/*
* 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 java.util.List;
import org.opengis.geometry.primitive.CurveSegment;
import org.opengis.annotation.UML;
import static org.opengis.annotation.Obligation.*;
import static org.opengis.annotation.Specification.*;
/**
* A curve at a constant distance from the basis curve. They can be useful as a cheap and
* simple alternative to constructing curves that are offsets by definition.
*
*
* @source $URL: http://svn.osgeo.org/geotools/branches/2.7.x/modules/library/opengis/src/main/java/org/opengis/geometry/coordinate/OffsetCurve.java $
* @version <A HREF="http://www.opengeospatial.org/standards/as">ISO 19107</A>
* @author Martin Desruisseaux (IRD)
* @since GeoAPI 2.0
*/
@UML(identifier="GM_OffsetCurve", specification=ISO_19107)
public interface OffsetCurve extends CurveSegment {
/**
* Returns the base curves.
*/
@UML(identifier="baseCurve", obligation=MANDATORY, specification=ISO_19107)
List<CurveSegment> getBaseCurves();
/**
* Returns the distance at which the offset curve is generated from the basis curve.
* In a 2D system, positive distances are to be left of the basis curve, and negative
* distances are right of the basis curve.
*
* @unitof Length
*/
@UML(identifier="distance", obligation=MANDATORY, specification=ISO_19107)
double getDistance();
/**
* Defines the vector direction of the offset curve from the basis curve. It can be
* omitted in the 2D case, where the distance can be positive or negative. In that
* case, distance defines left side (positive distance) or right side (negative distance)
* with respect to the tangent to the basis curve. In 3D the basis curve shall have a
* well-defined tangent direction for every point. The offset curve at any point
* (parameter) on the basis curve <var>c</var> is in the direction
*
* <P>(TODO: paste the formulae here)</P>
*
* <P>For the offset direction to be well-defined, <var>v</var> shall not on any point
* of the curve be in the same, or opposite, direction as <var>t</var>.
*
* The default value of the reference direction shall be the local coordinate axis
* vector for elevation, which indicates up for the curve in a geographic sense.
* If the reference direction is the positive tangent to the local elevation axis
* ("points upward"), then the offset vector points to the left of the curve when
* viewed from above.
*/
@UML(identifier="refDirection", obligation=OPTIONAL, specification=ISO_19107)
double[] getReferenceDirection();
}