TweakingDrivers < LinearCollider

---+ Tweaking the drivers

This is a very brief description of how one can tweaking the DD4hep drivers to change for example the way various detector sensors are placed, or simply to print detector id's and coordinates.

%TOC%

---++ Model components

The DD4hep model of each SiD sub-detector contains two important components:

   1. geometry description, in an XML file, e.g. =SiD/compact/SiD_o2_v01/SiTrackerBarrel_o2_v01_00.xml=
   1. the driver, in a C++ file, e.g. =detector/tracker/TrackerBarrel_o1_v03_geo.cpp=

Note that the file paths above assume you are located in =lcgeo/=.

---++ Identifying the driver

To find which driver is used, have a look in the XML file, in the example above
 
<img src="%PUBURLPATH%/%WEB%/%TOPIC%/whichdriver.png" alt="whichdriver.png" width="1000" height="123" />

In the example above, we use a *custom driver* which is normally located in the =detector/= subdirectory. In other cases, a *generic driver can be used*, e.g.

<img src="%PUBURLPATH%/%WEB%/%TOPIC%/genericdriver.png" alt="genericdriver.png" width="1000" height="75" />

Generic DD4hep drivers have names like =DD4hep_...= and their source code can be found in 
<verbatim>/cvmfs/ilc.desy.de/sw/x86_64_gcc48_sl6/v01-17-10/DD4hep/v00-16/DDDetectors/src/</verbatim>
A custom driver is very often a modified generic driver.
Note that in the case below, a custom driver located in =detector/calorimeter= is used, even though it's named =Generic_...=

<img src="%PUBURLPATH%/%WEB%/%TOPIC%/genericecal.png" alt="genericecal.png" width="1000" height="79" />

---++ Customising a driver

Let us say we want to customise our *ECalBarrel* driver, which in the example above was =GenericCalBarrel_o1_v01_geo.cpp=. We make a copy:
<verbatim>
cd detector/calorimeter/
cp GenericCalBarrel_o1_v01_geo.cpp MyECalBarrel_o1_v01_geo.cpp 
cd ../../
</verbatim>
and then we edit =SiD/compact/SiD_o2_v01/ECalBarrel_o2_v01_00.xml= to say
<verbatim>
... detector id="5" name="ECalBarrel" type="MyECalBarrel_o1_v01" ...
</verbatim>
Now let's edit the driver =MyECalBarrel_o1_v01_geo.cpp= and make it print out the module info, e.g. in function =placeStaves()= add the line
<verbatim>
std:cout <<	"Module: " << module <<	" X: " << posX << " Y: " << posY << " rotY: " << rotY << std:endl;
</verbatim>
and also change
<verbatim>
DECLARE_DETELEMENT(MyECalBarrel_o1_v01, create_detector)
</verbatim>
And now we *must recompile the drivers* as described in [[GlaSiDGettingStarted#Building_the_detector_model_lcge][here]], and watch for a message like 
<verbatim>
[ 59%] Building CXX object CMakeFiles/lcgeo.dir/detector/calorimeter/MyECalBarrel_o1_v01_geo.cpp.o
</verbatim>

---++ Running with the new driver

Now if you run for example =geoDisplay=, or =ddsim=
<verbatim>
ddsim --compactFile=SiD/compact/SiD_o2_v01/SiD_o2_v01.xml --runType=batch --inputFile mcparticles.slcio -N=1 --outputFile=testSiD_o2_v01.slcio
</verbatim>
you will notice that when the =ECalBarrel= is built, the following will be printed to the screen
<verbatim>
Module: 0 X: 34.5329 Y: 128.879 rotY: -0.261799
Module: 1 X: 94.3457 Y: 94.3457 rotY: -0.785398
Module: 2 X: 128.879 Y: 34.5329 rotY: -1.309
Module: 3 X: 128.879 Y: -34.5329 rotY: -1.8326
Module: 4 X: 94.3457 Y: -94.3457 rotY: -2.35619
Module: 5 X: 34.5329 Y: -128.879 rotY: -2.87979
Module: 6 X: -34.5329 Y: -128.879 rotY: -3.40339
Module: 7 X: -94.3457 Y: -94.3457 rotY: -3.92699
Module: 8 X: -128.879 Y: -34.5329 rotY: -4.45059
Module: 9 X: -128.879 Y: 34.5329 rotY: -4.97419
Module: 10 X: -94.3457 Y: 94.3457 rotY: -5.49779
Module: 11 X: -34.5329 Y: 128.879 rotY: -6.02139
</verbatim>

Follow this example to modify the drivers as needed.

Attachments

Topic attachments
I	Attachment	History	Action	Size	Date	Who	Comment
png	genericdriver.png	r1	manage	70.9 K	2016-10-25 - 01:14	DanProtopopescu	A generic DD4hep driver is used here
png	genericecal.png	r1	manage	82.4 K	2016-10-25 - 01:21	DanProtopopescu	Another example of a custom driver
png	whichdriver.png	r3 r2 r1	manage	85.2 K	2016-10-25 - 00:57	DanProtopopescu	Identifying the C++ driver

This topic: LinearCollider > WebHome > GlaSiD > GlaSiDGettingStarted > TweakingDrivers
Topic revision: r2 - 2016-10-27 - DanProtopopescu