/*
* 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 org.opengis.geometry.DirectPosition;
import org.opengis.annotation.UML;
import static org.opengis.annotation.Obligation.*;
import static org.opengis.annotation.Specification.*;
/**
* Common interface for {@linkplain org.opengis.geometry.primitive.Surface surface} and
* {@linkplain org.opengis.geometry.primitive.SurfacePatch surface patch}. {@code Surface}
* and {@code SurfacePatch} represent sections of surface geometry,
* and therefore share a number of operation signatures.
*
*
* @source $URL: http://svn.osgeo.org/geotools/branches/2.7.x/modules/library/opengis/src/main/java/org/opengis/geometry/coordinate/GenericSurface.java $
* @version <A HREF="http://www.opengeospatial.org/standards/as">ISO 19107</A>
* @author Martin Desruisseaux (IRD)
* @since GeoAPI 1.0
*
* @todo Investigate why this interface doesn't extends {@link Geometry}, since it is a cause
* of difficulty with {@link org.opengis.coverage.Coverage}.
*/
@UML(identifier="GM_GenericSurface", specification=ISO_19107)
public interface GenericSurface {
/**
* Returns a vector perpendicular to the {@code GenericSurface} at the
* {@linkplain DirectPosition direct position} passed, which must be on this
* {@code GenericSurface}. The upward normal always points upward in a
* manner consistent with the boundary. This means that the exterior boundary
* of the surface is counterclockwise when viewed from the side of the surface
* indicated by the {@code upNormal}. Interior boundaries are clockwise.
* The side of the surface indicated by the {@code upNormal} is referred
* to as the "top." The function "upNormal" shall be continuous and the length
* of the normal shall always be equal to 1.0.
*
* <blockquote><font size=2>
* <strong>NOTE:</strong> The upNormal along a boundary of a solid always points away from the
* solid. This is a slight semantics problem in dealing with voids within solids, where the
* upNormal (for sake of mathematical consistency) points into the center of the voided region,
* which linguistically can be considered the interior of the void. What the confusion is here
* is that the basic linguistic metaphors used in most languages for "interior of solid" and
* for "interior of container" use "inward" in inconsistent manners from a topological point
* of view. The void "in" rock is not inside the rock in the same manner as the solid material
* that makes up the substance of the rock. Nor is the coffee "in" the cup the same "in" as
* the ceramic glass "in" the cup. The use of these culturally derived metaphors may not be
* consistent across all languages, some of which may use different prepositions for these two
* different concepts. This specification uses the linguistically neutral concept of "interior"
* derived from mathematics (topology).
* </font></blockquote>
*
* @param point The point on this {@code GenericSurface} where to compute the upNormal.
* @return The upNormal unit vector.
*/
@UML(identifier="upNormal", obligation=MANDATORY, specification=ISO_19107)
double[] getUpNormal(DirectPosition point);
/**
* Returns the sum of the lengths of all the boundary components of this
* {@code GenericSurface}. Since perimeter, like length, is an accumulation
* (integral) of distance, its return value shall be in a reference system appropriate
* for measuring distances.
*
* <blockquote><font size=2>
* <strong>NOTE:</strong> The perimeter is defined as the sum of the lengths of all boundary
* components. The length of a curve or of a collection of curves is always positive and
* non-zero (unless the curve is pathological). This means that holes in surfaces will
* contribute positively to the total perimeter.
* </font></blockquote>
*
* @return The perimeter.
* @unitof Length
*/
@UML(identifier="perimeter", obligation=MANDATORY, specification=ISO_19107)
double getPerimeter();
/**
* Returns the area of this {@code GenericSurface}. The area of a 2-dimensional geometric
* object shall be a numeric measure of its surface area (in a square unit of distance). Since
* area is an accumulation (integral) of the product of two distances, its return value shall
* be in a unit of measure appropriate for measuring distances squared, such as meters squared
* (m<sup>2</sup>).
*
* <blockquote><font size=2>
* <strong>NOTE:</strong> Consistent with the definition of surface as a set of
* {@linkplain DirectPosition direct positions}, holes in the surfaces will not contribute to
* the total area. If the usual Green's Theorem (or more general Stokes' Theorem) integral is
* used, the integral around the holes in the surface are subtracted from the integral
* about the exterior of the surface patch.
* </font></blockquote>
*
* @return The area.
* @unitof Area
*/
@UML(identifier="area", obligation=MANDATORY, specification=ISO_19107)
double getArea();
}