Imagine a rocket is accelerating in a straight line toward PointA, picking up momentum every frame, then suddenly decides it wants to go toward PointB instead.
It can't just turn straight toward PointB and start accelerating, because the new acceleration plus the pre-existing momentum will carry it wildly off-course, and not straight toward PointB.
It could turn exactly 180° around to aim directly away from PointA and thrust until it comes to a stop, then turn toward PointB and start accelerating from scratch. But that's very inefficient, especially if the two points are in generally similar directions.
It would be more efficient to turn and start accelerating in some specific direction that will bleed off the unnecessary momentum but keep any useful momentum, course-correcting so that it is now moving toward PointB.
I'm trying to figure out how to calculate that "specific direction" that the rocket needs to start accelerating toward, in order to efficiently reach PointB. I have the rocket's position, the Vector3 of its inertia, and the Vector3 locations of PointA and PointB, but I'm not experienced enough in Vector Math to totally understand what's needed.
Especially since we're talking about acceleration (not just speed), so the angle will no doubt need to be recalculated each frame as the changing momentum leads to a changing angle toward PointB, etc.
Can anyone help me out?