#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 idle(void);

// global variable -- yuck
// you should create different arrays for diffuse
// and specular -- this is only so that
// they can be easily indexed for change 
float mat1[]={1.0f, 0.0f, 0.0f, 1.0f};
float mat2[]={0.0f, 0.0f, 1.0f, 1.0f};

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

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

  // register callback functions
  glutDisplayFunc(display);
  glutReshapeFunc(reshape); 
  glutKeyboardFunc(keyboard);
  glutIdleFunc(idle);

  
  // initalize opengl parameters
  init();

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

void idle()
{
	glutPostRedisplay();
}

void init()
{
  // initialize viewing system
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  gluPerspective(45.0, 1.0, 10.0, 100.0);
  glMatrixMode(GL_MODELVIEW);
 

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

  // enable depth buffering
  glEnable(GL_DEPTH_TEST);

  // shading model is smooth
  glEnable(GL_SMOOTH);

  // normalize normals
  glEnable(GL_NORMALIZE);

  // initialize light
  GLfloat lightPosition[] = {20.0f, 20.0f, -10.0f};	// set light position
  glLightfv(GL_LIGHT0, GL_POSITION, lightPosition);	// this will make it a 
													// positional light

  GLfloat whiteLight[] = {1.0f, 1.0f, 1.0f, 1.0f};	// set the light color to white
  glLightfv(GL_LIGHT0, GL_DIFFUSE, whiteLight);		// for diffuse
  glLightfv(GL_LIGHT0, GL_SPECULAR, whiteLight);	// and specular


  glLightModeli(GL_LIGHT_MODEL_TWO_SIDE, GL_TRUE);	// light both sides


  // enable lighting and the light we defined
  glEnable(GL_LIGHTING);
  glEnable(GL_LIGHT0);

}



void reshape(int width, int height)
{
  
  if (width< height)
	  glViewport(0,0,width, width);
  else
	  glViewport(0,0,height,height);

}

void display()
{
	static float angle;

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

	// initialize modelview matrix
	glLoadIdentity();


	//move teapot into scene
	glTranslatef(0.0f, 0.0f, -20.0f);

	// rotate about the y axis
	glRotatef(angle,0,1,0);
	angle += 1;


	// set material proprties
	glMaterialfv(GL_FRONT, GL_DIFFUSE, mat1);



	//draw triangle
	glBegin(GL_TRIANGLES);
	glNormal3f(1.0f,0.0f,0.0f);
	glVertex3f(0.0f,0.0f,0.0f);
	glVertex3f(10.0f,0.0f,0.0f);
	glVertex3f(8.0f, 4.0f,0.0f);
	glEnd();


	// draw to screen
	glutSwapBuffers();



}

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


}