1 #!/usr/bin/env python
2 """
3 ffgeom.py
4 Copyright (C) 2005 Aaron Cyril Spike, aaron@ekips.org
6 This file is part of FretFind 2-D.
8 FretFind 2-D is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2 of the License, or
11 (at your option) any later version.
13 FretFind 2-D is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with FretFind 2-D; if not, write to the Free Software
20 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 """
22 import math
23 try:
24 NaN = float('NaN')
25 except ValueError:
26 PosInf = 1e300000
27 NaN = PosInf/PosInf
29 class Point:
30 precision = 5
31 def __init__(self, x, y):
32 self.__coordinates = {'x' : float(x), 'y' : float(y)}
33 def __getitem__(self, key):
34 return self.__coordinates[key]
35 def __setitem__(self, key, value):
36 self.__coordinates[key] = float(value)
37 def __repr__(self):
38 return '(%s, %s)' % (round(self['x'],self.precision),round(self['y'],self.precision))
39 def copy(self):
40 return Point(self['x'],self['y'])
41 def translate(self, x, y):
42 self['x'] += x
43 self['y'] += y
44 def move(self, x, y):
45 self['x'] = float(x)
46 self['y'] = float(y)
48 class Segment:
49 def __init__(self, e0, e1):
50 self.__endpoints = [e0, e1]
51 def __getitem__(self, key):
52 return self.__endpoints[key]
53 def __setitem__(self, key, value):
54 self.__endpoints[key] = value
55 def __repr__(self):
56 return repr(self.__endpoints)
57 def copy(self):
58 return Segment(self[0],self[1])
59 def translate(self, x, y):
60 self[0].translate(x,y)
61 self[1].translate(x,y)
62 def move(self,e0,e1):
63 self[0] = e0
64 self[1] = e1
65 def delta_x(self):
66 return self[1]['x'] - self[0]['x']
67 def delta_y(self):
68 return self[1]['y'] - self[0]['y']
69 #alias functions
70 run = delta_x
71 rise = delta_y
72 def slope(self):
73 if self.delta_x() != 0:
74 return self.delta_x() / self.delta_y()
75 return NaN
76 def intercept(self):
77 if self.delta_x() != 0:
78 return self[1]['y'] - (self[0]['x'] * self.slope())
79 return NaN
80 def distanceToPoint(self, p):
81 s2 = Segment(self[0],p)
82 c1 = dot(s2,self)
83 if c1 <= 0:
84 return Segment(p,self[0]).length()
85 c2 = dot(self,self)
86 if c2 <= c1:
87 return Segment(p,self[1]).length()
88 return self.perpDistanceToPoint(p)
89 def perpDistanceToPoint(self, p):
90 len = self.length()
91 if len == 0: return NaN
92 return math.fabs(((self[1]['x'] - self[0]['x']) * (self[0]['y'] - p['y'])) - \
93 ((self[0]['x'] - p['x']) * (self[1]['y'] - self[0]['y']))) / len
94 def angle(self):
95 return math.pi * (math.atan2(self.delta_y(), self.delta_x())) / 180
96 def length(self):
97 return math.sqrt((self.delta_x() ** 2) + (self.delta_y() ** 2))
98 def pointAtLength(self, len):
99 if self.length() == 0: return Point(NaN, NaN)
100 ratio = len / self.length()
101 x = self[0]['x'] + (ratio * self.delta_x())
102 y = self[0]['y'] + (ratio * self.delta_y())
103 return Point(x, y)
104 def pointAtRatio(self, ratio):
105 if self.length() == 0: return Point(NaN, NaN)
106 x = self[0]['x'] + (ratio * self.delta_x())
107 y = self[0]['y'] + (ratio * self.delta_y())
108 return Point(x, y)
109 def createParallel(self, p):
110 return Segment(Point(p['x'] + self.delta_x(), p['y'] + self.delta_y()), p)
111 def intersect(self, s):
112 return intersectSegments(self, s)
114 def intersectSegments(s1, s2):
115 x1 = s1[0]['x']
116 x2 = s1[1]['x']
117 x3 = s2[0]['x']
118 x4 = s2[1]['x']
120 y1 = s1[0]['y']
121 y2 = s1[1]['y']
122 y3 = s2[0]['y']
123 y4 = s2[1]['y']
125 denom = ((y4 - y3) * (x2 - x1)) - ((x4 - x3) * (y2 - y1))
126 num1 = ((x4 - x3) * (y1 - y3)) - ((y4 - y3) * (x1 - x3))
127 num2 = ((x2 - x1) * (y1 - y3)) - ((y2 - y1) * (x1 - x3))
129 num = num1
131 if denom != 0:
132 x = x1 + ((num / denom) * (x2 - x1))
133 y = y1 + ((num / denom) * (y2 - y1))
134 return Point(x, y)
135 return Point(NaN, NaN)
137 def dot(s1, s2):
138 return s1.delta_x() * s2.delta_x() + s1.delta_y() * s2.delta_y()