cubeGL V1.0 dirty code

The first version of CubicVR Viewer "cubeGL" is now working. It still a dirty code.

一応CubicVR Viewer "cubeGL"が動きましたので、まだ汚いコードですが、参考になればと思い掲載します。本当はもっときれいなコードにしてから掲載したかったのですが、コードをきれいにすると動かなくなります。これをもとに、一から書き直した方が早いかもしれませんね。改良点としては、
１. glutMotionFunc( )を使ってマウスでグリグリ回せるようにした。
2. glutIdleFunc()を使って、マウスを放しても慣性力で回り続けるようにした。

# cube-GL V1.0 - still dirty code, but has minimum functionality set
# A Python/Open-GL based cubic VR viewer
# By R.Kishimoto 2009.2.18

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

tex_size = 256
window_size = (500, 500)
input_file_name = "./pcube/sj256.jpg"
mx=my=0
gx=gy=0
mod = 0
now = past = 0
xspeed = yspeed = 0

def prep_tex (pfname):
  global rc, image_x
  im=Image.open(pfname)
  size=im.size
  image_x = size[0]
  image_y = size[1]

  if image_x*6 == image_y:
    print "good y = 6x"
  else:
    print "error y != 6x"
    sys.exit

  rc = image_x / tex_size
  rc_mod = image_x % tex_size
  if rc_mod != 0:
    rc = rc + 1

  for face in range(6):
    for y in range(rc):
      for x in range(rc):
        x1 = tex_size*x
        x2 = x1 + tex_size
        y1 = face * image_x + tex_size * y
        y2 = y1 + tex_size
           
        box = (x1, y1, x2, y2)
        region = im.crop(box)
        fname = '%s%d%d%d%s' % (pfname, face, y, x, ".jpg")
        region.save(fname)
        print (face, y, x, x1, y1, x2, y2, fname)

fov = 120
vertices = ((-1.0, 1.0, -1.0), (1.0, 1.0, -1.0), (1.0, -1.0, -1.0), (-1.0, -1.0, -1.0),
            (-1.0, 1.0, 1.0), (1.0, 1.0, 1.0), (1.0, -1.0, 1.0), (-1.0, -1.0, 1.0))

def polygon(a, b, c, d):
  glBegin(GL_POLYGON)
  glTexCoord2f(0.0, 0.0)
  glVertex3fv(vertices[a])
  glTexCoord2f(1.0, 0.0)
  glVertex3fv(vertices[b])
  glTexCoord2f(1.0, 1.0)
  glVertex3fv(vertices[c])
  glTexCoord2f(0.0, 1.0)
  glVertex3fv(vertices[d])
  glEnd()
 
def cube():
  ti = 0
  step = 2.0 * 256.0 / 1000.0
  glEnable(GL_TEXTURE_2D)

  for y in range(rc):
    for x in range(rc):
      x1 = -1 + step * x
      x2 = x1 + step
      y1 = 1 - step * y
      y2 = y1 - step
      #print "x1,x2,y1,y2,step,ti", x1, x2, y1, y2, step, ti
      glBindTexture(GL_TEXTURE_2D, texture[ti])
      #polygon(0,1,2,3)
      glBegin(GL_POLYGON)
      glTexCoord2f(0.0, 0.0)
      glVertex3f(x1, y1, -1.0)
      glTexCoord2f(1.0, 0.0)
      glVertex3f(x2, y1, -1.0)
      glTexCoord2f(1.0, 1.0)
      glVertex3f(x2, y2, -1.0)
      glTexCoord2f(0.0, 1.0)
      glVertex3f(x1, y2, -1.0)
      glEnd()
      ti=ti+1
     
  for y in range(rc):
    for x in range(rc):
      x1 = -1 + step * x
      x2 = x1 + step
      y1 = 1 - step * y
      y2 = y1 - step
      #print "x1,x2,y1,y2,step,rc", x1, x2, y1, y2, step, rc
      glBindTexture(GL_TEXTURE_2D, texture[ti])
      #polygon(1,5,6,2)
      glBegin(GL_POLYGON)
      glTexCoord2f(0.0, 0.0)
      glVertex3f(1.0, y1, x1)
      glTexCoord2f(1.0, 0.0)
      glVertex3f(1.0, y1, x2)
      glTexCoord2f(1.0, 1.0)
      glVertex3f(1.0, y2, x2)
      glTexCoord2f(0.0, 1.0)
      glVertex3f(1.0, y2, x1)
      glEnd()
      ti=ti+1

