Java LineSegment类代码示例

import com.vividsolutions.jts.geom.LineSegment; //导入依赖的package包/类
private static LinearRing ringFromSegments(List<LineSegment> segments) {
    GeometryFactory factory = new GeometryFactory();
    int nSegs = segments.size();
    if (nSegs < 3) {
        return null;
    }
    int len = segments.size() + 1;
    CoordinateSequence seq = factory.getCoordinateSequenceFactory().create(
            len, 2);
    int i = 0;
    for (LineSegment line : segments) {
        seq.setOrdinate(i, 0, line.p0.x);
        seq.setOrdinate(i, 1, line.p0.y);
        i++;
    }
    seq.setOrdinate(i, 0, segments.get(0).p0.x);
    seq.setOrdinate(i, 1, segments.get(0).p0.y);
    return factory.createLinearRing(seq);
}
 

import com.vividsolutions.jts.geom.LineSegment; //导入依赖的package包/类
private void computeMinDistance(LineString line, Point pt,
                                GeometryLocation[] locGeom) {
    if (line.getEnvelopeInternal().distance(pt.getEnvelopeInternal())
            > this.minDistance) {
        return;
    }
    Coordinate[] coord0 = line.getCoordinates();
    Coordinate coord = pt.getCoordinate();
    // brute force approach!
    for (int i = 0; i < coord0.length - 1; i++) {
        double dist = CGAlgorithms.distancePointLine(
                coord, coord0[i], coord0[i + 1]);
        if (dist < this.minDistance) {
            this.minDistance = dist;
            LineSegment seg = new LineSegment(coord0[i], coord0[i + 1]);
            Coordinate segClosestPoint = seg.closestPoint(coord);
            locGeom[0] = new GeometryLocation(line, i, segClosestPoint);
            locGeom[1] = new GeometryLocation(pt, 0, coord);
        }
        if (this.minDistance <= this.terminateDistance) {
            return;
        }
    }
}
 

import com.vividsolutions.jts.geom.LineSegment; //导入依赖的package包/类
private void computeMinDistanceLinePoint(LineString line, Point point,
                                         boolean flip) {
    Coordinate[] lineCoord = line.getCoordinates();
    Coordinate coord = point.getCoordinate();
    // brute force approach!
    for (int i = 0; i < lineCoord.length - 1; i++) {
        double dist = CGAlgorithms3D.distancePointSegment(coord, lineCoord[i],
                lineCoord[i + 1]);
        if (dist < this.minDistance) {
            LineSegment seg = new LineSegment(lineCoord[i], lineCoord[i + 1]);
            Coordinate segClosestPoint = seg.closestPoint(coord);
            this.updateDistance(dist,
                    new GeometryLocation(line, i, segClosestPoint),
                    new GeometryLocation(point, 0, coord),
                    flip);
        }
        if (this.isDone) {
            return;
        }
    }
}
 

import com.vividsolutions.jts.geom.LineSegment; //导入依赖的package包/类
private int findFurthestPoint(Coordinate[] pts, int i, int j, double[] maxDistance) {
    LineSegment seg = new LineSegment();
    seg.p0 = pts[i];
    seg.p1 = pts[j];
    double maxDist = -1.0;
    int maxIndex = i;
    for (int k = i + 1; k < j; k++) {
        Coordinate midPt = pts[k];
        double distance = seg.distance(midPt);
        if (distance > maxDist) {
            maxDist = distance;
            maxIndex = k;
        }
    }
    maxDistance[0] = maxDist;
    return maxIndex;
}
 

