Pure Persuit and Lead Persuit
Here's something from the world of fighter jets, that could make for interesting play: Modes of Persuit.
Pure Persuit
Pure persuit is what we usually see as missile behavior. The missile puts the target in it's 12:00 -- dead ahead. This results in closing the range between them as fast as possible.
If speed is a close match, it is possible to evade a pure persuit attacker by simply placing it just rearward of your beam; as long as the persuer is in your rear arc, you can swing around it. Even if it started out in front of you, and you want to get past it.
Lead Persuit
Lead persuit is what is commonly referred to as an intercept course. It involves pointing the missile ahead of the target. However it is not usually found in video games, because it is often poorly implemented in computer science. I believe this is primarily due to our math training. We are taught a cartesian coordinate system, and use algebra to project the intersection of two vectors, a time consuming process.
Let me ask you this: Does a cheetah chasing a deer go through all that? What about a child playing tag? What is needed is a better implementation.
So...Re-consider this problem from a missile's-eye-view. To the missile, all it can deal with is the direction the target is at. Missile's 3:00, bearing 90 degrees right, whatever you want to call it, it's a heading relative to the missile.
The missile can also see one thing about the target: Which way the target is facing. The target is presenting it's rear to us, we are in the target's 6:00, the target's aspect angle is 180 degrees--They all mean the same thing.
And the only thing we can do about it is turn to put the target at a new heading from us. So where do we want our target, in order to head them off?
This is where the game turns into the visual equivalent of playing pool. It's all about the angles. If the target is heading straight at you or away from you, then obviously you should put them in your dead-ahead. At the other extreme, if the target is running with it's side facing you (you are in it's 3:00 or 9:00), then you will have to do the same. Put the target in your 9:00 or 3:00 and run in the same direction.
That is a 90-degree spread from heading straight at the target to running with it in the same direction. And we are determining the angle we should put the target in based only on the angle the target is showing to us.
The only remaining factor is speed difference. If there is a difference in speed, use it as a percentage of angle change.
Lag Persuit
There is one more type of persuit, called Lag Persuit. It is where the missile is pointed behind the target, and has the advantage of changing the target's aspect angle fastest. This is what a dog does, when it circles to get behind it's prey.
If weapon arcs are ever implemented in SEV, Lag Persuit would become useful.
|
Linear Mode
