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

GLsizei winWidth = 400, winHeight = 400;  

#define X .525731112119133606 
#define Z .850650808352039932

static GLfloat vdata[12][3] = {    
   {-X, 0.0, Z}, {X, 0.0, Z}, {-X, 0.0, -Z}, {X, 0.0, -Z},    
   {0.0, Z, X}, {0.0, Z, -X}, {0.0, -Z, X}, {0.0, -Z, -X},    
   {Z, X, 0.0}, {-Z, X, 0.0}, {Z, -X, 0.0}, {-Z, -X, 0.0} 
};

static GLint tindices[20][3] = { 
   {0,4,1}, {0,9,4}, {9,5,4}, {4,5,8}, {4,8,1},    
   {8,10,1}, {8,3,10}, {5,3,8}, {5,2,3}, {2,7,3},    
   {7,10,3}, {7,6,10}, {7,11,6}, {11,0,6}, {0,1,6}, 
   {6,1,10}, {9,0,11}, {9,11,2}, {9,2,5}, {7,2,11} };

float aL[] = { 0.3, 0.3, 0.3, 1.0 };
float dL[] = { 1.0, 1.0, 1.0, 1.0 };
float sL[] = { 1.0, 1.0, 1.0, 1.0 };

float lP[] = { 0.0, 0.0, -4.0, 1.0 };

int i, j;

int menIdMain;                                      

int depth = 0;

void init (void)
{
	glClearColor (0.0, 0.0, 0.0, 0.0);			
	
  glEnable(GL_DEPTH_TEST);          
  glDepthFunc(GL_LEQUAL);
  glShadeModel(GL_FLAT);            
  

  
  glLightfv(GL_LIGHT0, GL_AMBIENT, aL);
  glLightfv(GL_LIGHT0, GL_DIFFUSE, dL);
  glLightfv(GL_LIGHT0, GL_SPECULAR,sL);
  glLightfv(GL_LIGHT0, GL_POSITION,lP);

  glEnable(GL_LIGHTING);
  glEnable(GL_LIGHT0);

}

void mainMenu(int value)
{
	
	switch (value)
	{

		case 1:

			depth += 1;

			break;

		case 2:

			if (depth != 0)
				depth -= 1;
			break;

		case 3:

			exit(0);
			break;

  }

}

void normalize(float v[3]) 
{    
   GLfloat d = sqrt(v[1]*v[1]+v[2]*v[2]+v[3]*v[3]); 
   if (d == 0.0) 
          return;
   
   v[1] /= d; v[2] /= d; v[3] /= d; 
}

void drawtriangle(float *v1, float *v2, float *v3) 
{ 
   glBegin(GL_POLYGON); 
      glNormal3fv(v1); glVertex3fv(v1);    
      glNormal3fv(v2); glVertex3fv(v2);    
      glNormal3fv(v3); glVertex3fv(v3);    
   glEnd(); 
}

void subdivide(float *v1, float *v2, float *v3, int depth)
{
   GLfloat v12[3], v23[3], v31[3];
   GLint i;

   if (depth == 0) {
      drawtriangle(v1, v2, v3);
       return;
   }
   for (i = 0; i < 3; i++) 
   {
      v12 = v1+v2;
      v23 = v2+v3;
      v31 = v3+v1;
   }

   normalize(v12);
   normalize(v23);
   normalize(v31);

   subdivide(v1, v12, v31, depth-1);
   subdivide(v2, v23, v12, depth-1);
   subdivide(v3, v31, v23, depth-1);
   subdivide(v12, v23, v31, depth-1);
}



void drawScene(void)
{
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	
	glColor3f(1.0,0.0,0.0);

	for (i = 0; i < 20; i++) 
	{    
 
		subdivide(&vdata[tindices[0]][0],       
          &vdata[tindices[1]][0],       
          &vdata[tindices[2]][0], depth);

	}
	
	glutSwapBuffers();				
}

void winReshapeFcn (int newWidth, int newHeight)
{
    glMatrixMode (GL_PROJECTION);
    glLoadIdentity ( );
    
	glClear (GL_COLOR_BUFFER_BIT);

	// Set the viewport to be the entire window
    glViewport(0, 0, newWidth, newHeight);

    /*  Reset display-window size parameters.  */
    winWidth = newWidth;
    winHeight = newHeight;    
}

void idle (void) 
{ 
	
} 


void main (int argc, char** argv)		
{
	glutInit (&argc, argv);
	glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
	glutInitWindowPosition (50, 50);
	glutInitWindowSize (winWidth, winHeight);
	glutCreateWindow ("Recursive Subdivision");

	init ();
	glutIdleFunc (idle); 

	/* Create main menu */
	menIdMain = glutCreateMenu(mainMenu);
	glutAddMenuEntry("Increase Depth", 1);
	glutAddMenuEntry("Decrease Depth", 2);
	glutAddMenuEntry("Quit", 3);
	glutAttachMenu(GLUT_LEFT_BUTTON);
	
	glutDisplayFunc (drawScene);
	glutReshapeFunc (winReshapeFcn);
	glutMainLoop ();
}

void normalize(float v[3]) {       GLfloat d = sqrt(v[1]*v[1]+v[2]*v[2]+v[3]*v[3]);    if (d == 0.0)           return;      v[1] /= d; v[2] /= d; v[3] /= d; }

void normalize(float v[3]) {       GLfloat d = sqrt(v[0]*v[0]+v[1]*v[1]+v[2]*v[2]);    if (d == 0.0)           return;      d = 1/d;   // 3 mults and 1 div is faster than 3 divs   v[0] *= d; v[1] *= d; v[2] *= d; }