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/*
** 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.
*/
/*
* monotonizer.c++
*
*/
#include "glimports.h"
#include "mystdio.h"
#include "myassert.h"
#include "arc.h"
#include "arctess.h"
#include "bezierarc.h"
#include "bin.h"
#include "mapdesc.h"
#include "nurbsconsts.h"
#include "subdivider.h"
/*-----------------------------------------------------------------------------
* Subdivider::decompose - break all curves into monotone arcs
*-----------------------------------------------------------------------------
*/
int
Subdivider::decompose( Bin& bin, REAL geo_stepsize )
{
Arc_ptr jarc;
for( jarc=bin.firstarc(); jarc; jarc=bin.nextarc() ) {
if( ! jarc->isTessellated() ) {
/* points have not been transformed, therefore they may be either
homogeneous or inhomogeneous */
tessellate( jarc, geo_stepsize );
if( jarc->isDisconnected() || jarc->next->isDisconnected() )
return 1;
}
}
for( jarc=bin.firstarc(); jarc; jarc=bin.nextarc() ) {
monotonize( jarc, bin );
}
#ifndef NDEBUG
for( jarc=bin.firstarc(); jarc; jarc=bin.nextarc() ) {
assert( isMonotone( jarc ) != 0 );
}
#endif
return 0;
}
void
Subdivider::tessellate( Arc_ptr jarc, REAL geo_stepsize )
{
BezierArc *b = jarc->bezierArc;
Mapdesc *mapdesc = b->mapdesc;
if( mapdesc->isRational() ) {
REAL max = mapdesc->calcVelocityRational( b->cpts, b->stride, b->order );
REAL arc_stepsize = (max > 1.0) ? (1.0/max) : 1.0;
if( jarc->bezierArc->order != 2 )
arctessellator.tessellateNonlinear( jarc, geo_stepsize, arc_stepsize, 1 );
else {
arctessellator.tessellateLinear( jarc, geo_stepsize, arc_stepsize, 1 );
}
} else {
REAL max = mapdesc->calcVelocityNonrational( b->cpts, b->stride, b->order );
REAL arc_stepsize = (max > 1.0) ? (1.0/max) : 1.0;
if( jarc->bezierArc->order != 2 )
arctessellator.tessellateNonlinear( jarc, geo_stepsize, arc_stepsize, 0 );
else {
arctessellator.tessellateLinear( jarc, geo_stepsize, arc_stepsize, 0 );
}
}
}
/*-------------------------------------------------------------------------
* Subdivider::monotonize - break up a jordan arc into s,t-monotone
* components. This code will remove degenerate segments, including
* arcs of only a single point.
*-------------------------------------------------------------------------
*/
void
Subdivider::monotonize( Arc_ptr jarc, Bin& bin )
{
TrimVertex *firstvert = jarc->pwlArc->pts;
TrimVertex *lastvert = firstvert + (jarc->pwlArc->npts - 1);
long uid = jarc->nuid;
arc_side side = jarc->getside();
dir sdir = none;
dir tdir = none;
int degenerate = 1;
int nudegenerate;
int change;
TrimVertex *vert;
for( vert = firstvert; vert != lastvert; vert++ ) {
nudegenerate = 1;
change = 0;
/* check change relative to s axis, clear degenerate bit if needed */
REAL sdiff = vert[1].param[0] - vert[0].param[0];
if( sdiff == 0 ) {
if( sdir != same ) {
sdir = same;
change = 1;
}
} else if( sdiff < 0.0 ) {
if( sdir != down ) {
sdir = down;
change = 1;
}
nudegenerate = 0;
} else {
if( sdir != up ) {
sdir = up;
change = 1;
}
nudegenerate = 0;
}
/* check change relative to t axis, clear degenerate bit if needed */
REAL tdiff = vert[1].param[1] - vert[0].param[1];
if( tdiff == 0 ) {
if( tdir != same ) {
tdir = same;
change = 1;
}
} else if( tdiff < 0.0 ) {
if( tdir != down ) {
tdir = down;
change = 1;
}
nudegenerate = 0;
} else {
if( tdir != up ) {
tdir = up;
change = 1;
}
nudegenerate = 0;
}
if( change ) {
if( ! degenerate ) {
/* make last segment into separate pwl curve */
jarc->pwlArc->npts = vert - firstvert + 1;
jarc = (new(arcpool) Arc( side, uid ))->append( jarc );
jarc->pwlArc = new(pwlarcpool) PwlArc();
bin.addarc( jarc );
}
firstvert = jarc->pwlArc->pts = vert;
degenerate = nudegenerate;
}
}
jarc->pwlArc->npts = vert - firstvert + 1;
if( degenerate ) {
/* remove jarc from circularly linked list */
jarc->prev->next = jarc->next;
jarc->next->prev = jarc->prev;
assert( jarc->prev->check( ) != 0 );
assert( jarc->next->check( ) != 0 );
/* remove jarc from bin */
bin.remove_this_arc( jarc );
jarc->pwlArc->deleteMe( pwlarcpool ); jarc->pwlArc = 0;
jarc->deleteMe( arcpool );
}
}
/*-------------------------------------------------------------------------
* Subdivider::isMonotone - return true if arc is monotone AND non-degenerate
*-------------------------------------------------------------------------
*/
int
Subdivider::isMonotone( Arc_ptr jarc )
{
TrimVertex *firstvert = jarc->pwlArc->pts;
TrimVertex *lastvert = firstvert + (jarc->pwlArc->npts - 1);
if( firstvert == lastvert ) return 1;
TrimVertex *vert = firstvert;
enum dir sdir;
enum dir tdir;
REAL diff = vert[1].param[0] - vert[0].param[0];
if( diff == 0.0 )
sdir = same;
else if( diff < 0.0 )
sdir = down;
else
sdir = up;
diff = vert[1].param[1] - vert[0].param[1];
if( diff == 0.0 )
tdir = same;
else if( diff < 0.0 )
tdir = down;
else
tdir = up;
if( (sdir == same) && (tdir == same) ) return 0;
for( ++vert ; vert != lastvert; vert++ ) {
diff = vert[1].param[0] - vert[0].param[0];
if( diff == 0.0 ) {
if( sdir != same ) return 0;
} else if( diff < 0.0 ) {
if( sdir != down ) return 0;
} else {
if( sdir != up ) return 0;
}
diff = vert[1].param[1] - vert[0].param[1];
if( diff == 0.0 ) {
if( tdir != same ) return 0;
} else if( diff < 0.0 ) {
if( tdir != down ) return 0;
} else {
if( tdir != up ) return 0;
}
}
return 1;
}
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