// The ordering is reversed because push and pop are faster.
int CompareSweepEvent(SweepEvent e1, SweepEvent e2)
{
if (e1.Equals(e2))
{
return(0);
}
if (e1.p.x > e2.p.x) // Different x coordinate
{
return(-1);
}
if (e1.p.x < e2.p.x) // Different x coordinate
{
return(1);
}
if (e1.p != e2.p) // Different points, but same x coordinate. The event with lower y coordinate is processed first
{
return((e1.p.y > e2.p.y) ? -1 : 1);
}
if (e1.isLeft != e2.isLeft) // Same point, but one is a left endpoint and the other a right endpoint. The right endpoint is processed first
{
return((e1.isLeft) ? -1 : 1);
}
// Same point, both events are left endpoints or both are right endpoints. The event associate to the bottom segment is processed first
return(e1.isAbove(e2.otherSE.p) ? -1 : 1);
}
// Should only be called by segmentCompare
private bool CompareSweepEvent(SweepEvent e1, SweepEvent e2)
{
// if (e1.p.x > e2.p.x) // Different x coordinate
// return true;
//
// if (e2.p.x > e1.p.x) // Different x coordinate
// return false;
//
// if (e1.p != e2.p) // Different points, but same x coordinate. The event with lower y coordinate is processed first
// return e1.p.y > e2.p.y;
if (e1.p.x > e2.p.x + Point.PRECISION)
{
return(true);
}
if (e2.p.x > e1.p.x + Point.PRECISION)
{
return(false);
}
if (!Point.PointEquals(e1.p, e2.p))
{
return(e1.p.y > e2.p.y + Point.PRECISION);
}
if (e1.isLeft != e2.isLeft) // Same point, but one is a left endpoint and the other a right endpoint. The right endpoint is processed first
{
return(e1.isLeft);
}
// Same point, both events are left endpoints or both are right endpoints. The event associate to the bottom segment is processed first
return(e1.isAbove(e2.otherSE.p));
}
bool Sec(SweepEvent e1, SweepEvent e2)
{
// Different x coordinate
// if (e1.p.x != e2.p.x) {
if (e1.p.x - e2.p.x > Point.PRECISION || e1.p.x - e2.p.x < -Point.PRECISION)
{
return(e1.p.x > e2.p.x);
}
// Same x coordinate. The event with lower y coordinate is processed first
// if (e1.p.y != e2.p.y) {
if (e1.p.y - e2.p.y > Point.PRECISION || e1.p.y - e2.p.y < -Point.PRECISION)
{
return(e1.p.y > e2.p.y);
}
// Same point, but one is a left endpoint and the other a right endpoint. The right endpoint is processed first
if (e1.isLeft != e2.isLeft)
{
return(e1.isLeft);
}
// Same point, both events are left endpoints or both are right endpoints. The event associate to the bottom segment is processed first
return(e1.isAbove(e2.otherSE.p));
}
private bool SegmentCompare(SweepEvent e1, SweepEvent e2)
{
if (e1.Equals(e2))
{
return(false);
}
if (signedArea(e1.p, e1.otherSE.p, e2.p) != 0 || signedArea(e1.p, e1.otherSE.p, e2.otherSE.p) != 0)
{
// Segments are not collinear
// If they share their left endpoint use the right endpoint to sort
if (Point.PointEquals(e1.p, e2.p))
{
return(e1.isBelow(e2.otherSE.p));
}
if (CompareSweepEvent(e1, e2))
{
return(e2.isAbove(e1.p));
}
return(e1.isBelow(e2.p));
}
if (Point.PointEquals(e1.p, e2.p)) // Segments colinear
{
return(false);
}
return(CompareSweepEvent(e1, e2));
}
