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8</script></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">2.10. 
9How to Visualize the Detector and Events
10</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch02s09.html"><img src="AllResources/IconsGIF/prev.gif" alt="Prev"></a> </td><th width="60%" align="center">Chapter 2. 
11Getting Started with Geant4 - Running a Simple Example
12</th><td width="20%" align="right"> <a accesskey="n" href="ch03.html"><img src="AllResources/IconsGIF/next.gif" alt="Next"></a></td></tr></table><hr></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="sect.HowToVis"></a>2.10. 
13How to Visualize the Detector and Events
14</h2></div></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="sect.HowToVis.Intro"></a>2.10.1. 
15Introduction
16</h3></div></div></div><p>
17This section briefly explains how to perform Geant4 Visualization.
18The description here is based on the sample program
19<code class="literal">examples/novice/N03</code>. More details are given in
20<a href="ch08.html" title="Chapter 8. 
21Visualization
22">Chapter 8</a> "Visualization".
23Example macro files can be found in
24<code class="literal">examples/novice/N03/visTutor/exN03VisX.mac</code>.
25</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="sect.HowToVis.VisDrivers"></a>2.10.2. 
26Visualization Drivers
27</h3></div></div></div><p>
28The Geant4 visualization system was developed in response to a
29diverse set of requirements:
30
31</p><div class="orderedlist"><ol type="1" compact><li><p>
32  Quick response to study geometries, trajectories and hits
33  </p></li><li><p>
34  High-quality output for publications
35  </p></li><li><p>
36  Flexible camera control to debug complex geometries
37  </p></li><li><p>
38  Tools to show volume overlap errors in detector geometries
39  </p></li><li><p>
40  Interactive picking to get more information on visualized objects
41  </p></li></ol></div><p>
42</p><p>
43No one graphics system is ideal for all of these requirements,
44and many of the large software frameworks into which Geant4 has
45been incorporated already have their own visualization systems, so
46Geant4 visualization was designed around an abstract interface that
47supports a diverse family of graphics systems. Some of these
48graphics systems use a graphics library compiled with Geant4, such
49as OpenGL, while others involve a separate application, such as
50WIRED or DAWN.
51</p><p>
52You need not use all visualization drivers. You can select those
53suitable to your purposes. In the following, for simplicity, we
54assume that the Geant4 libraries are built (installed) with the
55"OpenGL-Xlib driver" and the "DAWNFILE driver" incorporated.
56</p><p>
57In order to use the DAWNFILE driver, you need Fukui Renderer
58DAWN, which is obtainable from the following Web site:
59<a href="http://geant4.kek.jp/GEANT4/vis" target="_top">
60http://geant4.kek.jp/GEANT4/vis</a>.
61</p><p>
62In order to use the the OpenGL drivers, you need the OpenGL
63library, which is installed in many platforms by default. You also
64need to set an environmental variable
65<code class="literal">G4VIS_BUILD_OPENGLX_DRIVER</code> to <code class="literal">1</code> in
66building (installing) Genat4 libraries, and also set another environmental
67variable <code class="literal">G4VIS_USE_OPENGLX</code> to <code class="literal">1</code> 
68in compiling your Geant4 executable. You may also have to set an
69environmental variable <code class="literal">OGLHOME</code> to the OpenGL root
70directory. For example,
71
72</p><div class="informalexample"><pre class="programlisting">
73     setenv G4VIS_BUILD_OPENGLX_DRIVER 1
74     setenv G4VIS_USE_OPENGLX 1
75     setenv OGLHOME /usr/X11R6
76</pre></div><p>
77</p><p>
78Some other visualization drivers depending on external libraries
79are also required to set the similar environmental variables,
80<code class="literal">G4VIS_BUILD_DRIVERNAME_DRIVER</code> and
81<code class="literal">G4VIS_USE_DRIVERNAME</code>, to <code class="literal">1</code>. All
82visualization drivers independent of external libraries, e.g. DAWNFILE and
83VRMLFILE drivers, need not such setting. (But you must prepare a
84proper visualization manager class and a proper <code class="literal">main()</code>
85function, anyway. See below.)
