/**
* Returns <code>true</code> if <code>other</code> has the same values for its points.
*
* @param o a <code>LineSegment</code> with which to do the comparison.
* @return <code>true</code> if <code>other</code> is a <code>LineSegment</code> with the same
* values for the x and y ordinates.
*/
public boolean equals(Object o) {
if (!(o instanceof LineSegment)) {
return false;
}
LineSegment other = (LineSegment) o;
return p0.equals(other.p0) && p1.equals(other.p1);
}
/**
* Compute the projection of a point onto the line determined by this line segment.
*
* <p>Note that the projected point may lie outside the line segment. If this is the case, the
* projection factor will lie outside the range [0.0, 1.0].
*/
public Coordinate project(Coordinate p) {
if (p.equals(p0) || p.equals(p1)) return new Coordinate(p);
double r = projectionFactor(p);
Coordinate coord = new Coordinate();
coord.x = p0.x + r * (p1.x - p0.x);
coord.y = p0.y + r * (p1.y - p0.y);
return coord;
}
/**
* Computes the closest point on this line segment to another point.
*
* @param p the point to find the closest point to
* @return a Coordinate which is the closest point on the line segment to the point p
*/
public Coordinate closestPoint(Coordinate p) {
double factor = projectionFactor(p);
if (factor > 0 && factor < 1) {
return project(p);
}
double dist0 = p0.distance(p);
double dist1 = p1.distance(p);
if (dist0 < dist1) return p0;
return p1;
}
public void findEdge(List dirEdgeList) {
/**
* Check all forward DirectedEdges only. This is still general, because each edge has a forward
* DirectedEdge.
*/
for (Iterator i = dirEdgeList.iterator(); i.hasNext(); ) {
DirectedEdge de = (DirectedEdge) i.next();
if (!de.isForward()) continue;
checkForRightmostCoordinate(de);
}
/**
* If the rightmost point is a node, we need to identify which of the incident edges is
* rightmost.
*/
Assert.isTrue(
minIndex != 0 || minCoord.equals(minDe.getCoordinate()),
"inconsistency in rightmost processing");
if (minIndex == 0) {
findRightmostEdgeAtNode();
} else {
findRightmostEdgeAtVertex();
}
/** now check that the extreme side is the R side. If not, use the sym instead. */
orientedDe = minDe;
int rightmostSide = getRightmostSide(minDe, minIndex);
if (rightmostSide == Position.LEFT) {
orientedDe = minDe.getSym();
}
}
/**
* Computes the closest points on two line segments.
*
* @param line the segment to find the closest point to
* @return a pair of Coordinates which are the closest points on the line segments
*/
public Coordinate[] closestPoints(LineSegment line) {
// test for intersection
Coordinate intPt = intersection(line);
if (intPt != null) {
return new Coordinate[] {intPt, intPt};
}
/**
* if no intersection closest pair contains at least one endpoint. Test each endpoint in turn.
*/
Coordinate[] closestPt = new Coordinate[2];
double minDistance = Double.MAX_VALUE;
double dist;
Coordinate close00 = closestPoint(line.p0);
minDistance = close00.distance(line.p0);
closestPt[0] = close00;
closestPt[1] = line.p0;
Coordinate close01 = closestPoint(line.p1);
dist = close01.distance(line.p1);
if (dist < minDistance) {
minDistance = dist;
closestPt[0] = close01;
closestPt[1] = line.p1;
}
Coordinate close10 = line.closestPoint(p0);
dist = close10.distance(p0);
if (dist < minDistance) {
minDistance = dist;
closestPt[0] = p0;
closestPt[1] = close10;
}
Coordinate close11 = line.closestPoint(p1);
dist = close11.distance(p1);
if (dist < minDistance) {
minDistance = dist;
closestPt[0] = p1;
closestPt[1] = close11;
}
return closestPt;
}
/**
* Computes the Projection Factor for the projection of the point p onto this LineSegment. The
* Projection Factor is the constant r by which the vector for this segment must be multiplied to
* equal the vector for the projection of <tt>p<//t> on the line defined by this segment.