import com.vividsolutions.jts.geom.LineSegment; //导入依赖的package包/类
/**
 * Densifies a coordinate sequence.
 *
 * @param pts
 * @param distanceTolerance
 * @return the densified coordinate sequence
 */
private static Coordinate[] densifyPoints(Coordinate[] pts,
                                          double distanceTolerance, PrecisionModel precModel) {
    LineSegment seg = new LineSegment();
    CoordinateList coordList = new CoordinateList();
    for (int i = 0; i < pts.length - 1; i++) {
        seg.p0 = pts[i];
        seg.p1 = pts[i + 1];
        coordList.add(seg.p0, false);
        double len = seg.getLength();
        int densifiedSegCount = (int) (len / distanceTolerance) + 1;
        if (densifiedSegCount > 1) {
            double densifiedSegLen = len / densifiedSegCount;
            for (int j = 1; j < densifiedSegCount; j++) {
                double segFract = (j * densifiedSegLen) / len;
                Coordinate p = seg.pointAlong(segFract);
                precModel.makePrecise(p);
                coordList.add(p, false);
            }
        }
    }
    coordList.add(pts[pts.length - 1], false);
    return coordList.toCoordinateArray();
}
 

import com.vividsolutions.jts.geom.LineSegment; //导入依赖的package包/类
/**
 * A basic strategy for finding split points when nothing extra is known about the geometry of
 * the situation.
 *
 * @param seg the encroached segment
 * @param encroachPt the encroaching point
 * @return the point at which to split the encroached segment
 */
@Override
public Coordinate findSplitPoint(Segment seg, Coordinate encroachPt) {
    LineSegment lineSeg = seg.getLineSegment();
    double segLen = lineSeg.getLength();
    double midPtLen = segLen / 2;
    SplitSegment splitSeg = new SplitSegment(lineSeg);

    Coordinate projPt = projectedSplitPoint(seg, encroachPt);
    /**
     * Compute the largest diameter (length) that will produce a split segment which is not
     * still encroached upon by the encroaching point (The length is reduced slightly by a
     * safety factor)
     */
    double nonEncroachDiam = projPt.distance(encroachPt) * 2 * 0.8; // .99;
    double maxSplitLen = nonEncroachDiam;
    if (maxSplitLen > midPtLen) {
        maxSplitLen = midPtLen;
    }
    splitSeg.setMinimumLength(maxSplitLen);

    splitSeg.splitAt(projPt);

    return splitSeg.getSplitPoint();
}
 

import com.vividsolutions.jts.geom.LineSegment; //导入依赖的package包/类
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 < this.minWidth) {
            this.minPtIndex = maxIndex;
            this.minWidth = maxPerpDistance;
            this.minWidthPt = pts[this.minPtIndex];
            this.minBaseSeg = new LineSegment(seg);
//      System.out.println(minBaseSeg);
//      System.out.println(minWidth);
        }
        return maxIndex;
    }
 

import com.vividsolutions.jts.geom.LineSegment; //导入依赖的package包/类
private static LineSegment computeSegmentForLine(double a, double b, double c) {
    Coordinate p0;
    Coordinate p1;
/*
* Line eqn is ax + by = c
* Slope is a/b.
* If slope is steep, use y values as the inputs
*/
    if (Math.abs(b) > Math.abs(a)) {
        p0 = new Coordinate(0.0, c / b);
        p1 = new Coordinate(1.0, c / b - a / b);
    } else {
        p0 = new Coordinate(c / a, 0.0);
        p1 = new Coordinate(c / a - b / a, 1.0);
    }
    return new LineSegment(p0, p1);
}
 

import com.vividsolutions.jts.geom.LineSegment; //导入依赖的package包/类
private double indexOfFromStart(Coordinate inputPt, double minIndex) {
    double minDistance = Double.MAX_VALUE;

    double ptMeasure = minIndex;
    double segmentStartMeasure = 0.0;
    LineSegment seg = new LineSegment();
    LinearIterator it = new LinearIterator(this.linearGeom);
    while (it.hasNext()) {
        if (!it.isEndOfLine()) {
            seg.p0 = it.getSegmentStart();
            seg.p1 = it.getSegmentEnd();
            double segDistance = seg.distance(inputPt);
            double segMeasureToPt = this.segmentNearestMeasure(seg, inputPt, segmentStartMeasure);
            if (segDistance < minDistance
                    && segMeasureToPt > minIndex) {
                ptMeasure = segMeasureToPt;
                minDistance = segDistance;
            }
            segmentStartMeasure += seg.getLength();
        }
        it.next();
    }
    return ptMeasure;
}
 

import com.vividsolutions.jts.geom.LineSegment; //导入依赖的package包/类
/**
 * Checks if the point is located on the given {@link LineSegment} (including endpoints).
 */
public static boolean isPointOnLineSegment(Coordinate point, LineSegment line) {
    double lengthOfLine = line.getLength();
    double distFromEnd1 = point.distance(line.p0);
    double distFromEnd2 = point.distance(line.p1);

