (key_pressed[GLFW_KEY_DOWN]) {
            transformObject(objects[1], translate(mat4(), vec3(0.0f, 0.0f, 0.17f)), ubo);
            transformObject(objects[2], translate(mat4(), vec3(0.0f, 0.0f, 0.06f)), ubo);
            transformObject(objects[3], translate(mat4(), vec3(0.0f, 0.0f, 0.11f)), ubo);
         }
      }

      // Render scene

      glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

      switch (curState) {
         case STATE_MAIN_MENU:
            renderMainMenu();
            renderMainMenuGui();
            break;
         case STATE_GAME:
            renderScene(objects,
               color_sp, texture_sp,
               vao, vao2,
               points_vbo, normals_vbo,
               colors_vbo, texcoords_vbo, selected_colors_vbo,
               selectedObject,
               shaderCounts, curShaderBase);
            renderSceneGui();
            break;
      }

      glfwSwapBuffers(window);

      if (GLFW_PRESS == glfwGetKey(window, GLFW_KEY_ESCAPE)) {
         glfwSetWindowShouldClose(window, 1);
      }

      float dist = cam_speed * elapsed_seconds;
      if (glfwGetKey(window, GLFW_KEY_A)) {
         vec3 dir = (inverse(R) * vec4(-1.0f, 0.0f, 0.0f, 1.0f)).xyz();
         cam_pos += dir * dist;

         cam_moved = true;
      }
      if (glfwGetKey(window, GLFW_KEY_D)) {
         vec3 dir = (inverse(R) * vec4(1.0f, 0.0f, 0.0f, 1.0f)).xyz();
         cam_pos += dir * dist;

         cam_moved = true;
      }
      if (glfwGetKey(window, GLFW_KEY_W)) {
         vec3 dir = (inverse(R) * vec4(0.0f, 0.0f, -1.0f, 1.0f)).xyz();
         cam_pos += dir * dist;

         cam_moved = true;
      }
      if (glfwGetKey(window, GLFW_KEY_S)) {
         vec3 dir = (inverse(R) * vec4(0.0f, 0.0f, 1.0f, 1.0f)).xyz();
         cam_pos += dir * dist;

         cam_moved = true;
      }
      /*
      if (glfwGetKey(window, GLFW_KEY_LEFT)) {
         cam_yaw += cam_yaw_speed * elapsed_seconds;
         cam_moved = true;
      }
      if (glfwGetKey(window, GLFW_KEY_RIGHT)) {
         cam_yaw -= cam_yaw_speed * elapsed_seconds;
         cam_moved = true;
      }
      if (glfwGetKey(window, GLFW_KEY_UP)) {
         cam_pitch += cam_pitch_speed * elapsed_seconds;
         cam_moved = true;
      }
      if (glfwGetKey(window, GLFW_KEY_DOWN)) {
         cam_pitch -= cam_pitch_speed * elapsed_seconds;
         cam_moved = true;
      }
      */
      if (cam_moved) {
         T = translate(mat4(), vec3(-cam_pos.x, -cam_pos.y, -cam_pos.z));

         mat4 yaw_mat = rotate(mat4(), -cam_yaw, vec3(0.0f, 1.0f, 0.0f));
         mat4 pitch_mat = rotate(mat4(), -cam_pitch, vec3(1.0f, 0.0f, 0.0f));
         R = pitch_mat * yaw_mat;

         view_mat = R*T;

