#include <GL/glut.h>
#include <math.h>
#include <stdio.h>

// Define a constant for the value of PI
#define GL_PI 3.1415f

GLfloat xRot = 0.0f;
GLfloat yRot = 0.0f;

//  fenyek beallitasahoz szukseges tombok

//  Ambiens feny szine {red, green, blue, alpha=1}
GLfloat ambientLight[] = {0.4f, 0.4f, 0.4f, 1.0f};

//  Diffuz feny szine {red, green, blue, alpha=1}
GLfloat diffuseLight[] = {0.6f, 0.6f, 0.6f, 1.0f};
//  Diffuz fenyforras pozicioja {x, y, z, w=1}
GLfloat lightPos[] = {25.0f, 25.0f, 25.0f, 1.0f};

//  Spekularis fenyforras pozicioja {red, green, blue, alpha=1}
GLfloat specularLight[] = {1.0f, 1.0f, 1.0f, 1.0f};

//  Spekularis anyagjellemzo szine
GLfloat specref[] = {1.0f, 1.0f, 1.0f, 1.0f};


//  egy kis negzetekre bontott negyzet modellezese
void drawQuad(float w, float h, int rows, int cols)
{
  int i, j;
  
  //  midnen sorba
  for(i=0; i<h; i++)
  {
    //  egy negyszog savban
    glBegin(GL_QUAD_STRIP);
    glNormal3f(0.0f, 0.0f, 1.0f);
      //  begigmegyunk az oszlopokon
      for(j=0; j<=w; j++)
      {
        //  kirajzoljuk a sav pontjait (also, felso)
        glVertex3f(w*j/cols-w/2, h*i/rows-h/2, 0);
        glVertex3f(w*j/cols-w/2, h*(i+1)/rows-h/2, 0);
      }
    glEnd();
  }
}

//  kocka rajzolasa kis negyzetekbol
void drawCube(float size, int slices)
{
  //  minden oldal egy kis negyzetekre osztott negyzetbol van, a megfelelo helyre transzformalva

  //  elso lap
  glPushMatrix();
    glRotatef(0.0f, 1.0f, 0.0f, 0.0f);  // 0 fokos forgatas, nem csinal semmit
    glTranslatef(0.0f, 0.0f, size/2);
    drawQuad(size, size, slices, slices);
  glPopMatrix();

  //  also lap
  glPushMatrix();
    glRotatef(90.0f, 1.0f, 0.0f, 0.0f);  // ez viszont mar tenyleg forgat
    glTranslatef(0.0f, 0.0f, size/2);
    drawQuad(size, size, slices, slices);
  glPopMatrix();

  //  hatso lap
  glPushMatrix();
    glRotatef(180.0f, 1.0f, 0.0f, 0.0f);
    glTranslatef(0.0f, 0.0f, size/2);
    drawQuad(size, size, slices, slices);
  glPopMatrix();

  //  felso lap
  glPushMatrix();
    glRotatef(270.0f, 1.0f, 0.0f, 0.0f);
    glTranslatef(0.0f, 0.0f, size/2);
    drawQuad(size, size, slices, slices);
  glPopMatrix();

  //  jobb lap
  glPushMatrix();
    glRotatef(90.0f, 0.0f, 1.0f, 0.0f);
    glTranslatef(0.0f, 0.0f, size/2);
    drawQuad(size, size, slices, slices);
  glPopMatrix();

  //  bal lap
  glPushMatrix();
    glRotatef(270.0f, 0.0f, 1.0f, 0.0f);
    glTranslatef(0.0f, 0.0f, size/2);
    drawQuad(size, size, slices, slices);
  glPopMatrix();
}


// Called to draw scene
void RenderScene(void)
{
  // Clear the window with current clearing color
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

  glPushMatrix();
  glRotatef(xRot, 1.0f, 0.0f, 0.0f);
  glRotatef(yRot, 0.0f, 1.0f, 0.0f);

  // >> Modellezo programresz

  //  Spekularis csillogas beallitasa
  glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, specref);
  glMateriali(GL_FRONT_AND_BACK, GL_SHININESS, 64);

  //  kocka modellezese normalvektorokkal
  glColor3f(1.0f, 0.0f, 0.0f);

  //  kocka rajzolo fuggveny hivasa
  drawCube(20, 20);

  // << Modellezo programresz

  glPopMatrix();
  
  // Flush drawing commands
  glutSwapBuffers();
}

// This function does any needed initialization on the rendering
// context. 
void SetupRC()
{
  // Black background
  glClearColor(0.0f, 0.0f, 0.0f, 1.0f );
  glEnable(GL_DEPTH_TEST);

  //  fenyek hasznalatanak engedelyezese
  glEnable(GL_LIGHTING);
  
  //  Ambiens es diffuz anyagjellemzok hozzakotese a szinhez
  glEnable(GL_COLOR_MATERIAL);
  glColorMaterial(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE);

