Recursive subdivision of tetrahedron to form 3D Sierpinski gasket using OpenGL

/* Recursive subdivision of tetrahedron to form 3D Sierpinski gasket */ #include #include typedef float point[3]; void menu(int); /* initial tetrahedron */ point v[]={{0.0, 0.0, 1.0}, {0.0, 0.942809, -0.33333}, {-0.816497, -0.471405, -0.333333}, {0.816497, -0.471405, -0.333333}}; static GLfloat theta[] = {0.0,0.0,0.0}; int n; void triangle( point a, point b, point c) /* display one triangle using a line loop for wire frame, a single normal for constant shading, or three normals for interpolative shading */ { glBegin(GL_POLYGON); glNormal3fv(a); glVertex3fv(a); glVertex3fv(b); glVertex3fv(c); glEnd(); } void divide_triangle(point a, point b, point c, int m) { /* triangle subdivision using vertex numbers righthand rule applied to create outward pointing faces */ 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) { /* Apply triangle subdivision to faces of tetrahedron */ 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 menu(int id) { if (id != 20) { n= id; } else { exit(0); } } 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); glutPostRedisplay(); } void main(int argc, char **argv) { int m_menu; if(argc>1) n=atoi(argv[1]); else n=4; glutInit(&argc, argv); glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH); glutInitWindowSize(500, 500); glutCreateWindow("3D Gasket"); m_menu= glutCreateMenu(menu); glutAddMenuEntry("1",1); glutAddMenuEntry("2",2); glutAddMenuEntry("3",3); glutAddMenuEntry("4",4); glutAddMenuEntry("5",5); glutAddMenuEntry("6",6); glutAddMenuEntry("7",7); glutAddMenuEntry("8",8); glutAddMenuEntry("9",9); glutAddMenuEntry("10",10); glutAddMenuEntry("11",11); // glutAddMenuEntry("12",12); // glutAddMenuEntry("13",13); glutAddMenuEntry("Exit",20); glutAttachMenu(GLUT_LEFT_BUTTON); glutReshapeFunc(myReshape); glutDisplayFunc(display); glEnable(GL_DEPTH_TEST); glClearColor (1.0, 1.0, 1.0, 1.0); glutMainLoop(); }