    // this seems to handle robustness errors (due to rounding) better
    if (distFromEnd1 + distFromEnd2 == lengthOfLine) {
        return true;
    }

    // Fallback to what should probably be the robust implementation (TODO: investigate precision issues)
    LineIntersector lineIntersector = new RobustLineIntersector();
    lineIntersector.computeIntersection(point, line.p0, line.p1);
    return lineIntersector.hasIntersection();
}
 

import com.vividsolutions.jts.geom.LineSegment; //导入依赖的package包/类
public EdgePair(LineSegment edgeA, LineSegment edgeB) {
    // determine the point where the edges would intersect if they were infinite lines
    IntersectionCoordinate intersectionPoint = GeometryUtils.getIntersectionPoint(edgeA, edgeB);

    this.edgeA = edgeA;
    this.edgeB = edgeB;

    // there will be 2 projected points at most
    projected0 = getProjectedVertex(edgeA.p1, edgeB, intersectionPoint);
    if (projected0.isNotValid()) {
        projected0 = getProjectedVertex(edgeB.p0, edgeA, intersectionPoint);
    }
    projected1 = getProjectedVertex(edgeB.p1, edgeA, intersectionPoint);
    if (projected1.isNotValid()) {
        projected1 = getProjectedVertex(edgeA.p0, edgeB, intersectionPoint);
    }
}
 

import com.vividsolutions.jts.geom.LineSegment; //导入依赖的package包/类
private EdgePairSubpolygons(LineSegment edgeA, LineSegment edgeB, ProjectedVertex projected0, ProjectedVertex projected1) {
    this.edgeA = Objects.requireNonNull(edgeA, "Edge A is required");
    this.edgeB = Objects.requireNonNull(edgeB, "Edge B is required");

    // build triangles if corresponding projected points are valid
    triangle1 = projected0.isValid() ? GeometryFactoryUtils.createTriangle(edgeA.p1, projected0, edgeB.p0) : null;
    triangle2 = projected1.isValid() ? GeometryFactoryUtils.createTriangle(edgeA.p0, projected1, edgeB.p1) : null;
    triangle1Area = triangle1 != null ? triangle1.getArea() : 0;
    triangle2Area = triangle2 != null ? triangle2.getArea() : 0;

    // build a trapezoid:
    // 1) if projected1 is on edgeA, add projected1, else add edgeA.p0
    // 2) if projected0 is on edgeA, add projected0, else add edgeA.p1
    // 3) if projected0 is on edgeB, add projected0, else add edgeB.p0
    // 4) if projected1 is on edgeB, add projected1, else add edgeB.p1
    // 5) close the polygon
    Coordinate coord1 = projected1.isOnEdge(edgeA) ? projected1 : edgeA.p0;
    Coordinate coord2 = projected0.isOnEdge(edgeA) ? projected0 : edgeA.p1;
    Coordinate coord3 = projected0.isOnEdge(edgeB) ? projected0 : edgeB.p0;
    Coordinate coord4 = projected1.isOnEdge(edgeB) ? projected1 : edgeB.p1;
    trapezoid = GeometryFactoryUtils.createPolygon(coord1, coord2, coord3, coord4);
    trapezoidArea = trapezoid.getArea();
}
 

import com.vividsolutions.jts.geom.LineSegment; //导入依赖的package包/类
@Test
public void projectionForEdgesFormingATrapezoid() throws Exception {
    LineSegment edgeA = new LineSegment(new Coordinate(0, 0), new Coordinate(10, 0));       // horizontal edge at y = 0, when x = [0; 10]
    LineSegment edgeB = new LineSegment(new Coordinate(5, 1), new Coordinate(15, 1));       // horizontal edge at y = 1, when x = [5; 15]

