Improve moveToTarget performance by reusing the diff vector

[Hwan-seok]

What could be improved

Add optional reusable diff argument which is Vector2 to the Vector2.moveToTarget.

flame/packages/flame/lib/src/extensions/vector2.dart

Lines 126 to 139 in 295cd72

	void moveToTarget(
	Vector2 target,
	double ds,
	) {
	if (this != target) {
	final diff = target - this;
	if (diff.length < ds) {
	setFrom(target);
	} else {
	diff.scaleTo(ds);
	setFrom(this + diff);
	}
	}
	}

Why should this be improved

At present, if there is a continuous call of the moveToTarget() inside for example update(), it could impact the performance since it has a clone().
Adding a reusable vector can prevent creating a new Vector2 object in every tick.

Any risks?

No

More information

Are you interested in working on a PR for this? Yes