Initial revision
diff --git a/Demo/sgi/gl/backface.py b/Demo/sgi/gl/backface.py
new file mode 100755
index 0000000..594b8ad
--- /dev/null
+++ b/Demo/sgi/gl/backface.py
@@ -0,0 +1,140 @@
+#! /usr/local/python
+
+# backface
+#
+# draw a cube that can run with backface() turned on or off.
+# cube is moved when LEFTMOUSE is pressed and mouse itself is moved.
+
+from gl import *
+from DEVICE import *
+from GL import *
+
+CUBE_SIZE = 200.0
+CUBE_OBJ = 1
+
+def main () :
+ #
+ x = 0
+ y = 0
+ moveit = 0
+ #
+ initialize()
+ #
+ while (1) :
+ #
+ while (qtest()) :
+ dev, val = qread()
+ #
+ if dev == ESCKEY :
+ backface(0)
+ return
+ #
+ elif dev == REDRAW :
+ reshapeviewport()
+ drawcube(x,y)
+ #
+ elif dev == LEFTMOUSE :
+ #
+ # LEFTMOUSE down
+ moveit = val
+ #
+ elif dev == BKEY :
+ backface(1)
+ drawcube(x,y)
+ #
+ elif dev == FKEY :
+ backface(0)
+ drawcube(x,y)
+ #
+ if moveit :
+ x = getvaluator(MOUSEX)
+ y = getvaluator(MOUSEY)
+ drawcube(x,y)
+
+
+def initialize () :
+ foreground ()
+ keepaspect (1, 1)
+ gid = winopen('backface')
+ winset(gid)
+ winconstraints()
+ #
+ doublebuffer()
+ gconfig()
+ shademodel(FLAT)
+ #
+ ortho(-1024.0, 1024.0, -1024.0, 1024.0, -1024.0, 1024.0)
+ #
+ qdevice(ESCKEY)
+ qdevice(REDRAW)
+ qdevice(LEFTMOUSE)
+ qdevice(BKEY)
+ qdevice(FKEY)
+ qenter(REDRAW,gid)
+ #
+ backface(1)
+
+#
+# define a cube
+def cube () :
+ #
+ # front face
+ pushmatrix()
+ translate(0.0,0.0,CUBE_SIZE)
+ color(RED)
+ rectf(-CUBE_SIZE,-CUBE_SIZE,CUBE_SIZE,CUBE_SIZE)
+ popmatrix()
+ #
+ # right face
+ pushmatrix()
+ translate(CUBE_SIZE, 0.0, 0.0)
+ rotate(900, 'y')
+ color(GREEN)
+ rectf(-CUBE_SIZE,-CUBE_SIZE,CUBE_SIZE,CUBE_SIZE)
+ popmatrix()
+ #
+ # back face
+ pushmatrix()
+ translate(0.0, 0.0, -CUBE_SIZE)
+ rotate(1800, 'y')
+ color(BLUE)
+ rectf(-CUBE_SIZE,-CUBE_SIZE,CUBE_SIZE,CUBE_SIZE)
+ popmatrix()
+ #
+ # left face
+ pushmatrix()
+ translate(-CUBE_SIZE, 0.0, 0.0)
+ rotate(-900, 'y')
+ color(CYAN)
+ rectf(-CUBE_SIZE,-CUBE_SIZE,CUBE_SIZE,CUBE_SIZE)
+ popmatrix()
+ #
+ # top face
+ pushmatrix()
+ translate(0.0, CUBE_SIZE, 0.0)
+ rotate(-900, 'x')
+ color(MAGENTA)
+ rectf(-CUBE_SIZE,-CUBE_SIZE,CUBE_SIZE,CUBE_SIZE)
+ popmatrix()
+ #
+ # bottom face
+ pushmatrix()
+ translate(0.0, -CUBE_SIZE, 0.0)
+ rotate(900, 'x')
+ color(YELLOW)
+ rectf(-CUBE_SIZE,-CUBE_SIZE,CUBE_SIZE,CUBE_SIZE)
+ popmatrix()
+
+def drawcube(x,y) :
+ #
+ pushmatrix()
+ rotate(2*x, 'x')
+ rotate(2*y, 'y')
+ color(BLACK)
+ clear()
+ cube()
+ popmatrix()
+ swapbuffers()
+
+
+main ()