dll/opengl/glu32/src/libnurbs/internals/monotonizer.cc

   1 /*
   2 ** License Applicability. Except to the extent portions of this file are
   3 ** made subject to an alternative license as permitted in the SGI Free
   4 ** Software License B, Version 1.1 (the "License"), the contents of this
   5 ** file are subject only to the provisions of the License. You may not use
   6 ** this file except in compliance with the License. You may obtain a copy
   7 ** of the License at Silicon Graphics, Inc., attn: Legal Services, 1600
   8 ** Amphitheatre Parkway, Mountain View, CA 94043-1351, or at:
   9 **
  10 ** http://oss.sgi.com/projects/FreeB
  11 **
  12 ** Note that, as provided in the License, the Software is distributed on an
  13 ** "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS
  14 ** DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND
  15 ** CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A
  16 ** PARTICULAR PURPOSE, AND NON-INFRINGEMENT.
  17 **
  18 ** Original Code. The Original Code is: OpenGL Sample Implementation,
  19 ** Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
  20 ** Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
  21 ** Copyright in any portions created by third parties is as indicated
  22 ** elsewhere herein. All Rights Reserved.
  23 **
  24 ** Additional Notice Provisions: The application programming interfaces
  25 ** established by SGI in conjunction with the Original Code are The
  26 ** OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
  27 ** April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
  28 ** 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
  29 ** Window System(R) (Version 1.3), released October 19, 1998. This software
  30 ** was created using the OpenGL(R) version 1.2.1 Sample Implementation
  31 ** published by SGI, but has not been independently verified as being
  32 ** compliant with the OpenGL(R) version 1.2.1 Specification.
  33 */
  34
  35 /*
  36  * monotonizer.c++
  37  *
  38  */
  39
  40 //#include "glimports.h"
  41 //#include "mystdio.h"
  42 //#include "myassert.h"
  43 #include "arc.h"
  44 //#include "arctess.h"
  45 #include "bezierarc.h"
  46 //#include "bin.h"
  47 #include "mapdesc.h"
  48 //#include "nurbsconsts.h"
  49 #include "subdivider.h"
  50
  51 /*-----------------------------------------------------------------------------
  52  * Subdivider::decompose - break all curves into monotone arcs
  53  *-----------------------------------------------------------------------------
  54  */
  55 int
  56 Subdivider::decompose( Bin& bin, REAL geo_stepsize )
  57 {
  58     Arc_ptr jarc;
  59     for( jarc=bin.firstarc(); jarc; jarc=bin.nextarc() ) {
  60         if( ! jarc->isTessellated() ) {
  61             /* points have not been transformed, therefore they may be either
  62                homogeneous or inhomogeneous */
  63             tessellate( jarc, geo_stepsize );
  64             if( jarc->isDisconnected() || jarc->next->isDisconnected() )
  65                 return 1;
  66         }
  67     }
  68
  69     for( jarc=bin.firstarc(); jarc; jarc=bin.nextarc() ) {
  70         monotonize( jarc, bin );
  71     }
  72
  73 #ifndef NDEBUG
  74     for( jarc=bin.firstarc(); jarc; jarc=bin.nextarc() ) {
  75         assert( isMonotone( jarc ) != 0 );
  76     }
  77 #endif
  78
  79     return 0;
  80 }
  81
  82 void
  83 Subdivider::tessellate( Arc_ptr jarc, REAL geo_stepsize )
  84 {
  85     BezierArc *b = jarc->bezierArc;
  86     Mapdesc *mapdesc = b->mapdesc;
  87
  88     if( mapdesc->isRational() ) {
  89         REAL max = mapdesc->calcVelocityRational( b->cpts, b->stride, b->order );
  90         REAL arc_stepsize = (max > 1.0) ? (1.0/max) : 1.0;
  91         if( jarc->bezierArc->order != 2 )
  92             arctessellator.tessellateNonlinear( jarc, geo_stepsize, arc_stepsize, 1 );
  93         else {
  94             arctessellator.tessellateLinear( jarc, geo_stepsize, arc_stepsize, 1 );
  95         }
  96     } else {
  97         REAL max = mapdesc->calcVelocityNonrational( b->cpts, b->stride, b->order );
  98         REAL arc_stepsize = (max > 1.0) ? (1.0/max) : 1.0;
  99         if( jarc->bezierArc->order != 2 )
 100             arctessellator.tessellateNonlinear( jarc, geo_stepsize, arc_stepsize, 0 );
 101         else {
 102             arctessellator.tessellateLinear( jarc, geo_stepsize, arc_stepsize, 0 );
 103         }
 104     }
 105 }
 106
 107 /*-------------------------------------------------------------------------
 108  * Subdivider::monotonize - break up a jordan arc into s,t-monotone
 109  *      components.  This code will remove degenerate segments, including
 110  *      arcs of only a single point.
