public int XcompareTo(Object obj) {
DepthSegment other = (DepthSegment) obj;
// if segments are collinear and vertical compare endpoints
if (isVertical() && other.isVertical() && upwardSeg.p0.x == other.upwardSeg.p0.x)
return compareX(this.upwardSeg, other.upwardSeg);
// check if segments are trivially ordered along X
if (upwardSeg.maxX() <= other.upwardSeg.minX()) return -1;
if (upwardSeg.minX() >= other.upwardSeg.maxX()) return 1;
/**
* try and compute a determinate orientation for the segments. Test returns 1 if other is left
* of this (i.e. this > other)
*/
int orientIndex = upwardSeg.orientationIndex(other.upwardSeg);
// if orientation is determinate, return it
if (orientIndex != 0) return orientIndex;
/**
* If comparison between this and other is indeterminate, try the opposite call order.
* orientationIndex value is 1 if this is left of other, so have to flip sign to get proper
* comparison value of -1 if this is leftmost
*/
if (orientIndex == 0) orientIndex = -1 * other.upwardSeg.orientationIndex(upwardSeg);
// if orientation is determinate, return it
if (orientIndex != 0) return orientIndex;
// otherwise, segs must be collinear - sort based on minimum X value
return compareX(this.upwardSeg, other.upwardSeg);
}
