Welcome, guest | Sign In | My Account | Store | Cart
import Tkinter
from Tkinter import*

def mod(a,b):
return ( a % b)

def StandardKnot():
global m
knot = []
L = len(points) - 2
if L <= m -2 :
print 'make more points than m'
return []
for i in range(m - 1):
knot.append(0)
for i in range(L - m + 3):
knot.append(i)
for i in range(m):
knot.append(L - m + 3)
return knot

def Nopen(k,m,t,knot):
if m <= 1:
if t < knot[k] or t >= knot[k + 1]:
Sum = 0.0
else:
Sum = 1.0
else:
d = knot[k+m-1]-knot[k]
if d <> 0:
Sum = (t-knot[k])*Nopen(k,m-1,t,knot)/d
else:
Sum = 0.0
d = knot[k+m] - knot[k+1]
if d <> 0:
Sum = Sum + (knot[k+m] - t)*Nopen(k + 1,m-1,t,knot)/d
return Sum

def Nclosed(k,m,t,knot):
L = len(points)
z = mod(t-k,L)
if z <= 0:
z += L
return Nopen(0,m,z,knot)

def P(t,knot,Ncycle):
L = len(points)
SumX = 0.0
SumY = 0.0
for k in range(L):
n = Ncycle(k,m,t,knot)
SumX = SumX + n * points[k]
SumY = SumY + n * points[k]
return [SumX,SumY]

def plot():
global m
global points
if lOpen:
knot = StandardKnot()
if len(knot) == 0:
return
print knot
print points
x = points
y = points
t = 0.0
step = 0.1
L = len(points)
while t <= L - m  + 1:
p = P(t,knot,Nopen)
C.create_line(x, y, p, p)
x = p
y = p
t = t + step
else:
L = len(points)
knot = range(L)
print knot
print points
p = P(0.0,knot,Nclosed)
x = p
y = p
step = 0.1
t = step
L = len(points)
while t <= L:
p = P(t,knot,Nclosed)
C.create_line(x, y, p, p)
x = p
y = p
t = t + step

def Spaceout():
global points
newpoints = []
L = len(points)
if lOpen:
newpoints.append(points)
knot = StandardKnot()
if len(knot) == 0:
return
for t in range( 1, L - m  + 2):
p = P(t - 0.5,knot,Nopen)
x = points[t] - p
y = points[t] - p
newpoints.append([points[t] + x,points[t] + y])
newpoints.append(points[-1])
else:
knot = range(L)
for t in range(L):
p = P(mod(t + 1.5,L),knot,Nclosed)
x = points[t] - p
y = points[t] - p
newpoints.append([points[t] + x,points[t] + y])
points = newpoints
plot()

def do_mouse(eventname):
def mouse_binding(event):
global points
if eventname == "Button-1":
x = event.x
y = event.y
print x, y
if x > 50 and y > 50:
points.append([x,y])
C.create_oval(x - 6,y - 6, x + 6, y + 6)
C.create_text(x, y, text = '%d' %(len(points)))
fram.bind_all( '<%s>' %eventname, mouse_binding)

def wipe():
global points
C.delete( ALL)
points = []

def fetch():
global m
m = mEntry.get()
m = int(m)
print 'm is now %d' %m

def CycleClosed(i):
global lOpen
lOpen = i
if lOpen:
print 'Cycle is open'
else:
print 'Cycle is closed'

def Blending():
global points
L = len(points)
if L <= m:
print 'Make some more points first!'
return
if lOpen:
knot = StandardKnot()
if len(knot) == 0:
return
else:
knot = range(L)
print knot
x0 = ScreenW * 0.2
y0 = ScreenH * 0.2
scaley = ScreenH * 0.7
scalex = ScreenW / L * 0.7
for k in knot:
x1 = k * scalex + x0
y1 = ScreenH - y0
C.create_line(x1, y1, x1, y1 + 20)
for k in range(L):
t = 0.0
step = 0.1
x1 = x0
y1 = y0
if lOpen:
z = L - m + 1
else:
z = L
while t <= z:
if lOpen:
p = Nopen(k,m,t,knot)
else:
p = Nopen(0,m,mod(t-k,L),knot)
x2 = t * scalex + x0
y2 = ScreenH - p * scaley - y0
C.create_line(x1, y1, x2, y2)
x1 = x2
y1 = y2
t = t + step

m = 3
lOpen = True
ScreenH = 600
ScreenW = 800
root = Tk()
root.title('Left click to add some points, then click [Plot] to draw the b-spline.')
fram = Frame(root)
Label(fram, text = 'M:').pack(side = LEFT,padx = 20)
mEntry = Entry(fram)
mEntry.insert(0,m)
mEntry.focus()
mEntry.bind('<Return>', (lambda event: fetch()))
mEntry.pack(side = LEFT)
butt1 = Button(fram, text = '  Plot  ',command = plot)
butt1.pack(side = LEFT)
butt3 = Button(fram, text = '  Wipe  ',command = wipe)
butt3.pack(side = LEFT)
butt4 = Button(fram, text = 'Blending',command = Blending)
butt4.pack(side = LEFT)
butt5 = Button(fram, text = 'Spaceout',command = Spaceout)
butt5.pack(side = LEFT)
fram.pack(side = TOP)
C = Canvas(root, width = ScreenW, height = ScreenH)
C.pack()
do_mouse('Button-1')
do_mouse('Button-3')
points = []
root.mainloop()