         //printVector("cam pos", cam_pos);

         glUseProgram(color_sp);
         glUniformMatrix4fv(view_test_loc, 1, GL_FALSE, value_ptr(view_mat));

         glUseProgram(texture_sp);
         glUniformMatrix4fv(view_mat_loc, 1, GL_FALSE, value_ptr(view_mat));

         cam_moved = false;
      }
   }

   ImGui_ImplGlfwGL3_Shutdown();
   ImGui::DestroyContext();

   glfwDestroyWindow(window);
   glfwTerminate();

   return 0;
}

void glfw_error_callback(int error, const char* description) {
   gl_log_err("GLFW ERROR: code %i msg: %s\n", error, description);
}

void mouse_button_callback(GLFWwindow* window, int button, int action, int mods) {
   double mouse_x, mouse_y;
   glfwGetCursorPos(window, &mouse_x, &mouse_y);

   if (button == GLFW_MOUSE_BUTTON_LEFT && action == GLFW_PRESS) {
      cout << "Mouse clicked (" << mouse_x << "," << mouse_y << ")" << endl;
      selectedObject = NULL;

      float x = (2.0f*mouse_x) / width - 1.0f;
      float y = 1.0f - (2.0f*mouse_y) / height;

      cout << "x: " << x << ", y: " << y << endl;

      vec4 ray_clip = vec4(x, y, -1.0f, 1.0f);
      vec4 ray_eye = inverse(proj_mat) * ray_clip;
      ray_eye = vec4(ray_eye.xy(), -1.0f, 1.0f);
      vec4 ray_world = inverse(view_mat) * ray_eye;

      vec4 cam_pos_temp = vec4(cam_pos, 1.0f);

      vec4 click_point;
      vec3 closest_point = vec3(0.0f, 0.0f, -FAR_CLIP); // Any valid point will be closer than the far clipping plane, so initial value to that
      SceneObject* closest_object = NULL;

      for (vector<SceneObject>::iterator it = objects.begin(); it != objects.end(); it++) {
         for (unsigned int p_idx = 0; p_idx < it->points.size(); p_idx += 9) {
            if (faceClicked(
               {
                  vec3(it->points[p_idx], it->points[p_idx + 1], it->points[p_idx + 2]),
                  vec3(it->points[p_idx + 3], it->points[p_idx + 4], it->points[p_idx + 5]),
                  vec3(it->points[p_idx + 6], it->points[p_idx + 7], it->points[p_idx + 8]),
               },
               &*it, ray_world, cam_pos_temp, click_point
            )) {
               click_point = view_mat * click_point;

               if (-NEAR_CLIP >= click_point.z && click_point.z > -FAR_CLIP && click_point.z > closest_point.z) {
                  closest_point = click_point.xyz();
                  closest_object = &*it;
               }
            }
         }
      }

      if (closest_object == NULL) {
         cout << "No object was clicked" << endl;
      } else {
         clickedObject = closest_object;
         cout << "Clicked object: " << clickedObject->id << endl;
      }
   }
}

void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods) {
   key_state[key] = action;

   // should be true for GLFW_PRESS and GLFW_REPEAT
   key_pressed[key] = (action != GLFW_RELEASE);
}


GLuint loadShader(GLenum type, string file) {
  cout << "Loading shader from file " << file << endl;

  ifstream shaderFile(file);
  GLuint shaderId = 0;

  if (shaderFile.is_open()) {
    string line, shaderString;

    while(getline(shaderFile, line)) {
      shaderString += line + "\n";
    }
    shaderFile.close();
    const char* shaderCString = shaderString.c_str();

    shaderId = glCreateShader(type);
    glShaderSource(shaderId, 1, &shaderCString, NULL);
    glCompileShader(shaderId);

    cout << "Loaded successfully" << endl;
  } else {
    cout << "Failed to load the file" << endl;
  }

  return shaderId;
}

GLuint loadShaderProgram(string vertexShaderPath, string fragmentShaderPath) {
   GLuint vs = loadShader(GL_VERTEX_SHADER, vertexShaderPath);
   GLuint fs = loadShader(GL_FRAGMENT_SHADER, fragmentShaderPath);

