Welcome, guest | Sign In | My Account | Store | Cart

An ordered set of points is created using the mouse. A smooth curve(spline) is created following the points with either an open or closed(cyclic) path.

Python, 225 lines
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
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][0]
        SumY = SumY + n * points[k][1]
    return [SumX,SumY]

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

def Spaceout():
    global points
    newpoints = []
    L = len(points)
    if lOpen:
       newpoints.append(points[0])
       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][0] - p[0]
           y = points[t][1] - p[1]
           newpoints.append([points[t][0] + x,points[t][1] + 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][0] - p[0]
           y = points[t][1] - p[1]
           newpoints.append([points[t][0] + x,points[t][1] + 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)
rad1 = Radiobutton(fram, text = 'Open',value=1,command=(lambda : CycleClosed(True)))
rad1.pack(side = LEFT)
rad2 = Radiobutton(fram, text = 'Closed',value=0,command=(lambda : CycleClosed(False)))
rad2.pack(side = LEFT)
rad1.select()
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()