/*$************************************************************************************************
**
** $Id: CurveSegment.java 831 2006-05-01 00:27:23Z Desruisseaux $
**
** $URL: http://svn.code.sf.net/p/geoapi/code/branches/2.0.x/geoapi/src/main/java/org/opengis/spatialschema/geometry/primitive/CurveSegment.java $
**
** Copyright (C) 2003-2005 Open GIS Consortium, Inc.
** All Rights Reserved. http://www.opengis.org/legal/
**
*************************************************************************************************/
package org.opengis.spatialschema.geometry.primitive;
// OpenGIS direct dependencies
import org.opengis.spatialschema.geometry.geometry.GenericCurve;
import org.opengis.spatialschema.geometry.geometry.PointArray;
// Annotations
import org.opengis.annotation.UML;
import static org.opengis.annotation.Obligation.*;
import static org.opengis.annotation.Specification.*;
/**
* Defines a homogeneous segment of a {@linkplain Curve curve}.
* Each {@code CurveSegment} shall be in, at most, one {@linkplain Curve curve}.
*
* @version Abstract specification 5
* @author Martin Desruisseaux (IRD)
* @since GeoAPI 1.0
*/
@UML(identifier="GM_CurveSegment", specification=ISO_19107)
public interface CurveSegment extends GenericCurve {
/**
* Returns the curve which own this curve segment.
*
*
* NOTE: In this specification, curve segments do not appear except in the
* context of a curve, and therefore this method should never returns {@code null}
* which would preclude the use of curve segments except in this manner. While this would
* not affect this specification, allowing {@code null} owner allows other standards
* based on this one to use curve segments in a more open-ended manner.
*
*
* @return The owner of this curve segment, or {@code null} if none.
*
* @see Curve#getSegments
*/
@UML(identifier="curve", obligation=OPTIONAL, specification=ISO_19107)
public Curve getCurve();
/**
* Specifies the curve interpolation mechanism used for this segment. This mechanism
* uses the control points and control parameters to determine the position of this
* {@code CurveSegment}.
*
* @return The interpolation mechanism used for this segment.
*/
@UML(identifier="interpolation", obligation=MANDATORY, specification=ISO_19107)
public CurveInterpolation getInterpolation();
/**
* Specifies the type of continuity between this curve segment and its immediate neighbors.
* If this is the first curve segment in the curve, this value is ignored.
*
*
* NOTE: Use of these values is only appropriate when the basic curve
* definition is an underdetermined system. For example, line strings and segments cannot
* support continuity above C0, since there is no spare control parameter to
* adjust the incoming angle at the end points of the segment. Spline functions on the
* other hand often have extra degrees of freedom on end segments that allow them to adjust
* the values of the derivatives to support C1 or higher continuity.
*
*
* @return The type of continuity between this curve semgent and its immediate neighbors.
*
* @see #getNumDerivativesInterior
* @see #getNumDerivativesAtEnd
*/
@UML(identifier="numDerivativesAtStart", obligation=MANDATORY, specification=ISO_19107)
public int getNumDerivativesAtStart();
/**
* Specifies the type of continuity that is guaranteed interior to the curve. The default
* value of "0" means simple continuity, which is a mandatory minimum level of continuity.
* This level is referred to as "C0" in mathematical texts. A value of 1 means
* that the function and its first derivative are continuous at the appropriate end point:
* "C1" continuity. A value of "n" for any integer means the function and its
* first n derivatives are continuous: "Cn" continuity.
*
* @return The type of continuity that is guaranteed interior to the curve.
*
* @see #getNumDerivativesAtStart
* @see #getNumDerivativesAtEnd
*/
@UML(identifier="numDerivativesInterior", obligation=MANDATORY, specification=ISO_19107)
public int getNumDerivativesInterior();
/**
* Specifies the type of continuity between this curve segment and its immediate neighbors.
* If this is the last curve segment in the curve, this value is ignored.
*
*
* NOTE: Use of these values is only appropriate when the basic curve
* definition is an underdetermined system. For example, line strings and segments cannot
* support continuity above C0, since there is no spare control parameter to
* adjust the incoming angle at the end points of the segment. Spline functions on the
* other hand often have extra degrees of freedom on end segments that allow them to adjust
* the values of the derivatives to support C1 or higher continuity.
*
*
* @return The type of continuity between this curve semgent and its immediate neighbors.
*
* @see #getNumDerivativesAtStart
* @see #getNumDerivativesInterior
*/
@UML(identifier="numDerivativesAtEnd", obligation=MANDATORY, specification=ISO_19107)
public int getNumDerivativesAtEnd();
/**
* Returns an ordered array of point values that lie on the {@linkplain CurveSegment curve segment}.
* In most cases, these will be related to control points used in the construction of the segment.
* The control points of a curve segment are use to control its shape, and are not always on the
* curve segment itself. For example in a spline curve, the curve segment is given as a weighted
* vector sum of the control points. Each weight function will have a maximum within the
* constructive parameter interval, which will roughly correspond to the point on the curve
* where it passes closest that the corresponding control point. These points, the values of
* the curve at the maxima of the weight functions, will be the sample points for the curve
* segment.
*
* @return The control points.
*/
@UML(identifier="samplePoint", obligation=MANDATORY, specification=ISO_19107)
public PointArray getSamplePoints();
/**
* Returns an ordered pair of points, which are the start point and end point of the curve.
* This method operates with the same semantics as that on {@linkplain Curve#getBoundary curve}
* except that the end points of a {@code CurveSegment} are not necessarily existing
* {@linkplain Point points} and thus the boundary may contain transient {@linkplain Point points}.
*
*
* NOTE: The above {@linkplain CurveBoundary curve boundary} will almost always
* be two distinct positions, but, like {@linkplain Curve curves}, {@code CurveSegment}s can
* be cycles in themselves. The most likely scenario is that all of the points used will be transients
* (constructed to support the return value), except for the start point and end point of the aggregated
* {@linkplain Curve curve}. These two positions, in the case where the {@linkplain Curve curve} is
* involved in a {@linkplain org.opengis.spatialschema.geometry.complex.Complex complex}, will be represented as
* {@linkplain Point points} in the same {@linkplain org.opengis.spatialschema.geometry.complex.Complex complex}.
*
*
* @return The sets of positions on the boundary.
*/
@UML(identifier="boundary", obligation=MANDATORY, specification=ISO_19107)
public CurveBoundary getBoundary();
/**
* Reverses the orientation of the parameterizations of the segment.
*
* @return The reverse of this curve segment.
*/
@UML(identifier="reverse", obligation=MANDATORY, specification=ISO_19107)
public CurveSegment reverse();
}
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