Source Code for Module glitter.convenience.matrices

 1  """Convenience factory methods for geometric transform matrices. 
 2   
 3  @author: Stephan Wenger 
 4  @date: 2012-03-05 
 5  """ 
 6   
 7  import numpy as _np 
 8   
 9 -def identity_matrix(): 
10      return _np.matrix(_np.eye(4)) 
11   
12 -def rotation_matrix(angle, axis, degrees=False): 
13      if degrees: 
14          angle = _np.deg2rad(angle) 
15      c, s = _np.cos(angle), _np.sin(angle) 
16      x, y, z = axis / _np.sqrt(sum(a ** 2 for a in axis)) 
17      return _np.matrix(( 
18          (x * x * (1 - c) + c,     x * y * (1 - c) - z * s, x * z * (1 - c) + y * s, 0), 
19          (y * x * (1 - c) + z * s, y * y * (1 - c) + c,     y * z * (1 - c) - x * s, 0), 
20          (z * x * (1 - c) - y * s, z * y * (1 - c) + x * s, z * z * (1 - c) + c,     0), 
21          (0,                       0,                       0,                       1), 
22          )) 
23   
24 -def scale_matrix(*s): 
25      if len(s) == 3: 
26          x, y, z = s 
27      elif len(s) == 1: 
28          x = y = z = s[0] 
29      else: 
30          raise ValueError("invalid scaling parameter") 
31      return _np.matrix(((x, 0, 0, 0), (0, y, 0, 0), (0, 0, z, 0), (0, 0, 0, 1))) 
32   
33  __all__ = ["identity_matrix", "rotation_matrix", "scale_matrix"] 
34