subdivider.cc

Go to the documentation of this file.

/*
** License Applicability. Except to the extent portions of this file are
** made subject to an alternative license as permitted in the SGI Free
** Software License B, Version 1.1 (the "License"), the contents of this
** file are subject only to the provisions of the License. You may not use
** this file except in compliance with the License. You may obtain a copy
** of the License at Silicon Graphics, Inc., attn: Legal Services, 1600
** Amphitheatre Parkway, Mountain View, CA 94043-1351, or at:
**
** http://oss.sgi.com/projects/FreeB
**
** Note that, as provided in the License, the Software is distributed on an
** "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS
** DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND
** CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A
** PARTICULAR PURPOSE, AND NON-INFRINGEMENT.
**
** Original Code. The Original Code is: OpenGL Sample Implementation,
** Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
** Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
** Copyright in any portions created by third parties is as indicated
** elsewhere herein. All Rights Reserved.
**
** Additional Notice Provisions: The application programming interfaces
** established by SGI in conjunction with the Original Code are The
** OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
** April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
** 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
** Window System(R) (Version 1.3), released October 19, 1998. This software
** was created using the OpenGL(R) version 1.2.1 Sample Implementation
** published by SGI, but has not been independently verified as being
** compliant with the OpenGL(R) version 1.2.1 Specification.
*/

/*
 * subdivider.cxx
 *
 */

#include "glimports.h"
#include "myassert.h"
#include "mystdio.h"
#include "subdivider.h"
#include "arc.h"
#include "bezierarc.h"
#include "bin.h"
#include "renderhints.h"
#include "backend.h"
#include "mapdesc.h"
#include "quilt.h"
#include "patchlist.h"
#include "patch.h"
#include "nurbsconsts.h"
#include "trimvertpool.h"
#include "simplemath.h"

#include "polyUtil.h" //for function area()

//#define  PARTITION_TEST
#ifdef PARTITION_TEST
#include "partitionY.h"
#include "monoTriangulation.h"
#include "dataTransform.h"
#include "monoChain.h"

#endif


#define OPTIMIZE_UNTRIMED_CASE


Bin*
Subdivider::makePatchBoundary( const REAL *from, const REAL *to )
{ 
    Bin* ret = new Bin();
    REAL smin = from[0];
    REAL smax = to[0];
    REAL tmin = from[1];
    REAL tmax = to[1];

    pjarc = 0;

    Arc_ptr jarc = new(arcpool) Arc( arc_bottom, 0 );
    arctessellator.bezier( jarc, smin, smax, tmin, tmin );
    ret->addarc( jarc  );
    pjarc = jarc->append( pjarc );

    jarc = new(arcpool) Arc( arc_right, 0 );
    arctessellator.bezier( jarc, smax, smax, tmin, tmax );
    ret->addarc( jarc  );
    pjarc = jarc->append( pjarc );

    jarc = new(arcpool) Arc( arc_top, 0 );
    arctessellator.bezier( jarc, smax, smin, tmax, tmax );
    ret->addarc( jarc  );
    pjarc = jarc->append( pjarc );

    jarc = new(arcpool) Arc( arc_left, 0 );
    arctessellator.bezier( jarc, smin, smin, tmax, tmin );
    ret->addarc( jarc  );
    jarc->append( pjarc );

    assert( jarc->check() != 0 );
    return ret;
}

/*---------------------------------------------------------------------------
 * Subdivider - construct a subdivider
 *---------------------------------------------------------------------------
 */

Subdivider::Subdivider( Renderhints& r, Backend& b ) 
    : slicer( b ),
      arctessellator( trimvertexpool, pwlarcpool ), 
      arcpool( sizeof( Arc), 1, "arcpool" ),
      bezierarcpool( sizeof( BezierArc ), 1, "Bezarcpool" ),
      pwlarcpool( sizeof( PwlArc ), 1, "Pwlarcpool" ),
      renderhints( r ),
      backend( b )
{
}

void
Subdivider::setJumpbuffer( JumpBuffer *j )
{
    jumpbuffer = j;
}

/*---------------------------------------------------------------------------
 * clear - reset all state after possible error condition
 *---------------------------------------------------------------------------
 */

void        
Subdivider::clear( void )
{
    trimvertexpool.clear();     
    arcpool.clear();
    pwlarcpool.clear();
    bezierarcpool.clear();
}

