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 } 260 261