 111  *-------------------------------------------------------------------------
 112  */
 113 void
 114 Subdivider::monotonize( Arc_ptr jarc, Bin& bin )
 115 {
 116     TrimVertex  *firstvert = jarc->pwlArc->pts;
 117     TrimVertex  *lastvert = firstvert + (jarc->pwlArc->npts - 1);
 118     long        uid = jarc->nuid;
 119     arc_side    side = jarc->getside();
 120     dir         sdir = none;
 121     dir         tdir = none;
 122     int         degenerate = 1;
 123
 124     int         nudegenerate;
 125     int         change;
 126
 127     TrimVertex *vert;
 128     for( vert = firstvert; vert != lastvert; vert++ ) {
 129
 130         nudegenerate = 1;
 131         change = 0;
 132
 133         /* check change relative to s axis, clear degenerate bit if needed */
 134         REAL sdiff = vert[1].param[0] - vert[0].param[0];
 135         if( sdiff == 0 ) {
 136             if( sdir != same ) {
 137                 sdir = same;
 138                 change = 1;
 139             }
 140         } else if( sdiff < 0.0 ) {
 141             if( sdir != down ) {
 142                 sdir = down;
 143                 change = 1;
 144             }
 145             nudegenerate = 0;
 146         } else {
 147             if( sdir != up ) {
 148                 sdir = up;
 149                 change = 1;
 150             }
 151             nudegenerate = 0;
 152         }
 153
 154         /* check change relative to t axis, clear degenerate bit if needed */
 155         REAL tdiff = vert[1].param[1] - vert[0].param[1];
 156         if( tdiff == 0 ) {
 157             if( tdir != same ) {
 158                 tdir = same;
 159                 change = 1;
 160             }
 161         } else if( tdiff < 0.0 ) {
 162             if( tdir != down ) {
 163                 tdir = down;
 164                 change = 1;
 165             }
 166             nudegenerate = 0;
 167         } else {
 168             if( tdir != up ) {
 169                 tdir = up;
 170                 change = 1;
 171             }
 172             nudegenerate = 0;
 173         }
 174
 175         if( change ) {
 176             if( ! degenerate ) {
 177                 /* make last segment into separate pwl curve */
 178                 jarc->pwlArc->npts = vert - firstvert + 1;
 179                 jarc = (new(arcpool) Arc( side, uid ))->append( jarc );
 180                 jarc->pwlArc = new(pwlarcpool) PwlArc();
 181                 bin.addarc( jarc );
 182             }
 183             firstvert = jarc->pwlArc->pts = vert;
 184             degenerate = nudegenerate;
 185         }
 186     }
 187     jarc->pwlArc->npts = vert - firstvert + 1;
 188
 189     if( degenerate ) {
 190         /* remove jarc from circularly linked list */
 191         jarc->prev->next = jarc->next;
 192         jarc->next->prev = jarc->prev;
 193
 194         assert( jarc->prev->check(  ) != 0 );
 195         assert( jarc->next->check(  ) != 0 );
 196
 197         /* remove jarc from bin */
 198         bin.remove_this_arc( jarc  );
 199
 200         jarc->pwlArc->deleteMe( pwlarcpool ); jarc->pwlArc = 0;
 201         jarc->deleteMe( arcpool );
 202     }
 203 }
 204
 205 /*-------------------------------------------------------------------------
 206  * Subdivider::isMonotone - return true if arc is monotone AND non-degenerate
 207  *-------------------------------------------------------------------------
 208  */
 209 int
 210 Subdivider::isMonotone( Arc_ptr jarc )
 211 {
 212     TrimVertex  *firstvert = jarc->pwlArc->pts;
 213     TrimVertex  *lastvert = firstvert + (jarc->pwlArc->npts - 1);
 214
 215     if( firstvert == lastvert ) return 1;
 216
 217     TrimVertex  *vert = firstvert;
 218     enum dir    sdir;
 219     enum dir    tdir;
 220
 221     REAL diff = vert[1].param[0] - vert[0].param[0];
 222     if( diff == 0.0 )
 223         sdir = same;
 224     else if( diff < 0.0 )
 225         sdir = down;
 226     else
 227         sdir = up;
 228
 229     diff = vert[1].param[1] - vert[0].param[1];
 230     if( diff == 0.0 )
 231         tdir = same;
 232     else if( diff < 0.0 )
 233         tdir = down;
 234     else
 235         tdir = up;
 236
 237     if( (sdir == same) && (tdir == same) ) return 0;
 238
 239     for( ++vert ; vert != lastvert; vert++ ) {
 240         diff = vert[1].param[0] - vert[0].param[0];
 241         if( diff == 0.0 ) {
 242             if( sdir != same ) return 0;
 243         } else if( diff < 0.0 ) {
 244             if( sdir != down ) return 0;
 245         } else {
 246             if( sdir != up ) return 0;
 247         }
 248
 249         diff = vert[1].param[1] - vert[0].param[1];
 250         if( diff == 0.0 ) {
 251             if( tdir != same ) return 0;
 252         } else if( diff < 0.0 ) {
 253             if( tdir != down ) return 0;
 254         } else {
 255             if( tdir != up ) return 0;
 256         }
 257     }
 258     return 1;
 259 }
 260