/*---------------------------------------------------------------------------
 * ~Subdivider - destroy a subdivider
 *---------------------------------------------------------------------------
 */

Subdivider::~Subdivider( void )
{
}

/*---------------------------------------------------------------------------
 * addArc - add a bezier arc to a trim loop and to a bin
 *---------------------------------------------------------------------------
 */
void
Subdivider::addArc( REAL *cpts, Quilt *quilt, long _nuid )
{
    BezierArc *bezierArc = new(bezierarcpool) BezierArc;
    Arc *jarc       = new(arcpool) Arc( arc_none, _nuid );
    jarc->pwlArc    = 0;
    jarc->bezierArc = bezierArc;
    bezierArc->order    = quilt->qspec->order;
    bezierArc->stride   = quilt->qspec->stride;
    bezierArc->mapdesc  = quilt->mapdesc;
    bezierArc->cpts = cpts;
    initialbin.addarc( jarc );
    pjarc       = jarc->append( pjarc );
}

/*---------------------------------------------------------------------------
 * addArc - add a pwl arc to a trim loop and to a bin
 *---------------------------------------------------------------------------
 */

void
Subdivider::addArc( int npts, TrimVertex *pts, long _nuid ) 
{
    Arc *jarc       = new(arcpool) Arc( arc_none, _nuid );
    jarc->pwlArc    = new(pwlarcpool) PwlArc( npts, pts );        
    initialbin.addarc( jarc  );
    pjarc       = jarc->append( pjarc );
}

void
Subdivider::beginQuilts( void )
{
    qlist = 0;
}

void
Subdivider::addQuilt( Quilt *quilt )
{
    quilt->next = qlist;
    qlist = quilt;
}

/*---------------------------------------------------------------------------
 * drawSurfaces - main entry point for surface tessellation
 *---------------------------------------------------------------------------
 */

void
Subdivider::drawSurfaces( long nuid )
{
    renderhints.init( );

    if (qlist == NULL) 
      {
    //initialbin could be nonempty due to some errors
    freejarcs(initialbin);
    return;
      }

    for( Quilt *q = qlist; q; q = q->next ) {
    if( q->isCulled( ) == CULL_TRIVIAL_REJECT ) {
        freejarcs( initialbin );
        return;
    }
    }


    REAL from[2], to[2];
    qlist->getRange( from, to, spbrkpts, tpbrkpts );
#ifdef OPTIMIZE_UNTRIMED_CASE
    //perform optimization only when the samplng method is 
    //DOMAIN_DISTANCE and the display methdo is either 
    //fill or outline_polygon.
    int optimize = (is_domain_distance_sampling && (renderhints.display_method != N_OUTLINE_PATCH));
#endif

    if( ! initialbin.isnonempty() ) {
#ifdef OPTIMIZE_UNTRIMED_CASE
        if(! optimize )
      { 

      makeBorderTrim( from, to );
      }
#else
    makeBorderTrim( from, to );
#endif
    } else {
    REAL rate[2];
    qlist->findRates( spbrkpts, tpbrkpts, rate );

        if( decompose( initialbin, min(rate[0], rate[1]) ) ) 
        mylongjmp( jumpbuffer, 31 );
    }

    backend.bgnsurf( renderhints.wiretris, renderhints.wirequads, nuid );

#ifdef PARTITION_TEST
 if(    initialbin.isnonempty() && spbrkpts.end-2 == spbrkpts.start && 
    tpbrkpts.end-2 == tpbrkpts.start)
{
    for(int i=spbrkpts.start; i<spbrkpts.end-1; i++){
      for(int j=tpbrkpts.start; j<tpbrkpts.end-1; j++){
    Real pta[2], ptb[2];
    pta[0] = spbrkpts.pts[i];
    ptb[0] = spbrkpts.pts[i+1];
    pta[1] = tpbrkpts.pts[j];
    ptb[1] = tpbrkpts.pts[j+1];
    qlist->downloadAll(pta, ptb, backend);

    directedLine *poly;