  for y in range(rc):
    for x in range(rc):
      x1 = 1 - step * x
      x2 = x1 - step
      y1 = 1 - step * y
      y2 = y1 - step
      #print "x1,x2,y1,y2,step,rc", x1, x2, y1, y2, step, rc
      glBindTexture(GL_TEXTURE_2D, texture[ti])
      #polygon(5,4,7,6)
      glBegin(GL_POLYGON)
      glTexCoord2f(0.0, 0.0)
      glVertex3f(x1, y1, 1.0)
      glTexCoord2f(1.0, 0.0)
      glVertex3f(x2, y1, 1.0)
      glTexCoord2f(1.0, 1.0)
      glVertex3f(x2, y2, 1.0)
      glTexCoord2f(0.0, 1.0)
      glVertex3f(x1, y2, 1.0)
      glEnd()
      ti=ti+1
 
  for y in range(rc):
    for x in range(rc):
      x1 = 1 - step * x
      x2 = x1 - step
      y1 = 1 - step * y
      y2 = y1 - step
      #print "x1,x2,y1,y2,step,rc", x1, x2, y1, y2, step, rc
      glBindTexture(GL_TEXTURE_2D, texture[ti])
      #polygon(4,0,3,7)
      glBegin(GL_POLYGON)
      glTexCoord2f(0.0, 0.0)
      glVertex3f(-1.0, y1, x1)
      glTexCoord2f(1.0, 0.0)
      glVertex3f(-1.0, y1, x2)
      glTexCoord2f(1.0, 1.0)
      glVertex3f(-1.0, y2, x2)
      glTexCoord2f(0.0, 1.0)
      glVertex3f(-1.0, y2, x1)
      glEnd()
      ti=ti+1
     
  for y in range(rc):
    for x in range(rc):
      x1 = -1 + step * x
      x2 = x1 + step
      y1 = 1 - step * y
      y2 = y1 - step
      #print "x1,x2,y1,y2,step,rc", x1, x2, y1, y2, step, rc
      glBindTexture(GL_TEXTURE_2D, texture[ti])
      #polygon(4,5,1,0)
      glBegin(GL_POLYGON)
      glTexCoord2f(0.0, 0.0)
      glVertex3f(x1, 1.0, y1)
      glTexCoord2f(1.0, 0.0)
      glVertex3f(x2, 1.0, y1)
      glTexCoord2f(1.0, 1.0)
      glVertex3f(x2, 1.0, y2)
      glTexCoord2f(0.0, 1.0)
      glVertex3f(x1, 1.0, y2)
      glEnd()
      ti=ti+1
     
  for y in range(rc):
    for x in range(rc):
      x1 = -1 + step * x
      x2 = x1 + step
      y1 = -1 + step * y
      y2 = y1 + step
      #print "x1,x2,y1,y2,step,rc", x1, x2, y1, y2, step, rc
      glBindTexture(GL_TEXTURE_2D, texture[ti])
      #polygon(3,2,6,7)
      glBegin(GL_POLYGON)
      glTexCoord2f(0.0, 0.0)
      glVertex3f(x1, -1.0, y1)
      glTexCoord2f(1.0, 0.0)
      glVertex3f(x2, -1.0, y1)
      glTexCoord2f(1.0, 1.0)
      glVertex3f(x2, -1.0, y2)
      glTexCoord2f(0.0, 1.0)
      glVertex3f(x1, -1.0, y2)
      glEnd()
      ti=ti+1

def drawText( value, x,y,  windowHeight, windowWidth, step = 18 ):
  """Draw the given text at given 2D position in window
  """
  glMatrixMode(GL_PROJECTION);
  # For some reason the GL_PROJECTION_MATRIX is overflowing with a single push!
  # glPushMatrix()
  matrix = glGetDouble( GL_PROJECTION_MATRIX )
   
  glLoadIdentity();
  glOrtho(0.0, windowHeight or 32, 0.0, windowWidth or 32, -1.0, 1.0)
  glMatrixMode(GL_MODELVIEW);
  glPushMatrix();
  glLoadIdentity();

