If you're asking what determines the shape of the arc, it's the skill_px (and _py and _pz) values. Here's a prototype I did in Processing (takes a moment to load) -- the target is shown in blue, and has _px and _py values equal (1.0). The camera is shown in orange, and has a _px of (I believe) 2.0 and a _py of 1.0, which means that the camera will approach its target more quickly.

If that all make sense. It's late.