SecondOrderProperties.h

//===========================================================================
// GoTools - SINTEF Geometry Tools
//
// GoTools module: Intersections, version 1.0
//
// Copyright (C) 2000-2007 SINTEF ICT, Applied Mathematics, Norway.
//
// This program is free software; you can redistribute it and/or          
// modify it under the terms of the GNU General Public License            
// as published by the Free Software Foundation version 2 of the License. 
//
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// but WITHOUT ANY WARRANTY; without even the implied warranty of         
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the          
// GNU General Public License for more details.                           
//
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// along with this program; if not, write to the Free Software            
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// SINTEF ICT, Department of Applied Mathematics,                         
// P.O. Box 124 Blindern,                                                 
// 0314 Oslo, Norway.                                                     
//
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//===========================================================================
#ifndef _SECONDORDERPROPERTIES_H
#define _SECONDORDERPROPERTIES_H

#include <vector>
#include "Point.h"
#include "SingularityType.h"

namespace Go {


// this structure encapsulates all information about a IntersectionPoint that 
// is or might be influenced by second order properties of the objects it is
// lying on. The need for this class arises because a geometrical object may
// carry a discontinuity in its second derivative at an IntersectionPoint, and
// its differential properties may therefore vary according to from where one
// look at the point.
// An IntersectionPoint lying on such a discontinuity (or more!), will therefore
// contain multiple SecondOrderProperties, all of which are correct depending
// on which point of view one takes.

struct SecondOrderProperties
{
    SecondOrderProperties() : 
        singularity_info_is_cached(false), tangent_is_oriented(false), tangent_2d_is_cached(false){}

    void clear() 
    {
        singularity_info_is_cached = false;
        tangent_is_oriented = false;
        tangent_2d_is_cached = false;
    }

    // caching of singularity type.  If the intersecting objects have 3D tangents (ie. they
    // are not parametrical functions), the 3D tangents will be cached simultaneously with
    // the SingularitytType.
    bool singularity_info_is_cached;
    Point tangent_3d[2]; // space for two tangents, in case of branch points
    SingularityType singularity_type;

    bool tangent_is_oriented;

    // caching of parametric tangent and related info
    bool tangent_2d_is_cached;
    Point tangent_2d_1[2]; // space for two tangents in case of branching point
    Point tangent_2d_2[2]; // space for two tangents in case of branching point

};

}; // end namespace Go

#endif // _SECONDORDERPROPERTIES_H

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