   GLuint shader_program = glCreateProgram();
   glAttachShader(shader_program, vs);
   glAttachShader(shader_program, fs);

   glLinkProgram(shader_program);

   return shader_program;
}

unsigned char* loadImage(string file_name, int* x, int* y) {
  int n;
  int force_channels = 4; // This forces RGBA (4 bytes per pixel)
  unsigned char* image_data = stbi_load(file_name.c_str(), x, y, &n, force_channels);

  int width_in_bytes = *x * 4;
  unsigned char *top = NULL;
  unsigned char *bottom = NULL;
  unsigned char temp = 0;
  int half_height = *y / 2;

  // flip image upside-down to account for OpenGL treating lower-left as (0, 0)
  for (int row = 0; row < half_height; row++) {
     top = image_data + row * width_in_bytes;
     bottom = image_data + (*y - row - 1) * width_in_bytes;
     for (int col = 0; col < width_in_bytes; col++) {
        temp = *top;
        *top = *bottom;
        *bottom = temp;
        top++;
        bottom++;
     }
  }

  if (!image_data) {
    fprintf(stderr, "ERROR: could not load %s\n", file_name.c_str());
  }

  // Not Power-of-2 check
  if ((*x & (*x - 1)) != 0 || (*y & (*y - 1)) != 0) {
     fprintf(stderr, "WARNING: texture %s is not power-of-2 dimensions\n", file_name.c_str());
  }

  return image_data;
}

bool faceClicked(array<vec3, 3> points, SceneObject* obj, vec4 world_ray, vec4 cam, vec4& click_point) {
   // LINE EQUATION:		P = O + Dt
   // O = cam
   // D = ray_world

   // PLANE EQUATION:	P dot n + d = 0
   // n is the normal vector
   // d is the offset from the origin

   // Take the cross-product of two vectors on the plane to get the normal
   vec3 v1 = points[1] - points[0];
   vec3 v2 = points[2] - points[0];

   vec3 normal = vec3(v1.y*v2.z - v1.z*v2.y, v1.z*v2.x - v1.x*v2.z, v1.x*v2.y - v1.y*v2.x);

   vec3 local_ray = (inverse(obj->model_mat) * world_ray).xyz();
   vec3 local_cam = (inverse(obj->model_mat) * cam).xyz();

   local_ray = local_ray - local_cam;

   float d = -glm::dot(points[0], normal);
   float t = -(glm::dot(local_cam, normal) + d) / glm::dot(local_ray, normal);

   vec3 intersection = local_cam + t*local_ray;

   if (insideTriangle(intersection, points)) {
      click_point = obj->model_mat * vec4(intersection, 1.0f);
      return true;
   } else {
      return false;
   }
}

bool insideTriangle(vec3 p, array<vec3, 3> triangle_points) {
   vec3 v21 = triangle_points[1] - triangle_points[0];
   vec3 v31 = triangle_points[2] - triangle_points[0];
   vec3 pv1 = p - triangle_points[0];

   float y = (pv1.y*v21.x - pv1.x*v21.y) / (v31.y*v21.x - v31.x*v21.y);
   float x = (pv1.x-y*v31.x) / v21.x;

   return x > 0.0f && y > 0.0f && x+y < 1.0f;
}

void printVector(string label, vec3 v) {
   cout << label << " -> (" << v.x << "," << v.y << "," << v.z << ")" << endl;
}

void print4DVector(string label, vec4 v) {
   cout << label << " -> (" << v.x << "," << v.y << "," << v.z << "," << v.w << ")" << endl;
}

void addObjectToScene(SceneObject& obj) {
   obj.id = objects.size(); // currently unused
   obj.num_points = obj.points.size() / 3;
   obj.model_transform = mat4();

   obj.normals.reserve(obj.points.size());
   for (int i = 0; i < obj.points.size(); i += 9) {
      vec3 point1 = vec3(obj.points[i], obj.points[i + 1], obj.points[i + 2]);
      vec3 point2 = vec3(obj.points[i + 3], obj.points[i + 4], obj.points[i + 5]);
      vec3 point3 = vec3(obj.points[i + 6], obj.points[i + 7], obj.points[i + 8]);

      vec3 normal = normalize(cross(point2 - point1, point3 - point1));

