private void CalculateFromTwoPolygonsInternal( Polygon home, Polygon boundary, CircleNE homeVertexCircle, Geometry g )
{
// ZZZ - We have to use the boundary, but that can be projected to infinity for some of the spherical tilings.
// Trying to use the Drawn tile produced weird (yet interesting) results.
Polygon poly1 = boundary;
Polygon poly2 = home;
if( poly1.Segments.Count < 3 ||
poly2.Segments.Count < 3 ) // Poor poor digons.
{
Debug.Assert( false );
return;
}
// Same?
Vector3D p1 = poly1.Segments[0].P1, p2 = poly1.Segments[1].P1, p3 = poly1.Segments[2].P1;
Vector3D w1 = poly2.Segments[0].P1, w2 = poly2.Segments[1].P1, w3 = poly2.Segments[2].P1;
if( p1 == w1 && p2 == w2 && p3 == w3 )
{
this.Mobius = Mobius.Identity();
return;
}
Mobius m = new Mobius();
m.MapPoints( p1, p2, p3, w1, w2, w3 );
this.Mobius = m;
// Worry about reflections as well.
if( g == Geometry.Spherical )
{
// If inverted matches the orientation, we need a reflection.
bool inverted = poly1.IsInverted;
if( !(inverted ^ poly1.Orientation) )
this.Reflection = homeVertexCircle;
}
else
{
if( !poly1.Orientation )
this.Reflection = homeVertexCircle;
}
// Some testing.
Vector3D test = this.Apply( boundary.Center );
if( test != home.Center )
{
// ZZZ: What is happening here is that the mobius can project a point to infinity before the reflection brings it back to the origin.
// It hasn't been much of a problem in practice yet, but will probably need fixing at some point.
//Trace.WriteLine( "oh no!" );
}
}