*
* <p>The projection factor will lie in the range <tt>(-inf, +inf)</tt>, or be <code>NaN</code> if
* the line segment has zero length..
*
* @param p the point to compute the factor for
* @return the projection factor for the point
*/
public double projectionFactor(Coordinate p) {
if (p.equals(p0)) return 0.0;
if (p.equals(p1)) return 1.0;
// Otherwise, use comp.graphics.algorithms Frequently Asked Questions method
/* AC dot AB
r = ---------
||AB||^2
r has the following meaning:
r=0 P = A
r=1 P = B
r<0 P is on the backward extension of AB
r>1 P is on the forward extension of AB
0<r<1 P is interior to AB
*/
double dx = p1.x - p0.x;
double dy = p1.y - p0.y;
double len = dx * dx + dy * dy;
// handle zero-length segments
if (len <= 0.0) return Double.NaN;
double r = ((p.x - p0.x) * dx + (p.y - p0.y) * dy) / len;
return r;
}
/**
* Returns <code>true</code> if <code>other</code> is topologically equal to this LineSegment
* (e.g. irrespective of orientation).
*
* @param other a <code>LineSegment</code> with which to do the comparison.
* @return <code>true</code> if <code>other</code> is a <code>LineSegment</code> with the same
* values for the x and y ordinates.
*/
public boolean equalsTopo(LineSegment other) {
return p0.equals(other.p0) && p1.equals(other.p1) || p0.equals(other.p1) && p1.equals(other.p0);
}
/**
* Compares this object with the specified object for order. Uses the standard lexicographic
* ordering for the points in the LineSegment.
*
* @param o the <code>LineSegment</code> with which this <code>LineSegment</code> is being
* compared
* @return a negative integer, zero, or a positive integer as this <code>LineSegment</code> is
* less than, equal to, or greater than the specified <code>LineSegment</code>
*/
public int compareTo(Object o) {
LineSegment other = (LineSegment) o;
int comp0 = p0.compareTo(other.p0);
if (comp0 != 0) return comp0;
return p1.compareTo(other.p1);
}
/**
* Computes the {@link Coordinate} that lies a given fraction along the line defined by this
* segment. A fraction of <code>0.0</code> returns the start point of the segment; a fraction of
* <code>1.0</code> returns the end point of the segment. If the fraction is < 0.0 or > 1.0 the
* point returned will lie before the start or beyond the end of the segment.
*
* @param segmentLengthFraction the fraction of the segment length along the line
* @return the point at that distance
*/
public Coordinate pointAlong(double segmentLengthFraction) {
Coordinate coord = new Coordinate();
coord.x = p0.x + segmentLengthFraction * (p1.x - p0.x);
coord.y = p0.y + segmentLengthFraction * (p1.y - p0.y);
return coord;
}
/**
* Puts the line segment into a normalized form. This is useful for using line segments in maps
* and indexes when topological equality rather than exact equality is desired. A segment in
* normalized form has the first point smaller than the second (according to the standard ordering
* on {@link Coordinate}).
*/
public void normalize() {
if (p1.compareTo(p0) < 0) reverse();
}
/**
* Computes the length of the line segment.
*
* @return the length of the line segment
*/
public double getLength() {
return p0.distance(p1);
}
/**
* Tests whether a given point is in an array of points. Uses a value-based test.
*
* @param pt a {@link Coordinate} for the test point
* @param pts an array of {@link Coordinate}s to test
* @return <code>true</code> if the point is in the array
* @deprecated
*/
public static boolean isInList(Coordinate pt, Coordinate[] pts) {
for (int i = 0; i < pts.length; i++) {
if (pt.equals(pts[i])) return true;
}
return false;
}
