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gugr_split.h

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/* LIBGUL - Geometry Utility Library
 * Copyright (C) 1998-1999 Norbert Irmer
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#ifndef GUGR_SPLIT_H
#define GUGR_SPLIT_H

namespace gugr {

template< class T >
struct GraphConvInfo
{
  T minx;    // normalization parameters
  T miny;
  T scale;
  
  guar::rational MinX;      // point to the left of all points
  guar::rational MaxX;
  guar::rational FarMinX;   // point far to the left 
  guar::rational FarMaxX;
  guar::rational MinY;
  guar::rational MaxY;
  guar::rational FarMinY;
  guar::rational FarMaxY;
};

struct GraphInfo
{
  gugr::graph_vertex      *P[2][2];
  int                face;

  gugr::graph_edge_list    E;
  gugr::graph_vertex_list  V;

  ~GraphInfo()
  {
    E.DeleteElems();
    V.DeleteElems();
  }
  void *operator new( size_t s )
  {
    size_t dummy;
    void *p = gust::PoolAlloc( s, &dummy );
    if( p == NULL ) throw gul::PoolAllocError();
    return(p);
  }  
  void operator delete( void *p, size_t s )
  {
    gust::PoolFree( p, s );
  }
};
typedef GraphInfo *GraphInfo4[4];


/*----------------------------------------------------------------------
  Special utility function, used in the tesselation of nurbs surfaces.
  It inserts the diagonal of a tesselation quad into the graph for this
  quad. It is assumed that width and height of quad are equal, i.e.
  x2-x1 = y2-y1
----------------------------------------------------------------------*/
void InsertDiagonal( 
              graph_edge_list *E, graph_vertex_list *V,
              graph_vertex *P11, graph_vertex *P22 );

/* -------------------------------------------------------------------------
  Calculates the intersection of a graph with horizontal cutting lines 
-------------------------------------------------------------------------- */
void IntersectWithHorizontals( 
          graph_edge_list *E, graph_vertex_list *V,
          const int nS, gul::Ptr< cut_info > S );

/* -------------------------------------------------------------------------
  Divide graph into an independant upper and lower part
-------------------------------------------------------------------------- */
void DivideHorizontalStrips( 
              cut_info *Sa, cut_info *Sb, int maxE,
              const rational& minx, const rational maxx,
              const rational& far_left, const rational& far_right,
              graph_vertex **minSaV, graph_vertex **minSbV,
              graph_vertex **maxSaV, graph_vertex **maxSbV );
              
/* -------------------------------------------------------------------------
  Calculates the intersection of a graph with vertical cutting lines 
-------------------------------------------------------------------------- */
void IntersectWithVerticals( 
          graph_edge_list *E, graph_vertex_list *V,
          const int nS, gul::Ptr< cut_info > S );

/* -------------------------------------------------------------------------
  Divide graph into an independant left and right part
-------------------------------------------------------------------------- */
void DivideVerticalStrips( 
              cut_info *Sb, cut_info *Sa, int maxE,
              const rational& miny, const rational maxy,
              const rational& far_bottom, const rational& far_top,
              graph_vertex **minSbV, graph_vertex **minSaV,
              graph_vertex **maxSbV, graph_vertex **maxSaV );


/* ---------------------------------------------------------------------------
  splits a graph into four independent parts
---------------------------------------------------------------------------- */
template< class T >
void SplitGraph( GraphInfo *G, T xmed, T ymed,
                 GraphConvInfo<T> *Gconv, GraphInfo4& sub );

/* ---------------------------------------------------------------------------
  inits a graph info
---------------------------------------------------------------------------- */
template< class T >
void InitGraph( 
       const rational& X1, const rational& X2,
       const rational& Y1, const rational& Y2,
       GraphConvInfo<T> *Gconv, graph_edge_list *E, graph_vertex_list *V,
       GraphInfo *G );

}
 
#endif

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