IConstructCircularArc.ConstructTangentChordArc() equivallent in Pro?

trushar

Hello Esri Team & Community, 

I need help creating a tangent curve. I only have two length (arc length and chord length) and a tangent bearing. 

I need help with finding an equivalent API in ArcGIS Pro. In ArcObject, we have:

/// <summary>Constructs an arc with a common tangent to the input segment, a given chord length and an arc length.</summary>
[MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
void ConstructTangentChordArc(
  [MarshalAs(UnmanagedType.Interface)] ISegment Segment,
bool atStart,
bool isCCW,
double chordDistance,
double arcDistance);

Would you guys happen to know?

Thank you,
Trushar

trushar

Hello Gintauta,

The link you referred has method that takes radius and arc:

public EllipticArcBuilderEx( 
   Segment tangentSegment,
   bool atStart,
   ArcOrientation orientation,
   double radius,
   double arcLength,
   SpatialReference spatialReference
)

My input parameters are chord and arc.

Here is my solution to this problem but it give invalid results:

private static EllipticArcSegment CircularArcFromArcAndChordWithTangentBearing(
    [NotNull] MetesAndBoundsEllipticCurveDrawDesc.IStandardizedDistance arcLength,
    [NotNull] MetesAndBoundsEllipticCurveDrawDesc.IStandardizedDistance chordLength,
    [NotNull] Segment previousSegment,
ArcOrientation orientation)
{
var arcLengthInMeters = (double)arcLength.Distance * LinearUnitExtensions.GetRatio<Meter>();
var chordLengthInMeters = (double)chordLength.Distance * LinearUnitExtensions.GetRatio<Meter>();

// until Esri provide similar API access to get center angle from
    // IConstructCircularArc.ConstructBearingChordArc().CentralAngle
    // which we can feed in MetesAndBoundsPathGenerator.ChordDirection()
    // to get chord bearing

    // calculate the radius of a circle if you know the length of a chord (c) and
    // the length of the corresponding arc (s) that the chord subtends.
    // To calculate the radius, you can use the following formula:
    // Radius (r) = (c^2) / (8s) + (s/2)
    // Where:
    // Radius (r) is the radius of the circle.
    //     Chord Length (c) is the length of the chord.
    //     Arc Length (s) is the length of the arc that corresponds to the chord
    var radiusInMeters = (chordLengthInMeters * chordLengthInMeters / (8 * arcLengthInMeters)) + (arcLengthInMeters / 2d);

// 2023-11-06 4:44pm trusharm, this is an additional step to the formula
    // above to get approximate radius (pure guess)
    radiusInMeters /= 2d;

using var e = new EllipticArcBuilder(
tangentSegment: previousSegment,
atStart: false,
orientation,
radiusInMeters,
arcLengthInMeters);
return e.ToSegment();
}

Thanks,
Trushar