      // Add the same normal for all 3 points
      for (int j = 0; j < 3; j++) {
         obj.normals.push_back(normal.x);
         obj.normals.push_back(normal.y);
         obj.normals.push_back(normal.z);
      }
   }

   objects.push_back(obj);
}

void populateBuffers(vector<SceneObject>& objects,
                     GLuint* points_vbo,
                     GLuint* colors_vbo,
                     GLuint* selected_colors_vbo,
                     GLuint* texcoords_vbo,
                     GLuint* normals_vbo,
                     GLuint* ubo,
                     GLuint* model_mat_idx_vbo,
                     map<GLuint, unsigned int>& shaderCounts,
                     map<GLuint, unsigned int>& curShaderBase) {
   GLsizeiptr points_buffer_size = 0;
   GLsizeiptr textures_buffer_size = 0;
   GLsizeiptr ubo_buffer_size = 0;
   GLsizeiptr model_mat_idx_buffer_size = 0;

   map<GLuint, unsigned int> curShaderOffset;

   map<GLuint, unsigned int> shaderUboCounts;
   map<GLuint, unsigned int> curShaderUboBase;
   map<GLuint, unsigned int> curShaderUboOffset;

   vector<SceneObject>::iterator it;

   /* Find all shaders that need to be used and  the number of objects and
    * number of points for each shader. Construct a map from shader id to count
    * of points being drawn using that shader (for thw model matrix ubo, we
    * need object counts instead). These will be used to get offsets into the
    * vertex buffer for each shader.
    */
   for (it = objects.begin(); it != objects.end(); it++) {
      points_buffer_size += it->points.size() * sizeof(GLfloat);
      textures_buffer_size += it->texcoords.size() * sizeof(GLfloat);
      ubo_buffer_size += 16 * sizeof(GLfloat);
      model_mat_idx_buffer_size += it->num_points * sizeof(GLuint);

      if (shaderCounts.count(it->shader_program) == 0) {
         shaderCounts[it->shader_program] = it->num_points;
         shaderUboCounts[it->shader_program] = 1;
      } else {
         shaderCounts[it->shader_program] += it->num_points;
         shaderUboCounts[it->shader_program]++;
      }
   }

   map<GLuint, unsigned int>::iterator shaderIt;
   unsigned int lastShaderCount = 0;
   unsigned int lastShaderUboCount = 0;

   /*
    * The counts calculated above can be used to get the starting offset of
    * each shader in the vertex buffer. Create a map of base offsets to mark
    * where the data for the first object using a given shader begins. Also,
    * create a map of current offsets to mark where to copy data for the next
    * object being added.
    */
   cout << "Shader counts:" << endl;
   for (shaderIt = shaderCounts.begin(); shaderIt != shaderCounts.end(); shaderIt++) {
      curShaderOffset[shaderIt->first] = 0;
      curShaderUboOffset[shaderIt->first] = 0;

      curShaderBase[shaderIt->first] = lastShaderCount;
      lastShaderCount += shaderCounts[shaderIt->first];

      curShaderUboBase[shaderIt->first] = lastShaderUboCount;
      lastShaderUboCount += shaderUboCounts[shaderIt->first];
   }

   // Initialize all the buffers using the counts calculated above

   *points_vbo = 0;
   glGenBuffers(1, points_vbo);
   glBindBuffer(GL_ARRAY_BUFFER, *points_vbo);
   glBufferData(GL_ARRAY_BUFFER, points_buffer_size, NULL, GL_DYNAMIC_DRAW);

   *colors_vbo = 0;
   glGenBuffers(1, colors_vbo);
   glBindBuffer(GL_ARRAY_BUFFER, *colors_vbo);
   glBufferData(GL_ARRAY_BUFFER, points_buffer_size, NULL, GL_DYNAMIC_DRAW);

