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/*
 *    GeoTools - The Open Source Java GIS Toolkit
 *    http://geotools.org
 *
 *    (C) 2011, Open Source Geospatial Foundation (OSGeo)
 *    (C) 2003-2005, Open Geospatial Consortium Inc.
 *
 *    All Rights Reserved. http://www.opengis.org/legal/
 */
package org.opengis.geometry.coordinate;

import static org.opengis.annotation.Obligation.*;
import static org.opengis.annotation.Specification.*;

import org.opengis.annotation.UML;

/**
 * A piecewise parametric polynomial or rational curve described in terms of control points and
 * basis functions. If the weights in the knots are equal then it is a polynomial spline. If not,
 * then it is a rational function spline. If the boolean {@link #isPolynomial} is set to {@code
 * true} then the weights shall all be set to 1. A B-spline curve is a piecewise Bézier curve if it
 * is quasi-uniform except that the interior knots have multiplicity "degree" rather than having
 * multiplicity one. In this subtype the knot spacing shall be 1.0, starting at 0.0. A piecewise
 * Bézier curve that has only two knots, 0.0, and 1.0, each of multiplicity (degree+1), is
 * equivalent to a simple Bézier curve.
 *
 * @version ISO 19107
 * @author Martin Desruisseaux (IRD)
 * @since GeoAPI 2.0
 * @see GeometryFactory#createBSplineCurve
 */
@UML(identifier = "GM_BSplineCurve", specification = ISO_19107)
public interface BSplineCurve extends SplineCurve {
    /** The algebraic degree of the basis functions. */
    @UML(identifier = "degree", obligation = MANDATORY, specification = ISO_19107)
    int getDegree();

    /**
     * Identifies particular types of curve which this spline is being used to approximate. It is
     * for information only, used to capture the original intention. If no such approximation is
     * intended, then the value of this attribute is {@code null}.
     */
    @UML(identifier = "curveForm", obligation = OPTIONAL, specification = ISO_19107)
    SplineCurveForm getCurveForm();

    /**
     * Gives the type of knot distribution used in defining this spline. This is for information
     * only and is set according to the different construction-functions.
     */
    @UML(identifier = "knotSpec", obligation = OPTIONAL, specification = ISO_19107)
    KnotType getKnotSpec();

    /** {@code true} if this is a polynomial spline. */
    @UML(identifier = "isPolynomial", obligation = MANDATORY, specification = ISO_19107)
    boolean isPolynomial();
}