      {

        poly = bin_to_DLineLoops(initialbin);
        
        poly=poly->deleteDegenerateLinesAllPolygons();          

    sampledLine* retSampledLines;
//printf("before MC_partition\n");      
        poly = MC_partitionY(poly, &retSampledLines);
//printf("after MC_partition\n");       

      }


    {
      primStream pStream(5000,5000);
      directedLine* temp;

      for(temp=poly; temp != NULL; temp=temp->getNextPolygon())

        monoTriangulation(temp, &pStream);

      slicer.evalStream(&pStream);

    }
    //need to clean up space
      }
    }
    freejarcs( initialbin );
    backend.endsurf();
    return;

    /*
    printf("num_polygons=%i\n", poly->numPolygons());
    printf("num_edges=%i\n", poly->numEdgesAllPolygons());
    poly->writeAllPolygons("zloutputFile");
    return;
    {
      primStream pStream(20,20);
      for(directedLine* tempD = poly; tempD != NULL; tempD = tempD->getNextPolygon())
    monoTriangulation(tempD, &pStream);
    }
    return;
    */
}
#endif //PARTITION_TEST


#ifdef OPTIMIZE_UNTRIMED_CASE
    if( (!initialbin.isnonempty())  && optimize )
      {
    int i,j;
    int num_u_steps;
        int num_v_steps;
    for(i=spbrkpts.start; i<spbrkpts.end-1; i++){
      for(j=tpbrkpts.start; j<tpbrkpts.end-1; j++){
        Real pta[2], ptb[2];
        pta[0] = spbrkpts.pts[i];
        ptb[0] = spbrkpts.pts[i+1];
        pta[1] = tpbrkpts.pts[j];
        ptb[1] = tpbrkpts.pts[j+1];
        qlist->downloadAll(pta, ptb, backend);
       
            num_u_steps = (int) (domain_distance_u_rate * (ptb[0]-pta[0]));
            num_v_steps = (int) (domain_distance_v_rate * (ptb[1]-pta[1]));

            if(num_u_steps <= 0) num_u_steps = 1;
            if(num_v_steps <= 0) num_v_steps = 1;

        backend.surfgrid(pta[0], ptb[0], num_u_steps, 
                 ptb[1], pta[1], num_v_steps);
        backend.surfmesh(0,0,num_u_steps,num_v_steps);

        

        continue;
        /* the following is left for reference purpose, don't delete
        {
        Bin* tempSource;    
          Patchlist patchlist(qlist, pta, ptb);
          patchlist.getstepsize();

          tempSource=makePatchBoundary(pta, ptb);

          tessellation(*tempSource, patchlist);

          render(*tempSource);
          delete tempSource;
        }
        */
      }
    }
      }
    else
      subdivideInS( initialbin );
#else

    subdivideInS( initialbin );
#endif

    backend.endsurf();

}

void
Subdivider::subdivideInS( Bin& source )
{
    if( renderhints.display_method == N_OUTLINE_PARAM ) {
    outline( source );
    freejarcs( source );
    } else {
    setArcTypeBezier();
    setNonDegenerate();
    splitInS( source, spbrkpts.start, spbrkpts.end );
    }
}


/*---------------------------------------------------------------------------
 * splitInS - split a patch and a bin by an isoparametric line
 *---------------------------------------------------------------------------
 */

void
Subdivider::splitInS( Bin& source, int start, int end )
{
    if( source.isnonempty() ) {
        if( start != end ) {
        int i = start + (end - start) / 2;
        Bin left, right;
        split( source, left, right, 0, spbrkpts.pts[i] );
        splitInS( left, start, i );
        splitInS( right, i+1, end );
        } else {
        if( start == spbrkpts.start || start == spbrkpts.end ) {
        freejarcs( source );
        } else if( renderhints.display_method == N_OUTLINE_PARAM_S ) {
        outline( source );
        freejarcs( source );
        } else {
        setArcTypeBezier();
        setNonDegenerate();
        s_index = start;
        splitInT( source, tpbrkpts.start, tpbrkpts.end );
        }
        }
    } 
}