   *selected_colors_vbo = 0;
   glGenBuffers(1, selected_colors_vbo);
   glBindBuffer(GL_ARRAY_BUFFER, *selected_colors_vbo);
   glBufferData(GL_ARRAY_BUFFER, points_buffer_size, NULL, GL_DYNAMIC_DRAW);

   *texcoords_vbo = 0;
   glGenBuffers(1, texcoords_vbo);
   glBindBuffer(GL_ARRAY_BUFFER, *texcoords_vbo);
   glBufferData(GL_ARRAY_BUFFER, textures_buffer_size, NULL, GL_DYNAMIC_DRAW);

   *normals_vbo = 0;
   glGenBuffers(1, normals_vbo);
   glBindBuffer(GL_ARRAY_BUFFER, *normals_vbo);
   glBufferData(GL_ARRAY_BUFFER, points_buffer_size, NULL, GL_DYNAMIC_DRAW);

   *ubo = 0;
   glGenBuffers(1, ubo);
   glBindBuffer(GL_UNIFORM_BUFFER, *ubo);
   glBufferData(GL_UNIFORM_BUFFER, ubo_buffer_size, NULL, GL_DYNAMIC_DRAW);

   *model_mat_idx_vbo = 0;
   glGenBuffers(1, model_mat_idx_vbo);
   glBindBuffer(GL_ARRAY_BUFFER, *model_mat_idx_vbo);
   glBufferData(GL_ARRAY_BUFFER, model_mat_idx_buffer_size, NULL, GL_DYNAMIC_DRAW);

   for (it = objects.begin(); it != objects.end(); it++) {
      it->vertex_vbo_offset = curShaderBase[it->shader_program] + curShaderOffset[it->shader_program];
      it->ubo_offset = curShaderUboBase[it->shader_program] + curShaderUboOffset[it->shader_program];

      glBindBuffer(GL_ARRAY_BUFFER, *points_vbo);
      glBufferSubData(GL_ARRAY_BUFFER, it->vertex_vbo_offset * sizeof(GLfloat) * 3, it->points.size() * sizeof(GLfloat), &it->points[0]);

      glBindBuffer(GL_ARRAY_BUFFER, *colors_vbo);
      glBufferSubData(GL_ARRAY_BUFFER, it->vertex_vbo_offset * sizeof(GLfloat) * 3, it->colors.size() * sizeof(GLfloat), &it->colors[0]);

      glBindBuffer(GL_ARRAY_BUFFER, *selected_colors_vbo);
      glBufferSubData(GL_ARRAY_BUFFER, it->vertex_vbo_offset * sizeof(GLfloat) * 3, it->selected_colors.size() * sizeof(GLfloat), &it->selected_colors[0]);

      glBindBuffer(GL_ARRAY_BUFFER, *texcoords_vbo);
      glBufferSubData(GL_ARRAY_BUFFER, it->vertex_vbo_offset * sizeof(GLfloat) * 2, it->texcoords.size() * sizeof(GLfloat), &it->texcoords[0]);

      glBindBuffer(GL_ARRAY_BUFFER, *normals_vbo);
      glBufferSubData(GL_ARRAY_BUFFER, it->vertex_vbo_offset * sizeof(GLfloat) * 3, it->normals.size() * sizeof(GLfloat), &it->normals[0]);

      glBindBuffer(GL_ARRAY_BUFFER, *model_mat_idx_vbo);
      for (int i = 0; i < it->num_points; i++) {
         glBufferSubData(GL_ARRAY_BUFFER, (it->vertex_vbo_offset + i) * sizeof(GLuint), sizeof(GLuint), &it->ubo_offset);
      }

      curShaderOffset[it->shader_program] += it->num_points;

      it->model_mat = it->model_base * it->model_transform;
      glBindBuffer(GL_UNIFORM_BUFFER, *ubo);
      glBufferSubData(GL_UNIFORM_BUFFER, it->ubo_offset * sizeof(mat4), sizeof(mat4), value_ptr(it->model_mat));

