Google Maps plugin auto-generate route from visitors location

Hey,
I cannot share my website yet, due to its underconstruction, but I have a question concerning the Google Maps plugin.
I would like, if possible, to have the route autogenerated from the visitors location to the Destination Pin.
Is there a way?
At the moment I found the only way is if the visitor clicks first on his own Location Pin, swap fields from B to A, and then click on the Destination Location, thus adding the Destination Location to field B, and then Get Directions.
Can I skip all this visitors input and autogenerate the route from visitors location to my Destination Pin ?

Thank you.