Init mag.field before initializing generator

shahor02 · shahor02 · commit 6ddb56c1c37e · 2020-09-08T17:18:02.000+02:00
diff --git a/run/O2PrimaryServerDevice.h b/run/O2PrimaryServerDevice.h
@@ -27,6 +27,8 @@
 #include <SimConfig/SimConfig.h>
 #include <CommonUtils/ConfigurableParam.h>
 #include <CommonUtils/RngHelper.h>
+#include "Field/MagneticField.h"
+#include <TGeoGlobalMagField.h>
 #include <typeinfo>
 #include <thread>
 #include <TROOT.h>
@@ -60,6 +62,31 @@ class O2PrimaryServerDevice final : public FairMQDevice
     TStopwatch timer;
     timer.Start();
     auto& conf = o2::conf::SimConfig::Instance();
+
+    // init magnetic field as it might be needed by the generator
+    int fld = conf.getConfigData().mField, fldAbs = std::abs(fld);
+    float fldCoeff;
+    o2::field::MagFieldParam::BMap_t fldType;
+    switch (fldAbs) {
+      case 5:
+        fldType = o2::field::MagFieldParam::k5kG;
+        fldCoeff = fld > 0 ? 1. : -1;
+        break;
+      case 0:
+        fldType = o2::field::MagFieldParam::k5kG;
+        fldCoeff = 0;
+        break;
+      case 2:
+        fldType = o2::field::MagFieldParam::k2kG;
+        fldCoeff = fld > 0 ? 1. : -1;
+        break;
+      default:
+        LOG(FATAL) << "Field option " << fld << " is not supported, use +-2, +-5 or 0";
+    };
+    auto field = new o2::field::MagneticField("Maps", "Maps", fldCoeff, fldCoeff, fldType);
+    TGeoGlobalMagField::Instance()->SetField(field);
+    TGeoGlobalMagField::Instance()->Lock();
+
     o2::eventgen::GeneratorFactory::setPrimaryGenerator(conf, &mPrimGen);
     mPrimGen.SetEvent(&mEventHeader);
 