86</p><p>
87For all visualization drivers available in your Geant4
88executable, the C-pre-processor flags <code class="literal">G4VIS_USE_DRIVERNAME</code>
89are automatically set by <code class="literal">config/G4VIS_USE.gmk</code> in
90compilation. Similarly, for all visualization drivers incorporated
91into the Geant4 libraries, the C-pre-processor flags
92<code class="literal">G4VIS_BUILD_DRIVERNAME_DRIVER</code> are automatically set by
93<code class="literal">config/G4VIS_BUILD.gmk</code> in installation.
94</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="sect.HowToVis.IncorpVisDrivers"></a>2.10.3. 
95How to Incorporate Visualization Drivers into an Executable
96</h3></div></div></div><p>
97You can realize (use) visualization driver(s) you want in your
98Geant4 executable. These can only be from the set installed in the
99Geant4 libraries. You will be warned if the one you request is not
100available.
101</p><p>
102In order to realize visualization drivers, you must instantiate
103and initialize a subclass of <code class="literal">G4VisManager</code> that implements
104the pure virtual function <code class="literal">RegisterGraphicsSystems()</code>. This
105subclass must be compiled in the user's domain to force the loading
106of appropriate libraries in the right order. The easiest way to do
107this is to use <code class="literal">G4VisExecutive</code>, a provided class with
108included implementation. <code class="literal">G4VisExecutive</code> is sensitive to
109the <code class="literal">G4VIS_USE...</code> variables mentioned above.
110</p><p>
111If you do wish to write your own subclass, you may do so. You
112will see how to do this by looking at <code class="literal">G4VisExecutive.icc</code>.
113A typical extract is:
114
115</p><div class="informalexample"><pre class="programlisting">
116     ...
117       RegisterGraphicsSystem (new G4DAWNFILE);
118     ...
119     #ifdef G4VIS_USE_OPENGLX
120       RegisterGraphicsSystem (new G4OpenGLImmediateX);
121       RegisterGraphicsSystem (new G4OpenGLStoredX);
122     #endif
123     ...
124</pre></div><p>
125</p><p>
126If you wish to use <code class="literal">G4VisExecutive</code> but register an
127additional graphics system, <code class="literal">XXX</code> say, you may do so either
128before or after initializing:
129
130</p><div class="informalexample"><pre class="programlisting">
131     visManager-&gt;RegisterGraphicsSytem(new XXX);
132     visManager-&gt;Initialize();
133</pre></div><p>
134</p><p>
135An example of a typical <code class="literal">main()</code> function is given
136below.
137</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="sect.HowToVis.WritingMain"></a>2.10.4. 
138Writing the <code class="literal">main()</code> Method to Include Visualization
139</h3></div></div></div><p>
140Now we explain how to write a visualization manager and the
141<code class="literal">main()</code> function for Geant4 visualization. In order that
142your Geant4 executable is able to perform visualization, you must
143instantiate and initialize <span class="emphasis"><em>your</em></span> Visualization Manager
144in the <code class="literal">main()</code> function. The typical
145<code class="literal">main()</code> 
146function available for visualization is written in the following style:
147
148</p><div class="example"><a name="programlist_HowToVis_1"></a><p class="title"><b>Example 2.26. 
149The typical <code class="literal">main()</code> routine available for visualization.
150</b></p><div class="example-contents"><pre class="programlisting">
151 //----- C++ source codes: main() function for visualization
152 #ifdef G4VIS_USE
153 #include "G4VisExecutive.hh"
154 #endif
155
156 .....
157
158 int main(int argc,char** argv) {
159
160 .....
161
162   // Instantiation and initialization of the Visualization Manager
163 #ifdef G4VIS_USE
164   // visualization manager
165   G4VisManager* visManager = new G4VisExecutive;
166   visManager-&gt;Initialize();
167 #endif
168
169 .....
170
171   // Job termination
172 #ifdef G4VIS_USE
173   delete visManager;
174 #endif
175
176 .....
