Getting information about incoming particles of a process

Through “track->GetCreatorProcess” I found out that a particle has been created by a certain process. Does someone know how I can get information (energy and creatorprocess) of the particles that induced this process, for example an incoming photon?


at a step, in which interaction happens you know primary particle and secondaries. At that step you may store the primary information and use it later.


Ok, so would you say if I only get the information that a particle has a certain CreatorProcess, it is too late to get information about the primary and I have to check before if a process happens?