/*---------------------------------------------------------------------------
 * splitInT - split a patch and a bin by an isoparametric line
 *---------------------------------------------------------------------------
 */

void
Subdivider::splitInT( Bin& source, int start, int end )
{
    if( source.isnonempty() ) {
        if( start != end ) {
        int i = start + (end - start) / 2;
        Bin left, right;
        split( source, left, right, 1, tpbrkpts.pts[i] );
        splitInT( left, start, i );
        splitInT( right, i+1, end );
        } else {
        if( start == tpbrkpts.start || start == tpbrkpts.end ) {
        freejarcs( source );
        } else if( renderhints.display_method == N_OUTLINE_PARAM_ST ) {
        outline( source );
        freejarcs( source );
        } else {
        t_index = start;
        setArcTypeBezier();
        setDegenerate();

        REAL pta[2], ptb[2];
        pta[0] = spbrkpts.pts[s_index-1];
        pta[1] = tpbrkpts.pts[t_index-1];

        ptb[0] = spbrkpts.pts[s_index];
        ptb[1] = tpbrkpts.pts[t_index];
        qlist->downloadAll( pta, ptb, backend );
        
        Patchlist patchlist( qlist, pta, ptb );
/*
printf("-------samplingSplit-----\n");
source.show("samplingSplit source");
*/
        samplingSplit( source, patchlist, renderhints.maxsubdivisions, 0 );
        setNonDegenerate();
        setArcTypeBezier();
        }
        }
    } 
}

/*--------------------------------------------------------------------------
 * samplingSplit - recursively subdivide patch, cull check each subpatch  
 *--------------------------------------------------------------------------
 */

void
Subdivider::samplingSplit( 
    Bin& source, 
    Patchlist& patchlist, 
    int subdivisions, 
    int param )
{
    if( ! source.isnonempty() ) return;

    if( patchlist.cullCheck() == CULL_TRIVIAL_REJECT ) {
    freejarcs( source );
    return;
    }

    patchlist.getstepsize();

    if( renderhints.display_method == N_OUTLINE_PATCH ) {
        tessellation( source, patchlist );
    outline( source );
    freejarcs( source );
    return;
    } 

    //patchlist.clamp();

    tessellation( source, patchlist );

    if( patchlist.needsSamplingSubdivision() && (subdivisions > 0) ) {
    if( ! patchlist.needsSubdivision( 0 ) )
        param = 1;
    else if( ! patchlist.needsSubdivision( 1 ) )
        param = 0;
    else
        param = 1 - param;

    Bin left, right;
    REAL mid = ( patchlist.pspec[param].range[0] +
             patchlist.pspec[param].range[1] ) * 0.5;
    split( source, left, right, param, mid );
    Patchlist subpatchlist( patchlist, param, mid );
    samplingSplit( left, subpatchlist, subdivisions-1, param );
    samplingSplit( right, patchlist, subdivisions-1, param );
    } else {
    setArcTypePwl();
    setDegenerate();
    nonSamplingSplit( source, patchlist, subdivisions, param );
    setDegenerate();
    setArcTypeBezier();
    }
}

void
Subdivider::nonSamplingSplit( 
    Bin& source, 
    Patchlist& patchlist, 
    int subdivisions, 
    int param )
{
    if( patchlist.needsNonSamplingSubdivision() && (subdivisions > 0) ) {
    param = 1 - param;

    Bin left, right;
    REAL mid = ( patchlist.pspec[param].range[0] +
             patchlist.pspec[param].range[1] ) * 0.5;
    split( source, left, right, param, mid );
    Patchlist subpatchlist( patchlist, param, mid );
    if( left.isnonempty() ) {
        if( subpatchlist.cullCheck() == CULL_TRIVIAL_REJECT ) 
        freejarcs( left );
        else
            nonSamplingSplit( left, subpatchlist, subdivisions-1, param );
    }
    if( right.isnonempty() )  {
        if( patchlist.cullCheck() == CULL_TRIVIAL_REJECT ) 
        freejarcs( right );
        else
            nonSamplingSplit( right, patchlist, subdivisions-1, param );
    }

