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

filter = 0

viewDistance = 7.0
viewRotY = 0.0
viewRotX = 0.0
cameraVelX = 0.0
cameraVelY = 0.0
prevTime = time.time()


def draw():
    glClearColor(0.5, 0.7, 1, 0)
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
    
    glMatrixMode(GL_PROJECTION)
    glLoadIdentity()
    gluPerspective(50.0, 1.0, 1.0, 100.0)
    glMatrixMode(GL_MODELVIEW)

    drawObjects()
    drawFilter()

    glutSwapBuffers()
    

def drawFilter():
    glMatrixMode(GL_PROJECTION)
    glLoadIdentity()
    glMatrixMode(GL_MODELVIEW)
    glLoadIdentity()
    glDisable(GL_LIGHTING)
    glEnable(GL_BLEND)

    if filter == 0:                     # Do nothing 
        glBlendFunc(GL_ZERO, GL_ONE)
    elif filter == 1:                   # Dim the scene
        glBlendFunc(GL_ZERO, GL_SRC_ALPHA)
        glColor4f(0, 0, 0, 0.5)
    elif filter == 2:                   # Dim the scene
        glBlendFunc(GL_ZERO, GL_SRC_COLOR)
        glColor4f(1, 0, 0.5, 1)
    elif filter == 3:                   # Invert all the colors
        glBlendFunc(GL_ONE_MINUS_DST_COLOR, GL_ZERO)
        glColor4f(1, 1, 1, 1)

    glBegin(GL_QUADS)
    glVertex2f(-1,-1)
    glVertex2f(1,-1)
    glVertex2f(1,1)
    glVertex2f(-1,1)
    glEnd()
    glDisable(GL_BLEND)


def drawObjects():
    glEnable(GL_LIGHTING)
    glLoadIdentity()
    glTranslatef(0.0, 0.0, -viewDistance)
    glRotatef(viewRotX, 1.0, 0.0, 0.0)
    glRotatef(viewRotY, 0.0, 1.0, 0.0)
    glLightfv(GL_LIGHT0, GL_POSITION, [-1, 1, 1, 0])

    glMaterialfv(GL_FRONT, GL_DIFFUSE, [1, 1, 1, 1])
    glPushMatrix()
    glTranslatef(0.0, -2.0, -5.0)
    glutSolidSphere(2.5, 16, 8)
    glPopMatrix()
   
    glMaterialfv(GL_FRONT, GL_DIFFUSE, [1, 0, 0, 1])
    glPushMatrix()
    glTranslatef(-1.0, -1.0, -2.0)
    glutSolidCube(2.0)
    glPopMatrix()
   
    glMaterialfv(GL_FRONT, GL_DIFFUSE, [0, 1, 0, 1])
    glPushMatrix()
    glTranslatef(1.0, -1.0, 0.0)
    glRotatef(-90.0, 1.0, 0.0, 0.0)
    glutSolidCone(1.5, 3.5, 16, 1)
    glPopMatrix()



def keyboard(key, x, y):
    global viewDistance, filter
    if key == chr(27):
        sys.exit(0)
    elif key == '.':
        viewDistance -= 1
    elif key == ',':
        viewDistance += 1
    elif key == ' ':
        filter = (filter + 1) % 4

def specialkey(key,x,y):
    global cameraVelX, cameraVelY
    if key == GLUT_KEY_LEFT:
        cameraVelY += 90
    elif key == GLUT_KEY_RIGHT:
        cameraVelY -= 90
    elif key == GLUT_KEY_UP:
        cameraVelX += 90
    elif key == GLUT_KEY_DOWN:
        cameraVelX -= 90

def specialkeyUp(key,x,y):
    global cameraVelX, cameraVelY
    if key == GLUT_KEY_LEFT:
        cameraVelY -= 90
    elif key == GLUT_KEY_RIGHT:
        cameraVelY += 90
    elif key == GLUT_KEY_UP:
        cameraVelX -= 90
    elif key == GLUT_KEY_DOWN:
        cameraVelX += 90

def update():
    global viewRotX, viewRotY, cameraVelX, cameraVelY
    global prevTime
    t = time.time()
    dt = t - prevTime
    prevTime = t
    viewRotX += cameraVelX * dt
    viewRotY += cameraVelY * dt
    glutPostRedisplay()

glutInit([])
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH)
glutInitWindowSize(500,500)
glutCreateWindow(sys.argv[0])
glutDisplayFunc(draw)
glutKeyboardFunc(keyboard)
glutSpecialFunc(specialkey)
glutSpecialUpFunc(specialkeyUp)
glutIgnoreKeyRepeat(1)
glutIdleFunc(update)
glEnable(GL_DEPTH_TEST)
glEnable(GL_LIGHTING)
glEnable(GL_LIGHT0)
glutMainLoop()