  glClearColor(1.0, 1.0, 1.0, 0.0)

  glBegin(GL_LINES)
  glColor3f(1.0, 1.0, 1.0)
  glVertex2i(x, y+20)
  glVertex2i(x+60, y+20)
  glVertex2i(x+60, y)
  glVertex2i(x+60, y+20)
  glVertex2i(x, y)
  glVertex2i(x, y+20)
  glEnd()
 
  glRasterPos2i(x, y);
  lines = 0
  for character in value:
    if character == '\n':
      glRasterPos2i(x, y-(lines*18))
    else:
      glutBitmapCharacter(GLUT_BITMAP_HELVETICA_18, ord(character));
  glPopMatrix();
  glMatrixMode(GL_PROJECTION);
  # For some reason the GL_PROJECTION_MATRIX is overflowing with a single push!
  # glPopMatrix();
  glLoadMatrixd( matrix ) # should have un-decorated alias for this...
   
  glMatrixMode(GL_MODELVIEW);
   
def display():
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
  glViewport(0, 0, window_size[0], window_size[1])
 
  glMatrixMode(GL_PROJECTION)
  glLoadIdentity()
 
  # set camera FOV=100 degree, aspect=1.0, near=0.01(0.0 will cause error), far=100.0
  gluPerspective(fov, 1.0, 0.01, 100.0)
 
  glMatrixMode(GL_MODELVIEW)
  glLoadIdentity()
  # eye, at, up
  gluLookAt(0.0, 0.0, 0.0, xxx, yyy, zzz, 0, 1, 0)
 
  cube()

  drawText( 'ksmt', 430, 1, window_size[0], window_size[1] )
  drawText( 'Z-OUT', 360, 1, window_size[0], window_size[1] )
  drawText( 'Z-IN', 290, 1, window_size[0], window_size[1] )
  drawText( 'DOWN', 220, 1, window_size[0], window_size[1] )
  drawText( 'UP', 150, 1, window_size[0], window_size[1] )
  drawText( '-->', 80, 1, window_size[0], window_size[1] )
  drawText( '<--', 10, 1, window_size[0], window_size[1] )
 
  glFlush()

def deg2rad(deg):
  rad = math.pi * deg / 360
  return rad

uuu = 10.0
fov = 120
xzd = -180
xyd = 0
xzt = deg2rad(xzd)
xyt = deg2rad(xyd)

yyy = math.sin(xyt)
zzz = math.sin(xzt) * math.cos(xyt)
xxx = math.cos(xzt) * math.cos(xyt)

def mykey(key, x, y):
  global xxx, yyy, zzz, fov, xzd, xyd
  print "key, mod ", key, glutGetModifiers()

  if key=='a': # -xzt
    xzd = xzd - uuu
  elif key=='d': # +xzt
    xzd = xzd + uuu
  elif key=='x': # -xyt
    if (xyd - uuu) >= -180 :
      xyd = xyd - uuu
  elif key=='w': # +xyt
    if (xyd + uuu) <= 180:
      xyd = xyd + uuu
  elif key=='s': # default
    xzd = -180.0
    xyd = 0.0
    fov = 120

  elif key=='e': # zoom out
    if fov <= 160:
      fov = fov + 10
  elif key=='z': # zoom in
    if fov > 10:
      fov = fov - 10

  elif key=='-': # zoom out
    if fov <= 160:
      fov = fov + 10
  elif key=='+': # zoom in
    if fov >=10:
      fov = fov - 10

  xzt = deg2rad(xzd)
  xyt = deg2rad(xyd)

  yyy = math.sin(xyt)
  zzz = math.sin(xzt) * math.cos(xyt)
  xxx = math.cos(xzt) * math.cos(xyt)

  glutPostRedisplay()

