////////////////////////////////////////////////////////////////////////////////////////////////////
/// <summary> Creates a circle event. </summary>
/// <remarks>Circle events are created at the circumcenters of three sites - the sites for poly1/2/3.</remarks>
/// <param name="poly1"> The first polygon. </param>
/// <param name="poly2"> The second polygon. </param>
/// <param name="poly3"> The third polygon. </param>
/// <param name="yScanLine"> The y coordinate scan line. </param>
/// <returns> A new circle event. </returns>
////////////////////////////////////////////////////////////////////////////////////////////////////
internal static CircleEvent CreateCircleEvent(FortunePoly poly1, FortunePoly poly2, FortunePoly poly3,
double yScanLine)
{
// Locals
CircleEvent cevtRet = null;
// Determine a circumcenter for the sites of poly1/2/3.
if (Geometry2D.FFindCircumcenter(poly1.VoronoiPoint, poly2.VoronoiPoint, poly3.VoronoiPoint, out var ptCenter))
{
// Determine y coordinate for the side of the circle
// The event will fire when the scan line hits that y position
var radius = Geometry2D.Distance(poly1.VoronoiPoint, ptCenter);
ptCenter.Y -= radius;
// If the circumcenter is above the scan line we've already passed it by, so don't put it in the queue
if (ptCenter.Y <= yScanLine)
{
cevtRet = new CircleEvent(ptCenter, radius);
}
}
return(cevtRet);
}
