Function seek

Seek (§12): move toward target at maxSpeed.

desiredVelocity = normalize(target − position) · maxSpeed
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From rest, and whenever the velocity error exceeds the budget, the result is exactly maxAcceleration pointed at the target. Standing on the target the desired velocity is zero, so seek brakes rather than producing NaN — which is also why seek alone orbits a target it is fast enough to overshoot; that is what arrive fixes.