public Point2DInt[] intersect(LineSegmentInt seg) {
if (seg.side(this) != 0) {
return new Point2DInt[0];
}
// Log.println("THIS=" + this);
// Log.println("LineSegment=" + seg);
final Point2DInt corners[] = getCorners();
final LineSegmentInt seg1 = new LineSegmentInt(corners[0], corners[1]);
final LineSegmentInt seg2 = new LineSegmentInt(corners[1], corners[2]);
final LineSegmentInt seg3 = new LineSegmentInt(corners[2], corners[3]);
final LineSegmentInt seg4 = new LineSegmentInt(corners[3], corners[0]);
final Point2DInt i1 = seg.getSegIntersection(seg1);
Point2DInt i2 = seg.getSegIntersection(seg2);
Point2DInt i3 = seg.getSegIntersection(seg3);
Point2DInt i4 = seg.getSegIntersection(seg4);
// Log.println("i1="+i1);
// Log.println("i2="+i2);
// Log.println("i3="+i3);
// Log.println("i4="+i4);
if (i2 != null && i2.equals(i1)) {
i2 = null;
}
if (i3 != null && (i3.equals(i1) || i3.equals(i2))) {
i3 = null;
}
if (i4 != null && (i4.equals(i1) || i4.equals(i2) || i4.equals(i3))) {
i4 = null;
}
final int nb = countNotNull(i1, i2, i3, i4);
assert nb >= 0 && nb <= 3 : nb;
int i = 0;
final Point2DInt result[] = new Point2DInt[nb];
if (i1 != null) {
result[i++] = i1;
}
if (i2 != null) {
result[i++] = i2;
}
if (i3 != null) {
result[i++] = i3;
}
if (i4 != null) {
result[i++] = i4;
}
assert i == nb;
assert getCornersOfOneSide(seg, 0).length
+ getCornersOfOneSide(seg, 1).length
+ getCornersOfOneSide(seg, -1).length
== 4;
return result;
}
public Point2DInt[] getCornersOfOneSide(LineSegmentInt seg, int sgn) {
final Point2DInt[] corners = getCorners();
final double sgn0 = seg.side(corners[0]);
final double sgn1 = seg.side(corners[1]);
final double sgn2 = seg.side(corners[2]);
final double sgn3 = seg.side(corners[3]);
int nb = 0;
if (Math.signum(sgn0) == sgn) {
nb++;
}
if (Math.signum(sgn1) == sgn) {
nb++;
}
if (Math.signum(sgn2) == sgn) {
nb++;
}
if (Math.signum(sgn3) == sgn) {
nb++;
}
final Point2DInt[] result = new Point2DInt[nb];
int i = 0;
if (Math.signum(sgn0) == sgn) {
result[i++] = corners[0];
}
if (Math.signum(sgn1) == sgn) {
result[i++] = corners[1];
}
if (Math.signum(sgn2) == sgn) {
result[i++] = corners[2];
}
if (Math.signum(sgn3) == sgn) {
result[i++] = corners[3];
}
assert nb == i;
return result;
}
