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; }