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23<FONT SIZE="-1" COLOR="#238E23">
24<B>Geant4 User's Guide</B>
25<BR>
26<B>For Application Developers</B>
27<BR>
28<B>Getting Started with Geant4</B>
29</FONT>
30</TD>
31</TR></TABLE>
32<BR><BR>
33
34<P ALIGN="Center">
35<FONT SIZE="+3" COLOR="#238E23">
36<B>2.10 How to Visualize the Detector and Events</B>
37</FONT>
38<BR><BR>
39
40<HR ALIGN="Center" SIZE="7%">
41<p>
42
43<a name="2.10.1">
44<h2>2.10.1 Introduction</h2></a>
45
46This section briefly explains how to perform Geant4 Visualization.  The
47description here is based on the sample program <tt>examples/novice/N03</tt>.
48More details are given in
49<a href="../Visualization/index.html">Section 8</a> "Visualization".  Example
50macro files can be found in
51<tt>examples/novice/N03/visTutor/exN03VisX.mac</tt>.
52<p>
53
54<hr>
55<a name="2.10.2">
56<H2>2.10.2 Visualization Drivers</H2></a>
57 The Geant4 visualization system was developed in response to a diverse set of requirements:
58  <OL>
59  <LI>Quick response to study geometries, trajectories and hits
60  <LI>High-quality output for publications
61  <LI>Flexible camera control to debug complex geometries
62  <LI>Tools to show volume overlap errors in detector geometries
63  <LI>Interactive picking to get more information on visualized objects
64 </OL>
65<P>
66 No one graphics system is ideal for all of these requirements, and many of the large
67 software frameworks into which Geant4 has been incorporated already have their own
68 visualization systems, so Geant4 visualization was designed around an abstract interface that
69 supports a diverse family of graphics systems.
70 Some of these graphics systems use a graphics library compiled with Geant4, such as OpenGL,
71 while others involve a separate application, such as WIRED or DAWN.
72<P>
73 You need not use all visualization drivers. You can select those suitable
74 to your purposes. In the following, for simplicity, we assume that the
75 Geant4 libraries are built (installed) with the "OpenGL-Xlib driver" and
76 the "DAWNFILE driver" incorporated.
77<P>
78In order to use the DAWNFILE driver, you need Fukui Renderer DAWN, which is
79obtainable from the following Web site:
80<a href="http://geant4.kek.jp/GEANT4/vis">http://geant4.kek.jp/GEANT4/vis</a>.
81<P>
82In order to use the the OpenGL drivers, you need the OpenGL library,
83which is installed in many platforms by default.  You also need to
84set an environmental variable <TT>G4VIS_BUILD_OPENGLX_DRIVER</TT> to <TT>1</TT>
85in building (installing) Genat4 libraries,
86and also set another environmental variable
87<TT>G4VIS_USE_OPENGLX </TT> to <TT>1</TT> in compiling your Geant4 executable.
88You may also have to set an environmental variable <TT>OGLHOME</TT> to the
89OpenGL root directory.
90For example,
91<PRE>
92     setenv G4VIS_BUILD_OPENGLX_DRIVER 1
93     setenv G4VIS_USE_OPENGLX 1
94     setenv OGLHOME /usr/X11R6
95</PRE>
96Some other visualization drivers depending on external libraries are
97also required to set the similar environmental variables,
98<tt>G4VIS_BUILD_DRIVERNAME_DRIVER</tt> and <tt>G4VIS_USE_DRIVERNAME</tt>,
99to <tt>1</tt>.
100All visualization drivers independent of external libraries,
101e.g. DAWNFILE and VRMLFILE drivers, need not such setting.
102(But you must prepare a proper visualization manager class and a proper
103<tt>main()</tt> function, anyway. See below.)
104<P>
105For all visualization drivers available in your Geant4 executable,   
106the C-pre-processor flags <tt>G4VIS_USE_DRIVERNAME</tt> 
107are automatically set by <tt>config/G4VIS_USE.gmk</tt> in compilation.
108Similarly, for all visualization drivers incorporated
109into the Geant4 libraries,
110the C-pre-processor flags <tt>G4VIS_BUILD_DRIVERNAME_DRIVER</tt> 
111are automatically set by <tt>config/G4VIS_BUILD.gmk</tt> in installation.
112
113<HR>
114<a name="2.10.3">
115<H2>2.10.3 How to Incorporate Visualization Drivers into an Executable</H2></a>
116
117 You can realize (use) visualization driver(s) you want
118 in your Geant4 executable.
119 These can only be from the set installed in the Geant4 libraries. You
120 will be warned if the one you request is not available.
121 <P>
122 In order to realize visualization drivers, you must instantiate
123 and initialize a subclass of <tt>G4VisManager</tt> that implements
124 the pure virtual function <tt>RegisterGraphicsSystems()</tt>.  This
125 subclass must be compiled in the user's domain to force the loading
126 of appropriate libraries in the right order.  The easiest way to do
127 this is to use <tt>G4VisExecutive</tt>, a provided class with
128 included implementation.  <tt>G4VisExecutive</tt> is sensitive to the
129 <tt>G4VIS_USE...</tt> variables mentioned above.