  //  Globalis ambiens feny beallitasa
  glLightModelfv(GL_LIGHT_MODEL_AMBIENT, ambientLight);

  //  0-s sorszamu feny parametereinek beallitasa
  //    diffuz feny szine
  glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuseLight);
  //    fenyforras pozicioja
  glLightfv(GL_LIGHT0, GL_POSITION, lightPos);
  //    spekularis feny szine
  glLightfv(GL_LIGHT0, GL_SPECULAR, specularLight);

  //  0-s sorszamu feny bekapcsolasa
  glEnable(GL_LIGHT0);
}

void SpecialKeys(int key, int x, int y)
{
  // ...
  int state;

  if(key == GLUT_KEY_UP)
    xRot-= 5.0f;
  
  if(key == GLUT_KEY_DOWN)
    xRot += 5.0f;
  
  if(key == GLUT_KEY_LEFT)
    yRot -= 5.0f;
  
  if(key == GLUT_KEY_RIGHT)
    yRot += 5.0f;
  
  if(xRot > 356.0f)
    xRot = 0.0f;
  
  if(xRot < 0.0f)
    xRot = 355.0f;
  
  if(yRot > 356.0f)
    yRot = 0.0f;
  
  if(yRot < -1.0f)
    yRot = 355.0f;

  printf("Funkciobillentyu lenyomva, kodja %d, pozicio (%d,%d). ", key, x, y);
  state = glutGetModifiers();
  if(state & GLUT_ACTIVE_SHIFT)
    printf("SHIFT lenyomva. ");
  if(state & GLUT_ACTIVE_CTRL)
    printf("CTRL lenyomva. ");
  if(state & GLUT_ACTIVE_ALT)
    printf("ALT lenyomva. ");
  printf("\n");
  fflush(stdout);

  // Refresh the Window
  glutPostRedisplay();
}

void Keyboard(unsigned char key, int x, int y)
{
  // ...
  int state;

  printf("Billentyu lenyomva, kodja %c, pozicio (%d,%d). ", key, x, y);
  state = glutGetModifiers();
  if(state & GLUT_ACTIVE_SHIFT)
    printf("SHIFT lenyomva. ");
  if(state & GLUT_ACTIVE_CTRL)
    printf("CTRL lenyomva. ");
  if(state & GLUT_ACTIVE_ALT)
    printf("ALT lenyomva. ");
  printf("\n");
  fflush(stdout);

  glutPostRedisplay();
}

void Timer(int value)
{
  printf("Timer esemeny (%d)\n", value);

  glutPostRedisplay();
  glutTimerFunc(1000, Timer, value + 1);
}

void Idle()
{

  glutPostRedisplay();
}

void ChangeSizeOrtho(int w, int h)
{
  GLfloat nRange = 25.0f;
  
  // Prevent a divide by zero
  if(h == 0)
    h = 1;
  
  // Set Viewport to window dimensions
  glViewport(0, 0, w, h);
  
  // Reset projection matrix stack
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  
  // Establish clipping volume (left, right, bottom, top, near, far)
  if (w <= h) 
    glOrtho (-nRange, nRange, -nRange*h/w, nRange*h/w, -nRange, nRange);
  else 
    glOrtho (-nRange*w/h, nRange*w/h, -nRange, nRange, -nRange, nRange);
  
  // Reset Model view matrix stack
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
}

void ChangeSizePerspective(GLsizei w, GLsizei h)
{
  GLfloat fAspect;
  
  // Prevent a divide by zero
  if(h == 0)
    h = 1;
  
  // Set Viewport to window dimensions
  glViewport(0, 0, w, h);
  
  fAspect = (GLfloat)w/(GLfloat)h;
  
  // Reset coordinate system
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  
  // Produce the perspective projection
  gluPerspective(60.0f,    // fovy
		 fAspect,  // aspect
		 10.0,     // zNear
		 100.0     // zFar
		 );
  gluLookAt(0.0, 0.0, 50.0, // eye
	    0.0, 0.0, 0.0,  // center
	    0.0, 1.0, 0.0   // up
	    );
  
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
}

int main(int argc, char* argv[])
{
  // >> Inicializalas

  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
  //glutInitWindowSize(300, 300);
  glutCreateWindow("GLUT Alap");

  // << Inicializalas

  // >> Callback fuggvenyek

  glutReshapeFunc(ChangeSizeOrtho); // Parhuzamos vetites
  //glutReshapeFunc(ChangeSizePerspective); // Perspektiv vetites

  glutSpecialFunc(SpecialKeys);
  glutKeyboardFunc(Keyboard);
  glutDisplayFunc(RenderScene);
  //glutTimerFunc(1000, Timer, 1); // 1 mp mulva meghivodik a Timer() fuggveny
  //glutIdleFunc(Idle); // Idle(), ha nem tortenik semmi
  
  // << Callback fuggvenyek

  SetupRC();
  glutMainLoop();
  
  return 0;
}