trimline.cc

/*
** 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.
*/

/*
 * trimline.c++
 *
 */

#include "glimports.h"
#include "myassert.h"
#include "mystdio.h"
#include "trimline.h"
#include "backend.h"

Trimline::Trimline()
{
    size = 0; pts = 0; numverts = 0;
    tinterp = &t; binterp = &b; 
}

Trimline::~Trimline()
{
    if( pts ) delete[] pts; 
}

void 
Trimline::init( TrimVertex *v )
{
    reset();
    grow(1);
    append(v);
}

inline void
Trimline::grow( long npts )
{
    if( size < npts ) {
        size = 2 * npts;
        if( pts ) delete[] pts; 
        pts = new TrimVertex_p[size];
    }
}

inline void
Trimline::append( TrimVertex *v )
{
    assert( numverts != size ); 
    pts[numverts++] = v;
}

void
Trimline::init( long npts, Arc_ptr jarc, long last )
{
    jarcl.init( jarc, 0, last );
    grow( npts + 2 );
}

inline void
Trimline::swap()
{
    TrimVertex *tmp=tinterp; 
    tinterp=binterp; 
    binterp=tmp;
}

void
Trimline::getNextPt()
{
    *binterp = *jarcl.getnextpt();    
}

void 
Trimline::getPrevPt()
{
    *binterp = *jarcl.getprevpt();
}

/*----------------------------------------------------------------------
 * getNextPts - make arrays of pointers to trim points on left and right
 *              hulls of trim strip.
 *----------------------------------------------------------------------
 */
void
Trimline::getNextPts( REAL vval, Backend& backend )
{
    reset(); swap(); append( tinterp );
    assert( tinterp->param[1] >= vval );

    register TrimVertex *p;
    for( p=jarcl.getnextpt() ; p->param[1] >= vval; p=jarcl.getnextpt() ) {
        append( p ); 
    }

    /* compute and copy pointer to final point on left hull */
    if( interpvert( last(), p, binterp, vval ) ) {
        binterp->nuid = p->nuid;
        backend.triangle( p, binterp, last() );
        append( binterp );
    }
    jarcl.reverse();
    (void) jarcl.getprevpt();   /* reset jarcl to proper position */
    jarcl.reverse();
}

void 
Trimline::getPrevPts( REAL vval, Backend& backend )
{
    reset(); swap(); append( tinterp );
    assert( tinterp->param[1] >= vval );

    register TrimVertex *q;
    for( q=jarcl.getprevpt(); q->param[1] >= vval; q=jarcl.getprevpt() ) {
        append( q );
    }

    /* compute and copy pointer to final point on right hull */
    if( interpvert( q, last(), binterp, vval ) ) {
        binterp->nuid = q->nuid;
        backend.triangle( last(), binterp, q );
        append( binterp );
    }
    jarcl.reverse();
    (void) jarcl.getnextpt();  /* reset jarcl to proper position */
    jarcl.reverse();
}

void
Trimline::getNextPts( Arc_ptr botarc )
{
    reset(); swap(); append( tinterp );

#ifndef NDEBUG
    PwlArc *lastpwl = botarc->prev->pwlArc;
    TrimVertex *lastpt1 = &lastpwl->pts[lastpwl->npts-1];
#endif
    TrimVertex *lastpt2 = botarc->pwlArc->pts;
    register TrimVertex *p = jarcl.getnextpt();
    for( append( p ); p != lastpt2; append( p ) ) {
        assert( p != lastpt1 );
        p = jarcl.getnextpt();
    }
}

void
Trimline::getPrevPts( Arc_ptr botarc )
{
    reset();  swap(); append( tinterp );

    PwlArc *lastpwl = botarc->prev->pwlArc;
    TrimVertex *lastpt1 = &lastpwl->pts[lastpwl->npts-1];
#ifndef NDEBUG
    TrimVertex *lastpt2 = botarc->pwlArc->pts;
#endif

    register TrimVertex *q =  jarcl.getprevpt();
    for( append( q ); q != lastpt1; append( q ) ) {
        assert( q != lastpt2 );
        q = jarcl.getprevpt();
    }
}


long
Trimline::interpvert( TrimVertex *a, TrimVertex *b, TrimVertex *c, REAL vval )
{
    REAL denom = a->param[1] - b->param[1];

    if(denom != 0) {
        if( vval == a->param[1] ) {
            c->param[0] = a->param[0]; 
            c->param[1] = a->param[1];
            c->nuid = a->nuid;
            return 0;
        } else if( vval == b->param[1] ) {
            c->param[0] = b->param[0]; 
            c->param[1] = b->param[1];
            c->nuid = b->nuid;
            return 0;
        } else {
            REAL r = (a->param[1] - vval)/denom;
            c->param[0] =  a->param[0] - r * (a->param[0] - b->param[0]);
            c->param[1] = vval;
            return 1;
        }
    } else {
        c->param[0] = a->param[0]; 
        c->param[1] = a->param[1];
        c->nuid = a->nuid;
        return 0;
    }
}