Value Seeking

Seek.cs

// example of how to move a current value towards a target value at a constant speed
// without going over the target value
// formula is the same for vectors of any dimension
Vector3 Seek(Vector3 currentValue, Vector3 targetValue, float maxSpeed, float dt)
{
  // delta/difference from current value to target value
  Vector3 delta = targetValue - currentValue;
  
  // don't take the square root of magnitude yet
  // so we can potentially early out on degenerate case of currenvValue ~= targetValue
  float deltaLenSqr = delta.sqrMagnitude;
  
  // just return target value if close enough
  if (deltaLenSqr < Epsilon /* very small value, say 1e-16f */)
    return targetValue;
    
  // now it's time to do the more expensive square root
  // and potentially float division later
  float deltaLen = Mathf.Sqrt(deltaLenSqr);
  
  // cap at target value if current step would overshoot
  float stepLen = maxSpeed * dt;
  if (stepLen >= deltaLen)
    return targetValue;
  
  // step direction
  Vector3 deltaDir = delta / deltaLen;
  
  // step towards target value
  return currentValue + deltaDir * stepLen;
}