def mymouse(button, state, x, y):
  global xxx, yyy, zzz, fov, xzd, xyd, start_x, start_y, gx, gy, mod
  sy = window_size[1] - y
  mod = glutGetModifiers()
  #print "click button, state, x, y, mod--------", button, state, x , sy, mod
  if state == 0 & button == 0:
    start_x = x
    start_y = sy
    if ((10 < x) & (x < 70) & (sy < 20)):
      xzd = xzd - uuu
      print "left ", x, sy
    elif ((80 < x) & (x < 140) & (sy < 20)):
      xzd = xzd + uuu
      print "right ", x, sy
    elif ((150 < x) & (x < 210) & (sy < 20)):
      if (xyd - uuu) >= -180 :
        xyd = xyd + uuu
        print "up ", x, sy
    elif ((220 < x) & (x < 280) & (sy < 20)):
      if (xyd + uuu) <= 180:
        xyd = xyd - uuu
        print "down ", x, sy
    elif ((290 < x) & (x < 350) & (sy < 20)):
      if fov <= 160:
        fov = fov - 10
        print "out ", x, sy
    elif ((360 < x) & (x < 420) & (sy < 20)):
      if fov > 10:
        fov = fov + 10
        print "in ", x, sy

  gx = x
  gy = sy

  xzt = deg2rad(xzd)
  xyt = deg2rad(xyd)

  yyy = math.sin(xyt)
  zzz = math.sin(xzt) * math.cos(xyt)
  xxx = math.cos(xzt) * math.cos(xyt)

  prev_state = state

  glutPostRedisplay()

   
def gentex(t, img):
  # use the given texture
  glBindTexture(GL_TEXTURE_2D, t)

  # read texture data from .bmp file using Image library
  image=Image.open(img)
  if len(image.getbands())!=4:
    image=image.convert("RGBA")
  size=image.size

  # generate texture from array image.tostring() inside current texture 'texture'
  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, size[0], size[1], 0, GL_RGBA, GL_UNSIGNED_BYTE, image.tostring())

  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST)
  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST)

def mymotion(x, y):
  global xxx, yyy, zzz, fov, xzd, xyd, start_x, start_y, gx, gy, mod, now, past, xspeed, yspeed
  y = window_size[1]-y
  #print "motion xy, frist_flag, gx, gy, mod", x, y, gx, gy, mod

  dx = x - gx
  dy = y - gy
  xzd = xzd + dx
  if ((xyd + dy) >= -180) & ((xyd + dy) <= 180):
    xyd = xyd + dy
   
  now = time.time()
  dtime = now - past
  if dtime == 0:
    xspeed = yspeed = 0
  else:
    xspeed = 0.9 * dx / dtime
    yspeed = 0.9 * dy / dtime

  speedlimit = 200.0
  if xspeed > speedlimit :
    xspeed = speedlimit
  elif xspeed < ( -1 * speedlimit) :
    xspeed = -1 * speedlimit
   
  if yspeed > speedlimit:
    yspeed = speedlimit
  elif yspeed < (-1 * speedlimit) :
    yspeed = -1 * speedlimit
   
  #print "xspeed, yspeed", xspeed, yspeed
  past = now

  if mod==GLUT_ACTIVE_SHIFT: # zoom in
    if fov > 10:
      fov = fov - 1
  elif mod==GLUT_ACTIVE_CTRL: # zoom out
    if fov <= 160:
      fov = fov + 1
     
  xzt = deg2rad(xzd)
  xyt = deg2rad(xyd)

  yyy = math.sin(xyt)
  zzz = math.sin(xzt) * math.cos(xyt)
  xxx = math.cos(xzt) * math.cos(xyt)
 
  glutPostRedisplay()
  gx = x
  gy = y

def myidle():
  global now, past, xspeed, yspeed, xxx, yyy, zzz, fov, xzd, xyd
  now = time.time()
  dtime = now - past

  dy = dtime * yspeed
  if ((xyd + dy) >= -180) & ((xyd + dy) <= 180):
    xyd = xyd + dy
  xzd = xzd + (dtime * xspeed)
 
  xzt = deg2rad(xzd)
  xyt = deg2rad(xyd)

  yyy = math.sin(xyt)
  zzz = math.sin(xzt) * math.cos(xyt)
  xxx = math.cos(xzt) * math.cos(xyt)
 
  glutPostRedisplay()
  past = now
  xspeed = xspeed * 0.99
  yspeed = yspeed * 0.99

def myspecial( key, x, y ):
  mod = glutGetModifiers()
  print "special key, x, y, mod ", key, x, y, mod

glutInit( sys.argv )
#glutInitDisplayMode( GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH )
glutInitDisplayMode( GLUT_RGBA | GLUT_SINGLE | GLUT_DEPTH )
glutInitWindowSize( window_size[0], window_size[1] )
glutInitWindowPosition(0,0)
glutCreateWindow( 'cube' )
glutDisplayFunc( display )
glutKeyboardFunc( mykey )
glutMouseFunc( mymouse )
glutMotionFunc( mymotion)
glutSpecialFunc( myspecial )
glutIdleFunc( myidle )
glEnable(GL_DEPTH_TEST)
#glEnable(GL_CULL_FACE)
#glCullFace(GL_BACK)
# prep_tex(input_file_name)

