import sys, math
from OpenGL.GLUT import *
from OpenGL.GL import *
from OpenGL.GLU import *

cameraDist = 15
cameraXrot = 0
cameraYrot = 0

def draw():
	global cameraDist, cameraXrot, cameraYrot
	glClearColor(0, 0.3, 0.5, 0)
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
	glMatrixMode(GL_PROJECTION)
	glLoadIdentity()
	gluPerspective(60, 1, 0.1, 1000)
	glMatrixMode(GL_MODELVIEW)
	glLoadIdentity()
	glTranslatef(0, 0, -cameraDist)
	glRotatef(-cameraXrot, 1, 0, 0)
	glRotatef(-cameraYrot, 0, 1, 0)

	glLightfv(GL_LIGHT0, GL_POSITION, [-1, 0, 1, 0])
	glMaterialfv(GL_FRONT, GL_DIFFUSE, [1, 0.7, 0, 1])
	glMaterialfv(GL_FRONT, GL_SPECULAR, [1, 1, 1, 1])
	glMaterialf(GL_FRONT, GL_SHININESS, 80)
	glShadeModel(GL_FLAT)
	drawRing()

	glutSwapBuffers()


def drawRing():
	glBegin(GL_TRIANGLE_STRIP)
	for theta in range(0,370,10):
		x = 5 * math.sin(theta * math.pi/180.0)
		z = 5 * math.cos(theta * math.pi/180.0)
		nx = math.sin(theta*math.pi/180.0)
		nz = math.cos(theta*math.pi/180.0)
		glNormal3f(nx, 0, nz)
		glVertex3f(x, -1, z)
		glVertex3f(x, 1, z)
	glEnd()


def keyboard(key, x, y):
	global cameraDist
	if key == chr(27):
		sys.exit(0)
	elif key == '.':
		cameraDist = cameraDist - 1
	elif key == ',':
		cameraDist = cameraDist + 1
	glutPostRedisplay()

def specialkey(key,x,y):
    global cameraXrot, cameraYrot
    if key == GLUT_KEY_LEFT:
        cameraYrot = cameraYrot - 3
    elif key == GLUT_KEY_RIGHT:
        cameraYrot = cameraYrot + 3
    elif key == GLUT_KEY_UP:
        cameraXrot = cameraXrot - 3
    elif key == GLUT_KEY_DOWN:
        cameraXrot = cameraXrot + 3
    glutPostRedisplay()


glutInit(sys.argv)
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH)
glutInitWindowSize(400, 400)
glutInitWindowPosition(0,0)
glutCreateWindow(sys.argv[0])
glutDisplayFunc(draw)
glutKeyboardFunc(keyboard)
glutSpecialFunc(specialkey)
glEnable(GL_DEPTH_TEST)
glEnable(GL_LIGHTING)
glEnable(GL_LIGHT0)
glutMainLoop()