Examples with ConvexHull org.locationtech.jts.algorithm.ConvexHull used on opensource projects

Example 1 with ConvexHull

use of org.locationtech.jts.algorithm.ConvexHull in project OpenSearch by opensearch-project.

the class RandomShapeGenerator method createShape.

/**
 * Creates a random shape useful for randomized testing, NOTE: exercise caution when using this to build random GeometryCollections
 * as creating a large random number of random shapes can result in massive resource consumption
 * see: {@link GeoShapeQueryTests#testQueryRandomGeoCollection()}
 *
 * The following options are included
 * @param nearPoint Create a shape near a provided point
 * @param within Create a shape within the provided rectangle (note: if not null this will override the provided point)
 * @param st Create a random shape of the provided type
 * @return the ShapeBuilder for a random shape
 */
private static ShapeBuilder createShape(Random r, Point nearPoint, Rectangle within, ShapeType st, boolean validate) throws InvalidShapeException {
    if (st == null) {
        st = ShapeType.randomType(r);
    }
    if (within == null) {
        within = xRandomRectangle(r, nearPoint);
    }
    // inside non overlapping bounding rectangles
    switch(st) {
        case POINT:
            Point p = xRandomPointIn(r, within);
            PointBuilder pb = new PointBuilder().coordinate(new Coordinate(p.getX(), p.getY(), Double.NaN));
            return pb;
        case MULTIPOINT:
        case LINESTRING:
            // for random testing having a maximum number of 10 points for a line string is more than sufficient
            // if this number gets out of hand, the number of self intersections for a linestring can become
            // (n^2-n)/2 and computing the relation intersection matrix will become NP-Hard
            int numPoints = RandomNumbers.randomIntBetween(r, 3, 10);
            CoordinatesBuilder coordinatesBuilder = new CoordinatesBuilder();
            for (int i = 0; i < numPoints; ++i) {
                p = xRandomPointIn(r, within);
                coordinatesBuilder.coordinate(p.getX(), p.getY());
            }
            ShapeBuilder pcb = (st == ShapeType.MULTIPOINT) ? new MultiPointBuilder(coordinatesBuilder.build()) : new LineStringBuilder(coordinatesBuilder);
            return pcb;
        case MULTILINESTRING:
            MultiLineStringBuilder mlsb = new MultiLineStringBuilder();
            for (int i = 0; i < RandomNumbers.randomIntBetween(r, 1, 10); ++i) {
                mlsb.linestring((LineStringBuilder) createShape(r, nearPoint, within, ShapeType.LINESTRING, false));
            }
            return mlsb;
        case POLYGON:
            numPoints = RandomNumbers.randomIntBetween(r, 5, 25);
            Coordinate[] coordinates = new Coordinate[numPoints];
            for (int i = 0; i < numPoints; ++i) {
                p = (Point) createShape(r, nearPoint, within, ShapeType.POINT, false).buildS4J();
                coordinates[i] = new Coordinate(p.getX(), p.getY());
            }
            // random point order or random linestrings can lead to invalid self-crossing polygons,
            // compute the convex hull for a set of points to ensure polygon does not self cross
            Geometry shell = new ConvexHull(coordinates, ctx.getGeometryFactory()).getConvexHull();
            Coordinate[] shellCoords = shell.getCoordinates();
            // when all else fails, use the bounding box as the polygon
            if (shellCoords.length < 3) {
                shellCoords = new Coordinate[4];
                shellCoords[0] = new Coordinate(within.getMinX(), within.getMinY());
                shellCoords[1] = new Coordinate(within.getMinX(), within.getMaxY());
                shellCoords[2] = new Coordinate(within.getMaxX(), within.getMaxY());
                shellCoords[3] = new Coordinate(within.getMaxX(), within.getMinY());
            }
            PolygonBuilder pgb = new PolygonBuilder(new CoordinatesBuilder().coordinates(shellCoords).close());
            if (validate) {
                // The validate flag will check for these possibilities and bail if an incorrect geometry is created
                try {
                    pgb.buildS4J();
                } catch (AssertionError | InvalidShapeException e) {
                    // or InvalidShapeException
                    return null;
                }
            }
            return pgb;
        default:
            throw new OpenSearchException("Unable to create shape of type [" + st + "]");
    }
}