    } else {
    // make bbox calls
    patchlist.bbox();
    backend.patch( patchlist.pspec[0].range[0], patchlist.pspec[0].range[1],
               patchlist.pspec[1].range[0], patchlist.pspec[1].range[1] );
    
    if( renderhints.display_method == N_OUTLINE_SUBDIV ) {
        outline( source );
        freejarcs( source );
    } else {
        setArcTypePwl();
        setDegenerate();
        findIrregularS( source );
        monosplitInS( source, smbrkpts.start, smbrkpts.end );
    }
    }
}

/*--------------------------------------------------------------------------
 * tessellation - set tessellation of interior and boundary of patch
 *--------------------------------------------------------------------------
 */

void
Subdivider::tessellation( Bin& bin, Patchlist &patchlist )
{
    // tessellate unsampled trim curves
    tessellate( bin, patchlist.pspec[1].sidestep[1], patchlist.pspec[0].sidestep[1],
     patchlist.pspec[1].sidestep[0], patchlist.pspec[0].sidestep[0] );

    // set interior sampling rates
    slicer.setstriptessellation( patchlist.pspec[0].stepsize, patchlist.pspec[1].stepsize );

    //added by zl: set the order which will be used in slicer.c++
    slicer.set_ulinear( (patchlist.get_uorder() == 2));
    slicer.set_vlinear( (patchlist.get_vorder() == 2));

    // set boundary sampling rates
    stepsizes[0] = patchlist.pspec[1].stepsize;
    stepsizes[1] = patchlist.pspec[0].stepsize;
    stepsizes[2] = patchlist.pspec[1].stepsize;
    stepsizes[3] = patchlist.pspec[0].stepsize;
}

/*---------------------------------------------------------------------------
 * monosplitInS - split a patch and a bin by an isoparametric line
 *---------------------------------------------------------------------------
 */

void
Subdivider::monosplitInS( Bin& source, int start, int end )
{
    if( source.isnonempty() ) {
        if( start != end ) {
        int i = start + (end - start) / 2;
        Bin left, right;
        split( source, left, right, 0, smbrkpts.pts[i] );
        monosplitInS( left, start, i );
        monosplitInS( right, i+1, end );
        } else {
        if( renderhints.display_method == N_OUTLINE_SUBDIV_S ) {
        outline( source );
        freejarcs( source );
        } else {
        setArcTypePwl();
        setDegenerate();
        findIrregularT( source );
        monosplitInT( source, tmbrkpts.start, tmbrkpts.end );
        }
        }
    } 
}

/*---------------------------------------------------------------------------
 * monosplitInT - split a patch and a bin by an isoparametric line
 *---------------------------------------------------------------------------
 */

void
Subdivider::monosplitInT( Bin& source, int start, int end )
{
    if( source.isnonempty() ) {
        if( start != end ) {
        int i = start + (end - start) / 2;
        Bin left, right;
        split( source, left, right, 1, tmbrkpts.pts[i] );
        monosplitInT( left, start, i );
        monosplitInT( right, i+1, end );
        } else {
        if( renderhints.display_method == N_OUTLINE_SUBDIV_ST ) {
        outline( source );
        freejarcs( source );
        } else {
/*
printf("*******render\n");
source.show("source\n");
*/
        render( source );
        freejarcs( source );
        }
        }
    } 
}


/*----------------------------------------------------------------------------
 * findIrregularS - determine points of non-monotonicity is s direction
 *----------------------------------------------------------------------------
 */

void
Subdivider::findIrregularS( Bin& bin )
{
    assert( bin.firstarc()->check() != 0 );

    smbrkpts.grow( bin.numarcs() );

    for( Arc_ptr jarc=bin.firstarc(); jarc; jarc=bin.nextarc() ) {
    REAL *a = jarc->prev->tail();
    REAL *b = jarc->tail();
    REAL *c = jarc->head();

    if( b[1] == a[1] && b[1] == c[1] ) continue;