      curShaderUboOffset[it->shader_program]++;
   }
}

void transformObject(SceneObject& obj, const mat4& transform, GLuint ubo) {
   obj.model_transform = obj.model_transform * transform;
   obj.model_mat = obj.model_transform * obj.model_base;

   glBindBuffer(GL_UNIFORM_BUFFER, ubo);
   glBufferSubData(GL_UNIFORM_BUFFER, obj.ubo_offset * sizeof(mat4), sizeof(mat4), value_ptr(obj.model_mat));
}

void renderScene(vector<SceneObject>& objects,
                  GLuint color_sp, GLuint texture_sp,
                  GLuint vao1, GLuint vao2,
                  GLuint points_vbo, GLuint normals_vbo,
                  GLuint colors_vbo, GLuint texcoords_vbo, GLuint selected_colors_vbo,
                  SceneObject* selectedObject,
                  map<GLuint, unsigned int>& shaderCounts,
                  map<GLuint, unsigned int>& curShaderBase) {

   glUseProgram(color_sp);
   glBindVertexArray(vao1);

   if (selectedObject != NULL) {
      glBindBuffer(GL_ARRAY_BUFFER, selected_colors_vbo);
      glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 0, 0);

      glDrawArrays(GL_TRIANGLES, selectedObject->vertex_vbo_offset, selectedObject->num_points);
   }

   glBindBuffer(GL_ARRAY_BUFFER, colors_vbo);
   glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 0, 0);

   glDrawArrays(GL_TRIANGLES, curShaderBase[color_sp], shaderCounts[color_sp]);

   glUseProgram(texture_sp);
   glBindVertexArray(vao2);

   glDrawArrays(GL_TRIANGLES, curShaderBase[texture_sp], shaderCounts[texture_sp]);
}

void renderSceneGui() {
   ImGui_ImplGlfwGL3_NewFrame();

   // 1. Show a simple window.
   // Tip: if we don't call ImGui::Begin()/ImGui::End() the widgets automatically appears in a window called "Debug".
   /*
   {
      static float f = 0.0f;
      static int counter = 0;
      ImGui::Text("Hello, world!");                           // Display some text (you can use a format string too)
      ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f    
      ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color

      ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our windows open/close state
      ImGui::Checkbox("Another Window", &show_another_window);

      if (ImGui::Button("Button"))                            // Buttons return true when clicked (NB: most widgets return true when edited/activated)
         counter++;
      ImGui::SameLine();
      ImGui::Text("counter = %d", counter);

      ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
   }
   */

   {
      ImGui::SetNextWindowSize(ImVec2(85, 22), ImGuiCond_Once);
      ImGui::SetNextWindowPos(ImVec2(10, 50), ImGuiCond_Once);
      ImGui::Begin("WndStats", NULL,
         ImGuiWindowFlags_NoTitleBar |
         ImGuiWindowFlags_NoResize |
         ImGuiWindowFlags_NoMove);
      ImGui::Text("Score: ???");
      ImGui::End();
   }

   {
      ImGui::SetNextWindowPos(ImVec2(380, 10), ImGuiCond_Once);
      ImGui::SetNextWindowSize(ImVec2(250, 35), ImGuiCond_Once);
      ImGui::Begin("WndMenubar", NULL,
         ImGuiWindowFlags_NoTitleBar |
         ImGuiWindowFlags_NoResize |
         ImGuiWindowFlags_NoMove);
      ImGui::InvisibleButton("", ImVec2(155, 18));
      ImGui::SameLine();
      if (ImGui::Button("Main Menu")) {
         events.push(EVENT_GO_TO_MAIN_MENU);
      }
      ImGui::End();
   }

   ImGui::Render();
   ImGui_ImplGlfwGL3_RenderDrawData(ImGui::GetDrawData());
}

void renderMainMenu() {
}

void renderMainMenuGui() {
   ImGui_ImplGlfwGL3_NewFrame();