130<P>If you do wish to write your own subclass, you may do so.  You will
131see how to do this by looking at <tt>G4VisExecutive.icc</tt>.  A
132typical extract is:
133
134<PRE>
135     ...
136       RegisterGraphicsSystem (new G4DAWNFILE);
137     ...
138     #ifdef G4VIS_USE_OPENGLX
139       RegisterGraphicsSystem (new G4OpenGLImmediateX);
140       RegisterGraphicsSystem (new G4OpenGLStoredX);
141     #endif
142     ...
143</PRE>
144<P>If you wish to use <tt>G4VisExecutive</tt> but register an
145additional graphics system, <tt>XXX</tt> say, you may do so either
146before or after initializing:
147<PRE>
148     visManager->RegisterGraphicsSytem(new XXX);
149     visManager->Initialize();
150</PRE>
151<P>An example of a typical <tt>main()</tt> function is given below.
152
153<HR>
154<a name="2.10.4">
155<H2>2.10.4 Writing the <tt>main()</tt> Method to Include Visualization</H2></a>
156
157 Now we explain how to write a visualization manager and the <tt>main()</tt>
158 function for Geant4 visualization.
159 In order that your Geant4 executable is able to perform visualization,
160 you must instantiate and initialize <I>your</I> Visualization Manager in
161 the <tt>main()</tt> function.
162 The typical <tt>main()</tt> function available for visualization
163 is written in the following style:
164<p>
165<center>
166<table border=2 cellpadding=10>
167<tr>
168<td>
169<PRE>
170 //----- C++ source codes: main() function for visualization
171 #ifdef G4VIS_USE
172 #include "G4VisExecutive.hh"
173 #endif
174
175 .....
176
177 int main(int argc,char** argv) {
178
179 .....
180
181   // Instantiation and initialization of the Visualization Manager
182 #ifdef G4VIS_USE
183   // visualization manager
184   G4VisManager* visManager = new G4VisExecutive;
185   visManager->Initialize();
186 #endif
187
188 .....
189
190   // Job termination
191 #ifdef G4VIS_USE
192   delete visManager;
193 #endif
194
195 .....
196
197   return 0;
198 }
199
200 //----- end of C++
201</PRE>
202</td>
203</tr>
204<tr>
205<td align=center>
206 Source listing 2.10.1<BR>
207 The typical <tt>main()</tt> routine available for visualization.
208</td>
209</tr>
210</table></center>
211<p>
212 In the instantiation, initialization, and deletion of the
213 Visualization Manager, the use of the macro <tt>G4VIS_USE</tt> is
214 recommended. This is set unless the environment variable
215 <tt>G4VIS_NONE</tt> is set.  This allows one easily to build an
216 executable without visualization, if required, without changing the
217 code (but remember you have to force recompilation whenever you
218 change the environment). Note that it is your responsibility to
219 delete the instantiated Visualization Manager by yourself.  A
220 complete description of a sample <tt>main()</tt> function is
221 described in <tt>examples/novice/N03/exampleN03.cc</tt>.
222<p>
223
224<HR>
225<a name="2.10.5">
226<H2>2.10.5 Sample Visualization Sessions </H2></a>
227
228In this section we present typical sessions of
229Geant4 visualization.
230You can test them with the sample program geant4/examples/novice/N03.
231Run a binary executable "exampleN03" without an argument,
232and then execute the commands below in the "Idle>" state.
233Explanation of each command will be described later.
234(Note that the OpenGL-Xlib driver and the DAWNFILE driver are
235 incorporated into the executable, and that
236 Fukui Renderer DAWN is installed in your machine. )
237
238<H2>2.10.5.1 <tt>Visualization of detector components</tt></H2>
239
240The following session visualizes detector components with
241the OpenGL-Xlib driver and then with the DAWNFILE driver.
242The former exhibits minimal visualization commands to visualize
243detector geometry, while the latter exhibits customized visualization
244(visualization of a selected physical volume, coordinate axes, texts, etc).
245<P>
246
247<PRE>
248###################################################
249#  vis1.mac:
250#    A Sample macro to demonstrate visualization
251#    of detector geometry.
252#
253#  USAGE:
254#   Save the commands below as a macro file, say,
255#   "vis1.mac", and execute it as follows:
256#
257#   % $(G4BINDIR)/exampleN03
258#   Idle> /control/execute vis1.mac
259#############################################
260
261#############################################
262# Visualization of detector geometry
263#  with the OGLIX (OpenGL Immediate X) driver
264#############################################
265
266# Invoke the OGLIX driver:
267#  Create a scene handler and a viewer for the OGLIX driver
268/vis/open OGLIX
269
270# Visualize the whole detector geometry
271#  with the default camera parameters.
272#  Command "/vis/drawVolume" visualizes the detector geometry,
273#  and command "/vis/viewer/flush" declares the end of visualization.
274#  (The command /vis/viewer/flush  can be omitted for the OGLIX
275#   and OGLSX drivers.)
