src/glu/sgi/libnurbs/internals/varray.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  * varray.c++
  37  *
  38  */
  39
  40 #include "glimports.h"
  41 #include "myassert.h"
  42 #include "mystdio.h"
  43 #include "varray.h"
  44 #include "arc.h"
  45 #include "simplemath.h"         // glu_abs()
  46
  47 #define TINY 0.0001
  48 inline long sgn( REAL x )
  49 {
  50     return (x < -TINY) ? -1 :  ((x > TINY) ? 1 : 0 );
  51 }
  52
  53
  54 Varray::Varray( void )
  55 {
  56     varray = 0;
  57     size = 0;
  58 }
  59
  60 Varray::~Varray( void )
  61 {
  62     if( varray ) delete[] varray;
  63 }
  64
  65 inline void
  66 Varray::update( Arc_ptr arc, long dir[2], REAL val )
  67 {
  68     register long ds = sgn(arc->tail()[0] - arc->prev->tail()[0]);
  69     register long dt = sgn(arc->tail()[1] - arc->prev->tail()[1]);
  70
  71     if( dir[0] != ds || dir[1] != dt ) {
  72         dir[0] = ds;
  73         dir[1] = dt;
  74         append( val );
  75     }
  76 }
  77
  78 void
  79 Varray::grow( long guess )
  80 {
  81     if( size < guess ) {
  82         size = guess * 2;
  83         if( varray ) delete[] varray;
  84         varray = new REAL[size];
  85         assert( varray != 0 );
  86     }
  87 }
  88
  89 long
  90 Varray::init( REAL delta, Arc_ptr toparc, Arc_ptr botarc )
  91 {
  92     Arc_ptr left = toparc->next;
  93     Arc_ptr right = toparc;
  94     long ldir[2], rdir[2];
  95
  96     ldir[0] = sgn( left->tail()[0] - left->prev->tail()[0] );
  97     ldir[1] = sgn( left->tail()[1] - left->prev->tail()[1] );
  98     rdir[0] = sgn( right->tail()[0] - right->prev->tail()[0] );
  99     rdir[1] = sgn( right->tail()[1] - right->prev->tail()[1] );
 100
 101     vval[0] = toparc->tail()[1];
 102     numquads = 0;
 103
 104     while( 1 ) {
 105         switch( sgn( left->tail()[1] - right->prev->tail()[1] ) ) {
 106         case 1:
 107             left = left->next;
 108             update( left, ldir, left->prev->tail()[1] );
 109             break;
 110         case -1:
 111             right = right->prev;
 112             update( right, rdir, right->tail()[1] );
 113             break;
 114         case 0:
 115             if( glu_abs(left->tail()[1] - botarc->tail()[1]) < TINY) goto end;
 116             if( glu_abs(left->tail()[0]-right->prev->tail()[0]) < TINY &&
 117                 glu_abs(left->tail()[1]-right->prev->tail()[1]) < TINY) goto end;
 118             left = left->next;
 119             break;
 120         }
 121     }
 122
 123 end:
 124     append( botarc->tail()[1] );
 125
 126     grow( ((long) ((vval[0] - vval[numquads])/delta)) + numquads + 2 );
 127
 128     long i, index = 0;
 129     for( i=0; i<numquads; i++ ) {
 130         voffset[i] = index;
 131         varray[index++] = vval[i];
 132         REAL dist = vval[i] - vval[i+1];
 133         if( dist > delta ) {
 134             long steps = ((long) (dist/delta)) +1;
 135             float deltav = - dist / (REAL) steps;
 136             for( long j=1; j<steps; j++ )
 137                 varray[index++] = vval[i] + j * deltav;
 138         }
 139     }
 140     voffset[i] = index;
 141     varray[index] = vval[i];
 142     return index;
 143 }
 144