177
178   return 0;
179 }
180
181 //----- end of C++
182</pre></div></div><p><br class="example-break">
183</p><p>
184In the instantiation, initialization, and deletion of the
185Visualization Manager, the use of the macro <code class="literal">G4VIS_USE</code> is
186recommended. This is set unless the environment variable
187<code class="literal">G4VIS_NONE</code> is set. This allows one easily to build an
188executable without visualization, if required, without changing the
189code (but remember you have to force recompilation whenever you
190change the environment). Note that it is your responsibility to
191delete the instantiated Visualization Manager by yourself. A
192complete description of a sample <code class="literal">main()</code> function is
193described in <code class="literal">examples/novice/N03/exampleN03.cc</code>.
194</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="sect.HowToVis.SampleVis"></a>2.10.5. 
195Sample Visualization Sessions
196</h3></div></div></div><p>
197In this section we present typical sessions of Geant4
198visualization. You can test them with the sample program
199geant4/examples/novice/N03. Run a binary executable "exampleN03"
200without an argument, and then execute the commands below in the
201"Idle&gt;" state. Explanation of each command will be described
202later. (Note that the OpenGL-Xlib driver and the DAWNFILE driver
203are incorporated into the executable, and that Fukui Renderer DAWN
204is installed in your machine. )
205</p><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="sect.HowToVis.SampleVis.VisDetector"></a>2.10.5.1. 
206Visualization of detector components
207</h4></div></div></div><p>
208The following session visualizes detector components with the
209OpenGL-Xlib driver and then with the DAWNFILE driver. The former
210exhibits minimal visualization commands to visualize detector
211geometry, while the latter exhibits customized visualization
212(visualization of a selected physical volume, coordinate axes,
213texts, etc).
214
215</p><div class="informalexample"><pre class="programlisting">
216###################################################
217#  vis1.mac:
218#    A Sample macro to demonstrate visualization
219#    of detector geometry.
220#
221#  USAGE:
222#   Save the commands below as a macro file, say,
223#   "vis1.mac", and execute it as follows:
224#
225#   % $(G4BINDIR)/exampleN03
226#   Idle&gt; /control/execute vis1.mac
227#############################################
228
229#############################################
230# Visualization of detector geometry
231#  with the OGLIX (OpenGL Immediate X) driver
232#############################################
233
234# Invoke the OGLIX driver:
235#  Create a scene handler and a viewer for the OGLIX driver
236/vis/open OGLIX
237
238# Visualize the whole detector geometry
239#  with the default camera parameters.
240#  Command "/vis/drawVolume" visualizes the detector geometry,
241#  and command "/vis/viewer/flush" declares the end of visualization.
242#  (The command /vis/viewer/flush  can be omitted for the OGLIX
243#   and OGLSX drivers.)
244#  The default argument of "/vis/drawVolume" is "world".
245/vis/drawVolume
246/vis/viewer/flush
247
248#########################################
249# Visualization with the DAWNFILE driver
250#########################################
251
252# Invoke the DAWNFILE driver
253#  Create a scene handler and a viewer for the DAWNFILE driver
254/vis/open DAWNFILE
255
256# Bird's-eye view of a detector component (Absorber)
257#  drawing style: hidden-surface removal
258#  viewpoint  : (theta,phi) = (35*deg, 45*deg),
259#  zoom factor: 1.1 of the full screen size
260#  coordinate axes:
261#     x-axis:red,  y-axis:green,  z-axis:blue
262#     origin: (0,0,0),  length: 500 mm
263#
264/vis/viewer/reset
265/vis/viewer/set/style          surface
266/vis/viewer/zoom               1.1
267/vis/viewer/set/viewpointThetaPhi  35 45
268/vis/drawVolume                Absorber
269/vis/scene/add/axes            0 0 0 500 mm
270/vis/scene/add/text            0 0 0 mm  40 -100 -140   Absorber
271/vis/viewer/flush
272
273# Bird's-eye view of the whole detector components
274#  * "/vis/viewer/set/culling global false" makes the invisible
275#    world volume visible.
276#    (The invisibility of the world volume is set
277#     in ExN03DetectorConstruction.cc.)
278/vis/viewer/set/style     wireframe
279/vis/viewer/set/culling   global false
280/vis/drawVolume
281/vis/scene/add/axes       0 0 0 500 mm
282/vis/scene/add/text       0 0 0 mm 50 -50 -200   world
283/vis/viewer/flush
284################### END of vis1.mac ###################
285</pre></div><p>
286</p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="sect.HowToVis.SampleVis.VisEvents"></a>2.10.5.2. 