### TEXTURE
rc=4
tex_num=0
glEnable(GL_TEXTURE_2D)
texture=glGenTextures(rc*rc*6)
for face in range(6):
  for y in range(rc):
    for x in range(rc):
      fname = '%s%d%d%d%s' % ("./pcube/sjtex", face, y, x, ".jpg")
      gentex(texture[tex_num], fname)
      #print 'reading texture %s %d' % (fname, tex_num)
      tex_num = tex_num+1

#Menu
def selectMessage():
  return 1
  print "select message meny selected"

glutMainLoop()

#
# Six Cubic face global mapping
# 0-----1
# |     |
# |  F0 |
# 3-----2
# 1-----5
# |     |
# |  R1 |
# 2-----6
# 5-----4
# |     |
# |  B2 |
# 6-----7
# 4-----0
# |     |
# |  L3 |
# 7-----3
# 4-----5
# |     |
# |  U4 |
# 0-----1
# 3-----2
# |     |
# |  D5 |
# 7-----6
#
#        4-----5
#        |     |
#        |  U4 |
#        0-----1
# 4-----00-----11-----55-----4
# |     ||     ||     ||     |
# |  L3 ||  F0 ||  R1 ||  B2 |
# 7-----33-----22-----66-----7
#        3-----2
#        |     |
#        |  D5 |
#        7-----6
#
# local texture mapping
#
# 0.0----------------------------1.0
# |-----------image_x--------------|
# |--tex_size--|
# |<-- (tex_size/image_x) * 0
#              |<-- (tex_size/image_x) * 1
#                           |<-- (tex_size/image_x) * 2

The result of 360 degree cubic panorama player looks like this. Type keys to rotate/zoom the panorama image.
"s" home position
"a" rotate left
"d" rotate right
"w" rotate up
"x" rotate down
"-" zoom in
"+" zoom out

実行するとこんな感じで表示されます。キーボードを使って回転させます。

I should do the following thins to fix issues or enhance usability.　次のような点を改善しなければなりません。
1. Rotate -90 degree of the initial image
2. Use mouse rather than keyboard
3. Fix bugs of rotation
4. Limit the FOV not to show black portion

QTVR functionality usign OpenGL (1)

To display 360 degree cubic panorama movie, either QuickTime(QTVR) or Adobe Flash player is used as viewer. I like QTVR very much and I participate "World Wide Panorama" ten times, http://geoimages.berkeley.edu/worldwidepanorama/wwppeople/html/RikuichiKishimoto.html
360度キュービックVRの表示には通常QuickTime(QTVR)またはAdobe Flash Playerが使われます。私はQTVRの製作が趣味でして、World Wide Panoramaにも参加しています。

It would be very easy to implement 360 degree cubic panorama viewer using OpenGL. The source image has 6 cubic faces in one JPEG file.
OpenGLでキュービックパノラマを実現することは、割と簡単だと思われますので、やってみました。普通は次のような６面の画像を繋げたJPEGの画像を使いますが、簡単化のため６枚の別々の写真に分けました。
I manually cut the image into 6 pieces to simplify the OpenGL program.
Convert six JPEG files into six texture and attach to six cubic faces. It's very straight foward. The following code still have some bugs, but I can show you the basic idea. It's really a "inside rotating cube".　まだバグなどがありますが、アイデアとしては次のようなものになります。