    Coordinate projectedPoint = GeometryUtils.getProjectedPoint(edgeB.p0, edgeA, null);     // project point (5; 1) onto y = 0
    assertEquals(5, projectedPoint.x, EXACT_PRECISION);
    assertEquals(0, projectedPoint.y, EXACT_PRECISION);
    projectedPoint = GeometryUtils.getProjectedPoint(edgeB.p1, edgeA, null);                // project point (15; 1) onto y = 0
    assertNull(projectedPoint);

    projectedPoint = GeometryUtils.getProjectedPoint(edgeA.p0, edgeB, null);                // project point (0; 0) onto y = 1
    assertNull(projectedPoint);
    projectedPoint = GeometryUtils.getProjectedPoint(edgeA.p1, edgeB, null);                // project point (10; 0) onto y = 1
    assertEquals(10, projectedPoint.x, EXACT_PRECISION);
    assertEquals(1, projectedPoint.y, EXACT_PRECISION);
}
 

import com.vividsolutions.jts.geom.LineSegment; //导入依赖的package包/类
@Test
public void projectionForPerpendicularEdges() throws Exception {
    LineSegment edgeA = new LineSegment(new Coordinate(0, 1), new Coordinate(0, 10));       // vertical   edge at x = 0, when y = [1; 10]
    LineSegment edgeB = new LineSegment(new Coordinate(2, 0), new Coordinate(7, 0));        // horizontal edge at y = 0, when x = [2; 7]

    IntersectionCoordinate intersection = new IntersectionCoordinate(0, 0, edgeA, edgeB);

    Coordinate projectedPoint = GeometryUtils.getProjectedPoint(edgeB.p0, edgeA, intersection);     // project point (2; 0) onto y axis
    assertEquals(0, projectedPoint.x, EXACT_PRECISION);
    assertEquals(2, projectedPoint.y, EXACT_PRECISION);
    projectedPoint = GeometryUtils.getProjectedPoint(edgeB.p1, edgeA, intersection);                // project point (7; 0) onto y axis
    assertEquals(0, projectedPoint.x, EXACT_PRECISION);
    assertEquals(7, projectedPoint.y, EXACT_PRECISION);

    projectedPoint = GeometryUtils.getProjectedPoint(edgeA.p0, edgeB, intersection);                // project point (0; 1) onto x axis
    assertNull(projectedPoint);
    projectedPoint = GeometryUtils.getProjectedPoint(edgeA.p1, edgeB, intersection);                // project point (0; 10) onto x axis
    assertNull(projectedPoint);
}
 

import com.vividsolutions.jts.geom.LineSegment; //导入依赖的package包/类
@Test
public void projectionForIntersectingEdges() throws Exception {
    LineSegment edgeA = new LineSegment(new Coordinate(0, 0), new Coordinate(0, 40));       // vertical edge at x = 0, when y = [0; 40]
    LineSegment edgeB = new LineSegment(new Coordinate(30, 10), new Coordinate(10, 20));    // sloping edge that would intersect edgeA if extended

    IntersectionCoordinate intersection = new IntersectionCoordinate(0, 25, edgeA, edgeB);

    Coordinate projectedPoint = GeometryUtils.getProjectedPoint(edgeB.p0, edgeA, intersection);     // project point (30; 10) onto vertical edge
    assertNull(projectedPoint);

    projectedPoint = GeometryUtils.getProjectedPoint(edgeB.p1, edgeA, intersection);                // project point (10; 20) onto vertical edge
    assertEquals(0, projectedPoint.x, EXACT_PRECISION);
    assertEquals(13.819660112501051, projectedPoint.y, EXACT_PRECISION);

    projectedPoint = GeometryUtils.getProjectedPoint(edgeA.p0, edgeB, intersection);                // project point (0; 0) onto sloping edge
    assertEquals(22.360679774997898, projectedPoint.x, EXACT_PRECISION);
    assertEquals(13.819660112501051, projectedPoint.y, EXACT_PRECISION);

    projectedPoint = GeometryUtils.getProjectedPoint(edgeA.p1, edgeB, intersection);                // project point (0; 20) onto sloping edge
    assertNull(projectedPoint);
}