include/geometry/polygonUtilities.h

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/******************************************************************************
** Copyright (c) 2005 MAK Technologies, Inc.
** All rights reserved.
******************************************************************************/
/******************************************************************************
** $RCSfile: polygonUtilities.h,v $ $Revision: 1.8 $ $State: Exp $
******************************************************************************/
#ifndef polygonUtilities_H_
#define polygonUtilities_H_

//
// \file polygonUtilities.h
// \brief Contains utility functions for interacting with/on DtGeometricPolygons.
//
#include "geometry/geometryDefines.h"
#include <vlutil/vlConfig.h>
#include <vector>

class DtPoint;
class DtCircle;
class DtPolygon2D;
class DtChord;
class DtExtent;


// Determines if the specified point is inside the specified polygon by performing 
// and edge crossings test, originally presented by Eric Haines in Graphics Gems IV.
//
// \return A boolean indicating whether or not the pointToTest is inside the polygon
// or not.  
//
// \note This function will work with concave polygons, as opposed to the pointInPolygonXy
// function below, \see DtPointInPolygonXy, which is more efficient but only works 
// with convex polygons.
DT_DLL_geometry bool DtCrossingsTest(const DtPolygon2D& polygon, const DtPoint& pointToTest);


// Determines if the specified point is inside the specified polygon in the XY plane.
// Does this by creating and edge between the point and each vertex of the polygon
// and testing the angle between that edge and the edges of the polygon to see if
// the edge is interior to the polygon.  If this is true for all possible point-vertex
// edges, then the point is inside the polygon.
//
// \return A boolean indicating whether or not the pointToTest is inside the polygon
// or not.  
//
// \note It is most likely better to use the above function as it isn't always less
// efficient and is better behaved when the input is not completely clean (convex, etc.)
DT_DLL_geometry bool DtPointInPolygonInXy(const DtPolygon2D& polygon, const DtPoint& pointToTest);


// Determines if the specified polygon and edge intersect, in the boolean sense.
// \return A boolean specifying whether or not any piece of the edge, or the entire
// edge, is inside the polygon.  
// \note This function also handles the case where the polygon is concave.
DT_DLL_geometry bool DtIntersectsInXy(const DtPolygon2D& polygon, const DtChord& chord);


// Determines if the specified polygon and edge intersect, in the boolean sense, 
// and returns through the specified input container, all the pieces of the edge
// that are inside the polygon.  In the majority of cases, and always with convex
// polygons, the container should have one edge.  However, when the polygon is 
// concave, it might have several as the chord is "clipped" in several places by
// the polygon.  If the chord is completely contained in the polygon, the function
// returns true and the container will hold a copy of hte specified chord.
//
// \return A boolean specifying whether or not any piece of the edge, or the entire
// edge, is inside the polygon.  
// \note This function also handles the case where the polygon is concave.
DT_DLL_geometry bool DtGetIntersectionInXy(const DtPolygon2D& polygon, const DtChord& chord, 
                           std::vector<DtChord>& chordPolyIntersection);


// Determines if the specified polygons intersect, in the boolean sense.  
// \return A boolean indicating whether or not there is \b any overlap of the two
// polygons in the XY plane.  
//
// \note This means that if either polygon completely contains the other, they are considered
// to intersect.  
DT_DLL_geometry bool DtIntersectsInXy(const DtPolygon2D& polygon1, const DtPolygon2D& polygon2);


// Determines if the specified chord intersects any of the \b edges of the specified
// polygon, in the XY plane.
//
// \return A boolean indicating whether or not the chord intersects any of the
// edges of the specified polygon. 
//
// \note This will \b return false if the chord is completely contained inside
// the polygon.
DT_DLL_geometry bool DtEdgesIntersectInXy(const DtPolygon2D& polygon, const DtChord& chord);


DT_DLL_geometry bool DtPolygonContains(const DtPolygon2D& polygon1, const DtPolygon2D& polygon2);

//bool DtIntersectsInXy(const DtCircle& circle, const DtPolygon2D& polygon);
//
//
//bool DtBoundsInXy(const DtPolygon2D& boundingPolygon, const DtPolygon2D& polygonToTest);
//
//bool DtBoundsInXy(const DtCircle& boundingCircle, const DtPolygon2D& polygonToTest);


#endif