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);
}
public static void computeDistance(LineString line, Coordinate pt, PointPairDistance ptDist) {
LineSegment tempSegment = new LineSegment();
Coordinate[] coords = line.getCoordinates();
for (int i = 0; i < coords.length - 1; i++) {
tempSegment.setCoordinates(coords[i], coords[i + 1]);
// this is somewhat inefficient - could do better
Coordinate closestPt = tempSegment.closestPoint(pt);
ptDist.setMinimum(closestPt, pt);
}
}
private DepthSegment createRandomDepthSegment() {
double scale = 10;
int max = 10;
double x0 = randint(max);
double y0 = randint(max);
double ang = 2 * Math.PI * Math.random();
double x1 = Math.rint(x0 + max * Math.cos(ang));
double y1 = Math.rint(y0 + max * Math.sin(ang));
LineSegment seg = new LineSegment(x0, y0, x1, y1);
seg.normalize();
return new DepthSegment(seg, 0);
}
/**
* Defines a comparison operation on DepthSegments which orders them left to right
*
* <pre>
* DS1 < DS2 if DS1.seg is left of DS2.seg
* DS1 > DS2 if DS1.seg is right of DS2.seg
* </pre>
*
* @param obj
* @return the comparison value
*/
public int compareTo(Object obj) {
DepthSegment other = (DepthSegment) obj;
if (!envelopesOverlap(upwardSeg, other.upwardSeg))
return upwardSeg.compareTo(other.upwardSeg);
// check orientations
int orientIndex = upwardSeg.orientationIndex(other.upwardSeg);
if (orientIndex != 0) return orientIndex;
orientIndex = -other.upwardSeg.orientationIndex(upwardSeg);
if (orientIndex != 0) return orientIndex;
// segments cross or are collinear. Use segment ordering
return upwardSeg.compareTo(other.upwardSeg);
}
/**
* Compute the width information for a ring of {@link Coordinate}s. Leaves the width information
* in the instance variables.
*
* @param pts
*/
private void computeConvexRingMinDiameter(Coordinate[] pts) {
// for each segment in the ring
minWidth = Double.MAX_VALUE;
int currMaxIndex = 1;
LineSegment seg = new LineSegment();
// compute the max distance for all segments in the ring, and pick the minimum
for (int i = 0; i < pts.length - 1; i++) {
seg.p0 = pts[i];
seg.p1 = pts[i + 1];
currMaxIndex = findMaxPerpDistance(pts, seg, currMaxIndex);
}
}
public boolean envelopesOverlap(LineSegment seg1, LineSegment seg2) {
if (seg1.maxX() <= seg2.minX()) return false;
if (seg2.maxX() <= seg1.minX()) return false;
if (seg1.maxY() <= seg2.minY()) return false;
if (seg2.maxY() <= seg1.minY()) return false;
return true;
}
/**
* Gets a {@link LineString} which is a minimum diameter
*
* @return a {@link LineString} which is a minimum diameter
*/
public LineString getDiameter() {
computeMinimumDiameter();
// return empty linestring if no minimum width calculated
if (minWidthPt == null) return inputGeom.getFactory().createLineString((Coordinate[]) null);
Coordinate basePt = minBaseSeg.project(minWidthPt);
return inputGeom.getFactory().createLineString(new Coordinate[] {basePt, minWidthPt});
}
private int findMaxPerpDistance(Coordinate[] pts, LineSegment seg, int startIndex) {
double maxPerpDistance = seg.distancePerpendicular(pts[startIndex]);
double nextPerpDistance = maxPerpDistance;
int maxIndex = startIndex;
int nextIndex = maxIndex;
while (nextPerpDistance >= maxPerpDistance) {
maxPerpDistance = nextPerpDistance;
maxIndex = nextIndex;
nextIndex = nextIndex(pts, maxIndex);
nextPerpDistance = seg.distancePerpendicular(pts[nextIndex]);
}
// found maximum width for this segment - update global min dist if appropriate
if (maxPerpDistance < minWidth) {
minPtIndex = maxIndex;
minWidth = maxPerpDistance;
minWidthPt = pts[minPtIndex];
