Initial revision
diff --git a/Demo/sgi/gl/nurbs.py b/Demo/sgi/gl/nurbs.py
new file mode 100755
index 0000000..fb76aa9
--- /dev/null
+++ b/Demo/sgi/gl/nurbs.py
@@ -0,0 +1,171 @@
+#! /usr/local/python
+
+# Rotate a 3D surface created using NURBS.
+#
+# Press left mouse button to toggle surface trimming.
+# Press ESC to quit.
+#
+# See the GL manual for an explanation of NURBS.
+
+from gl import *
+from GL import *
+from DEVICE import *
+
+TRUE = 1
+FALSE = 0
+ORDER = 4
+
+idmat = [1,0,0,0, 0,1,0,0, 0,0,1,0, 0,0,0,1]
+
+surfknots = [-1, -1, -1, -1, 1, 1, 1, 1]
+
+def make_ctlpoints():
+ c = []
+ #
+ ci = []
+ ci.append(-2.5, -3.7, 1.0)
+ ci.append(-1.5, -3.7, 3.0)
+ ci.append(1.5, -3.7, -2.5)
+ ci.append(2.5, -3.7, -0.75)
+ c.append(ci)
+ #
+ ci = []
+ ci.append(-2.5, -2.0, 3.0)
+ ci.append(-1.5, -2.0, 4.0)
+ ci.append(1.5, -2.0, -3.0)
+ ci.append(2.5, -2.0, 0.0)
+ c.append(ci)
+ #
+ ci = []
+ ci.append(-2.5, 2.0, 1.0)
+ ci.append(-1.5, 2.0, 0.0)
+ ci.append(1.5, 2.0, -1.0)
+ ci.append(2.5, 2.0, 2.0)
+ c.append(ci)
+ #
+ ci = []
+ ci.append(-2.5, 2.7, 1.25)
+ ci.append(-1.5, 2.7, 0.1)
+ ci.append(1.5, 2.7, -0.6)
+ ci.append(2.5, 2.7, 0.2)
+ c.append(ci)
+ #
+ return c
+
+ctlpoints = make_ctlpoints()
+
+trimknots = [0., 0., 0., 1., 1., 2., 2., 3., 3., 4., 4., 4.]
+
+def make_trimpoints():
+ c = []
+ c.append(1.0, 0.0, 1.0)
+ c.append(1.0, 1.0, 1.0)
+ c.append(0.0, 2.0, 2.0)
+ c.append(-1.0, 1.0, 1.0)
+ c.append(-1.0, 0.0, 1.0)
+ c.append(-1.0, -1.0, 1.0)
+ c.append(0.0, -2.0, 2.0)
+ c.append(1.0, -1.0, 1.0)
+ c.append(1.0, 0.0, 1.0)
+ return c
+
+trimpoints = make_trimpoints()
+
+def main():
+ init_windows()
+ setup_queue()
+ make_lights()
+ init_view()
+ #
+ set_scene()
+ setnurbsproperty( N_ERRORCHECKING, 1.0 )
+ setnurbsproperty( N_PIXEL_TOLERANCE, 50.0 )
+ trim_flag = 0
+ draw_trim_surface(trim_flag)
+ #
+ while 1:
+ while qtest():
+ dev, val = qread()
+ if dev == ESCKEY:
+ return
+ elif dev == WINQUIT:
+ dglclose(-1) # this for DGL only
+ return
+ elif dev == REDRAW:
+ reshapeviewport()
+ set_scene()
+ draw_trim_surface(trim_flag)
+ elif dev == LEFTMOUSE:
+ if val:
+ trim_flag = (not trim_flag)
+ set_scene()
+ draw_trim_surface(trim_flag)
+
+def init_windows():
+ foreground()
+ #prefposition(0, 500, 0, 500)
+ wid = winopen('nurbs')
+ wintitle('NURBS Surface')
+ doublebuffer()
+ RGBmode()
+ gconfig()
+ lsetdepth(0x000, 0x7fffff)
+ zbuffer( TRUE )
+
+def setup_queue():
+ qdevice(ESCKEY)
+ qdevice(REDRAW)
+ qdevice(RIGHTMOUSE)
+ qdevice(WINQUIT)
+ qdevice(LEFTMOUSE) #trimming
+
+def init_view():
+ mmode(MPROJECTION)
+ ortho( -4., 4., -4., 4., -4., 4. )
+ #
+ mmode(MVIEWING)
+ loadmatrix(idmat)
+ #
+ lmbind(MATERIAL, 1)
+
+def set_scene():
+ lmbind(MATERIAL, 0)
+ RGBcolor(150,150,150)
+ lmbind(MATERIAL, 1)
+ clear()
+ zclear()
+ #
+ rotate( 100, 'y' )
+ rotate( 100, 'z' )
+
+def draw_trim_surface(trim_flag):
+ bgnsurface()
+ nurbssurface(surfknots, surfknots, ctlpoints, ORDER, ORDER, N_XYZ)
+ if trim_flag:
+ bgntrim()
+ nurbscurve(trimknots, trimpoints, ORDER-1, N_STW)
+ endtrim()
+ endsurface()
+ swapbuffers()
+
+def make_lights():
+ lmdef(DEFLMODEL,1,[])
+ lmdef(DEFLIGHT,1,[])
+ #
+ # define material #1
+ #
+ a = []
+ a = a + [EMISSION, 0.0, 0.0, 0.0]
+ a = a + [AMBIENT, 0.1, 0.1, 0.1]
+ a = a + [DIFFUSE, 0.6, 0.3, 0.3]
+ a = a + [SPECULAR, 0.0, 0.6, 0.0]
+ a = a + [SHININESS, 2.0]
+ a = a + [LMNULL]
+ lmdef(DEFMATERIAL, 1, a)
+ #
+ # turn on lighting
+ #
+ lmbind(LIGHT0, 1)
+ lmbind(LMODEL, 1)
+
+main()