287Visualization of events
288</h4></div></div></div><p>
289The following session visualizes events (tajectories) with the
290OpenGL-Xlib driver and then with the DAWNFILE driver. The former
291exhibits minimal visualization commands to visualize events, while
292the latter exhibits customized visualization. Note that the run
293action and event action classes should be described properly. (See,
294for example, the following classes:
295"examples/novice/N03/src/ExN03RunAction.cc",
296
297</p><div class="informalexample"><pre class="programlisting">
298###################################################
299#  vis2.mac:
300#    A Sample macro to demonstrate visualization
301#    of events (trajectories).
302#
303#  USAGE:
304#   Save the commands below as a macro file, say,
305#   "vis2.mac", and execute it as follows:
306#
307#   % $(G4BINDIR)/exampleN03
308#   Idle&gt; /control/execute vis1.mac
309#############################################
310
311#####################################################
312# Store particle trajectories for visualization
313/tracking/storeTrajectory 1
314#####################################################
315
316########################################################
317# Visualization with the OGLSX (OpenGL Stored X) driver
318########################################################
319
320# Invoke the OGLSX driver
321#  Create a scene handler and a viewer for the OGLSX driver
322/vis/open OGLSX
323
324# Create an empty scene and add detector components to it
325/vis/drawVolume
326
327# Add trajectories to the current scene
328#  Note: This command is not necessary in, e.g.,
329#        examples/novice/N03, since the C++ method DrawTrajectory()
330#        is described in the event action.
331#/vis/scene/add/trajectories
332
333# Set viewing parameters
334/vis/viewer/reset
335/vis/viewer/set/viewpointThetaPhi  10 20
336
337# Visualize one it.
338/run/beamOn 1
339
340##########################################################
341# Visualization with the DAWNFILE driver
342##########################################################
343
344# Invoke the DAWNFILE driver
345#  Create a scene handler and a viewer for the DAWNFILE driver
346/vis/open DAWNFILE
347
348# Create an empty scene and add detector components to it
349/vis/drawVolume
350
351# Add trajectories to the current scene
352#  Note: This command is not necessary in exampleN03,
353#        since the C++ method DrawTrajectory() is
354#        described in the event action.
355#/vis/scene/add/trajectories
356
357# Visualize plural events (bird's eye view)
358#  drawing style: wireframe
359#  viewpoint  : (theta,phi) = (45*deg, 45*deg)
360#  zoom factor: 1.5 x (full screen size)
361/vis/viewer/reset
362/vis/viewer/set/style  wireframe
363/vis/viewer/set/viewpointThetaPhi   45 45
364/vis/viewer/zoom        1.5
365/run/beamOn             2
366
367# Set the drawing style to "surface"
368#  Candidates: wireframe, surface
369/vis/viewer/set/style  surface
370
371# Visualize plural events (bird's eye view) again
372#  with another drawing style (surface)
373/run/beamOn             2
374
375################### END of vis2.mac ###################
376</pre></div><p>
377</p></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="sect.HowToVis.MoreInfo"></a>2.10.6. 
378For More Information on Geant4 Visualization
379</h3></div></div></div><p>
380See the <a href="ch08.html" title="Chapter 8. 
381Visualization
382">Chapter 8</a> "Visualization"
383part of this user guide.
384</p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ch02s09.html"><img src="AllResources/IconsGIF/prev.gif" alt="Prev"></a> </td><td width="20%" align="center"><a accesskey="u" href="ch02.html"><img src="AllResources/IconsGIF/up.gif" alt="Up"></a></td><td width="40%" align="right"> <a accesskey="n" href="ch03.html"><img src="AllResources/IconsGIF/next.gif" alt="Next"></a></td></tr><tr><td width="40%" align="left" valign="top">2.9. 
385How to Execute a Program
386 </td><td width="20%" align="center"><a accesskey="h" href="index.html"><img src="AllResources/IconsGIF/home.gif" alt="Home"></a></td><td width="40%" align="right" valign="top"> Chapter 3. 
387Toolkit Fundamentals
388</td></tr></table></div></body></html>
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