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


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

// Rotation amounts
static GLfloat xRot = 0.0f;
static GLfloat yRot = 0.0f;

static int wireframe = 1;
static int showNormals = 1;

// Light values and coordinates
static GLfloat lightPos[] = { 0.0f, 0.0f, 75.0f, 1.0f };
static GLfloat specular[] = { 1.0f, 1.0f, 1.0f, 1.0f};
static GLfloat specref[] =  { 1.0f, 1.0f, 1.0f, 1.0f };
static GLfloat ambientLight[] = { 0.2f, 0.2f, 0.2f, 1.0f};
static GLfloat spotDir[] = { 0.0f, 0.0f, -1.0f };

static int piecesX = 20;
static int piecesY = 20;

static int shine = 128;

void BitmapText(GLfloat x, GLfloat y, char *string)
{
  int len, i;
  glRasterPos2f(x, y);
  len = (int) strlen (string);
  for (i = 0; i < len; i++){
    glutBitmapCharacter (GLUT_BITMAP_HELVETICA_18, string[i]);
  }
}

void SolidQuad(float width, int piecesX, int piecesY)
{
  float h, wx, wy, x, y;
  int i, j;
  //int pieces = 10;

  h = width / 2.0;
  wx = width / piecesX;
  wy = width / piecesY;

  glBegin(GL_QUADS);
  glNormal3f(0.0, 0.0, 1.0);

  for(y = h, j = 0; j < piecesY; y -= wy, j++)
    for(x = -h, i = 0; i < piecesX; x += wx, i++)
      {
	glVertex3f(x, y, 0);
	glVertex3f(x, y - wy, 0);
	glVertex3f(x + wx, y - wy, 0);
	glVertex3f(x + wx, y, 0);
      }

  glEnd();
}

void SolidQuadNormals(float width, int piecesX, int piecesY)
{
  float h, wx, wy, x, y;
  int i, j;
  //int pieces = 10;

  h = width / 2.0;
  wx = width / piecesX;
  wy = width / piecesY;

  glBegin(GL_QUADS);
  glNormal3f(0.0, 0.0, 1.0);

  for(y = h, j = 0; j < piecesY; y -= wy, j++)
    for(x = -h, i = 0; i < piecesX; x += wx, i++)
      {
	glVertex3f(x, y, 0);
	glVertex3f(x, y - wy, 0);
	glVertex3f(x + wx, y - wy, 0);
	glVertex3f(x + wx, y, 0);
      }

  glEnd();

  glColor3f(0.0, 0.8, 0.0);
  glBegin(GL_LINES);
  for(y = h, j = 0; j < piecesY; y -= wy, j++)
    for(x = -h, i = 0; i < piecesX; x += wx, i++)
      {
	glVertex3f(x, y, 0);
	glVertex3f(x, y, 10);
	glVertex3f(x, y - wy, 0);
	glVertex3f(x, y - wy, 10);
	glVertex3f(x + wx, y - wy, 0);
	glVertex3f(x + wx, y - wy, 10);
	glVertex3f(x + wx, y, 0);
	glVertex3f(x + wx, y, 10);
      }
  glEnd();
}

void SolidCube(float width, int piecesX, int piecesY, int piecesZ)
{
  glPushMatrix();
  glTranslatef(0.0, 0.0, width / 2.0);
  SolidQuad(width, piecesX, piecesY);
  glPopMatrix();

  glPushMatrix();
  glTranslatef(0.0, 0.0, -width / 2.0);
  glRotatef(180.0, 0.0, 1.0, 0.0);
  SolidQuad(width, piecesX, piecesY);
  glPopMatrix();

  glPushMatrix();
  glTranslatef(width / 2.0, 0.0, 0.0);
  glRotatef(90.0, 0.0, 1.0, 0.0);
  SolidQuad(width, piecesZ, piecesY);
  glPopMatrix();

  glPushMatrix();
  glTranslatef(-width / 2.0, 0.0, 0.0);
  glRotatef(-90.0, 0.0, 1.0, 0.0);
  SolidQuad(width, piecesZ, piecesY);
  glPopMatrix();

  glPushMatrix();
  glTranslatef(0.0, width / 2.0, 0.0);
  glRotatef(-90.0, 1.0, 0.0, 0.0);
  SolidQuad(width, piecesX, piecesZ);
  glPopMatrix();

  glPushMatrix();
  glTranslatef(0.0, -width / 2.0, 0.0);
  glRotatef(90.0, 1.0, 0.0, 0.0);
  SolidQuad(width, piecesX, piecesZ);
  glPopMatrix();
}

// Called to draw scene
void RenderScene(void)
{
  char buff[255];

	// Clear the window with current clearing color
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

	if(wireframe)
	  glPolygonMode(GL_FRONT, GL_LINE);
	else
	  glPolygonMode(GL_FRONT, GL_FILL);

	glPushMatrix();
	// Specify new position and direction in rotated coords.
	////glRotatef(90.0, 0.0, 1.0, 0.0);
	//glRotatef(yRot, 0.0f, 1.0f, 0.0f);
	//glRotatef(xRot, 1.0f, 0.0f, 0.0f);

	glMateriali( GL_FRONT, GL_SHININESS, shine );

	glLightfv(GL_LIGHT0,GL_POSITION,lightPos);
	glLightfv(GL_LIGHT0,GL_SPOT_DIRECTION,spotDir);