minBaseSeg = new LineSegment(seg);
// System.out.println(minBaseSeg);
// System.out.println(minWidth);
}
return maxIndex;
}
private void computeWidthConvex(Geometry convexGeom) {
// System.out.println("Input = " + geom);
if (convexGeom instanceof Polygon)
convexHullPts = ((Polygon) convexGeom).getExteriorRing().getCoordinates();
else convexHullPts = convexGeom.getCoordinates();
// special cases for lines or points or degenerate rings
if (convexHullPts.length == 0) {
minWidth = 0.0;
minWidthPt = null;
minBaseSeg = null;
} else if (convexHullPts.length == 1) {
minWidth = 0.0;
minWidthPt = convexHullPts[0];
minBaseSeg.p0 = convexHullPts[0];
minBaseSeg.p1 = convexHullPts[0];
} else if (convexHullPts.length == 2 || convexHullPts.length == 3) {
minWidth = 0.0;
minWidthPt = convexHullPts[0];
minBaseSeg.p0 = convexHullPts[0];
minBaseSeg.p1 = convexHullPts[1];
} else computeConvexRingMinDiameter(convexHullPts);
}
/**
* Gets the minimum rectangular {@link Polygon} which encloses the input geometry. The rectangle
* has width equal to the minimum diameter, and a longer length. If the convex hull of the input
* is degenerate (a line or point) a {@link LineString} or {@link Point} is returned.
*
* <p>The minimum rectangle can be used as an extremely generalized representation for the given
* geometry.
*
* @return the minimum rectangle enclosing the input (or a line or point if degenerate)
*/
public Geometry getMinimumRectangle() {
computeMinimumDiameter();
// check if minimum rectangle is degenerate (a point or line segment)
if (minWidth == 0.0) {
if (minBaseSeg.p0.equals2D(minBaseSeg.p1)) {
return inputGeom.getFactory().createPoint(minBaseSeg.p0);
}
return minBaseSeg.toGeometry(inputGeom.getFactory());
}
// deltas for the base segment of the minimum diameter
double dx = minBaseSeg.p1.x - minBaseSeg.p0.x;
double dy = minBaseSeg.p1.y - minBaseSeg.p0.y;
/*
double c0 = computeC(dx, dy, minBaseSeg.p0);
double c1 = computeC(dx, dy, minBaseSeg.p1);
*/
double minPara = Double.MAX_VALUE;
double maxPara = -Double.MAX_VALUE;
double minPerp = Double.MAX_VALUE;
double maxPerp = -Double.MAX_VALUE;
// compute maxima and minima of lines parallel and perpendicular to base segment
for (int i = 0; i < convexHullPts.length; i++) {
double paraC = computeC(dx, dy, convexHullPts[i]);
if (paraC > maxPara) maxPara = paraC;
if (paraC < minPara) minPara = paraC;
double perpC = computeC(-dy, dx, convexHullPts[i]);
if (perpC > maxPerp) maxPerp = perpC;
if (perpC < minPerp) minPerp = perpC;
}
// compute lines along edges of minimum rectangle
LineSegment maxPerpLine = computeSegmentForLine(-dx, -dy, maxPerp);
LineSegment minPerpLine = computeSegmentForLine(-dx, -dy, minPerp);
LineSegment maxParaLine = computeSegmentForLine(-dy, dx, maxPara);
LineSegment minParaLine = computeSegmentForLine(-dy, dx, minPara);
// compute vertices of rectangle (where the para/perp max & min lines intersect)
Coordinate p0 = maxParaLine.lineIntersection(maxPerpLine);
Coordinate p1 = minParaLine.lineIntersection(maxPerpLine);
Coordinate p2 = minParaLine.lineIntersection(minPerpLine);
Coordinate p3 = maxParaLine.lineIntersection(minPerpLine);
LinearRing shell =
inputGeom.getFactory().createLinearRing(new Coordinate[] {p0, p1, p2, p3, p0});
return inputGeom.getFactory().createPolygon(shell, null);
}
public String toString() {
return upwardSeg.toString();
}
public static void computeDistance(LineSegment segment, Coordinate pt, PointPairDistance ptDist) {
Coordinate closestPt = segment.closestPoint(pt);
ptDist.setMinimum(closestPt, pt);
}
