#include<stdlib.h>
#include<stdio.h>
#include<GL/glut.h>

typedef float point [3];
int n;
point v[] = { {0.0, 0.0, 0.0}, {0.0, 1.0, -1.0},{-1.0, -1.0, -1.0}, {1.0, -1.0, -1.0} };

void triangle(point a, point b, point c)
{
	glBegin(GL_POLYGON);
	glVertex3fv(a);
	glVertex3fv(b);
	glVertex3fv(c);
	glEnd();
}

void divide_triangle(point a, point b, point c, int m)
{
	point v1, v2, v3;
	int j;
	if (m > 0)
	{
		for (j = 0; j < 3; j++) v1[j] = (a[j] + b[j]) / 2;
		for (j = 0; j < 3; j++) v2[j] = (a[j] + c[j]) / 2;
		for (j = 0; j < 3; j++) v3[j] = (b[j] + c[j]) / 2;
		divide_triangle(a, v1, v2, m - 1);
		divide_triangle(c, v2, v3, m - 1);
		divide_triangle(b, v3, v1, m - 1);
	}
	else(triangle(a, b, c)); /* draw triangle at end of recursion */
}
void tetrahedron(int m)
{
	glColor3f(1.0, 0.0, 0.0);
	divide_triangle(v[0], v[1], v[2], m);
	glColor3f(0.0, 1.0, 0.0);
	divide_triangle(v[3], v[2], v[1], m);
	glColor3f(0.0, 0.0, 1.0);
	divide_triangle(v[0], v[3], v[1], m);
	glColor3f(0.0, 0.0, 0.0);
	divide_triangle(v[0], v[2], v[3], m);
}
void display(void)
{
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glLoadIdentity();
	tetrahedron(n);
	glFlush();
}
void myReshape(int w, int h)
{
	glViewport(0, 0, w, h);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	if (w <= h)
		glOrtho(-2.0, 2.0, -2.0 * (GLfloat)h / (GLfloat)w, 2.0 * (GLfloat)h / (GLfloat)w, -10.0, 10.0);
	else
		glOrtho(-2.0 * (GLfloat)w / (GLfloat)h,
			2.0 * (GLfloat)w / (GLfloat)h, -2.0, 2.0, -10.0, 10.0); glMatrixMode(GL_MODELVIEW);
}
void main(int argc, char** argv)
{
	printf(" Enter the Number of Divisions ? ");
	scanf_s("%d", &n);
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH); 
	glutInitWindowSize(500, 500); 
	glutCreateWindow("3D Gasket USN:1AH18CS092");
	glutReshapeFunc(myReshape);
	glutDisplayFunc(display);
	glEnable(GL_DEPTH_TEST);
	glClearColor(1.0, 1.0, 1.0, 1.0);
	glutMainLoop();
}