| Geant4 Cross Reference |
1 README file for the Geant4 BlineTracer module
2
3 Author : Laurent Desorgher (desorgher@phim.uni
4
5 --------------------------------
6
7 The BlineTracer module allows to trace and vis
8 lines in a Geant4 application where particle a
9 magnetic field (in future, these functionaliti
10 the Geant4 kernel).
11 To use the tracer, the user should copy the cl
12 his/her own application/example and create som
13 an instance of a G4BlineTracer object.
14 It can be anywhere (for example in the main co
15 defining the magnetic field):
16
17 #include "G4BlineTracer.hh"
18 G4BlineTracer* theBlineTool = new G4BlineTra
19
20
21 Design principles:
22
23 The core of the tool is the method ComputeBlin
24 In this method a bline is computed by tracking
25 defined magnetic field and by using a Bline eq
26 G4BlineEquation, motion along the field) inste
27
28 During the execution of this method :
29
30 -The user defined equations of motion assoc
31 global and local fields are replaced by in
32 associated to the same fields.
33 The G4BlineEquation class defines the diffe
34 magnetic field line.
35
36 -User defined ChordFinders are replaced by n
37 associated to the G4BlineEquation object.
38
39 -The user primary generator action, run acti
40 stepping action are replaced by instances o
41 G4BlinePrimaryGeneratorAction, G4BlineTrace
42 and G4BlineSteppingAction respectively. Oth
43 a NULL pointer.
44
45 After the execution of the method, the origina
46 of motions and chord-finders are restored.
47
48 In other words, the deafult run-action is temp
49 G4BlineTracer run-action using the same Geomet
50 but with a different equation of motion and us
51
52 The GeneratePrimaries() method of the G4Bline
53 call the GeneratePrimaries() method of the use
54 for defining the start position and start time
55 Start position for user application and for Bl
56 controlled by the same UI commands.
57 The type of particles to be tracked when traci
58 to Charged-Geantino. This allows to switch off
59 and hadronics physics when tracing field lines
60
61
62 The G4BlineEventAction class is responsible to
63 lines as a vector of Polylines and Polymarkers
64 These vectors can be drawn and reset at any ti
65
66 The stepping action does nothing in this imple
67 in future versions to limit field line tracing
68 by the user. For this purpose a G4BlineStackin
69 implemented.
70
71 User Manual:
72
73 General description:
74
75 The BlineTracer is controlled by the UI comman
76 /vis/blineTracer. By calling the command 'comp
77 lines passing through user defined start posit
78 Start positions are generated by the user prim
79 By doing so, the definition of start positions
80 tracking and magnetic field line tracking.
81
82 A magnetic field line is computed as a track o
83 along the field line. The user can define the
84 (only valid for Bline tracing purposes) by the
85 command.
86 By using small enough maximum step length, smo
87 obtained. By using the command 'stockLines' an
88 can decide to store the series of tracking ste
89 a magnetic field line as a Polyline object and
90 (circles) respectively.
91 These objects are stored in vectors of PolyLin
92 By using the command 'draw', these vectors are
93 of the visualisation manager, provided that a
94 visualisation driver have been properly create
95 The scene is visualised by invoking the vis co
96 Polyline objects are visualised as line segmen
97 step positions defining a line, while for a Po
98 (here circles), are drawn at each step positi
99 By using the 'setColour' the user defines the
100 that will be associated to the next computed m
101 By calling 'setPointSize' the user defines the
102 that will be associated to the next computed
103 The user can remove the vector of Polymarker a
104 by invoking 'resetMaterialToBeDrawn'.
105 When using small max step size and polymarkers
106 thickness of a smooth magnetic field line is o
107 Marker size parameter ('setPointSize')
108
109 Command description:
110 /vis/blineTracer/computeBline nb_of_lines :
111 Parameters: integer nb_of_lines
112 Description: Compute nb_of_lines different
113
114 /vis/blineTracer/setMaxStepLength max_step_l
115 Parameters: double max_step_length
116 Description: Set the maximum tracking step
117 magnetic field lines
118
119 /vis/blineTracer/setColour red green
120 Parameters: double red, green, blue
121 Description: Define the colour for visual
122 next computed magnetic field lines.
123 defined by a RGB code (red,green,bl
124 parameters smaller than 1.
125
126 /vis/blineTracer/stockLines aBool
127 Parameters: boolean aBool
128 Description: If true the next computed fie
129 as Polylines for further visualisa
130 /vis/blineTracer/stockLines aBool
131 Parameters: boolean aBool
132 Description: If true the next computed fie
133 as Polymarkers for further visuali
134
135 /vis/blineTracer/setPointSize point_size
136 Parameters: double point_size
137 DEscription: set the size of the visualisa
138 that will be associated with the ne
139 magnetic field lines
140
141 /vis/blineTracer/resetMaterialToBeDraw
142 Parameters: none
143 Description: The vector of Polyline and Po
144 magnetic field lines to be visualis
145 from memory
146
147 /tracking/storeTrajectory 1 :
148 If the storeTrajectory parameter is n
149 stored.
150
151 An example for Bline visualisation is provid
152
153 Current limitations & known problems:
154
155 The tool is working properly only for detect
156 field are defined. It is planned in th
157 field lines in regions where no fields are e