/[escript]/trunk/pyvisi/py_src/streamlinemodule.py
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Contents of /trunk/pyvisi/py_src/streamlinemodule.py

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Revision 946 - (show annotations)
Wed Jan 31 03:08:04 2007 UTC (12 years, 6 months ago) by jongui
File MIME type: text/x-python
File size: 3224 byte(s)
added colouring option to use either scalar data or vector data.
1 """
2 @author: John NGUI
3 """
4
5 import vtk
6
7 class StreamLineModule:
8 """
9 Class that defines streamline.
10 """
11
12 def __init__(self, object, source):
13 """
14 Initialise the streamline.
15
16 @type object: vtkUnstructuredGrid, etc
17 @param object: Input for the streamline
18 @type source: vtkPolyData
19 @param source: Source to generate the starting points
20 """
21
22 self.__object = object
23 self.__source = source
24 self.__vtk_stream_line = vtk.vtkStreamLine()
25
26 self.__setupStreamLineModule()
27
28 def __setupStreamLineModule(self):
29 """
30 Setup the streamline.
31 """
32
33 self.__setInput()
34 self.__setSource()
35 # Default maximum propagation time is 100.
36 self.setMaximumPropagationTime(100)
37 # Default step length is 0.1
38 self.setStepLength(0.1)
39 # Default integration step length is 0.1
40 self.setIntegrationStepLength(0.1)
41 # Default integration is set to both directions.
42 self.setIntegrationToBothDirections()
43 # Default integrator is set to vtkRungeKutta4
44 self.setIntegrator(vtk.vtkRungeKutta4())
45 self.__vtk_stream_line.Update()
46
47 def __setInput(self):
48 """
49 Set the input for the streamline.
50 """
51
52 self.__vtk_stream_line.SetInput(self.__object)
53
54 def __setSource(self):
55 """
56 Set the source to generate the starting points for the streamlines.
57 """
58
59 self.__vtk_stream_line.SetSource(self.__source)
60
61 def setMaximumPropagationTime(self, time):
62 """
63 Set the maximum length of the streamline expressed in elapsed time.
64
65 @type time: Number
66 @param time: Maximum length of the streamline expressed in elapsed time
67 """
68
69 self.__vtk_stream_line.SetMaximumPropagationTime(time)
70
71 def setStepLength(self, length):
72 """
73 Set the length of the line segment expressed in elapsed time. A smaller
74 value results in a smoother streamline (but is more expensive). Setting
75 the step length usually goes hand-in-hand with setting the integration
76 step length. Otherwise, errors such as "... can't compute normals" may
77 arise. However, it does not usually apply the other way around.
78
79 @type length: Number
80 @param length: Length of the line segment expressed in elapsed time
81 """
82
83 self.__vtk_stream_line.SetStepLength(length)
84
85 def setIntegrationStepLength(self, length):
86 """
87 Set the integration step size expressed as a fraction of the size of
88 each cell. A smaller length results in a better image (but is more
89 expensive).
90
91 @type length: Number
92 @param length: Length of the integration step expressed as a fraction
93 """
94
95 self.__vtk_stream_line.SetIntegrationStepLength(length)
96
97 def setIntegrationToBothDirections(self):
98 """
99 Set the integration to occur both sides: forward (where the streamline
100 goes) and backward (where the streamline came from).
101 """
102
103 self.__vtk_stream_line.SetIntegrationDirectionToIntegrateBothDirections()
104
105 def setIntegrator(self, integrator):
106 """
107 Set the integrator to be used in the streamline calculation.
108
109 @type integrator: vtkInitialValueProblemSolver
110 @param integrator: Integrator type. i.e. vtkRungeKutta2, vtkRungeKutta4
111 """
112
113 self.__vtk_stream_line.SetIntegrator(integrator)
114
115 def _getOutput(self):
116 """
117 Return the streamline.
118
119 @rtype: vtkPolyData
120 @return Polygonal data
121 """
122
123 return self.__vtk_stream_line.GetOutput()

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