protected override Vector3 CalculateForce()
{
if (_quarry == null)
{
this.enabled = false;
return(Vector3.zero);
}
var force = Vector3.zero;
var offset = _quarry.Position - Vehicle.Position;
var distance = offset.magnitude;
var radius = Vehicle.ScaledRadius + _quarry.ScaledRadius + _acceptableDistance;
if (distance > radius)
{
Vector3 unitOffset = offset / distance;
// how parallel are the paths of "this" and the quarry
// (1 means parallel, 0 is pependicular, -1 is anti-parallel)
float parallelness = Vector3.Dot(transform.forward, _quarry.transform.forward);
// how "forward" is the direction to the quarry
// (1 means dead ahead, 0 is directly to the side, -1 is straight back)
float forwardness = Vector3.Dot(transform.forward, unitOffset);
float directTravelTime = distance / Vehicle.Speed;
int f = OpenSteerUtility.intervalComparison(forwardness, -0.707f, 0.707f);
int p = OpenSteerUtility.intervalComparison(parallelness, -0.707f, 0.707f);
float timeFactor = 0; // to be filled in below
// Break the pursuit into nine cases, the cross product of the
// quarry being [ahead, aside, or behind] us and heading
// [parallel, perpendicular, or anti-parallel] to us.
switch (f)
{
case +1:
switch (p)
{
case +1: // ahead, parallel
timeFactor = 4;
break;
case 0: // ahead, perpendicular
timeFactor = 1.8f;
break;
case -1: // ahead, anti-parallel
timeFactor = 0.85f;
break;
}
break;
case 0:
switch (p)
{
case +1: // aside, parallel
timeFactor = 1;
break;
case 0: // aside, perpendicular
timeFactor = 0.8f;
break;
case -1: // aside, anti-parallel
timeFactor = 4;
break;
}
break;
case -1:
switch (p)
{
case +1: // behind, parallel
timeFactor = 0.5f;
break;
case 0: // behind, perpendicular
timeFactor = 2;
break;
case -1: // behind, anti-parallel
timeFactor = 2;
break;
}
break;
}
// estimated time until intercept of quarry
float et = directTravelTime * timeFactor;
float etl = (et > _maxPredictionTime) ? _maxPredictionTime : et;
// estimated position of quarry at intercept
Vector3 target = _quarry.PredictFuturePosition(etl);
force = Vehicle.GetSeekVector(target, _slowDownOnApproach);
#if ANNOTATE_PURSUIT
Debug.DrawRay(Vehicle.Position, force, Color.blue);
Debug.DrawLine(Quarry.Position, target, Color.cyan);
Debug.DrawRay(target, Vector3.up * 4, Color.cyan);
#endif
}
return(force);
}