    //corrected code
    if((b[1]<=a[1] && b[1] <= c[1]) ||
       (b[1]>=a[1] && b[1] >= c[1]))
      {
        //each arc (jarc, jarc->prev, jarc->next) is a 
        //monotone arc consisting of multiple line segements.
        //it may happen that jarc->prev and jarc->next are the same,
        //that is, jarc->prev and jarc form a closed loop.
        //In such case, a and c will be the same.
            if(a[0]==c[0] && a[1] == c[1])
          {
        if(jarc->pwlArc->npts >2)
          {
            c = jarc->pwlArc->pts[jarc->pwlArc->npts-2].param;
          }
        else
          {
            assert(jarc->prev->pwlArc->npts>2);
            a = jarc->prev->pwlArc->pts[jarc->prev->pwlArc->npts-2].param;
          }
            
          }
        if(area(a,b,c) < 0)
          {
        smbrkpts.add(b[0]);
          }

      }

    /* old code, 
    if( b[1] <= a[1] && b[1] <= c[1] ) {
        if( ! ccwTurn_tr( jarc->prev, jarc ) )
                smbrkpts.add( b[0] );
    } else if( b[1] >= a[1] && b[1] >= c[1] ) {
        if( ! ccwTurn_tl( jarc->prev, jarc ) )
                smbrkpts.add( b[0] );
        }
    */

    }

    smbrkpts.filter();
} 

/*----------------------------------------------------------------------------
 * findIrregularT - determine points of non-monotonicity in t direction
 *           where one arc is parallel to the s axis.
 *----------------------------------------------------------------------------
 */

void
Subdivider::findIrregularT( Bin& bin )
{
    assert( bin.firstarc()->check() != 0 );

    tmbrkpts.grow( bin.numarcs() );

    for( Arc_ptr jarc=bin.firstarc(); jarc; jarc=bin.nextarc() ) {
    REAL *a = jarc->prev->tail();
    REAL *b = jarc->tail();
    REAL *c = jarc->head();

    if( b[0] == a[0] && b[0] == c[0] ) continue;

    if( b[0] <= a[0] && b[0] <= c[0] ) {
        if( a[1] != b[1] && b[1] != c[1] ) continue; 
        if( ! ccwTurn_sr( jarc->prev, jarc ) )
                tmbrkpts.add( b[1] );
    } else if ( b[0] >= a[0] && b[0] >= c[0] ) {
        if( a[1] != b[1] && b[1] != c[1] ) continue; 
        if( ! ccwTurn_sl( jarc->prev, jarc ) )
                tmbrkpts.add( b[1] );
    }
    }
    tmbrkpts.filter( );
}

/*-----------------------------------------------------------------------------
 * makeBorderTrim - if no user input trimming data then create 
 * a trimming curve around the boundaries of the Quilt.  The curve consists of
 * four Jordan arcs, one for each side of the Quilt, connected, of course,
 * head to tail. 
 *-----------------------------------------------------------------------------
 */

void
Subdivider::makeBorderTrim( const REAL *from, const REAL *to )
{ 
    REAL smin = from[0];
    REAL smax = to[0];
    REAL tmin = from[1];
    REAL tmax = to[1];

    pjarc = 0;

    Arc_ptr jarc = new(arcpool) Arc( arc_bottom, 0 );
    arctessellator.bezier( jarc, smin, smax, tmin, tmin );
    initialbin.addarc( jarc  );
    pjarc = jarc->append( pjarc );

    jarc = new(arcpool) Arc( arc_right, 0 );
    arctessellator.bezier( jarc, smax, smax, tmin, tmax );
    initialbin.addarc( jarc  );
    pjarc = jarc->append( pjarc );

    jarc = new(arcpool) Arc( arc_top, 0 );
    arctessellator.bezier( jarc, smax, smin, tmax, tmax );
    initialbin.addarc( jarc  );
    pjarc = jarc->append( pjarc );

    jarc = new(arcpool) Arc( arc_left, 0 );
    arctessellator.bezier( jarc, smin, smin, tmax, tmin );
    initialbin.addarc( jarc  );
    jarc->append( pjarc );

    assert( jarc->check() != 0 );
}

/*----------------------------------------------------------------------------
 * render - renders all monotone regions in a bin and frees the bin
 *----------------------------------------------------------------------------
 */

void
Subdivider::render( Bin& bin )
{
    bin.markall();