	// Draw a red cone to enclose the light source
	glColor3ub(255,0,0);	
	
	// Translate origin to move the cone out to where the light
	// is positioned.
	glTranslatef(lightPos[0],lightPos[1],lightPos[2]);
	glutSolidCone(4.0f,6.0f,15,15);
	
	// Draw a smaller displaced sphere to denote the light bulb
	// Save the lighting state variables
	glPushAttrib(GL_LIGHTING_BIT);
	
	// Turn off lighting and specify a bright yellow sphere
	glDisable(GL_LIGHTING);
	glColor3ub(255,255,0);
	glutSolidSphere(3.0f, 15, 15);
	
	glColor3f(1.0, 1.0, 1.0);
	BitmapText(-60, 60, "Nyilak, W, N, F1, F2, F3, F4");
	
	sprintf( buff, "Shininess: %d", shine );
	BitmapText(-60, -60, buff);
	
	// Restore lighting state variables
	glPopAttrib();
	glPopMatrix();

	glColor3f(1.0, 0.0, 0.0);
	// Save the matrix state and do the rotations
	glPushMatrix();
	glRotatef(yRot, 0.0f, 1.0f, 0.0f);
	glRotatef(xRot, 1.0f, 0.0f, 0.0f);
	//glRotatef(10, 0.5f, 1.0f, 0.5f);

	if(showNormals)
	  SolidQuadNormals(80.0, piecesX, piecesY);
	else
	  SolidQuad(80.0, piecesX, piecesY);

	// Restore the matrix state
	glPopMatrix();
	// Display the results
	glutSwapBuffers();
}

// This function does any needed initialization on the rendering
// context. 
void SetupRC()
{
	glEnable(GL_DEPTH_TEST);	// Hidden surface removal
	glFrontFace(GL_CCW);		// Counter clock-wise polygons face out
	//glEnable(GL_CULL_FACE);		// Do not calculate inside of jet
	glShadeModel(GL_SMOOTH);

	// Light blue background
	glClearColor(0.0f, 0.0f, 0.0f, 1.0f );

	glEnable(GL_LIGHTING);
	glLightModelfv(GL_LIGHT_MODEL_AMBIENT, ambientLight);

	// Setup and enable light 0
	//glLightfv(GL_LIGHT0, GL_AMBIENT, ambientLight);
	glLightfv(GL_LIGHT0, GL_SPECULAR, specular);
	//glLightfv(GL_LIGHT0, GL_POSITION, lightPos);

	// Specific spot effects
	// Cut off angle
	glLightf(GL_LIGHT0, GL_SPOT_CUTOFF, 60.0f);

	// Fairly shiny spot
	glLightf(GL_LIGHT0, GL_SPOT_EXPONENT, 80.0f);	

	glEnable(GL_LIGHT0);

	// Enable Material color tracking
	glEnable(GL_COLOR_MATERIAL);
	// Front material ambient and diffuse colors track glColor
	glColorMaterial(GL_FRONT, GL_AMBIENT_AND_DIFFUSE);

	// All materials hereafter have full specular reflectivity
	// with a high shine
	glMaterialfv(GL_FRONT, GL_SPECULAR, specref);

	glEnable(GL_NORMALIZE);
}

void SpecialKeys(int key, int x, int y)
{
	if(key == GLUT_KEY_UP)
		xRot-= 1.0f;

	if(key == GLUT_KEY_DOWN)
		xRot += 1.0f;

	if(key == GLUT_KEY_LEFT)
		yRot -= 1.0f;

	if(key == GLUT_KEY_RIGHT)
		yRot += 1.0f;

	if(xRot > 359.0f)
		xRot = 0.0f;

	if(xRot < 0.0f)
		xRot = 359.0f;

	if(yRot > 359.0f)
		yRot = 0.0f;

	if(yRot < 0.0f)
		yRot = 359.0f;

	if(key == GLUT_KEY_F1)
	  {
	    piecesX ++;
	    piecesY ++;
	  }

	if((key == GLUT_KEY_F2) && (piecesX > 1))
	  {
	    piecesX --;
	    piecesY --;
	  }

	if( ( key == GLUT_KEY_F3 ) && ( shine > 0 ) )
	  shine --;

	if( ( key == GLUT_KEY_F4 ) && ( shine < 128 ) )
	  shine ++;

	// Refresh the Window
	glutPostRedisplay();
}


void ChangeSize(int w, int h)
{
	GLfloat nRange = 80.0f;
	// Prevent a divide by zero
	if(h == 0)
		h = 1;

	// Set Viewport to window dimensions
    glViewport(0, 0, w, h);

	// Reset coordinate system
	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);

	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
}

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);

  if(key == 'w' || key == 'W')
    {
      wireframe = !wireframe;
    }

  if(key == 'n' || key == 'N')
    {
      showNormals = !showNormals;
    }

  glutPostRedisplay();
}
 
int main(int argc, char* argv[])
{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
	glutCreateWindow("Spotlight - Tank");
	glutReshapeFunc(ChangeSize);
	glutSpecialFunc(SpecialKeys);
	glutKeyboardFunc(Keyboard);
	glutDisplayFunc(RenderScene);
	SetupRC();
	glutMainLoop();

	return 0;
}