276#  The default argument of "/vis/drawVolume" is "world".
277/vis/drawVolume
278/vis/viewer/flush
279
280#########################################
281# Visualization with the DAWNFILE driver
282#########################################
283
284# Invoke the DAWNFILE driver
285#  Create a scene handler and a viewer for the DAWNFILE driver
286/vis/open DAWNFILE
287
288# Bird's-eye view of a detector component (Absorber)
289#  drawing style: hidden-surface removal
290#  viewpoint  : (theta,phi) = (35*deg, 45*deg),
291#  zoom factor: 1.1 of the full screen size
292#  coordinate axes:
293#     x-axis:red,  y-axis:green,  z-axis:blue
294#     origin: (0,0,0),  length: 500 mm
295#
296/vis/viewer/reset
297/vis/viewer/set/style          surface
298/vis/viewer/zoom               1.1
299/vis/viewer/set/viewpointThetaPhi  35 45
300/vis/drawVolume                Absorber
301/vis/scene/add/axes            0 0 0 500 mm
302/vis/scene/add/text            0 0 0 mm  40 -100 -140   Absorber
303/vis/viewer/flush
304
305# Bird's-eye view of the whole detector components
306#  * "/vis/viewer/set/culling global false" makes the invisible
307#    world volume visible.
308#    (The invisibility of the world volume is set
309#     in ExN03DetectorConstruction.cc.)
310/vis/viewer/set/style     wireframe
311/vis/viewer/set/culling   global false
312/vis/drawVolume
313/vis/scene/add/axes       0 0 0 500 mm
314/vis/scene/add/text       0 0 0 mm 50 -50 -200   world
315/vis/viewer/flush
316################### END of vis1.mac ###################
317</PRE>
318<BR>
319
320<H2>2.10.5.2 <tt>Visualization of events</tt></H2>
321
322The following session visualizes events (tajectories)
323with the OpenGL-Xlib driver and then with the DAWNFILE driver.
324The former exhibits minimal visualization commands to visualize events,
325while the latter exhibits customized visualization.
326Note that the run action and event action classes should be
327described properly. (See, for example, the following classes:<BR>
328"examples/novice/N03/src/ExN03RunAction.cc",
329"examples/novice/N03/src/ExN03EventAction.cc").
330
331<P>
332
333<PRE>
334###################################################
335#  vis2.mac:
336#    A Sample macro to demonstrate visualization
337#    of events (trajectories).
338#
339#  USAGE:
340#   Save the commands below as a macro file, say,
341#   "vis2.mac", and execute it as follows:
342#
343#   % $(G4BINDIR)/exampleN03
344#   Idle> /control/execute vis1.mac
345#############################################
346
347#####################################################
348# Store particle trajectories for visualization
349/tracking/storeTrajectory 1
350#####################################################
351
352########################################################
353# Visualization with the OGLSX (OpenGL Stored X) driver
354########################################################
355
356# Invoke the OGLSX driver
357#  Create a scene handler and a viewer for the OGLSX driver
358/vis/open OGLSX
359
360# Create an empty scene and add detector components to it
361/vis/drawVolume
362
363# Add trajectories to the current scene
364#  Note: This command is not necessary in, e.g.,
365#        examples/novice/N03, since the C++ method DrawTrajectory()
366#        is described in the event action.
367#/vis/scene/add/trajectories
368
369# Set viewing parameters
370/vis/viewer/reset
371/vis/viewer/set/viewpointThetaPhi  10 20
372
373# Visualize one it.
374/run/beamOn 1
375
376##########################################################
377# Visualization with the DAWNFILE driver
378##########################################################
379
380# Invoke the DAWNFILE driver
381#  Create a scene handler and a viewer for the DAWNFILE driver
382/vis/open DAWNFILE
383
384# Create an empty scene and add detector components to it
385/vis/drawVolume
386
387# Add trajectories to the current scene
388#  Note: This command is not necessary in exampleN03,
389#        since the C++ method DrawTrajectory() is
390#        described in the event action.
391#/vis/scene/add/trajectories
392
393# Visualize plural events (bird's eye view)
394#  drawing style: wireframe
395#  viewpoint  : (theta,phi) = (45*deg, 45*deg)
396#  zoom factor: 1.5 x (full screen size)
397/vis/viewer/reset
398/vis/viewer/set/style  wireframe
399/vis/viewer/set/viewpointThetaPhi   45 45
400/vis/viewer/zoom        1.5
401/run/beamOn             2
402
403# Set the drawing style to "surface"
404#  Candidates: wireframe, surface
405/vis/viewer/set/style  surface
406
407# Visualize plural events (bird's eye view) again
408#  with another drawing style (surface)
409/run/beamOn             2
410
411################### END of vis2.mac ###################
412</PRE>
413<BR>
414<HR>
415<a name="2.10.6">
416<H2>2.10.6 For More Information on Geant4 Visualization </H2></a>
417See the <A HREF="../Visualization/index.html">Visualization</a> part of this user guide.
418
419<BR>
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