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

vertices = ((-1.0, -1.0, 1.0), (-1.0, 1.0, 1.0), (1.0, 1.0, 1.0), (1.0, -1.0, 1.0),
            (-1.0, -1.0, -1.0), (-1.0, 1.0, -1.0), (1.0, 1.0, -1.0), (1.0, -1.0, -1.0))
uuu = 0.1
fov = 120
xzt = yzt = 0
yyy = math.sin(yzt)
r = math.cos(yzt)
zzz = r * math.sin(xzt)
xxx = r * math.cos(xzt)

def polygon(a, b, c, d):
  glBegin(GL_POLYGON)
  glTexCoord2f(0.0, 0.0)
  glVertex3fv(vertices[a])
  glTexCoord2f(0.0, 1.0)
  glVertex3fv(vertices[b])
  glTexCoord2f(1.0, 1.0)
  glVertex3fv(vertices[c])
  glTexCoord2f(1.0, 0.0)
  glVertex3fv(vertices[d])
  glEnd()

def cube():
  global texture
  glEnable(GL_TEXTURE_2D)
  glBindTexture(GL_TEXTURE_2D, texture[4])
  polygon(4,5,6,7)
  glBindTexture(GL_TEXTURE_2D, texture[1])
  polygon(1,5,4,0)
  glBindTexture(GL_TEXTURE_2D, texture[2])
  polygon(3,7,6,2)
  glBindTexture(GL_TEXTURE_2D, texture[0])
  polygon(0,4,7,3)
  glBindTexture(GL_TEXTURE_2D, texture[5])
  polygon(1,0,3,2)
  glBindTexture(GL_TEXTURE_2D, texture[3])
  polygon(2,6,5,1)

def display():
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
 
  glMatrixMode(GL_PROJECTION)
  glLoadIdentity()
 
  # set camera FOV=100 degree, aspect=1.0, near=1.0(0.0 will cause error), far=100.9
  gluPerspective(fov, 1.0, 0.5, 100.0)
 
  glMatrixMode(GL_MODELVIEW)
  glLoadIdentity()
  # eye, at, up
  gluLookAt(0.0, 0.0, 0.0,  xxx,yyy,zzz, 0,1,0)

  cube()
  glFlush()

def mykey(key, x, y):
  global xxx, yyy, zzz, fov, xzt, yzt
  if key=='a': # -xzt
    xzt = xzt - uuu
  elif key=='d': # +xzt
    xzt = xzt + uuu
  elif key=='x': # -yzt
    yzt = yzt - uuu
  elif key=='w': # +yzt
    yzt = yzt + uuu
  elif key=='s': # default
    xzt = yzt = 0.0

  elif key=='-': # zoom out
    fov = fov - 10
  elif key=='+': # default
    fov = fov + 10

  yyy = math.sin(yzt)
  rrr = math.cos(yzt)
  zzz = rrr * math.sin(xzt)
  xxx = rrr * math.cos(xzt)

  print "xyzf:", xxx, yyy, zzz, fov
  glutPostRedisplay()

def gentex(t, img):
  # use the given texture
  glBindTexture(GL_TEXTURE_2D, t)
  print "texture", t

  # read texture data from .bmp file using Image library
  image=Image.open(img)
  if len(image.getbands())!=4:
    image=image.convert("RGBA")
  size=image.size

  # generate texture from array image.tostring() inside current texture 'texture'
  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, size[0], size[1], 0, GL_RGBA, GL_UNSIGNED_BYTE, image.tostring())

  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST)
  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST)

glutInit( sys.argv )
#glutInitDisplayMode( GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH )
glutInitDisplayMode( GLUT_RGBA | GLUT_SINGLE | GLUT_DEPTH )
glutInitWindowSize( 500, 500 )
glutInitWindowPosition(0,0)
glutCreateWindow( 'cube' )
glutDisplayFunc( display )
glutKeyboardFunc(mykey)

glEnable(GL_DEPTH_TEST) #hidden-surface removal
# glEnable(GL_CULL_FACE) #don't draw back side surface
# glCullFace(GL_BACK) #don't draw back side surface

### TEXTURE
glEnable(GL_TEXTURE_2D)

# generate continuous two texture
# different format from C, void glGenTexture(n, *name)
texture=glGenTextures(6)

gentex(texture[0], "./pcube/r1.bmp")
gentex(texture[1], "./pcube/r2.bmp")
gentex(texture[2], "./pcube/r3.bmp")
gentex(texture[3], "./pcube/r4.bmp")
gentex(texture[4], "./pcube/rb.bmp")
gentex(texture[5], "./pcube/rt.bmp")

glutMainLoop()