include/geometry/chordUtilities.h

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/******************************************************************************
** Copyright (c) 2005 MAK Technologies, Inc.
** All rights reserved.
******************************************************************************/
/******************************************************************************
** $RCSfile: chordUtilities.h,v $ $Revision: 1.6 $ $State: Exp $
******************************************************************************/
#ifndef chordUtilities_H_
#define chordUtilities_H_

//
// \file chordUtilities.h
// \brief Contains utility functions for chords, such as intersection, distance from,
// and the closest point to.
//

#include "geometry/geometryDefines.h"
#include "geometry/point.h"

class DtChord;


// The DtChordIntersectionResult enum contains the different possible intersection
// values between two chords.  
typedef enum
{
   DtNonParallelNonIntersecting = 0,
   DtNonParallelIntersecting,
   DtParallelOverlapping,
   DtParallelNonOverlapping,
   DtSameChord
} DtChordIntersectionResult;


// A helper function designed to turn the intersection result above into a 
// simple bool when a simple yes/no intersection result is desired.
DT_DLL_geometry bool DtChordsIntersect(DtChordIntersectionResult intersectionResult);

// If two segments have an angle between them less than this value
// they are treated as parallel.
DT_DLL_geometry double theParallelAngle();


// Calculate if the projections onto the x-y plane of another segment 
// and this segment intersect.  
DT_DLL_geometry DtChordIntersectionResult DtIntersectInXY(const DtChord& chord1, 
   const DtChord& chord2);
DT_DLL_geometry DtChordIntersectionResult DtIntersectInXY(const DtPoint& chord1EndPoint0, 
   const DtPoint& chord1EndPoint1, const DtChord& chord2);
DT_DLL_geometry DtChordIntersectionResult DtIntersectInXY(const DtChord& chord1, 
   const DtPoint& chord2EndPoint0, const DtPoint& chord2EndPoint1);
DT_DLL_geometry DtChordIntersectionResult DtIntersectInXY(const DtPoint& chord1EndPoint0,
   const DtPoint& chord1EndPoint1, const DtPoint& chord2EndPoint0, const DtPoint& chord2EndPoint1);

// Calculate if the projections onto the x-y plane of two chords, and see if the
// projections intersect.  Calculate the closest point on each chord's 
// projection to the other chord's projection.  If the two chords intersect, 
// then the closest point is the intersection point.
//
// \param distanceSquared The distance between the two chords squared,
// \param thisX/thisY hold the closest points on chord1
// \param otherX/otherY hold the closest point on chord2.  
DT_DLL_geometry DtChordIntersectionResult DtIntersectInXY(const DtChord& chord1, 
   const DtChord& chord2, double& distanceSquared, double& chord1X, double& chord1Y, 
   double& chord2X, double& chord2Y);


DT_DLL_geometry double DtPointChordDistanceInXY(double pointX, double pointY,
                                double end0X,  double end0Y,
                                double end1X,  double end1Y);

DT_DLL_geometry double DtPointChordDistanceInXY(double pointX, double pointY,
                                double end0X,  double end0Y,
                                double end1X,  double end1Y,
                                double& outX,  double& outY);


DT_DLL_geometry void DtClosestPoint(const DtChord& chord, const DtPoint& pointOfInterest, 
   DtPoint& closestPoint, double& distance);

DT_DLL_geometry void DtClosestPoint(const DtPoint& chordEndPoint0, const DtPoint& chordEndPoint1,
   const DtPoint& pointOfInterest, DtPoint& closestPoint, double& distance);


DT_DLL_geometry void DtClosestPointInXY(const DtChord& chord, const DtPoint& pointOfInterest, 
   DtPoint& closestPnt, double& distance);

DT_DLL_geometry void DtClosestPointInXY(const DtPoint& chordEndPoint0, const DtPoint& chordEndPoint1,
   const DtPoint& pointOfInterest, DtPoint& closestPnt, double& distance);

// Finds the closest approach between the two specified chords in 3D.
// The points on each chord are passed back in chord1Point and chord2Point.
// The time value (0 - 1.0) along each chord of the points are passed back
// in chord1T and chord2T.
// \return The square of the distance at the closest approach.
DT_DLL_geometry double DtClosestApproachChordToChord(const DtChord& chord1,
                                                     const DtChord& chord2,
                                                     double& chord1T,
                                                     double& chord2T,
                                                     DtPoint& chord1Point,
                                                     DtPoint& chord2Point);

#endif