//  6/7/06
//  Andrew Monshizadeh
//  OpenGL 3d engine using glut

#include <GL/glut.h>
#include <cmath>
#include <iostream>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
using namespace std;

// window global variables
int WINDOW_WIDTH = 800;
int WINDOW_HEIGHT = 600;
int windowids[1];  // can be used to store multiple window ids in case there are multiple windows
char title[13] = "test engine";

// call back functions to be used
void initializecallbacks();
void displaycallback();
void keyboardcallback(unsigned char key, int x, int y);
void passivemotioncallback(int x, int y);
void reshapecallback(int w, int h);
void timercallback(int time);

// setup visual requirments
void initializevisuals();

// variables used for movement
const float piover180 = 0.0174532925f;  // pi / 180, for degree to radian transform
float heading; // direction character is facing
float xpos; // x-axis position of the player
float zpos; // z-axis position of the player
float ypos = 0.5; // y-axis position of the player
GLfloat	yrot; // y-axis rotation
GLfloat lookupdown = 0.0f; // value to look up or down
GLfloat	z=0.0f;				// Depth Into The Screen
int mousebasex = WINDOW_WIDTH/2;
int mousebasey = WINDOW_HEIGHT/2;

int main(int argc, char* argv[])
{
  glutInit(&argc, argv);
  initializevisuals();
  initializecallbacks();
  
  glutMainLoop();
  
  return 0;
}

//----------------------------------------------------------------------------//
//                              call back section                             //
//----------------------------------------------------------------------------//
void initializecallbacks()
{
  // setting up the call back functions
  glutDisplayFunc(displaycallback);  // display call back
  glutKeyboardFunc(keyboardcallback);  //  keyboard call back
  glutPassiveMotionFunc(passivemotioncallback);  // passive mouse motion call back
  glutReshapeFunc(reshapecallback); // screen reshape call back
  glutTimerFunc(15, timercallback, 0);  // timer call back
}

void keyboardcallback(unsigned char key, int x, int y)
{
  switch (key)
  {
    // miscellaneous input
    case 27: // 'esc'
      exit(0); // end the program
      break;
    
    // movement input
    case 'a':
      xpos -= (float)sin(heading*piover180 + 90.0f*piover180) * 0.05f;
      zpos -= (float)cos(heading*piover180 + 90.0f*piover180) * 0.05f;
			break;
		case 'd':
      xpos += (float)sin(heading*piover180 + 90.0f*piover180) * 0.05f;
      zpos += (float)cos(heading*piover180 + 90.0f*piover180) * 0.05f;
      break;
    case 'w':
      xpos -= (float)sin(heading*piover180) * 0.05f;
			zpos -= (float)cos(heading*piover180) * 0.05f;
			break;
		case 's':
      xpos += (float)sin(heading*piover180) * 0.05f;
      zpos += (float)cos(heading*piover180) * 0.05f;
  }
  
  int dims[4];
  glGetIntegerv(GL_VIEWPORT, dims);
  
  int dx = x - mousebasex;
  int dy = y - mousebasey;
  mousebasex = x;
  mousebasey = y;
  
//  if (x < 20)
//  {
//    glutWarpPointer(dims[2]/2, y);
//    mousebasex = dims[2]/2;
//  }
//  if (x > (dims[2]/2 - 20))
//  {
//    glutWarpPointer(dims[2]/2, y);
//    mousebasex = dims[2]/2;
//  }
  
  lookupdown += dy * 0.5f;
  heading -= dx * 0.5f;
  if(heading < 0.0f)
    heading = heading + 360.0f;
  else if(heading > 360.0f)
    heading = heading - 360.0f;
  yrot = heading;
}

void passivemotioncallback(int x, int y)
{
  int dims[4];
  glGetIntegerv(GL_VIEWPORT, dims);
  
  int dx = x - mousebasex;
  int dy = y - mousebasey;
  mousebasex = x;
  mousebasey = y;
  
  if (x < 20)
  {
    glutWarpPointer(dims[2]/2, y);
    mousebasex = dims[2]/2;
  }
  if (x > (dims[2] - 20))
  {
    glutWarpPointer(dims[2]/2, y);
    mousebasex = dims[2]/2;
  }
  
  lookupdown += dy * 0.5f;
  heading -= dx * 0.5f;
  if(heading < 0.0f)
    heading = heading + 360.0f;
  else if (heading > 360.0f)
    heading = heading - 360.0f;
  yrot = heading;
}

void reshapecallback(int w, int h)
{
  glViewport(0, 0, w, h);
 
 	glMatrixMode(GL_PROJECTION);						// Select The Projection Matrix
	glLoadIdentity();									// Reset The Projection Matrix

	// Calculate The Aspect Ratio Of The Window
	gluPerspective(45.0f,(GLfloat)w/(GLfloat)h,0.1f,100.0f);

	glMatrixMode(GL_MODELVIEW);							// Select The Modelview Matrix
	glLoadIdentity();									// Reset The Modelview Matrix
}

void timercallback(int time)
{
  glutPostRedisplay();
  glutTimerFunc(10, timercallback, 0);
}

void displaycallback()
{
  int dims[4];
  glGetIntegerv(GL_VIEWPORT, dims);
  
