void Init(Tuple <GeoAnchor, GeoAnchor> anchors)
{
// To compute the distance between two geographical co-ordinates, we first need to
// convert to MapKit co-ordinates
fromAnchorFloorplanPoint = anchors.Item1.Pixel;
fromAnchorMKPoint = MKMapPoint.FromCoordinate(anchors.Item1.LatitudeLongitude);
MKMapPoint toAnchorMKPoint = MKMapPoint.FromCoordinate(anchors.Item2.LatitudeLongitude);
// So that we can use MapKit's helper function to compute distance.
// this helper function takes into account the curvature of the earth.
var distanceBetweenPointsMeters = (nfloat)MKGeometry.MetersBetweenMapPoints(fromAnchorMKPoint, toAnchorMKPoint);
var dx = anchors.Item1.Pixel.X - anchors.Item2.Pixel.X;
var dy = anchors.Item1.Pixel.Y - anchors.Item2.Pixel.Y;
// Distance between two points in pixels (on the floorplan image)
var distanceBetweenPointsPixels = Hypot(dx, dy);
// This gives us pixels/meter
PixelsPerMeter = distanceBetweenPointsPixels / distanceBetweenPointsMeters;
// Get the 2nd anchor's eastward/southward distance in meters from the first anchor point.
var hyp = FetchRect(fromAnchorMKPoint, toAnchorMKPoint);
// Angle of diagonal to east (in geographic)
nfloat angleFromEastAndHypo = NMath.Atan2(hyp.South, hyp.East);
// Angle of diagonal to horizontal (in floorplan)
nfloat angleFromXAndHypo = NMath.Atan2(dy, dx);
// Rotation amount from the geographic anchor line segment
// to the floorplan anchor line segment
// This is angle between X axis and East direction. This angle shows how you floor plan exists in real world
radiansRotated = angleFromXAndHypo - angleFromEastAndHypo;
}
// Compute the rotation matrix from one point to another on a unit sphere.
SCNMatrix4 RotationFromPoint(Vector3 start, Vector3 end)
{
var axis = Vector3.Cross(start, end);
var angle = NMath.Atan2(axis.Length, Vector3.Dot(start, end));
return(SCNMatrix4.CreateFromAxisAngle(axis, (float)angle));
}
