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Standard interfaces implemented throughout the library.

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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 java.util.List;
import org.opengis.annotation.UML;

/**
 * A planar polygon defined by 3 corners. That is, a triangle would be the result of a constructor
 * of the form: {@code Polygon(LineString({P1, P2, P3, P1}))} where P₁,
 * P₂, and P₃ are three {@linkplain Position positions}.
 * Triangles have no holes. Triangle shall be used to construct {@linkplain TriangulatedSurface
 * triangulated surfaces}.
 *
 * Note: The points in a triangle can be located in terms of their corner points
 * by defining a set of barycentric coordinates, three nonnegative numbers c₁,
 * c₂, and c₃ such that
 *
 * 
c₁ + c₂ + c₃ = 1.0.
 *
 * 
Then, each point P in the triangle can be expressed for some set of barycentric
 * coordinates as:
 *
 * 

 *
 * 

 *
 * P = c₁P₁ +
 * c₂P₂ +
 * c₃P₃
 *
 * 
 *
 * @version ISO 19107
 * @author Martin Desruisseaux (IRD)
 * @since GeoAPI 2.0
 */
@UML(identifier = "GM_Triangle", specification = ISO_19107)
public interface Triangle extends Polygon {
    /** Returns the triangle corner. The list must contains exactly 3 elements. */
    @UML(identifier = "corners", obligation = MANDATORY, specification = ISO_19107)
    List getCorners();

    /** Returns the patch which own this surface patch. */
    @UML(identifier = "surface", obligation = MANDATORY, specification = ISO_19107)
    TriangulatedSurface getSurface();
}