 	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);	// Clear The Screen And The Depth Buffer
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();									// Reset The View

	GLfloat xtrans = -xpos;
	GLfloat ztrans = -zpos;
	GLfloat ytrans = 0; // -walkbias-0.25f;
	GLfloat sceneroty = 360.0f - yrot;
	
  glRotatef(lookupdown,1.0f,0,0);
	glRotatef(sceneroty,0,1.0f,0);
	glTranslatef(xtrans, ytrans, ztrans);
	
	glBegin(GL_QUADS);
		glColor3f(0.0f,1.0f,0.0f);			// Set The Color To Green
		glVertex3f( 0.5f, 0.5f,-0.5f);			// Top Right Of The Quad (Top)
		glVertex3f(-0.5f, 0.5f,-0.5f);			// Top Left Of The Quad (Top)
		glVertex3f(-0.5f, 0.5f, 0.5f);			// Bottom Left Of The Quad (Top)
		glVertex3f( 0.5f, 0.5f, 0.5f);			// Bottom Right Of The Quad (Top)
		
		glColor3f(1.0f,0.5f,0.0f);			// Set The Color To Orange
		glVertex3f( 0.5f,-0.5f, 0.5f);			// Top Right Of The Quad (Bottom)
		glVertex3f(-0.5f,-0.5f, 0.5f);			// Top Left Of The Quad (Bottom)
		glVertex3f(-0.5f,-0.5f,-0.5f);			// Bottom Left Of The Quad (Bottom)
		glVertex3f( 0.5f,-0.5f,-0.5f);			// Bottom Right Of The Quad (Bottom)
		
		glColor3f(1.0f,0.0f,0.0f);			// Set The Color To Red
		glVertex3f( 0.5f, 0.5f, 0.5f);			// Top Right Of The Quad (Front)
		glVertex3f(-0.5f, 0.5f, 0.5f);			// Top Left Of The Quad (Front)
		glVertex3f(-0.5f,-0.5f, 0.5f);			// Bottom Left Of The Quad (Front)
		glVertex3f( 0.5f,-0.5f, 0.5f);			// Bottom Right Of The Quad (Front)
		
		glColor3f(1.0f,1.0f,0.0f);			// Set The Color To Yellow
		glVertex3f( 0.5f,-0.5f,-0.5f);			// Bottom Left Of The Quad (Back)
		glVertex3f(-0.5f,-0.5f,-0.5f);			// Bottom Right Of The Quad (Back)
		glVertex3f(-0.5f, 0.5f,-0.5f);			// Top Right Of The Quad (Back)
		glVertex3f( 0.5f, 0.5f,-0.5f);			// Top Left Of The Quad (Back)
		
		glColor3f(0.0f,0.0f,1.0f);			// Set The Color To Blue
		glVertex3f(-0.5f, 0.5f, 0.5f);			// Top Right Of The Quad (Left)
		glVertex3f(-0.5f, 0.5f,-0.5f);			// Top Left Of The Quad (Left)
		glVertex3f(-0.5f,-0.5f,-0.5f);			// Bottom Left Of The Quad (Left)
		glVertex3f(-0.5f,-0.5f, 0.5f);			// Bottom Right Of The Quad (Left)
		
		glColor3f(1.0f,0.0f,1.0f);			// Set The Color To Violet
		glVertex3f( 0.5f, 0.5f,-0.5f);			// Top Right Of The Quad (Right)
		glVertex3f( 0.5f, 0.5f, 0.5f);			// Top Left Of The Quad (Right)
		glVertex3f( 0.5f,-0.5f, 0.5f);			// Bottom Left Of The Quad (Right)
		glVertex3f( 0.5f,-0.5f,-0.5f);			// Bottom Right Of The Quad (Right)
	glEnd();						// Done Drawing The Quad
	
	glFlush();
	glutSwapBuffers();
}


void initializevisuals()
{
  // creating the window and drawing buffers  
  glutInitDisplayMode(GLUT_DOUBLE | GLUT_DEPTH); // create double buffer and z-depth buffer
  glutInitWindowSize(WINDOW_WIDTH, WINDOW_HEIGHT); // create window using predetermined window sizes
  glutInitWindowPosition(0,0);
  windowids[0]=glutCreateWindow(title);
  glClearColor(0.0f, 0.0f, 0.0f, 0.0f); // set background color to white
	glClearDepth(1.0); // enables clearing of the depth buffer
  glEnable(GL_DEPTH_TEST); // enable depth testing
	glDepthFunc(GL_LESS);	// the type of depth test to do
	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);	// really nice perspective calculations, got from NeHe tutorial 10

  int dims[4];
  glGetIntegerv(GL_VIEWPORT, dims);

	glMatrixMode(GL_PROJECTION);						// Select The Projection Matrix
	glLoadIdentity();									// Reset The Projection Matrix

	// Calculate The Aspect Ratio Of The Window
	gluPerspective(45.0f,(GLfloat)dims[2]/(GLfloat)dims[3],0.1f,100.0f);

	glMatrixMode(GL_MODELVIEW);							// Select The Modelview Matrix
	glLoadIdentity();									// Reset The Modelview Matrix
}