/* ** 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++ * * $Date: 2001/03/17 00:25:41 $ $Revision: 1.1 $ * $Header: /home/krh/git/sync/mesa-cvs-repo/Mesa/src/glu/sgi/libnurbs/internals/monotonizer.cc,v 1.1 2001/03/17 00:25:41 brianp Exp $ */ #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; }