Included deep trigger example with impact parameter

Author: jackal1-66

MC/bin/o2_hybrid_gen.py

@@ -57,6 +57,7 @@ def main():
     parser.add_argument('--mode', type=str, help='Run generator in sequential or parallel mode for quicker event generation (multi-threading)')
     parser.add_argument('--output', type=str, required=True, help='Output JSON file path')
     parser.add_argument('--clone', type=int, help='Number of clones to make of the generator list')
+    parser.add_argument('--trigger', action='store_true', help='Add triggers to the template JSON file')
 
     args = parser.parse_args()
 
@@ -72,15 +73,7 @@ def main():
     # Available options for trigger are "off", "or", "and"
     # in all the other cases the trigger is forced "off"
 
-    trgbase = {
-        "mode": "off",
-        "specs": [
-            {
-                "macro": "",
-                "function": ""
-            }
-        ]
-    }
+    add_trigger = lambda d: d.update({"triggers": {"mode": "off", "specs": [{"macro": "", "function": ""}]}}) if args.trigger else None
 
     # put in a list all the elementes in the gen flag
     noConfGen = ["pythia8pp", "pythia8hf", "pythia8hi", "pythia8powheg"]
@@ -96,25 +89,25 @@ def main():
                     configs = [get_params(cmd_instance, cmd_params), get_params(gens_instances[gen], gens_params[gen])]
                     gens.append({
                         'name': gen,
-                        'triggers': trgbase,
                         'config': {
                             "configcmd": configs[0],
                             "confighepmc": configs[1]
                         }
                     })
+                    add_trigger(gens[-1])
                 else:
                     configs = get_params(gens_instances[gen],gens_params[gen])
                     gens.append({
                         'name': gen,
-                        'triggers': trgbase,
                         'config': configs
                     })
+                    add_trigger(gens[-1])
             elif gen in noConfGen:
                 gens.append({
                     "name": gen,
-                    'triggers': trgbase,
                     "config": ""
                 })
+                add_trigger(gens[-1])
             else:
                 print(f"Generator {gen} not found in the list of available generators")
                 exit(1)
@@ -129,9 +122,9 @@ def main():
             configs["iniFile"] = ini
             gens.append({
                 'name': 'external',
-                'triggers': trgbase,
                 'config': configs
             })
+            add_trigger(gens[-1])
 
     if args.clone:
         if args.clone < 2:

MC/config/examples/trigger/trigger_impactb.macro

@@ -0,0 +1,45 @@
+#include "Generators/Trigger.h"
+#include "TParticle.h"
+#include <iostream>
+
+// a very simple trigger example, examining generated particles              
+o2::eventgen::Trigger trigger()
+{
+  //
+  return [](const std::vector<TParticle>& particles) -> bool {
+    std::cout << "Running trigger on event with size " << particles.size() << "\n";
+    if (particles.size() > 10000) {
+      return true;
+    }
+    return false;
+  };
+}
+
+#include "Pythia8/Pythia.h"
+#include "Pythia8/HIInfo.h"
+#include <fairlogger/Logger.h>
+// a deep trigger example, looking into the internal generator state
+o2::eventgen::DeepTrigger
+  trigger_impactb_pythia8(double bmin = 5., double bmax = 10.)
+{
+  return [bmin, bmax](void* interface, std::string name) -> bool {
+    if (!name.compare("pythia8")) {
+      auto py8 = reinterpret_cast<Pythia8::Pythia*>(interface);
+#if PYTHIA_VERSION_INTEGER < 8300
+      auto hiinfo = py8->info.hiinfo;
+#else
+      auto hiinfo = py8->info.hiInfo;
+#endif
+      if (!hiinfo) {
+        LOG(fatal) << "Cannot define impact parameter: is \'pythia8\' running in heavy-ion mode?";
+      }
+      auto b = hiinfo->b();
+      auto selected = (b > bmin && b < bmax);
+      LOG(info) << "Impact parameter = " << b << " fm: " << (selected ? "selected" : "rejected");
+      return selected;
+    } else {
+      LOG(fatal) << "Cannot define impact parameter for generator interface \'" << name << "\'";
+    }
+    return false;
+  };
+}