   {
      int padding = 4;
      ImGui::SetNextWindowPos(ImVec2(-padding, -padding), ImGuiCond_Once);
      ImGui::SetNextWindowSize(ImVec2(width + 2 * padding, height + 2 * padding), ImGuiCond_Once);
      ImGui::Begin("WndMain", NULL,
         ImGuiWindowFlags_NoTitleBar |
         ImGuiWindowFlags_NoResize |
         ImGuiWindowFlags_NoMove);

      ImGui::InvisibleButton("", ImVec2(10, 80));
      ImGui::InvisibleButton("", ImVec2(285, 18));
      ImGui::SameLine();
      if (ImGui::Button("New Game")) {
         events.push(EVENT_GO_TO_GAME);
      }

      ImGui::InvisibleButton("", ImVec2(10, 15));
      ImGui::InvisibleButton("", ImVec2(300, 18));
      ImGui::SameLine();
      if (ImGui::Button("Quit")) {
         events.push(EVENT_QUIT);
      }

      ImGui::End();
   }

   ImGui::Render();
   ImGui_ImplGlfwGL3_RenderDrawData(ImGui::GetDrawData());
}

void spawnAsteroid(vec3 pos, GLuint shader) {
   SceneObject obj = SceneObject();
   obj.shader_program = shader;

   obj.points = {
      // front
      1.0f,  1.0f,  1.0f,
      -1.0f,  1.0f,  1.0f,
      -1.0f, -1.0f,  1.0f,
      1.0f,  1.0f,  1.0f,
      -1.0f, -1.0f,  1.0f,
      1.0f, -1.0f,  1.0f,

      // top
      1.0f,  1.0f, -1.0f,
      -1.0f,  1.0f, -1.0f,
      -1.0f,  1.0f,  1.0f,
      1.0f,  1.0f, -1.0f,
      -1.0f,  1.0f,  1.0f,
      1.0f,  1.0f,  1.0f,

      // bottom
      1.0f, -1.0f,  1.0f,
      -1.0f, -1.0f,  1.0f,
      -1.0f, -1.0f, -1.0f,
      1.0f, -1.0f,  1.0f,
      -1.0f, -1.0f, -1.0f,
      1.0f, -1.0f, -1.0f,

      // back
      1.0f,  1.0f, -1.0f,
      -1.0f, -1.0f, -1.0f,
      -1.0f,  1.0f, -1.0f,
      1.0f,  1.0f, -1.0f,
      1.0f, -1.0f, -1.0f,
      -1.0f, -1.0f, -1.0f,

      // right
      1.0f,  1.0f, -1.0f,
      1.0f,  1.0f,  1.0f,
      1.0f, -1.0f,  1.0f,
      1.0f,  1.0f, -1.0f,
      1.0f, -1.0f,  1.0f,
      1.0f, -1.0f, -1.0f,

      // left
      -1.0f,  1.0f,  1.0f,
      -1.0f,  1.0f, -1.0f,
      -1.0f, -1.0f, -1.0f,
      -1.0f,  1.0f,  1.0f,
      -1.0f, -1.0f, -1.0f,
      -1.0f, -1.0f,  1.0f,
   };
   obj.colors = {
      // front
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,

      // top
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,

      // bottom
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,

      // back
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,

      // right
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,

      // left
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
      0.8f, 0.0f, 0.0f,
   };
   obj.texcoords = { 0.0f };
   obj.selected_colors = { 0.0f };

   mat4 T = translate(mat4(), pos);
   mat4 R = rotate(mat4(), 60.0f * (float)ONE_DEG_IN_RAD, vec3(1.0f, 1.0f, -1.0f));
   obj.model_base = T * R * scale(mat4(), vec3(0.2f, 0.2f, 0.2f));

   addObjectToScene(obj);
}