So far as I'm aware; the closest they've gotten before now is in the novel '
Bloodline' that covers Leia's connection to Vader being outed as a means of discrediting her whole political career as a New Republic Senator. It's not even a depiction or anything, but a discussion between two of her aids grappling with the idea that Amidala and Vader could ever have had a relationship, with one briefly questioning whether Anakin "assaulted" Padme, before quickly dismissing it.
(Before anyone raises the point: yes he did actually assault her, but not like *that*, and the implication of their conversation is quite clearly in reference to how Luke & Leia were conceived.)