attachment:genimg.py of rbox

   1 import math
   2 from scipy import gplt
   3 
   4 def dot(a,b):
   5     l = len(a)
   6     lb = len(b)
   7     assert(l == lb)
   8     r = 0.0
   9     for i in range(l):
  10         r += a[i]*b[i]
  11     return r
  12 
  13 def cross(a,b):
  14     la = len(a)
  15     lb = len(b)
  16     assert(la == 3 and lb == 3)
  17     r1 = a[1]*b[2] - a[2]*b[1]
  18     r2 = a[0]*b[2] - a[2]*b[0]
  19     r3 = a[0]*b[1] - a[1]*b[0]
  20     return [r1, -r2, r3]
  21 
  22 def p(lb, le, t):
  23     l = len(lb)
  24     r = list()
  25     for i in range(l):
  26         r.append(lb[i]*(1-t) + le[i]*t)
  27     return r
  28 
  29 def genxy(l , r, ep=0.005):
  30     lb = l[0]
  31     le = l[1]
  32     t = 0.0
  33     rx = list()
  34     ry = list()
  35     while t<=1.0:
  36         tp = p(lb, le, t)
  37         x = dot(tp,r)
  38         s = cross(tp,r)
  39         y = d(s)
  40         rx.append(x)
  41         ry.append(y)
  42         t += ep
  43     return rx,ry
  44 
  45 def d(a):
  46     s = 0.0
  47     for x in a:
  48         s +=x**2
  49     return math.sqrt(s)
  50 
  51 def unit(a):
  52     dd = d(a)
  53     r = list()
  54     for x in a:
  55         r.append(x/dd)
  56     return r
  57 
  58 def elementp(a,b):
  59     l = len(a)
  60     r = list()
  61     for i in range(l):
  62         r.append(a[i]*b[i])
  63     return r
  64 def genlines(a, b, c):
  65     lines = list()
  66     trans = [[1, 1, 1],
  67          [-1, -1, 1],
  68          [1, -1, -1],
  69          [-1, 1, -1]
  70         ]
  71     for t in trans:
  72         [ta, tb, tc]  = elementp([a,b,c],t)
  73         tlines = [
  74             [[ ta, tb, tc], [-ta, tb, tc]],
  75             [[ ta, tb, tc], [ ta,-tb, tc]],
  76             [[ ta, tb, tc], [ ta, tb,-tc]]
  77             ]
  78         lines = lines + tlines
  79     return lines
  80 
  81 import sys
  82 def plotl(a, b, c, ep=0.005):
  83     r = unit([a,b,c])
  84     lines = genlines(r[0],r[1],r[2])
  85     lis = [(0,0),(0,1)]
  86     for l in lines:
  87         rx, ry = genxy(l, r, ep)
  88         lis.append(rx)
  89         lis.append(ry)
  90     apply(gplt.plot,lis)
  91     gplt.title("l(t)-- a=%f, b=%f, c=%f"%(r[0],r[1],r[2]))
  92     gplt.xaxis([-1.0,1.0])
  93     gplt.yaxis([0,1])
  94     sys.stderr.write("press RETURN to continue:")
  95     raw_input()
  96 
  97 def main():
  98     plotl(1, 1, 1)
  99     plotl(1, 0.5, 0.5)
 100     plotl(1, 1.5, 1.5)
 101     plotl(1, 2, 3)
 102     plotl(1, 1.5, 2)
 103 if __name__ == "__main__":
 104     main()
 105