#ifdef N_ISOLINE_S
    slicer.setisolines( ( renderhints.display_method == N_ISOLINE_S ) ? 1 : 0 );
#else
    slicer.setisolines( 0 );
#endif

    for( Arc_ptr jarc=bin.firstarc(); jarc; jarc=bin.nextarc() ) {
    if( jarc->ismarked() ) {
        assert( jarc->check( ) != 0 );
        Arc_ptr jarchead = jarc;
        do {
        jarc->clearmark();
        jarc = jarc->next;
        } while (jarc != jarchead);
        slicer.slice( jarc );
    }
    }
}

/*---------------------------------------------------------------------------
 * outline - render the trimmed patch by outlining the boundary 
 *---------------------------------------------------------------------------
 */

void
Subdivider::outline( Bin& bin )
{
    bin.markall();
    for( Arc_ptr jarc=bin.firstarc(); jarc; jarc=bin.nextarc() ) {
    if( jarc->ismarked() ) {
        assert( jarc->check( ) != 0 );
        Arc_ptr jarchead = jarc;
        do {
        slicer.outline( jarc );
        jarc->clearmark();
        jarc = jarc->prev;
        } while (jarc != jarchead);
    }
    }
}

/*---------------------------------------------------------------------------
 * freejarcs - free all arcs in a bin
 *---------------------------------------------------------------------------
 */

void
Subdivider::freejarcs( Bin& bin )
{
    bin.adopt();    /* XXX - should not be necessary */

    Arc_ptr jarc;
    while( (jarc = bin.removearc()) != NULL ) {
    if( jarc->pwlArc ) jarc->pwlArc->deleteMe( pwlarcpool ); jarc->pwlArc = 0;
    if( jarc->bezierArc) jarc->bezierArc->deleteMe( bezierarcpool ); jarc->bezierArc = 0;
    jarc->deleteMe( arcpool );
    }
}

/*----------------------------------------------------------------------------
 * tessellate - tessellate all Bezier arcs in a bin
 *         1) only accepts linear Bezier arcs as input 
 *         2) the Bezier arcs are stored in the pwlArc structure
 *         3) only vertical or horizontal lines work
 *      -- should 
 *         1) represent Bezier arcs in BezierArc structure
 *            (this requires a multitude of changes to the code)
 *         2) accept high degree Bezier arcs (hard)
 *         3) map the curve onto the surface to determine tessellation
 *         4) work for curves of arbitrary geometry
 *----------------------------------------------------------------------------
 */


void
Subdivider::tessellate( Bin& bin, REAL rrate, REAL trate, REAL lrate, REAL brate )
{
    for( Arc_ptr jarc=bin.firstarc(); jarc; jarc=bin.nextarc() ) {
    if( jarc->isbezier( ) ) {
            assert( jarc->pwlArc->npts == 2 );  
        TrimVertex  *pts = jarc->pwlArc->pts;
            REAL s1 = pts[0].param[0];
            REAL t1 = pts[0].param[1];
            REAL s2 = pts[1].param[0];
            REAL t2 = pts[1].param[1];
        
            jarc->pwlArc->deleteMe( pwlarcpool ); jarc->pwlArc = 0;
        
        switch( jarc->getside() ) {
        case arc_left:
            assert( s1 == s2 );
            arctessellator.pwl_left( jarc, s1, t1, t2, lrate );
            break;
        case arc_right:
            assert( s1 == s2 );
            arctessellator.pwl_right( jarc, s1, t1, t2, rrate );
            break;
        case arc_top:
            assert( t1 == t2 );
            arctessellator.pwl_top( jarc, t1, s1, s2, trate );
            break;
        case arc_bottom:
            assert( t1 == t2 );
            arctessellator.pwl_bottom( jarc, t1, s1, s2, brate );
            break;
        case arc_none:
            (void) abort();
            break;
        }
        assert( ! jarc->isbezier() );
            assert( jarc->check() != 0 );
    }
    }
}