private MinDistanceAtTPair GetClosestTParameter(BezierTParameterRequest _request, MinDistanceAtTPair _compareWith)
{
float mid = (_request.startingT + _request.endT) / 2.0f;
// Base case for recursion.
if ((_request.endT - _request.startingT) < _request.thresholdT)
{
_compareWith.tParameter = mid;
return(_compareWith);
}
// The two halves have param range [start, mid] and [mid, end]. We decide which one to use by using a midpoint param calculation for each section.
float paramA = (_request.startingT + mid) / 2.0f;
float paramB = (mid + _request.endT) / 2.0f;
Vector3 posA = Spline.GetPoint(paramA);
Vector3 posB = Spline.GetPoint(paramB);
float distASq = (posA - _request.pointToCheck).sqrMagnitude;
float distBSq = (posB - _request.pointToCheck).sqrMagnitude;
if (distASq < distBSq)
{
_request.endT = mid;
_compareWith.minSqrDistance = distASq;
}
else
{
_request.startingT = mid;
_compareWith.minSqrDistance = distBSq;
}
// The (tail) recursive call.
return(GetClosestTParameter(_request, _compareWith));
}
public float GetTParameter(Vector3 _pointToCheck)
{
MinDistanceAtTPair result = new MinDistanceAtTPair(float.NaN, float.NaN);
for (int i = 0; i < Spline.ControlPointCount - 1; i += 3)
{
BezierTParameterRequest request = new BezierTParameterRequest(_pointToCheck);
result = GetClosestTParameter(request, result);
}
return(result.tParameter);
}
