#include <GL/glut.h>
#include <iostream.h>



// function prototypes
void display(void);
void reshape(int width, int height);
void keyboard(unsigned char key, int x, int y);
void init(void);
void menu(int menuItem);
void printMatrix(float matrix[16]);

enum {MY_MENU_PROJECTION, MY_MENU_PROJECTION_MATRIX, MY_MENU_MODELVIEW_MATRIX};




int 
main(int argc, char **argv)
{

  // set up window
  glutInitWindowSize(400, 400);
  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
  glutCreateWindow("My starter code");

  // register callback functions
  glutDisplayFunc(display);
  glutReshapeFunc(reshape); 
  glutKeyboardFunc(keyboard);
  
  // initalize opengl parameters
  init();

  // loop until something happens
  glutMainLoop();
  return 0;           
}

void init()
{
  // initialize viewing system
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();

  // we start in orthographic mode
  glOrtho(-1, 1, -1, 1, 1, 3);   // the near plane is at -1 and the far plane at -3
								// because the glOrtho call reverses the signs!
  glMatrixMode(GL_MODELVIEW);
 

  // initialize background color to black
  glClearColor(0.0,0.0,0.0,0.0);

  // enable depth buffering
  glEnable(GL_DEPTH_TEST);

  // build menu
  glutCreateMenu(menu);
  glutAddMenuEntry("Toggle Projection Mode", MY_MENU_PROJECTION);
  glutAddMenuEntry("Print Projection Matrix",MY_MENU_PROJECTION_MATRIX);
  glutAddMenuEntry("Print Modelview Matrix",MY_MENU_MODELVIEW_MATRIX);
  glutAttachMenu(GLUT_RIGHT_BUTTON);


  // set up printing for matrix
	cout.setf(ios::showpoint);
	cout.setf(ios::showpos);
	cout.precision(4);
	cout.setf(ios::fixed);



}



void reshape(int width, int height)
{

}

void display()
{

	// clear the buffers
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

	// initialize modelview matrix
	glLoadIdentity();

	//draw a triangle
	glColor3f(1,0,0);
	glBegin(GL_TRIANGLES);
	glVertex3f(0,0,-1.1);
	glVertex3f(1,0,-1.1);
	glVertex3f(0.3f,0.5f,-1.1);
	glEnd();

	//draw a triangle
	glColor3f(0,0,1);
	glBegin(GL_TRIANGLES);
	glVertex3f(-1,0,-1.5f);
	glVertex3f(1,0,-1.5f);
	glVertex3f(0.2f,0.5f,-1.5f);
	glEnd();

	//draw a triangle
	glColor3f(0,1,0);
	glBegin(GL_TRIANGLES);
	glVertex3f(-1,0,-1.9);
	glVertex3f(1,0,-1.9);
	glVertex3f(0.1f,0.6f,-1.9);
	glEnd();

	// draw to screen
	glutSwapBuffers();



}

void keyboard(unsigned char key, int x, int y)
{

if (key == ' ')
	cout << "You hit the space bar." << endl;

}


void menu(int menuItem)
{

	static bool perspective=false;
	float matrix[16];

	switch(menuItem) {
	case MY_MENU_PROJECTION:  // toggle projection mode
		{
			glMatrixMode(GL_PROJECTION);
			glLoadIdentity();
			if (perspective) {
				cout << endl << "Switching to orthographic projection." << endl;
				glOrtho(-1, 1, -1, 1, 1, 3);
			}
			else {
				cout << endl << "Switching to perspective projection." << endl;
				glFrustum(-1,1,-1,1,1,3);
			}
			perspective = !perspective;
			glMatrixMode(GL_MODELVIEW);
			glutPostRedisplay();
			break;
		}

	case MY_MENU_PROJECTION_MATRIX:  // print current projection matrix
		{
			glGetFloatv(GL_PROJECTION_MATRIX, matrix);
			cout << endl << "Current Projection Matrix ";
			if (perspective)
				cout << "(Perspective l=-1, r=1, b=-1, t=1, n=1, f=3):" << endl;
			else 
				cout << "(Orthographic l=-1, r=1, b=-1, t=1, n=1, f=3):" << endl;
			printMatrix(matrix);
			break;
		}

	case MY_MENU_MODELVIEW_MATRIX:	// print current modeling matrix
		{
			glGetFloatv(GL_MODELVIEW_MATRIX, matrix);
			cout << endl << "Current Modelview Matrix " << endl;
			printMatrix(matrix);
			break;
		}

	default:
			break;
	}
}


void printMatrix(float matrix[16])
{


	for (int i=0;i<4;i++) {
		for (int j=0; j<4; j++)
			cout << matrix[i+j*4] << "       ";
		cout << endl;
	}
}